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Cells,
tissue types
and
organs
MFEL3010
Ingunn Bakke (MD, PhD)
Dept of Cancer research and Molecular Medicine
Faculty of Medicine
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Outline
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?
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Structural & functional organizations
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Organ system of the body
•Lymphatic
•Respiratory
•Digestive
•Intergumentary
•Skeletal
•Muscular
•Nervous
•Endocrine
•Cardiovascular
•Urinary
•Female reproductive
•Male reproductive
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Organs of the body
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Four basic tissue types:
1
4
2
3
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You are made up of millions of cells
However, you started your life as a single fertilized egg……
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Four-cell stage of a
human embryo
Day 6: Blastocyst
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Tissues
General: embryo becomes arranged into three different tissues
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
Nature Biotechnology 23, 699 - 708 (2005)
Differentiation
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Cell structure and function
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• 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
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Plasma membrane
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Plasma membrane
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Membrane lipids
Cholesterol
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Membrane proteins
• Functioning depends on 3-D shape and chemical
characteristics
• markers
• attachment sites
• channels
• receptors
• enzymes
• or carriers
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Membrane proteins
Glycoprotein
(cell surface marker)
attachment sites
marker
receptor
enzymes
carrier
channel
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Movement through the Plasma Membrane
• Diffusion
• Osmosis
• Filtration
• Mediated transport mechanisms
– Facilitated diffusion
– Active transport
– Secondary active transport
• Endocytosis and exocytosis
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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
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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
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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)
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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
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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
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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 channelmediated. Passive.
– Active transport
– Secondary active transport
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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
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Secondary active transport
Na+
•
Ions or molecules move in same (symport) or different (antiport)
direction
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Endocytosis
Particle
Cell
processes
Phagocytic
vesicle
• Internalization of substances by
formation of a vesicle
• Types
 Phagocytosis
 Pinocytosis
 Receptor-mediated
endocytosis
Exocytosis
Accumulated vesicle
secretions expelled from cell
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Cytoplasm containing organelles
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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)
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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
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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
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Nuclear pores
Nucleus
Ribosomes
Nucleoplasm
Outer membrane
Space
Inner membrane
Nuclear
envelope
Nucleolus
Chromatin
Nuclear
envelope
Outer membrane
of nuclear envelope
Interior of
nucleus
Inner membrane
of nuclear envelope
Nuclear pores
Nucleolus
Chromatin
TEM 20,000x
• Membrane-bound
• Nucleoplasm, nucleolus and nuclear envelope
• Much of the DNA in a cell located here
SEM 50,000x
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Cells: 10-50 µm
Chromosomes: 2n =46 (diploid)
DNA: 2m
Organic base pairs: 3000mill
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How your DNA is packaged into your cells
Kinetochore
Chromosome
Chromatin
Centromere
Chromatid
Proteins
DNA
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Ribosomes
• Sites of protein
synthesis
• Composed of a large
and a small subunit
• Types
– free
– attached
(to endoplasmic
reticulum)
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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
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Golgi apparatus
• Modification, packaging,
distribution of proteins
and lipids for secretion
or internal use
• Flattened membrane
sacs stacked on each
other
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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
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Mitochondria
•
•
Major site of ATP synthesis
Mitochondria increase in number when cell energy requirements increase.
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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
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Outline
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?
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Relationship between cell
structure and cell function
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Eukaryotic cell
Form and function!
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cultured hippocampal neurons
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Human Cervical Adenocarcinoma Cells (HeLa Line)
•peroxisomes and intracellular microtubular network,
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),
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Human Cervical Adenocarcinoma Cells (HeLa Line)
Nuclear DNA
Filamentous actin
Golgi apperatures
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Human Bone Osteosarcoma Cells (U-2 OS)
endoplasmic reticulum
filamentous actin
nuclear DNA
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How do cells make proteins?
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Overview of protein synthesis
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Overview of protein synthesis
Transcription: DNA used to form RNA
Translation: synthesis of protein at the ribosomes
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Transcription
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
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Post-transcriptional modification of mRNA
Pre-mRNA formed
Transcription
DNA
Specific RNA regions
Pre-mRNA
Pre-mRNA
Exon 1
Intron Exon 2
Cut
Cut
Intron
Processing
Exon 1
mRNA
Exon 2
Exon 1
Exon 2
Splice
The genes of most living things are
divided up into exons (coding) and
introns (non-coding).
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Translation
Animation:
http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf
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Protein structure
• Primary, secondary, tertiary,
quaternary
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Cell cycle
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DNA-replication
Cytosine
Thymine
Guanine
Adenine
Original
DNA molecule
5′
3′
DNA strands
seperate
5′
Old strand
(template)
Nucleotide
3′
Old strand
(template)
New
strands
5′
5′
3′
New DNA molecule
3′
New DNA molecule
The protein BRCA1 helps repair DNA.
Suhail Islam, Imperial Cancer Research Fund, London
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Steps of Mitosis
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Meiosis
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Why do cells differ?
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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.
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Transcription factors
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Structural & functional organizations
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Four basic tissue types:
1
4
2
3
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Skin and hypodermis
Hairs
Epidermis
Sebaceous
gland
Arrector pili
(smooth muscle)
Hair follicle
Skin
Dermis
Nerve
Vein
Artery
Sweat gland
Fat
Hypodermis
(subcutaneous
tissue)
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How do cells communicate?
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Homeostasis
Stimuli ex. cold exposure
Hypothalamus
Pituitary
Thyroid
gland
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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
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Signaling can be LOCAL or DISTANT
Neuroendocrine ECL cell
in a gastric gland
Gustafsson et al 2011; 46: 531-7.
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Intracellular signal transduction
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Selected websites
CellsAlive.com:
Animations and images of human cells.
http://www.cellsalive.com/howbig.htm
http://www.stolaf.edu/people/giannini/flashanimat/celldivision/crome3.swf
http://www.johnkyrk.com/meiosis.html