Introduction to the Introduction to the Medical Biology. Medical Biology.
Structural and functional Structural and functional organization of cells and organization of cells and
viruses.viruses.
LectorLector: : professor Fedonyuk L.Ya.professor Fedonyuk L.Ya.
Questions for discussion: General and medical Biology as the sciences. Levels of living organization. Characteristics of living things. The cell theory in its modern form. Cellular level of life organization: -prokaryotic and eukaryotic cells -the differences between plant and animal cells. The main components of eukaryotic cell.1. Cell membrane (plasmalemma)
2. Cytoplasm (organelles and inclusions)
3. Nucleus
Biology literally means
"the study of life".
Biology is such a broad field, covering the minute workings of chemical machines inside our cells, to broad scale concepts of ecosystems and global climate change.
Biologists study intimate details of the human brain, the composition of our genes, and even the functioning of our reproductive system.
Biologists recently all but completed the deciphering of the human genome, the sequence of deoxyribonucleic acid (DNA) bases that may determine much of our innate capabilities and predispositions to certain forms of behavior and illnesses.
DNA sequences have played major roles in criminal cases (OJ. Simpson, as well as the reversal of death penalties for many wrongfully convicted individuals), as well as the impeachment of President Clinton (the stain at least did not lie). We are bombarded with headlines about possible health risks from favorite foods (Chinese, Mexican, hamburgers, etc.) as well as the potential benefits of eating other foods such as cooked tomatoes. Infomercials tout the benefits of metabolism-adjusting drugs for weight loss.
Modern biology is based on several great ideas, or theories:
1.The Cell Theory
2.The Theory of Evolution
3.Gene Theory
4.Homeostasis
Levels of living organization
Biosphere Ecosystem Community Populations Individuals Organ System Organ Tissue Cell Organelle Molecule
LEVELS OF LIVING LEVELS OF LIVING ORGANIZATIONORGANIZATION
MICROSYSTEMSMICROSYSTEMS
molecularmolecular((sizesize - ≤ 1 - ≤ 1 nmnm))
subcellularsubcellular((sizesize - 1 - 1 nmnm – 100 – 100 nmnm))
cellularcellular((sizesize – 0,2 – 20 – 0,2 – 20 mkmmkm))
MESOSYSTEMSMESOSYSTEMS
TissueTissue((sizesize – 10-100 – 10-100 mkmmkm))
OrganOrgan((sizesize - 0,1 - 0,1 mm and moremm and more))
OrganismOrganism((sizesize – – 1 sm1 sm and moreand more))
MACROSYSTEMMACROSYSTEM
• Community Community
•EcosysteEcosystemm
•BiosphereBiosphere
Levels of living organization
Biosphere Ecosystem Community Populations Individuals Organ System Organ
Tissue Cell Organelle Molecule
Levels of living organization
Biosphere Ecosystem Community Populations Individuals Organ System Organ Tissue Cell Organelle Molecule
Population level
Community level (I) A community is the set of all populations that inhabit
a certain area. Communities can have different sizes and boundaries. These are often identified with some difficulty.
An ecosystem is a higher level of organization the community plus its physical environment. Ecosystems include both the biological and physical components affecting the community/ecosystem. We can study ecosystems from a structural view of population distribution or from a functional view of energy flow and other processes.
Community level (II) There are two basic
categories of communities: terrestrial (land) and aquatic (water). These two basic types of community contain eight smaller units known as biomes. A biome is a large-scale category containing many communities of a similar nature, whose distribution is largely controlled by climate
Terrestrial Biomes: tundra, grassland, desert, taiga, temperate forest, tropical forest.
Aquatic Biomes: marine, freshwater
Biosphere The sum of all living things
taken in conjunction with their environment. In essence, where life occurs, from the upper reaches of the atmosphere to the top few meters of soil, to the bottoms of the oceans. We divide the earth into atmosphere (air), lithosphere (earth), hydrosphere (water),
and biosphere (life)
Levels of the living organizationLevels of the living organization
MAIN METHODS OF MAIN METHODS OF SCIENTIFIC SCIENTIFIC
INVESTIGATIONINVESTIGATION• light microscopy;light microscopy;• lectron microscopylectron microscopy;;
Steps in the scientific method commonly include: 1. Observation: defining the problem
you wish to explain. 2. Hypothesis: one or more falsifiable
explanations for the observation. 3. Experimentation: Controlled
attempts to test one or more hypotheses.
4. Conclusion: was the hypothesis supported or not? After this step the hypothesis is either modified or rejected, which causes a repeat of the steps above.
ROBERT HOOKEROBERT HOOKE microscope microscope
ANTON VAN LEEUWENHOEK microscope
CharacteristicsCharacteristics of living things of living things
use energyuse energy – have a – have a metabolismmetabolism - the building up and breaking down of - the building up and breaking down of chemicals chemicals
grow and developgrow and develop become larger and more complex respond to their surroundingbecome larger and more complex respond to their surrounding
reproducereproduce- produce offspring that are similar to the parents - produce offspring that are similar to the parents have the chemicals of lifehave the chemicals of life, carbohydrates, proteins, lipids and nucleic acids , carbohydrates, proteins, lipids and nucleic acids
(genetic material) (genetic material) have cellshave cells
The The fundamental characteristics of living thingsfundamental characteristics of living things:: reproductionreproduction ((self-reproductionself-reproduction)), which is the process that gives rise to , which is the process that gives rise to
offspring; offspring; genesgenes ((self-renewalself-renewal) are the units of inheritance, passed prom parent to ) are the units of inheritance, passed prom parent to
offspring, that control many daily functions. offspring, that control many daily functions. Finally, Finally, populationpopulationss of living organisms adjust to environment variations through of living organisms adjust to environment variations through
evolution,evolution, a change in the traits of a species over time a change in the traits of a species over time ((self-regulationself-regulation))..
