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BIO 121 – Molecular Cell Biology
Lecture Section 1
A. Fundamental Cell Theory and Taxonomy
B. Species Variability and Cellular Genomics
C. Sources and Regulation of Genetic Change
D. The Role of Cells in Multicellular Organisms
E. Multiple Cell Types in Complex Tissues
A. Fundamental Cell Theory and Taxonomy
1. How do we define ‘alive’?
2. How do we classify living organisms?
3. What are the universal features of cells?
1. What is Life? = What are Cells?
“The basic unit of life on Earth”
“All life is cellular”
“No entity not composed of cells is alive”
OK – So What is Life?
(Our current definition of life is descriptive at best)
•
Homeostasis: Regulation of the internal environment.
•
Organization: Being structurally composed of one or more cells.
•
Metabolism: Transformation of energy by converting chemicals and
energy into cellular components (anabolism) and decomposing organic
matter (catabolism).
•
Growth: Maintenance of a higher rate of anabolism than catabolism.
•
Adaptation: The ability to change over a period of time in response to
the environment.
•
Response to stimuli: from simple to complex.
•
Reproduction: The ability to produce new individual organisms.
Fig. 16-3
Phage
head
Tail
sheath
Tail fiber
Bacterial
cell
100 nm
DNA
1. What is Life?
• Viruses are most often considered replicators rather than
forms of life.
• They have been described as "organisms at the edge of
life", since they possess genes, evolve by natural
selection, and replicate by creating multiple copies of
themselves through self-assembly.
• However, viruses do not metabolize and require a host cell
to make new products.
• Virus self-assembly within host cells has implications for
the study of the origin of life, as it may support the
hypothesis that life could have started as self-assembling
organic molecules. (Wikipedia, 2010)
1. What is Life?
• A prion is an infectious agent that causes bovine
spongiform encephalopathy and Creutzfeldt–Jakob
disease.
• Prions are mis-folded proteins that propagate by entering a
healthy organism and inducing normal forms of the protein
to convert into the rogue form.
• Since the new prions can then go on to convert more
proteins themselves, this triggers a chain reaction that
produces large amounts of the prion form.
• Evolutionarily, prion replication has been shown to be
subject to mutation and natural selection just like other
forms of replication. (Wikipedia, 2010)
2. How do we classify living organisms?
• Domains: Archaea, Bacteria, Eukarya
• Old Version: Prokarya and Eukarya
(Kingdoms in Prokarya: Bacteria, Archaea)
• Kingdoms in Eukarya: Animalia, Plantae,
Fungi, Protista
Figure 1-21 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
How do we classify living organisms?
•
Phyla (Animalia):
Chordata, Echinodermata, Arthropoda, Annelida, Mollusca,
Nematoda, Platyhelminthes, Cnidaria, Porifera
•
Sub-Phyla (Chordata): Vertebrata, Urochordata, Cephalochordata
•
Class (Vertebrata): Mammalia, Amphibia, Reptilia, Osteicthyes, Aves
•
Order (Mammalia): Primates, Rodentia, Artiodactyla, Perissodactyla......
•
Genus/Species (Primates):
Homo sapiens Pan troglodytes Macaca mulatta........
The closer together the taxa, the more similarities in the cells...
How many cellular species are there?
• Estimates range from 10-100 million species
• Only ~1.8 million have been identified and
named
• Vertebrates
• Invertebrates
62,305
1,305,250
• Plants
321,212
• Fungi
100,000
• Estimated 5–10 million bacteria
3. The universal features of cells
a. Basic features of all cells
Plasma membrane: Selectively permeable lipid bilayer
Cytosol: Variably viscous internal fluid
Double-stranded DNA, RNA and proteins
Require an external source of energy
Metabolism: Build-up and break-down of molecules
Intracellular homeostasis
Ability to sense and respond to the environment
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
b. Differences Between Euks and Proks
• Eukaryotic cells are generally much larger than prokaryotic
cells (a few mm, 15X larger, 1000X greater in volume)
• Eukaryotic cells are also characterized by having stuff
prokaryotes don’t have:
– Membrane-bound organelles
– Compartmentalized function
– Multicellular organisms
– *Extracellular homeostasis
– *Cytoskeleton
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Prokaryotic
examples of
these have
begun to blur
the lines!
