1
Cells, tissue types
and organs
MFEL3010 Ingunn Bakke (MD, PhD) Dept of Cancer research and Molecular Medicine Faculty of Medicine
2
I: •Structural and functional organization •Cell structure and functions
•Plasma membrane •Movement through the Plasma membrane
•Cytoplasm containing organelles II:
•Relationship between cell structure and function •How do cells make proteins? •Cell cycle •Why do cells differ? •How do cells communicate?
Outline
3 Structural & functional organizations
4
Organ system of the body
•Lymphatic •Respiratory •Digestive •Intergumentary •Skeletal •Muscular •Nervous •Endocrine •Cardiovascular •Urinary •Female reproductive •Male reproductive
5
Organs of the body
6
Four basic tissue types: 1 2 3
4
7
You are made up of millions of cells
However, you started your life as a single fertilized egg……
8
Day 6: Blastocyst
Four-cell stage of a human embryo
9
ectoderm gives rise to skin and nervous system mesoderm give rise to muscle, skeleton, and organs of circulation reproduction, and excretion endoderm gives rise to lining of gut and associated organs
Tissues General: embryo becomes arranged into three different tissues
Nature Biotechnology 23, 699 - 708 (2005)
Differentiation
10
Cell structure and function
11 • Basic structure of the cell – Plasma membrane – Cytoplasm containing organelles – Nucleus
• Functions of the cell
– Basic unit of life – Protection and support through production and secretion
of various kinds of molecules – Movement. Various kinds occur because of specialized
proteins produced in the cell – Communication. Cells produce and receive electrical and
chemical signals – Cell metabolism and energy release – Inheritance. Each cell contains DNA. Some cells are
specialized to gametes for exchange during sexual intercourse
12
13
Plasma membrane
14
Plasma membrane
15
Membrane lipids
Cholesterol
16
• Functioning depends on 3-D shape and chemical characteristics • markers • attachment sites • channels • receptors • enzymes • or carriers
Membrane proteins
17
Glycoprotein(cell surface marker)
Membrane proteins
receptor enzymes carrier channel
marker
attachment sites
18
Movement through the Plasma Membrane • Diffusion • Osmosis • Filtration
• Mediated transport mechanisms
– Facilitated diffusion – Active transport – Secondary active transport
• Endocytosis and exocytosis
19
Diffusion • Movement of solutes from an area of higher
concentration to lower concentration in solution – Concentration or density gradient: difference
between two points – Viscosity: how easily a liquid flows
20
Osmosis
• Diffusion of water (solvent) across a selectively permeable membrane. Water moves from an area of low concentration of solute to an area of high concentration of solute
• Osmotic pressure: force required to prevent water from moving across a membrane by osmosis
21
Osmosis and cells • Important because large volume changes caused by water
movement disrupt normal cell function • Cell shrinkage or swelling
Isotonic: cell neither shrinks nor swells Hypertonic: cell shrinks (crenation) Hypotonic: cell swells (lysis)
22
Filtration • Works like a sieve
• Depends on pressure
difference on either side of a partition
• Moves from side of greater pressure to lower
• Example: urine formation in the kidneys. Water and small molecules move through the membrane while large molecules remain in the blood
23
Mediated transport mechanisms • Involve carrier proteins or
channels in the cell membrane
• Characteristics – Specificity for a single type
of molecule – Competition among molecules
of similar shape – Saturation: rate of transport
limited to number of available carrier proteins
24
Mediated transport mechanisms • Move large, water soluble
molecules or electrically charged molecules across the plasma membrane.
• Amino acids and glucose in, manufactured proteins out. – Facilitated diffusion:
carrier- or channel-mediated. Passive.
– Active transport – Secondary active transport
25
Active transport • Requires ATP. The use of energy
allows the cell to accumulate substances
• Rate of transport depends on concentration of substrate and on concentration of ATP
• Example: Na/K exchange pump that creates electrical potentials across membranes
26
Secondary active transport
• Ions or molecules move in same (symport) or different (antiport) direction
Na+
27 Endocytosis
• Internalization of substances by formation of a vesicle
• Types Phagocytosis Pinocytosis Receptor-mediated
endocytosis
Particle
Cellprocesses
Phagocyticvesicle
Exocytosis
Accumulated vesicle secretions expelled from cell
28
Cytoplasm containing organelles
29
Cytoplasm • Cellular material outside
nucleus but inside plasma membrane
• Composed of Cytosol, Cytoskeleton, Cytoplasmic Inclusions, Organelles
• Cytosol: fluid portion. Dissolved molecules (ions in water) and colloid (proteins in water)
30
Cytoskeleton • Supports the cell but has to allow
for movements like changes in cell shape and movements of cilia – Microtubules: hollow, made of
tubulin. • Internal scaffold, transport,
cell division – Microfilaments: actin.