CELLULAR LEVEL OF LIVING CELLULAR LEVEL OF LIVING ORGANIZATIONORGANIZATION
no cellular living forms - viruses
CLASSIFICATION OF CELLSCLASSIFICATION OF CELLS1. According to the cell’s nucleus presence:- Prokariotic - Eukaroitic
2. According to the nature:- Plant cells- Animal cells
3. According to the type:- Somatic cells- Sex cells
cellular living forms - cells
Kingdoms of living organisms
Monera
Monera, the most primitive kingdom, contain living organisms remarkably similar to ancient fossils. Organisms in this group lack membrane-bound organelles associated with higher forms of life. Such organisms are known as prokaryotes. Bacteria (technically the Eubacteria) and blue-green bacteria (sometimes called blue-green algae, or cyanobacteria) are the major forms of life in this kingdom. The most primitive group, the archaebacteria, are today restricted to marginal habitats such as hot springs or areas of low oxygen concentration.
ProtistaProtista were the first of the
eukaryotic kingdoms, these organisms
and all others have membrane-bound
organelles, which allow for
compartmentalization and dedication of
specific areas for specific functions. The
chief importance of Protista is their role
as a stem group for the remaining
Kingdoms: Plants, Animals, and Fungi.
Major groups within the Protista include
the algae, euglenoids, ciliates, protozoa,
and flagellates.
FungiFungi are almost entirely multicellular
(with yeast, Saccharomyces cerviseae, being a
prominent unicellular fungus), heterotrophic
(deriving their energy from another organism,
whether alive or dead), and usually having
some cells with two nuclei (multinucleate, as
opposed to the more common one, or
uninucleate) per cell. Ecologically this kingdom
is important (along with certain bacteria) as
decomposers and recyclers of nutrients.
Economically, the Fungi provide us with food
(mushrooms; Bleu cheese/Roquefort cheese;
baking and brewing), antibiotics (the first of the
wonder drugs, Penicillin, was isolated from a
fungus Penicillium), and crop parasites (doing
several billion dollars per year of damage).
Plantae Plantae include multicelled
organisms that are all autotrophic (capable
of making their own food by the process of
photosynthesis, the conversion of sunlight
energy into chemical energy). Ecologically,
this kingdom is generally (along with
photosynthetic organisms in Monera and
Protista) termed the producers, and rest at
the base of all food webs. A food web is an
ecological concept to trace energy flow
through an ecosystem. Economically, this
kingdom is unparalleled, with agriculture
providing billions of dollars to the economy
(as well as the foundation of "civilization").
Food, building materials, paper, drugs (both
legal and illegal), and roses, are plants or
plant-derived products.
Animalia
Animalia consists entirely of multicelluar heterotrophs that are all capable (at some point during their life history) of mobility. Ecologically, this kingdom occupies the level of consumers, which can be subdivided into herbivore (eaters of plants) and carnivores (eaters of other animals). Humans, along with some other organisms, are omnivores (capable of functioning as herbivores or carnivores). Economically, animals provide meat, hides, beasts of burden, pleasure (pets), transportation, and scents (as used in some perfumes).
Cell theory ROBERT HOOKE- first (1665) looked at a slice
of dried cork. He noticed that plant tissues are made up of small, regulatory cavities surrounded by walls. Hooke called this “cell”.
ANTON VAN LEEUWENHOEK – made his own lenses made first compound microscope drew pictures that we can still identify today
SCHLEIDEN – concluded all plants are made of cells
TEODOR SCHWANN – concluded all living things are made up of cells. The first strong statement that “all living organisms consist of cell” was made by him in 1839.
In 1858 Rudolf Virchov suggested that “all cells come from pre-existing cells”.
MAIN PRINCIPLESMAIN PRINCIPLES OF THE CELL THEORYOF THE CELL THEORY: :
•1. All organisms are composed of one 1. All organisms are composed of one or more cells, within which the life or more cells, within which the life processes of metabolism and processes of metabolism and hereditary occur.hereditary occur.
•2. Cells are the smallest living things, 2. Cells are the smallest living things, the basic unit of organizationthe basic unit of organization
of all organisms.of all organisms.
•3. Cells arise only by division3. Cells arise only by division
of a previously existing cell. of a previously existing cell.
The cell is the basic unit of life. Microorganisms such as bacteria, yeast, and amoebae exist as single cells. By contrast, the adult human is made up of about 30 trillion cells (1 trillion = 1012) which are mostly organized into collectives called tissues.
Properties - biomembrane enclosed - four biomolecules: proteins, polysacharides, nucleic acids, lipids - metabolism and energy transformation
Lots of shapes and sizes
What are the differences between prokaryotic and eukaryotic cells?