Prokaryotes:
Cytoplasm bound by plasma membrane, no organelles
No nucleus, DNA in an unbound region called the nucleoid
Nucleoid
Plasma membrane
Bacterial
chromosome
Cell wall
The plasma membrane is a selective
barrier that allows sufficient passage of
oxygen, nutrients, and waste to service
the volume of every cell
Nuclear
envelope
Typical
animal
cell
Rough ER
Smooth ER
Plasma
membrane
CYTOSKELETON:
Microfilaments
Intermediate
filaments
Microtubules
Golgi
apparatus
Mitochondrion
Lysosome
Fig. 6-9b
Nuclear envelope
Rough endoplasmic
reticulum
Plant and
animal cells
have most of
the same
organelles
Smooth endoplasmic
reticulum
Central vacuole
Golgi
apparatus
Microfilaments
Intermediate
filaments
Microtubules
CYTOSKELETON
Mitochondrion
Chloroplast
Plasma
membrane
Cell wall
Plasmodesmata
Wall of adjacent cell
Same for fungi
and protists.....
B. Species Variability and Cellular Genomics
1. The Existing Genomes in the World Today
2. Non-Nuclear Contributions to the Genome
3. Gene Conservation and Model Organisms
All cells store their hereditary info in doublestranded DNA, use RNA as an intermediate and
protein as the principle functional molecules.
genome = a species’ DNA sequence
genotype = an individual within a species DNA sequence
•
Nearly all of the cells in an individual have exactly the same DNA, only
the sex cells are different by being randomly assorted haploids
traditional genetic phenotype = variations in visible ‘characters’
molecular phenotype = variations in protein sequence and function
cellular phenotype = cell specialization in multicellular organisms
resulting from expression of a subset of the inherited genotype
1. The Existing Genomes in the World
a. The number of bases and the complexity of their
organization vary far more than the number of
genes
b. The conservation of critical functions and the
base sequence of the genes that code for them
show that all cells are related
c. These close structure and function relationships
allow us to gain information about ourselves from
a wide variety of organisms
a. Life’s genetic complexity is less than you think.
• The smallest genome: Mycoplasma genitalia has
477 genes (580,070 bases)
• The largest animal genome: The waterflea,
Daphnia pulex, has 31,000 genes (200M bases)
• Arguably, the most complex: Homo sapiens has
~24,000 genes and ~3 billion bases in our 46
chromosomes.
• There is a fundamental ‘core’ of genes shared by
ALL organisms of about 60 genes
Figure 1-37 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
• 477 genes compared to 31,000 = ~65X
• 580K bases compared to 3B = ~5,000X
• We have only a 40 fold increase in gene
number over Mycoplasma genitalia!
• The big difference between eukarya and
prokarya is in non-coding sequence
Mycoplasma genitalia
Figure 1-14a Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Mycoplasma genitalium: 477 genes, 580,070 basepairs
37 code for non-messenger RNAs
297 of the 440 that code for protein are ‘known’
153 processing of DNA, RNA, protein
71 involved in metabolism
33 involved in nutrient transport
29 involved in surface membrane
11 involved in cell division
143 remain unidentified
Prokaryotic cells
DNA is a single, circular double helix containing 106-107
base pairs and 1,000-6,000 genes
Eukaryotic cells
Chromosomes are linear DNA molecules (fruit flies have
10, we have 46, dogs 78, etc.)
Smallest chromosome in humans is 2 million bases, total
DNA is 3.2 x 109 base pairs
As animals become more complex, not just more DNA in
the nucleus, embedded controls become more complex
Our chromosomes are 50% protein!!
Plants have greater tendency to have [DNA] change
2. Eukaryotes also have genes from their
mitochondria and/or chloroplasts
• Our mitochondria have a genome of 16,569
base pairs which codes for:
– 13 proteins
– 2 ribosomal RNA components
– 22 transfer RNAs
– The rest of the functional DNA components for
mitochondrial function reside in the nucleus
Human Mitochondrial Genome
Several neuromuscular
diseases are associated
with mitochondrial mutations
Chloroplast Genome
Usually 110-120 genes
Some as high as 200
3. Gene Conservation and Model Organisms
1. If the function is essential and unchanged, the
structure (sequence) must be unchanged because you’d die if you lost an essential function.