• Structure, support for microvilli, contractility, movement
– Intermediate filaments: mechanical strength
• Cytoplasmic inclusions: aggregates of chemicals such as lipid droplets, melanin
31
Organelles
• Small specialized structures with particular functions
• Most have membranes that separate interior of organelles from cytoplasm
• Related to specific structure and function of the cell
32
Nucleus
• Membrane-bound • Nucleoplasm, nucleolus and nuclear envelope • Much of the DNA in a cell located here
TEM 20,000x SEM 50,000x
Nuclearenvelope
Interior ofnucleus
Nucleolus
Chromatin
Outer membraneof nuclear envelope
Inner membraneof nuclear envelopeNuclear pores
Nuclearenvelope
Chromatin
Nuclear poresRibosomes
NucleoplasmOuter membraneSpaceInner membrane
Nucleolus
33
Cells: 10-50 µm Chromosomes: 2n =46 (diploid) DNA: 2m Organic base pairs: 3000mill
34
How your DNA is packaged into your cells
DNA
ChromatinChromosome
Kinetochore
Centromere
ChromatidProteins
35
Ribosomes
• Sites of protein synthesis
• Composed of a large and a small subunit
• Types – free – attached
(to endoplasmic reticulum)
36
Endoplasmic Reticulum (ER)
• Types – Rough
• Has attached ribosomes
• Proteins produced and modified here
– Smooth • No attached
ribosomes • Manufactures lipids
• Cisternae: Interior spaces
isolated from rest of cytoplasm
37
Golgi apparatus
• Modification, packaging, distribution of proteins and lipids for secretion or internal use
• Flattened membrane sacs stacked on each other
38
Action of Lysosomes Peroxisomes
Smaller than lysosomes Contain enzymes to break down fatty acids and amino acids Hydrogen peroxide is a by-product of breakdown
Proteasomes Consist of large protein complexes Include several enzymes that break down and recycle proteins in cell
39
Mitochondria • Major site of ATP synthesis • Mitochondria increase in number when cell energy requirements increase.
40
Overview of Cell metabolism
• Production of ATP necessary for life
• ATP production takes place in the cytosol (anaerobic) and mitochondria (aerobic) – Anaerobic does not
require oxygen. Results in very little ATP production
– Aerobic requires oxygen. Results in large amount of ATP
41
41
42
I: •Structural and functional organization •Cell structure and functions
•Plasma membrane •Movement through the Plasma membrane
•Cytoplasm containing organelles II:
•Relationship between cell structure and function •How do cells make proteins? •Cell cycle •Why do cells differ? •How do cells communicate?
Outline
43
Relationship between cell structure and cell function
44
Eukaryotic cell
Form and function!
45
cultured hippocampal neurons
46
Human Cervical Adenocarcinoma Cells (HeLa Line)
The HeLa line is one of the best-known cell lines in the world. Derived in 1951 from an adenocarcinoma of the cervix found in a 31-year-old woman (Henrietta Lacks),
•peroxisomes and intracellular microtubular network,
47
Human Cervical Adenocarcinoma Cells (HeLa Line)
Nuclear DNA Filamentous actin Golgi apperatures
48
Human Bone Osteosarcoma Cells (U-2 OS)
endoplasmic reticulum filamentous actin nuclear DNA
49
How do cells make proteins?
50
Overview of protein synthesis
51
Overview of protein synthesis
Transcription: DNA used to form RNA Translation: synthesis of protein at the ribosomes
52
Transcription
Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)
53 Post-transcriptional modification of mRNA
The genes of most living things are divided up into exons (coding) and introns (non-coding).
Splice
Pre-mRNA formedTranscription
Specific RNA regions
Pre-mRNA
DNA
Pre-mRNA Exon 1 Exon 2Intron
Intron
Cut Cut
Exon 1 Exon 2
Exon 1 Exon 2mRNA
Processing
54 Translation
http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf
Animation:
55
Protein structure
• Primary, secondary, tertiary, quaternary
56
Cell cycle
57
DNA-replication CytosineThymine Adenine
Guanine
3′
5′
5′ 3′
OriginalDNA molecule
DNA strandsseperate
Nucleotide
Old strand(template)
Old strand(template)
Newstrands
5′
5′
3′
New DNA moleculeNew DNA molecule
3′
The protein BRCA1 helps repair DNA. Suhail Islam, Imperial Cancer Research Fund, London
58
Steps of Mitosis
59
Steps of Mitosis
60
Steps of Mitosis
61
Steps of Mitosis
62
Steps of Mitosis
63
Steps of Mitosis
64
Steps of Mitosis
65
Steps of Mitosis
66
Steps of Mitosis
67
Meiosis
68
Why do cells differ?
69
Regulation of protein synthesis
• All nucleated cells except germ cells have the full complement of DNA.
• During development, differentiation occurs and some segments of DNA are turned off in some cells while those segments remain “on” in other cells (gene expression).
• During the lifetime of a cell, the rate of protein synthesis varies depending upon chemical signals that reach the cell.
70 Transcription factors
71
Structural & functional organizations
72
Four basic tissue types: 1 2 3
4
73
Sebaceousgland Skin
Epidermis
Dermis
Hypodermis(subcutaneoustissue)
Hairs
Fat
Arrector pili(smooth muscle)
Sweat glandArtery
VeinNerve
Hair follicle
Skin and hypodermis
74
How do cells communicate?
75
Homeostasis Stimuli ex. cold exposure
Hypothalamus
Pituitary
Thyroid gland
76
Cell connection Found on lateral and basal surfaces of cells Functions •Form •permeability layer •Bind cells together •Provide mechanism for intercellular communication
Types
Desmosomes Tight junctions Gap junctions
77
Signaling can be LOCAL or DISTANT
Neuroendocrine ECL cell in a gastric gland
Gustafsson et al 2011; 46: 531-7.
78
Intracellular signal transduction
79
http://www.stolaf.edu/people/giannini/flashanimat/celldivision/crome3.swf http://www.johnkyrk.com/meiosis.html
http://www.cellsalive.com/howbig.htm
Selected websites CellsAlive.com: Animations and images of human cells.