Kindoms Kindoms1. Monera (Fubacteria) 1. Protista2. Archaea (Archaebacteria) 2. Fungi 3. Plantae
4. AnimaliaCharacteristics Characteristics1. Lack a nuclear membrane 1. Have a nuclear membrane2. Have no membrane bound organels 2. Have membrane bound organels
Current evidence indicates that eukaryotic evolved from prokaryotic between 1 and 1,5 billion years ago
Eukaryotic cell hasEukaryotic cell hasthree main componentsthree main components: : 1) 1) nucleusnucleus; ; 2) 2) cytoplasmcytoplasm; ; 3) 3) cell membranecell membrane..
Separates the living cell from its nonliving surroundings. It is 7,5-11 nm (that is, 7,5-11 billionths of a meter) thick. This membrane envelops the cell, and nothing can enter or leave the cell without crossing it.
CELL MEMBRANE CELL MEMBRANE ((plasma plasma membranemembrane))
Plasma membrane
Composed of:outer leaflet – GLYCOCALIX – facing the extracellular environment
lipid bilayer with associated proteins – BIOLOGICAL MEMBRANE)
inner leaflet – CORTICAL LAYER – facing the cytoplasm
Biological membrane Organization: The widely accepted fluid mosaic model describes biologic membranes as “protein icebergs in a lipid sea.” It is omposed of lipid bilayer and associated proteins.
Lipids are present in cell membranes as Lipids are present in cell membranes as phospholipids,phospholipids, sphingolipids,sphingolipids, and and cholesterol.cholesterol. Each phospholipid molecule has a Each phospholipid molecule has a polar polar (hydrophilic) phosphate-containing head(hydrophilic) phosphate-containing head group and group and a a nonpolar (hydrophobic) pair of fatty-acid tailsnonpolar (hydrophobic) pair of fatty-acid tails. . Membrane phospholipids are arranged in a bilayer Membrane phospholipids are arranged in a bilayer with their tails directed toward one another at the with their tails directed toward one another at the center of the membrane. In electron micrographs of center of the membrane. In electron micrographs of osmium-stained tissue, a single membrane, or osmium-stained tissue, a single membrane, or unit unit membrane,membrane, has 2 dark outer lines with a lighter has 2 dark outer lines with a lighter layer between them.layer between them.
1 – heads; 2 – tails; 3 – integral proteins.
Fluid-mosaic structure of the cell membrane
ProteinProtein may comprise over 50 % of membrane weight. Most membrane may comprise over 50 % of membrane weight. Most membrane proteins are globular and belong to one of the following 2 groups:proteins are globular and belong to one of the following 2 groups:
a.a.Integral membrane proteins Integral membrane proteins are tightly lodged in the lipid bilayer; are tightly lodged in the lipid bilayer; detergents are required to extract them. They are folded, with their detergents are required to extract them. They are folded, with their hydrophilic amino acids in contact with the phosphate groups of the hydrophilic amino acids in contact with the phosphate groups of the membrane phospholipids and their hydrophobic amino acids in contact membrane phospholipids and their hydrophobic amino acids in contact with the fatty-acid tails. Some protrude from only one membrane surface, with the fatty-acid tails. Some protrude from only one membrane surface, while others, called transmembrane proteins, penetrate the entire while others, called transmembrane proteins, penetrate the entire membrane and protrude from both sides.membrane and protrude from both sides.
b. b. Peripheral membrane proteins Peripheral membrane proteins are more loosely associated with the are more loosely associated with the inner or outer membrane surface; some are globular, some filamentous.inner or outer membrane surface; some are globular, some filamentous.
Cell membrane proteins
GLYCOCALYXGLYCOCALYXCarbohydrates occur on plasma membranes mainly as oligosaccharide moieties of membrane glycoproteins and glycolipids. Membrane oligosaccharides have a characteristic branching structure and project from the cell’s outer surface, forming a superficial coat called the glycocalyx that participates in cell adhesion and recognition.
Glycocalyx is a sugar coat
commonly associated with the extracytoplasmic aspects of the outer leaflet of plasma membrane (in animal cells).
Functions aiding in cellular
attachment to extracellular matrix components
binding of cellular and enzymes to the cell
CORTICAL LAYERCORTICAL LAYERIs located inside the cytoplasm of the cell. It is composed by microtubules and microfilaments, which formed the cytoskeleton of the cell. Aids in cellular support and movement.Cytoskeleton is composed of three components:
1. Microfilaments - globular protein (actin)- support and cellular contraction
2. Intermediate filaments - fibrous protein- support
3. Microtubles - globular protein (tubulin)- support and cell motility
In these cells, actin In these cells, actin filaments appear filaments appear light purple, light purple, microtubules microtubules yellow, and nuclei yellow, and nuclei greenish blue. This greenish blue. This image, which has image, which has been digitally been digitally colored, won first colored, won first place in the 2003 place in the 2003 Nikon Small World Nikon Small World Competition.Competition.
FUNCTIONS OF THE CELL MEMBRANEFUNCTIONS OF THE CELL MEMBRANE::
•Acts as selective barrierActs as selective barrier•Regulate movement of material Regulate movement of material into and out of the cellinto and out of the cell•Cellular recognitionCellular recognition
Plasma Membrane Transport Processes.
These processes include transport of a single molecule (uniport) or cotransport of two different molecules in the same (symport) or opposite (antiport) direction.