2. Example 1: All cells from bacteria to humans have
extremely high sequence homology (structure) in
the small ribosomal sub-unit because they use the
same mechanism to express DNA (function).
3. Example 2: MADS-box family transcription factors
have been found in every eukaryotic cell type on
Earth.1. MEF-2, agrafens, deficiens, SRF
Conservation of sequence of the small ribosomal subunit
Figure 1-22 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Model Organisms
1. Prokaryotic bacteria: Escherichia coli
2. Eukaryotic yeast: Saccharomyces cerivisiae
3. Eukaryotic protists: Tetrahymena pyriformis
4. Complex plants: Lycopersicon esculentum and Arabidopsis thaliana
5. Nematode worms and fruitflies: Caenorhabditis elegans and Drosophila
melanogaster
6. Frogs, fish and birds: Xenopus laevis, Danio rerio, Gallus gallus,
Coturnix coturnix
7. Rats and mouse: Rattus norvegicus and Mus musculus
8. Chimpanzees and monkeys: Pan troglodytes, Macaca mulatta (rhesus)
9. Humans: Homo sapiens
Figure 4-83 Molecular Biology of the Cell (© Garland Science 2008)
Saccharomyces
cerevisiae
Figure 1-42a Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Arabidopsis
thaliana
Figure 1-46 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Caenorhabditis elegans
Figure 1-47 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Drosophila
melanogaster
Figure 1-48 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Xenopus
tropicalis
Xenopus
laevis
Figure 1-50 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Figure 1-53 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
C. Sources and Regulation of Genetic Variability
1. Natural genetic flow
2. Generation of new genes
3. Disruption or loss of existing genes
4. Size of a genome reflects the relative DNA
addition and DNA loss
1. Natural Genetic Flow
• Bacteria have multiple mechanisms
– Plasmids can cause horizontal gene transfer
across species
– Viruses can cause horizontal gene transfer
across species
Independent Assortment of Chromosomes during
Meiosis in Sexually Reproducing Organisms
• Homologous pairs of chromosomes orient randomly at
metaphase I of meiosis
• In independent assortment, each pair of chromosomes
sorts maternal and paternal homologues into daughter
cells independently of the other pairs
• The number of combinations possible when chromosomes
assort independently into gametes is 2n, where n is the
haploid number
• For humans (n = 23), there are more than 8 million (223)
possible combinations of chromosomes
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13-12-5
Prophase I
of meiosis
Pair of
homologs
Nonsister
chromatids
held together
during synapsis
Chiasma
Centromere
Crossing over
TEM
Anaphase I
Anaphase II
Daughter
cells
Recombinant chromosomes
Random Fertilization
• Random fertilization adds to genetic variation
because any sperm can fuse with any ovum
(unfertilized egg)
• The fusion of two gametes (each with 8.4
million possible chromosome combinations
from independent assortment) produces a
zygote with any of about 70 trillion diploid
combinations
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Crossing Over
• Crossing over produces recombinant chromosomes,
which combine genes inherited from each parent
• Crossing over begins very early in prophase I, as
homologous chromosomes pair up gene by gene
• In crossing over, homologous portions of two nonsister
chromatids trade places
• Crossing over contributes to genetic variation by combining
DNA from two parents into a single chromosome
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Transposable Elements
• “Parasitic” DNA sequences that colonize genomes
and spread within them – many resemble viruses
• Can disrupt gene function, alter regulation
• Can create new genes by integration within and
fusion with host gene segments
• Half of all human DNA has homology to known
transposons
• 10% of currently occurring mouse mutations are
transposon-driven
Figure 4-17 Molecular Biology of the Cell (© Garland Science 2008)
2. Generation of New Genes: New genes are generated from
preexisting genes, no mechanism for new synthesis
a. Gene Duplication - provides an important source of
genetic novelty
b. DNA Shuffling - Reassortment during homologous
recombination
c. Horizontal Transfer - Genes transferred between
organisms, in the lab and in nature
d. Transposable elements
e. Mutation - Accidents/mistakes followed by nonrandom survival
Figure 1-23 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
The evolution of sex has had a big impact on
the first three.....
