The Cell (PPT from Mrs. Brenda Lee)

transcript

Cell Structures and Functions

The Cellthe smallest unit of life that can carry out all the functions of a living thing.

fundamental building blocks of organisms.

Brief History of the Cell

Antonie van Leeuwenhoek (1632-1723)

Robert Hooke (1635-1703)

Cork Cell

The word cell comes from the Latin cella, a small room.

The Cell Theory Robert Brown (1831)

Described the nucleus of the cell Matthias Schleiden (1838)

All plants are composed of cells. Theodor Schwann (1838)

All animals are composed of cells Rudolph Virchow (1850s)

Cells reproduce

The Cell Theory

All organisms are composed of cells.

Cells are the basic units of structure and function in organisms.

Cells come only from pre-existing cells because cells are self-reproducing.

Microscopy Today

Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale.

Sizes of Living Things10 m1 m0.1 m1 cm1 mm100 nm10 nm1 nm0.1 nm

mousefrog egg

human eggmost bacteria

protein

atomant

electron microscope

light microscope

human eye

humanblue whale

chloroplastrose

1 km100 m100 m10 m1 m

plant and animal

cellsaminoacid

ostrichegg

Microscopy Today

Topography: shows the surface features of an object or "how it looks", its texture; and materials properties (hardness, reflectivity...etc.)

Morphology: shows shape and size of the particles making up the object; and materials properties (ductility, strength, reactivity...etc.)

Animal Cell Anatomy

*not in plant cells

Plasma membrane:outer surface thatregulates entrance andexit of molecules

phospholipid

protein

Cytoskeleton: maintainscell shape and assists movementof cell parts:

Actin filaments: proteinfibers that play a role inchange of shape

Cytoplasm: semifluidmatrix outside nucleusthat contains organelles

Intermediate filaments:protein fibers that providestability of shape

Microtubules: proteincylinders that moveorganelles

Vesicle: small membrane-bounded sac that storesand transports substances

Centrioles*: shortcylinders of microtubulesof unknown function

Centrosome: microtubuleorganizing center thatcontains a pair of centrioles

Lysosome*: vesicle thatdigests macromoleculesand even cell parts

Nucleus: command center of cell

Rough ER: studded withribosomes that synthesizeproteins

Ribosomes:particles that carryout protein synthesis

Golgi apparatus: processes, packages,and secretes modified proteins

Peroxisome: vesiclethat is involved infatty acid metabolism

Smooth ER: lacksribosomes, synthesizeslipid molecules

Endoplasmic reticulum:protein and lipid metabolism

Mitochondrion: organellethat carries out cellular respiration, producing ATP molecules

Polyribosome: string ofribosomes simultaneouslysynthesizing same protein

Nucleolus: region that producessubunits of ribosomes

Chromatin: diffuse threadscontaining DNA and protein

Nuclear envelope: doublemembrane with nuclear poresthat encloses nucleus

Microscopy and Cheek Cells

Bright-field. Lightpassing through thespecimen is broughtdirectly into focus. Usually,the low level of contrastwithin the specimeninterferes with viewing allbut its largest components.

Bright-field (stained).Dyes are used to stainthe specimen. Certaincomponents take upthe dye more than othercomponents, and thereforecontrast is enhanced.

Differential interferencecontrast. Optical methodsare used to enhancedensity differences withinthe specimen so thatcertain regions appearbrighter than others. Thistechnique is used to viewliving cells, chromosomes,and organelle masses.

Phase contrast. Densitydifferences in thespecimen cause light raysto come out of “phase.”The microscope enhancesthese phase differences sothat some regions of thespecimen appear brighteror darker than others. Thetechnique is widely usedto observe living cells andorganelles.

Dark-field. Light is passedthrough the specimen atan oblique angle so thatthe objective lens receivesonly light diffracted andscattered by the object.This technique is used toview organelles, whichappear quite bright againsta dark field.