Passive transport includes simple and facilitated diffusion.
Neither of these processes requires energy because molecules move across the plasma membrane down a concentration or electrochemical gradient.
1. Simple diffusion transports small nonpolar molecules (02 and N2) and small, uncharged, polar molecules (H20, C02, and glycerol).
2. Facilitated diffusion occurs via ion channel and/or carrier proteins, structures that exhibit specificity for the transported molecules. It is faster than simple diffusion.
3. Osmosis is the diffusion of water across a selectively permeable membrane in response to its concentration gradient.
Active transport is an energy-requiring process which
transports a molecule against an electrochemical gradient via carrier proteins.
Na+-K+pump. The Na+-K+ pump involves the antiport transport of Na+ and K+ ions mediated by the carrier protein, Na+-K+ ATPase.
Na+ ions are pumped out of the cell and two K+ ions are pumped into the cell.
Comparison active and passive transport
Exocytosis
is way that substances can exit cells.
Part of the plasma membrane pinches off and forms a small membrane-bound sac, or vesicle, around some substance.
Vesicles even form around tiny cells (such as a bacterium) and fluids.
In exocytosis vesicles form inside the cytoplasm and then move to the plasma membrane and fuse with it, so that their contents are moved to the outside.
Endocytosis
is way that substances can exit cells.
a patch of plasma membrane encloses material at the cell surface.
it sinks in and pinches off, forming a vesicle that either transports the material into the cytoplasm or stores it there.
Phagocytosis
Phagocytosis (cell eating) is transport process by which amoeboid-type cells engulf large material, forming an intracellular vacuole.
Pinocytosis
When macromolecules are taken in by endocytosis, the process is called Pinocytosis (cell drinking), and the result is formation of vesicle.
Both phagocytic vacuoles and pinocytic vesicles can fuse with lysosomes, whose enzymes digest their contents.
CYTOPLASMCYTOPLASM- - inner environment of the cell,
working apparatus, were take place main metabolic processes
ORGANELLESORGANELLES – – are membrane-bound, enzyme-are membrane-bound, enzyme-containing, permanent subcellular compatrmentscontaining, permanent subcellular compatrmentsOrganelles are divided to:• generalgeneral (are present in all cells)
• specialspecial (are present only in some)
General organellesGeneral organelles::Mitochondria and plastidsMitochondria and plastidsRibosomesRibosomesEndoplasmic reticulumEndoplasmic reticulumGolgi apparatus (complex)Golgi apparatus (complex)LysosomesLysosomesPeroxisomesPeroxisomesVacuolesVacuolesCCell centerell centerMicrotubulesMicrotubulesMicrofilamentsMicrofilaments
Special organellesSpecial organelles::tonofibrilstonofibrils,,neurofibrilsneurofibrils,,myofibrilsmyofibrils,,villivilli,,flagellaflagella..
Mitochondria and plastidsMitochondria and plastids Endoplasmic reticulumEndoplasmic reticulum Golgi apparatus (complex)Golgi apparatus (complex) LysosomesLysosomes PeroxisomesPeroxisomes VacuolesVacuoles
RibosomesRibosomes CCell centerell center MicrotubulesMicrotubules MicrofilamentsMicrofilaments
Membranedorganelles
Nonmembaned organelles
MICROSCOPICMICROSCOPIC
SUBMICROSCOPISUBMICROSCOPICC
MITOCHONDRIONMITOCHONDRION – – general microscopicgeneral microscopic membraned organellemembraned organelle
The largest of the cytoplasmic organelles, mitochondria are the energy providers (“powerhouses”) of the cell.Structure. Mitochondria are comparable in size to bacteria (usually 2-6 mm in lenght and 0.2 mm in diameter but quite variable) and have various shapes: spheric, ovoid, filamentous. Each mitochondrion is bounded by 2 unit membranes.
The outer mitochondrial membrane has a smooth contour and forms a continuous but relatively porous covering. It is freely permeable to various small molecules.The inner mitochondrial membrane is less porous and is therefore semipermeable. It has numerous infoldings, or cristae, that project into the mitochondrion’s interior. The mitochondrial cristae of most cells are shelflike, but those in steroid-secreting cells are typically more tubular.
Mitochondrion
The mitochondrial membranes create 2 membrane-limited spaces. The intermembrane space is located between the inner and outer membranes and is continuous with the interacristal space that extends into the cristae. The intercristal space, or matrix space, is enclosed by the inner membrane and contains the mitochondrial matrix.The mitochondrial matrix contains water, solutes, and large matrix granules, believed to be concerned with mitochondrial calcium-ion concentrations. It also contains circular DNA and mitochondrial ribosomes similar to those of bacteria.
Mitochondrion Function. Mitochondria provide the cell with the energy for chemical and mechanical work by storing energy generated from cellular metabolites in the high-energy bonds of ATP.
Location. Mitochondria are found in nearly all eukaryotic cells, and in most they are dispersed throughout the cytoplasm. However, they accumulate in the highest concentrations in cell types and intracellular regions with the highest energy requirements. Cardiac muscle cells are notable for the abundance of their mitochondria. Epithelial cells lining the kidney tubules have abundant mitochodria interdigitated between basal plasma membrane infoldings where active transport of ions and water occurs.
Plastids are membrane-bound
organelles that only occur in plants and photosynthetic eukaryotes.