• Gene Duplication
• DNA Shuffling
• Horizontal Transfer
Gene Duplication
• The idea is that during meiosis in sexually
reproducing organisms, crossover mutations
can form multiple copies of an exon, a gene, a
chromosome or the entire genome.
• The organism survived just fine with one copy
so it only repairs damages to one copy, leaving
the other to freely mutate.
• Once in a blue moon the mutated copy
develops new, advantageous functions.
Gene Duplication
Figure 4-86 Molecular Biology of the Cell (© Garland Science 2008)
Xenopus
tropicalis
Xenopus
laevis
Figure 1-50 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Whole
genome
duplication!
DNA Shuffling
• Pieces of different genes can be combined to
form new genes with hybrid functions
• Incomplete or partial cross-over events
• Insertion of small numbers of nucleotides
may alter the reading frame, producing a
frameshift mutation and produce novel
gene functions
Gene Families
a. Gene duplications give rise to families of
related genes in a single cell
b. More than 200 gene families are common to
all three domains
c. The function of a gene can often be deduced
from its sequence
Duplication and Divergence Give Rise to
Related Genes – Very Common Events!
• 4873 protein-coding gene families have been
identified in life on earth
– 264 are designated ‘ancient’ - in all lineages
– 63 are ubiquitous in all genomes analyzed
• Most of the shared ‘ancient’ families perform:
– replication and transcription
– translation and amino acid metabolism
Bacillus subtilis
4014 Genes
47% in families
ABC Transporter
family has 77
members in this
single bacterium!
Figure 1-24 Molecular Biology of the Cell, Fifth Edition (© Garland Science 2008)
Expansion of gene families gives rise to function
• Transcription factors regulate gene expression and, thus,
cell diversity and complexity in multicellular organisms
–
bHLH TFs: 7 in yeast, 41 in worms, 84 in flies, 131 in humans
• Adhesion and signaling are far more critical in multicellular
animals
–
2000 major plasmamembrane proteins in worms not present or in
low numbers in yeast
3. Disruption or loss of existing genes
a. DNA Shuffling - Reassortment during homologous
recombination
b. Transposable elements
c. Mutation - Accidents/mistakes followed by non-random
survival
c. Background on DNA Mutations
1. Mutation rates are extremely low but
are an essential component of
evolutionary change
2. The most common source of DNA
mutation is error during replication
3. Environmental damage to the DNA
is independent of DNA mutation but
can also be the underlying cause
Potential outcomes in protein expression and
phenotype
a. Silent mutations have no effect on the amino acid
produced because of redundancy
b. Missense mutations still code for an amino acid,
but not necessarily the right amino acid
c. Nonsense mutations change an amino acid
codon into a stop codon, nearly always leading to
a nonfunctional protein
d. Insertion or deletion of nucleotides may alter the
reading frame, producing a frameshift mutation
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
1. Intragenic Mutation
• Only 1 nucleotide pair per 1,000 is randomly
changed in the germline per 1 million years
however.....