25 m 25 m 25 m30 m 30 m

(Bright field): © Ed Reschke; (Bright field stained): © Biophoto Associates/Photo Researchers, Inc.;(Differential, Phase contrast, Dark field): © David M. Phillips/Visuals Unlimited

Prokaryotic

Eukaryotic

Two Basic Types of Cell Structure

Prokaryotic “pro” = before, “kary”= nut

(nucleus) NO nucleus or NO organelles Genetic material (DNA) is naked in

the cytoplasm Cell division is called binary fission

Prokaryotic

Believed to be the first cells to evolve.

Ribosomes are the only organelle.

Binary Fission: Prokaryotes Cell Division

Prokaryotic• Kingdom Monera

• Kingdom Archaea

Prokaryotic

Eukaryotic

Eukaryotic Nucleus containing DNA “Eu” - true Organelles (membrane bound) with specialized functions

Cell division: mitosis and meiosis

Eukaryotic• Kingdom Protista• Kingdom Fungi• Kingdom Plantae• Kingdom Animalia

Differences between Prokaryotic & Eukaryotic cellsBacterial cells also contain flagellum, plasmid and capsule.

Feature Prokaryote Eukaryote

Size Small about 0.5 micrometers

Up to 40 micrometers

Genetic material

Circular DNA (in cytoplasm)

DNA in form of linear chromosomes ( in nucleus)

Organelles Few present, none membrane bound

Many organelles:•Double membranes e.g.: nucleus, mitochondria & chloroplasts•Single membrane e.g.: GA, ER & lysosomes

Cell wallsRigid formed from glycoproteins (mainly murein)

•Fungi: rigid, formed from polysaccharide, chitin. •Plant: rigid, formed from polysaccharides. E.g.: cellulose. •Animals no cell wall

Ribosome’s 70s 80s

Section 7-2

Figure 7-5 Plant and Animal Cells

Go to Section:

Animal Cell

NucleusNucleolus

Cell Membrane

Cytoplasm

Eukaryotic Cell Organelles and Function

1. Nucleus Nickname: “The Control

Center” Function: holds the DNA Parts:

1. Nucleolus: dark spot in the middle of the nucleus that helps make ribosomes

Section 7-2

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Animal Cell

Nucleus

Nucleolus RibosomesCell Membrane

Cytoplasm

2. Ribosomes Function: makes

proteins Found in all cells,

prokaryotic and eukaryotic

3. Endoplasmic Reticulum (ER)

Nickname: “Roads” Function: The internal

delivery system of the cell

Section 7-2

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Animal Cell

Nucleus

Nucleolus

Rough Endoplasmic Reticulum

Smooth Endoplasmic Reticulum

Cell Membrane

Cytoplasm

Ribosomes

Endoplasmic Reticulum

Rough ER: Rough appearance because of ribosomes

Function: helps make proteins, that’s why it has ribosomes

Smooth ER:• similar in appearance with RER but NO ribosomes•Function: functions depending on the specific cell type including lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, and control of calcium release in muscle cell contraction.

Endoplasmic Reticulum

Section 7-2

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Animal Cell

Nucleus

Nucleolus

Ribosomes

Golgi Complex

Cell Membrane

Cytoplasm

4. Golgi Complex Nickname: The shippers Function: packages, modifies,

and transports materials to different location inside/outside of the cell

Appearance: stack of pancakes

Golgi Complex Modifies

proteins and lipids made by the ER and prepares them for export from the cell

Section 7-2

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Animal Cell

Nucleus

Nucleolus

Ribosomes

Golgi Bodies

Cell Membrane

Cytoplasm

5. Lysosomes: circular, but bigger than ribosomes

Nickname: “Clean-up Crews” Function: to break down

food into particles the rest of the cell can use and to destroy old cells

Single membrane bound structure.

Contains digestive enzymes that break down cellular waste and debris and nutrients for use by the cell.