Plastids
roughrough
smoothsmooth
ENDOPLASMIC RETICULUM ENDOPLASMIC RETICULUM --general submicroscopic general submicroscopic membraned organellemembraned organelle The endoplasmic reticulum is a complex organelle involved in the synthesis, packaging, and processing of various cell substances. It is a freely anastomosing network (reticulum) of membranes that form cisternae; these may be elongated, flattened, rounded, or tubular. ER occurs in 2 forms, called rough and smooth.
ROUGH ENDOPLASMIC RETICULUMROUGH ENDOPLASMIC RETICULUMStructure. Structure. RER, also called granular endoplasmic reticulum, is studded with RER, also called granular endoplasmic reticulum, is studded with ribosomes, many of them in polysomal clusters. RER cisternae are typically ribosomes, many of them in polysomal clusters. RER cisternae are typically parallel, flattened, and elongated, especially in cells specialized for protein parallel, flattened, and elongated, especially in cells specialized for protein secretion (eg, pancreatic acinar cells, plasma cells), in which RER is secretion (eg, pancreatic acinar cells, plasma cells), in which RER is particularly abundant. The ribosomes give RER basophilic staining particularly abundant. The ribosomes give RER basophilic staining properties. The fine structure of RER (membranes and individual properties. The fine structure of RER (membranes and individual ribosomes) is visible only with the electron microscope.ribosomes) is visible only with the electron microscope.Function. Function. RER is mainly concerned with the synthesis of proteins for RER is mainly concerned with the synthesis of proteins for sequestration from the rest of the cytoplasm, ie, secretory proteins such as sequestration from the rest of the cytoplasm, ie, secretory proteins such as collagen, proteins for incorporation into cell membranes, and lysosomal collagen, proteins for incorporation into cell membranes, and lysosomal enzymes (separated from the rest of the cytoplasm to prevent autolysis). enzymes (separated from the rest of the cytoplasm to prevent autolysis). RER in protein-secreting epithelial cells often lies in the basal cytoplasm, RER in protein-secreting epithelial cells often lies in the basal cytoplasm, between the plasma membrane and the nucleus.between the plasma membrane and the nucleus.
Endoplasmic reticulum
Structure. Structure. SER lacks ribosomes and thus appears smooth in electron micrographs. SER cisternae are more tubular or vesicular than those of RER. SER stains poorly, if at all, so with the light microscope it is indistinguishable from the rest of the cytoplasm.Function. Because it lacks ribosomes, the SER cannot synthesize proteins. It has many enzymes, important in lipid metabolism, steroid hormone synthesis, glycogen synthesis (glucose-6-phosphatase), and detoxification.Location. Location. The SER is suspended in the cytoplasm of many cells and is especially abundant in cells that synthesize steroid hormones (eg, cells of the adrenal cortex and the gonads). It is also abundant in liver cells (hepatocytes), where it is involved in glycogen synthesis and drug detoxification. Specialized SER termed sarcoplasmic reticulum is found in striated muscle cells, where it helps to regulate muscle contraction by sequestering and releasing calcium ions.
SMOOTHSMOOTH ENDOPLASMIC ENDOPLASMIC RETICULUMRETICULUM
RIBOSOMES RIBOSOMES –– general submicroscopicgeneral submicroscopic nonmembraned organellesnonmembraned organelles The ribosomes are protein-synthesizing organelles. There are 2 basic types. Mitochondrial (like prokaryotic) ribosomes are smaller (20 nm) than the cytoplasmic ribosomes of eukaryotes (25 nm).
StructureStructure. . Each type of ribosome has 2 unequal ribosomal subunits. Cytoplasmic ribosomes are composed of ribosomal RNA (rRNA) synthesized in the nucleos and associated proteins synthesized in the cytoplasm. They are intensely basophilic. Light microscopy reveals cytoplasmic accumulations of ribosomes as basophilic patches, formerly termed ergastoplasm in grandular cells and Nissl bodies in neurons. In electron micrographs, ribosomes appear as small, electron-dense cytoplasmic granules.
Location and function. Location and function. Cytoplasmic ribosomes occur in 2 forms. Free Cytoplasmic ribosomes occur in 2 forms. Free ribosomes are individual ribosomes dispersed in cytoplasm. ribosomes are individual ribosomes dispersed in cytoplasm. Polyribosomes, or polysomes, are groups of ribosomes evenly distributed Polyribosomes, or polysomes, are groups of ribosomes evenly distributed along a single strand of messenger RNA (mRNA), an arrangement that along a single strand of messenger RNA (mRNA), an arrangement that permits synthesis of multiple copies of a protein from the same message. permits synthesis of multiple copies of a protein from the same message. Polysomal ribosomes read (translate) the mRNA code and thus play a Polysomal ribosomes read (translate) the mRNA code and thus play a critical role in assembling amino acids into specific proteins. Polysomes critical role in assembling amino acids into specific proteins. Polysomes are found free in the cytoplasm (free polysomes) and attached to are found free in the cytoplasm (free polysomes) and attached to membranes of the rough endoplasmic reticulum (polysomes of the membranes of the rough endoplasmic reticulum (polysomes of the endoplasmic reticulum). Free polysomes are involved in the synthesis of endoplasmic reticulum). Free polysomes are involved in the synthesis of structural proteins and enzymes for intracellular use. Polysomes of the structural proteins and enzymes for intracellular use. Polysomes of the rough endoplasmic reticulum are involved in synthesizing proteins that rough endoplasmic reticulum are involved in synthesizing proteins that are secreted or isolated.are secreted or isolated.