• This means that in a population of 10,000
every possible nucleotide substitution will have
been tried out ~20 times in a million years
Mutation rates are extremely low but are an essential
component of evolutionary change
• Mutations that become part of the multicellular
genome must occur in the cells of the germ line
• Somatic mutations may or may not affect the
individual but cannot affect the population
• Low rates of mutation can result in high rates of
evolution in single-celled organisms
Figure 5-1 Molecular Biology of the Cell (© Garland Science 2008)
2. The most common source of DNA mutation is
error during replication
• There is an average mistake of 1 base pair
every 10,000
• Due to proofreading and repair mechanisms
this rate declines to 1 every 1,000,000,000
• Inherent in meiosis are assortment and crossover events that lead to highly significant
changes in germ line DNA sequences
c. Single-stranded and double-stranded
breaks can result from reactive oxygen
species activity
1. ROS are generated by either endogenous metabolic
processes or exogenous ionizing radiation (like gamma
and X-rays)
2. DNA mutation is the loss or gain of significant amounts
of DNA, including chromosomal deletions, additions
3. Potential outcomes range from gene shuffling in or
across chromosomes, gene inactivation, altered gene
regulation, gene duplication
4. DNA repair system that can remove these mutations
1. ROS are generated by either endogenous metabolic
processes or exogenous ionizing radiation (like gamma
and X-rays)
c. Size of a genome reflects the relative DNA
addition and DNA loss
• Both loss and gain occur constantly
• The relative rates determine size
The Fugu – experienced a long period of low rates of
DNA addition accompanied by normal rates of DNA loss
Figure 4-81 Molecular Biology of the Cell (© Garland Science 2008)
The huntington Gene
-High homology
-Perfect exon alignment
-Small introns
-Little non-coding DNA
Figure 4-82 Molecular Biology of the Cell (© Garland Science 2008)
D. The Role of Cells in Multicellular Organisms
1. Regulation of Organism Size by Cell Mass
2. Regulation of Extracellular Structure
3. Regulation of Cell Adhesion
4. Regulation of the Internal Aqueous Environment
5. Regulation by Intercellular Communication
6. Regulation by Cell Specialization
1. Regulation of Organism Size by Total Cell Mass
Cell mass determines the size of an organism
and is a combination of cell size and number
a. The size of cells varies among organisms
b. Cell number is a balance between cell division
and cell death
b. Numbers in a Cell Population
•
Cell number is a combination of....
• Cell divisions – Cell deaths (necrotic + programmed)
• Necrosis is premature cell death
– disease, injury, starvation, toxicity, excitotoxicity
• Programmed cell death is death by design
– apoptosis, anoikis, cornification, autophagy
•
Same for an organism, system, organ or tissue, and for single cell
populations in an ecosystem
We’ve even learned to control it.........
A mutation in a signal molecule that limits muscle cell division has been bred in.
Figure 17-69 Molecular Biology of the Cell (© Garland Science 2008)
2. Regulation of Extracellular Structure
• These extracellular materials are produced
and organized by the cells themselves.
• Extracellular structures keep the organism
intact and allow coordinated function
• Mechanical support and defense
• Adhesion for cells and tissues
• Substrate for cell and organismal movement
• Regulation of cell growth and function
• Animal cells secrete an elaborate “ECM”
•
Vertebrate four compound ECM
•
Exoskeletal carapace in many arthropods
• Plants, fungi and prokaryotes secrete a sugar “cell wall”
•
Cellulose cell wall in plant cells
•
Chitin in fungi
•
(Pseudo-) peptidoglycan in prokaryotes
• Bacterial cells secrete “plaques”
•
Extracellular polymeric substance: DNA, protein and
polysaccarides (including cellulose)
b. Variations in Animal ECM
• Basic components
Vertebrates
• Sugar Ground Substance
glycosaminoglycans
• Protein Organizers
proteoglycans
• Tensile Strength
collagen, fibronectin
• Tissue Flexibility
elastic proteins
• Hardening Agents
Ca2+-apatite for bone
Figure 19-56 Molecular Biology of the Cell (© Garland Science 2008)
b. Variations in Animal ECM
• Basic components
Arthropods
• Sugar Ground Substance
chitin
• Proteinaceous matrix
leathery structure
• Hardening Agents
Ca2+-carbonate
b. Variations in sugar cell walls
• Plants/Algae
cellulose
pectin
crossslinking glycan
Fungi
Prokaryotes
chitin
Bacteria
peptidoglycan
Archaea
pseudopeptidoglycan
Figure 19-79 Molecular Biology of the Cell (© Garland Science 2008)
Bacterial Biofilms are ECM for Populations
Cells become:
-adherent
-differentiated
-cooperative
Components:
-DNA
-proteins
-polysaccharides
(cellulose)
3. Regulation of Cell Adhesion
• Most of the cells of multicellular organisms
must adhere to survive – VERY few are free
• Cells adhere to other cells, the ECM or, quite
commonly, to both
• It is also common for cells that lose their
appropriate attachments to undergo anoikis
Figure 19-1 Molecular Biology of the Cell (© Garland Science 2008)
4. The Internal Aqueous Environment
• All multicellular organisms on Earth maintain
an aqueous environment
• Most animals have the roughly the same pH
and ion concentrations as sea water
• Plants are more dependent on their external
environment for these
• Some of us maintain the water temperature,
others rely on solar energy
• All plants and animals have water in their cells and
in the extracellular matrix
• Some also have water in a vascular system that
can exchange that water with tissues
• Animals with a GI or respiratory systems also
exchange water with those systems
• Vertebrate animals also have a specialized
cerebrospinal and lymphatic fluid systems
5. Regulation by Intercellular Communication
Single celled organisms use intercellular signals to
coordinate such things as gene expression, mating,
sporulation and cell death in response to population
density, nutrients, stress and other cues.