Http://micro.magnet.fsu.edu/cells/animals/lysosome/html

Animation

Section 7-2

Figure 7-5 Plant and Animal CellsAnimal Cell

Nucleus

Nucleolus

Ribosomes

Golgi Bodies

MitochondriaCell Membrane

Cytoplasm

6. Mitochondria Nickname: “The Powerhouse” Function: Energy formation

Breaks down food to make ATP ATP: is the major fuel for all

cell activities that require energy

Animal Cell

Nucleus

Nucleolus

Ribosomes

Golgi Bodies

Mitochondria

Cell Membrane

Cytoplasm

7. Plasma Membrane

• Another name: Cell Membrane; “traffic enforcer”

• Function: hold the cell together. It keeps all of the pieces, like the organelles and the CYTOPLASM inside; regulates the entrance and exit of materials in and out the cell.

Plasma Membrane

Fluid Mosaic Model of Plasma Membrane

Lipid bilayera. Phospholipids: polar head and nonpolar tailb. Cholesterol: makes membrane a bit more rigidc. Proteins: provide means of transportation through membrane and receptor proteinsd. Carbohydrates: recognition patterns for cells and organisms (“self” markers to avoid immune system attack)

Fluid Mosaic Model of the Plasma MembraneThe membrane is seen as a bilayer of phospholipids in which protein molecules are embedded.

8. Cytoskeleton-composed of filaments and microtubules that maintain the cell shape and assist movement of its part

9. Cilia and flagella External

appendages from the cell membrane that aid in locomotion of the cell.

Cilia also help to move substance past the membrane.

• The most common examples of ciliated cells are those that line the trachea, or wind pipe of animals. • The cilia move mucus containing dirt and other inhaled particles up the windpipe and into the esophagus where they can be coughed up or swallowed.

Cilia and Flagella

Paramecium sp.

This unicellular organism sweeps food into its mouth by using cilia.

Cilia and Flagella

Sperm cell has a tail or "flagellum" which executes the lashing movements to propel the sperm.

10. Centrioles Found only in animal cells.

Self-replicating Made of bundles

of microtubules. Help in organizing

cell division.

11. Cytosol/Cytoplasm• The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism

occurs.* Though mostly water, the cytosol

is full of proteins that control cell

metabolism including signal transduction

pathways, glycolysis, and transcription

factors.

Structures only found in PLANT Cells

Section 7-2

Go to Section:

Plant Cell

Cell Membrane

Vacuole

11. Huge vacuoles Function: store water, waste

products, food, and other cellular materials.

It may take up most of the cell's volume.

When there is no water, the plant wilts

Section 7-2

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Plant Cell

Cell Membrane

Vacuole

Chloroplasts

12. Chloroplasts Function: traps energy from

the sun to produce food for the plant cell

Green in color because of chlorophyll

Chloroplasts

Section 7-2

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Plant Cell

Cell Membrane

Vacuole

Chloroplasts

Cell Wall

9. Cell Wall Function: provides support

and protection to the cell membrane; gives rigidity to the cell structure.

Found outside the cell membrane in plant cells.

Plant Cell

Cell Membrane

Vacuole

Chloroplasts

Cell Wall

Nucleolus

Nucleus

Rough ER

Smooth ER

Golgi Bodies

Mitochondria

Ribosomes

Cytoplasm

Muscle cells: contain numerous mitochondria providing energy needed for muscle contraction (action).

Cell Structure Reflects Cell Function

Cells of renal tubule lining are cube-shaped (helps with their function of absorption/secretion)

Nerve cells: are long and thin to carry impulses over distance.

Columnar epithelium with cilia on the free surface lines of the respiratory tract, fallopian tubes and uterus. The cilia beat rhythmically to transport particles.

Sperm cell has a tail or "flagellum" which executes the lashing movements to propel the sperm.

Red blood cells contain hemoglobin which permits them to transport oxygen (and carbon dioxide).

Animal Cell vs. Plant Cell

Comparing Plant and Animal CellsPlant Animal

The Cell (PPT from Mrs. Brenda Lee)

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