GOLGI COMPLEXGOLGI COMPLEX– – general microscopicgeneral microscopic membraned membraned organelleorganelle
This membranous organelle is composed of 3 major compartments:(1) a conspicious stack of 3-10 discrete, slightly curved, flattened cisternae; (2) numerous small vesicles peripheral to the stack; and (3) a few large vacuoles, sometimes called condensing vacuoles, at the concave surface of the stack. The cis face (convex face, forming face) of the stack is usually closest to adjacent dilated ER cisternae and is surrounded by transfer vesicles. Its cisternae stain more darkly with osmium. The trans face (concave face, maturing face) often harbors several condensing vacuoles and generally faces away from the nucleus.
Golgi Apparatus
flattened membranes, flattened membranes, secretory vesicles, secretory vesicles, transport vacuolestransport vacuoles
Location. Location. The Golgi complex is typically The Golgi complex is typically near the nucleus (juxtanuclear) and is near the nucleus (juxtanuclear) and is often found near centrioles (which may often found near centrioles (which may also have an important role in directing also have an important role in directing vesicle traffic). Golgi complexes are best vesicle traffic). Golgi complexes are best developed in neurons and glandular cells, developed in neurons and glandular cells, which are specialized for secretion.which are specialized for secretion.
Golgi Apparatus: Functions
After leaving the ER, many transport vacuoles travel to the GA. GA involved in packaging and secretion of proteins
GA is a center of : 1) modification of proteins and lipids; 2) storing of macromolecules; 3) storing of biological compounds; 4) “shipping” of macromolecules; 5) formation of lysosomes.
LYSOSOMESLYSOSOMES – – general submicroscopic membraned organellesgeneral submicroscopic membraned organelles
Lysosomes are Lysosomes are spherical, membrane-limited spherical, membrane-limited vesicles that may contain more vesicles that may contain more than 50 enzymes each and than 50 enzymes each and function as the cellular function as the cellular digestive system. Their digestive system. Their characteristic enzyme activities characteristic enzyme activities distinguish them from other distinguish them from other cellular granules. The enzyme cellular granules. The enzyme most widely exploited for their most widely exploited for their identification is identification is acid acid phosphate,phosphate, because it occurs because it occurs almost exclusively in almost exclusively in lysosomes. Other enzymes lysosomes. Other enzymes common in lysosomes are common in lysosomes are ribonucleases, ribonucleases, deoxyribonucleases, deoxyribonucleases, cathepsins, ,sulfatases, b-cathepsins, ,sulfatases, b-glucoronidase, and glucoronidase, and phospholipases and other phospholipases and other proteases, glucosidases, and proteases, glucosidases, and lipases. Lysosomal enzymes lipases. Lysosomal enzymes usually occur as glycoproteins usually occur as glycoproteins and are most active at an and are most active at an acidic pH. acidic pH.
Lysosomes occur in various sizes and Lysosomes occur in various sizes and electron densities, depending on electron densities, depending on their level of activity.their level of activity.Primary lysosomesPrimary lysosomes are small (5-8 are small (5-8 nm in diameter), with electron-dense nm in diameter), with electron-dense contents; they appear as black contents; they appear as black circles in electron micrographs. They circles in electron micrographs. They are the storage form of lysosomes, are the storage form of lysosomes, and their enzymes are mostly and their enzymes are mostly inactive. Lysosomes enzymes inactive. Lysosomes enzymes synthesized and coreglycosylated in synthesized and coreglycosylated in the RER are transferred to the Golgi the RER are transferred to the Golgi complex for further glycosylation; it complex for further glycosylation; it is uncertain whether their final is uncertain whether their final packaging as primary lysosomes packaging as primary lysosomes occurs in the Golgi complex or in occurs in the Golgi complex or in GERL. The primary lysosomes GERL. The primary lysosomes disperse through the cytoplasm. They disperse through the cytoplasm. They are found in most cells but are most are found in most cells but are most abundant in phagocytic cells (eg, abundant in phagocytic cells (eg, macrophages, neutrophils).macrophages, neutrophils).
Secondary lysosomesSecondary lysosomes are larger and less electron-dense and have a are larger and less electron-dense and have a mottled appearance in electron micrographs. They are formed by the fusion of one mottled appearance in electron micrographs. They are formed by the fusion of one or more primary lysosomes with a phagosome. Their primary function is the or more primary lysosomes with a phagosome. Their primary function is the digestion of products of heterophagy and autophagy; when the lysosomal enzymes digestion of products of heterophagy and autophagy; when the lysosomal enzymes mix with the phagosome contents, they become active. Lysosomal enzymes also mix with the phagosome contents, they become active. Lysosomal enzymes also catabolize certain products of cell synthesis, thus regulating the quality and quantity catabolize certain products of cell synthesis, thus regulating the quality and quantity of secretory material. Secondary lysosomes occur throughout the cytoplasm in many of secretory material. Secondary lysosomes occur throughout the cytoplasm in many cells, in numbers that reflect the cell’s lysosomal and phagocytic activity.cells, in numbers that reflect the cell’s lysosomal and phagocytic activity.
Residual bodies Residual bodies are membrane-limited inclusion of varying size and are membrane-limited inclusion of varying size and electron density associated with the terminal phases of lysosome electron density associated with the terminal phases of lysosome function. They contain undigestible materials such as function. They contain undigestible materials such as pigments, crystals, and certain lipids.
FUNCTION:FUNCTION:1. participation in1. participation indigestion of all classes of digestion of all classes of macromoleculesmacromolecules2. phagocytosis2. phagocytosis3. recycling the cells own 3. recycling the cells own organic material organic material (autophagy)(autophagy)
Vacuoles Large membrane-
closed sac for cellular storage
Three types Food vacuole
(lysosomes attach) Contractile vacuole
(Protozoons) Central vacuole
(mature plant cell)
CELL CENTERCELL CENTER – – general microscopic nonmembraned general microscopic nonmembraned organelleorganelle
- found in found in animal cells only animal cells only
- p- paired cylindrical organelles aired cylindrical organelles near nucleusnear nucleus
- - ccomposed of nine tubes, omposed of nine tubes, each with three tubuleseach with three tubules
- - iinvolved in cellular divisionnvolved in cellular division
-llie at right angles to each ie at right angles to each other other
CYTOSKELETON IS A NETWORK OF FIBERS THROUGHOUT THE CYTOPLASMCYTOSKELETON IS A NETWORK OF FIBERS THROUGHOUT THE CYTOPLASM
Cytoskeleton Cytoskeleton is constructed from three types of fibers. is constructed from three types of fibers.
♦♦ microtubules are the thickestmicrotubules are the thickest
♦ ♦ microfilaments (actin filament) are the thinnest microfilaments (actin filament) are the thinnest
♦ ♦ intermediate filaments are a collection of fibers.intermediate filaments are a collection of fibers.
Actin miofilaments - redActin miofilaments - red,,microtubuls - greenmicrotubuls - green. .
ELEMENTS OF THE CYTOSKELETON ELEMENTS OF THE CYTOSKELETON - give mechanical support to the cell and help maintain its shape.- give mechanical support to the cell and help maintain its shape.- enables a cell to change its shape. - enables a cell to change its shape. - is associated with motility: movement of the entire cell or - is associated with motility: movement of the entire cell or movement of organelles and vesicles within the cell. The fibers of movement of organelles and vesicles within the cell. The fibers of the cytoskeleton are not only the cells “bones” but also its the cytoskeleton are not only the cells “bones” but also its “muscles”.“muscles”.- contractile component of cytoskeleton manipulate the plasma - contractile component of cytoskeleton manipulate the plasma membrane to form vacuoles during phagocytosis. membrane to form vacuoles during phagocytosis.
INCLUSSIONSINCLUSSIONS
– непостійні компоненти клітини, що є продуктом її життєдіяльності, виникають і зникають залежно від функціонального стану клітини. Вони можуть складатись із хімічних речовин різноманітної природи: ліпідів, вуглеводів, білків, вітамінів.
NUCLEUSNUCLEUS – – is is a conspicuous membrane-bound cellular a conspicuous membrane-bound cellular componentcomponent..Nucleus of an eukaryotic cell contains the cell's hereditary Nucleus of an eukaryotic cell contains the cell's hereditary apparatus and isolates it from the rest of the cell.apparatus and isolates it from the rest of the cell.
Red blood cells Red blood cells don’t have a don’t have a nucleus.nucleus.
Skeletal muscle Skeletal muscle cells have multiple cells have multiple nucleinuclei
FFunctions of the nucleus are:unctions of the nucleus are:Store genes into chromosomes to allow cell divisionTransport regulatory factors and gene products vie nuclear poresProduce messages (messenger ribonucleic acid or mRNA) that code for proteinsOrganise the incoiling of DNA to replicate key genes
MAIN COMPONENTS OF THE NUCLEUSMAIN COMPONENTS OF THE NUCLEUS::•nuclear envelopenuclear envelope;;•nucleoplasmnucleoplasm;;•nucleolusnucleolus;;•chromatin.chromatin.•..
Nuclear Nuclear envelopeenvelope The nuclear contents are set apart from
the cytoplasm by a double membrane called the nuclear envelope and a narrow (40-70 nm) intermembrane space called the perinuclear space. The nuclear envelope is often considered an exctension of the RER, because its outer surface is often peppered with ribosomes and shows occasional continuities with the RER. The inside of the inner membrane is lined with the fibrous lamina, a layer consisting of proteins called lamins.
The envelope is perforated by many nuclear pores, each of which has a diameter of about 70 nm and is bounded by 8 globular subunits called annular proteins, which present an octagonal appearance in some preparations. Each pore is covered by a proteinaceous diaphragm that is thinner than the envelope. The pores provide a channel for the movement of important molecules between the nucleus and cytoplasm; these molecules include nucleic acids synthesized in the nucleus and used in the cytoplasm (mRNA, rRNA, tRNA) and proteins synthesized in the cytoplasm and used in the nucleus (histones, polymerases).
Structure of the nuclear pores
Nuclear pores are embedded -with Nuclear pores are embedded -with many proteins that act as many proteins that act as molecular channels, permitting molecular channels, permitting certain molecules to pass into and certain molecules to pass into and out of the nucleus. Passage is out of the nucleus. Passage is restricted primarily to two kinds of restricted primarily to two kinds of molecules: (1) proteins moving molecules: (1) proteins moving into the nucleus, where they will into the nucleus, where they will be incorporated into nuclear be incorporated into nuclear structures or serve to catalyze structures or serve to catalyze nuclear activities; and (2) RNA and nuclear activities; and (2) RNA and protein-RNA complexes formed in protein-RNA complexes formed in the nucleus and subsequently the nucleus and subsequently exported to the cytoplasm.exported to the cytoplasm.
NUCLEOPLASM.NUCLEOPLASM. The nucleoplasm is the matrix in which The nucleoplasm is the matrix in which
the other intranuclear components are the other intranuclear components are embedded. It is composed of enzymatic and embedded. It is composed of enzymatic and nonenzymatic proteins, metabolites, ions, and nonenzymatic proteins, metabolites, ions, and water. It includes the water. It includes the nuclear matrix –nuclear matrix – a a fibrillar “nucleoskeletal” structure that appears fibrillar “nucleoskeletal” structure that appears to bind certain hormone receptors-and newly to bind certain hormone receptors-and newly synthesized DNA.synthesized DNA.
NUCLEOLUSNUCLEOLUSDuring interphase
(between mitoses), each nucleus usually has at least one (or2) intensely basophilic body called a nucleolus. Nucleoli are the synthesis sites for most ribosomal RNA (rRNA). The nucleolus disappears in preparation for mitosis and reappears after mitosis is completed.
• The pars fibrosa The pars fibrosa consists of densely packed ribonucleoprotein consists of densely packed ribonucleoprotein fibers, 5-10 nm in diameter. These fibers consist of the newly fibers, 5-10 nm in diameter. These fibers consist of the newly synthesized primary transcripts of the rRNA genes and associated synthesized primary transcripts of the rRNA genes and associated proteins.proteins.
• The pars granulosa The pars granulosa contains dense granules, 15-20 nm in contains dense granules, 15-20 nm in diameter, that represent maturing ribosomal subunits during diameter, that represent maturing ribosomal subunits during assembly for export to the cytoplasm.assembly for export to the cytoplasm.
The term nucleolonema is used by light microscopists to refer to a threadlike basophilic substructure of the nucleolus. The nucleolonema contains 2 rRNA-rich components distinguishable by electron microscopy.
ChromatinChromatinNuclear chromatin is an Nuclear chromatin is an
intensely basophilic substance intensely basophilic substance consisting of DNA and associated consisting of DNA and associated histone and nonhistone proteins histone and nonhistone proteins visible at interphase nuclei. visible at interphase nuclei. Types of the chromatinTypes of the chromatin::
•euchromatineuchromatin,,•heterochromatinheterochromatin. .
EUCHROMATIN. EUCHROMATIN. Uncoiled chromatin, termed euchromatin, stains poorly and is difficult to distinguish even with electron microscopy. Large, pale-staining (euchromatic) nuclei usually indicate greater transcriptional activity and faster cell division.
HETEROCHROMATINHETEROCHROMATIN. . Nuclei containing highly coiled chromatin, termed heterochromatin, stain darkly with basic dyes. Because the DNA of chromatin must uncoil to be transcribed, cells with dark-staining (heterochromatic) nuclei are less active in DNA transcription than other cells, using a smaller portion of their total genome.
ГЕТЕРОХРОМАТИН ПОДІЛЯЄТЬСЯНА СТРУКТУРНИЙ ТА ФАКУЛЬТАТИВНИЙ
Структурний гетерохроматин – це ділянки хромосом, що постійно конденсовані.
Факультативний гетерохроматин за необхідності може конденсуватись та переходити в еухроматин.
CHROMOSOMES.CHROMOSOMES. The The chromosomes, the most chromosomes, the most highly condensed form of highly condensed form of chromatin, are visible during chromatin, are visible during mitosis. mitosis.
In females, only one X chromosome (either of In females, only one X chromosome (either of the 2) is used by each cell; the inactive X the 2) is used by each cell; the inactive X chromosome is often visible as a clump of chromosome is often visible as a clump of heterochromatin termed heterochromatin termed sex chromatin, or the Barr sex chromatin, or the Barr body. body. In most cells, the Barr body is attached to the In most cells, the Barr body is attached to the inner surface of the nuclear envelope. In a inner surface of the nuclear envelope. In a neutrophilic leukocyte, it may appear as a neutrophilic leukocyte, it may appear as a drumstick-shaped appendage of the lobulated drumstick-shaped appendage of the lobulated nucleus.nucleus.
Types of chromosomes
KARYOTYPE is a diploid number of KARYOTYPE is a diploid number of chromosomes and it is a characteristics of chromosomes and it is a characteristics of
the number and morphology of the number and morphology of chromosomes, that is peculiarities of each chromosomes, that is peculiarities of each
species. species.
Human karyotype includesHuman karyotype includes46 46 chromosomes:chromosomes:4444 – – autosomesautosomes22– – sex chromosomessex chromosomes
Female karyotypeFemale karyotype46=22A+XX46=22A+XX
Male karyotypeMale karyotype46=22A+XY46=22A+XY
THANK YOU FOR ATTENTION THANK YOU FOR ATTENTION !!
SEE YOU NEXT SEE YOU NEXT TIME !TIME !