Multicellular organisms use intercellular communications
to coordinate the activities of their component cells.
– The overall purpose is to coordinate the activities of
multiple cells in response to the needs of the organism
and changes in its environment.
• We have evolved very complex cell
communications systems to regulate our
100 trillion cells
• These pathways are similar to and likely
arose from those that single celled
organisms use to molecularly sense their
environments.
• Much of our genetic energy is spent on
cell signaling and control.
1. Paracrine signaling
2. Endocrine signaling
3. Synaptic signaling
4. Juxtacrine signalling
5. Cytosolic sharing
Figure 15-5a Molecular Biology of the Cell (© Garland Science 2008)
Figure 15-4c Molecular Biology of the Cell (© Garland Science 2008)
“Juxtacrine”
Figure 15-4a Molecular Biology of the Cell (© Garland Science 2008)
Fig. 6-31
Plasmodesmata in Plant Cells
Cell walls
Interior
of cell
Interior
of cell
0.5 µm
Plasmodesmata Plasma membranes
Gap Junctions in Animal Cells
6. Regulation by Cell Specialization
Cells of an organism share the exact same
DNA but they can be very different
a. There are over 200 cell types in adult humans
b. Cell types are determined by differential gene expression
Anatomical Organization in Multicellular
Organisms is Based on Cell Functions
Tissues are made up of multiple cell types
Organs are made up of multiple tissue types
Systems are made up of multiple organs
Anatomical Organization in Multicellular
Organisms is Based on Cell Functions
• Characteristic Types of Cells
• epithelial vs. mesenchymal
• parenchymal vs. support
• stem cells vs. adult cells
E. Four Types of Vertebrate Tissue
1.Epithelium
2.Connective Tissue
3.Muscle
4.Nervous Tissue
1. Architecture of Epithelium
• Simple, Stratified, Pseudostratified, Transitional
• Squamous, Cuboidal, Columnar
• Ciliated or not
• Examples:
–
Small Intestine = Simple Columnar Epithelium
–
Trachea = Ciliated Pseudostratified Columnar Epithelium
–
Blood Vessel = Simple Squamous Epithelium
–
Skin = Stratified Squamous Epithelium
Structure equals Function
– Small Intestine:
Simple Columnar Epithelium = absorption
– Trachea:
Ciliated Pseudostratified Columnar Epithelium = filtering debris
– Blood Vessel:
Simple Squamous Epithelium = gas exchange
– Skin:
Stratified Squamous Epithelium = protective physical barrier
Simple,
Columnar
Epithelium
Function:
1. absorption of nutrients
2. enzymatic digestion at neutral pH
3. multiple defensive mechanisms
4 Cell types in Small Intestine
Small Intestine
Cellular Adhesion in Small Intestine
Desmosomes
Hemidesmosomes
Adherens Junctions
Occluding Junctions
Tracheal Epithelium
Ciliated
Pseudostratified
Columnar Epithelium
with Goblet Cells
1. Mucus traps dust and
air-borne
microorganisms
2. Ciliar waving gets rid of
unwanted material
The Vasculature: Simple, Squamous
Epithelium
Gas Exchange
Fluid Exchenge
Epidermis of Skin
Stratified
Squamous
Epithelium
Creates
tough,
waterproof
barrier
Differentiation and Direction of Movement in
Epidermis
Cornification
is the overproduction
of
cytokeratins,
ECM and
the
adhesions to
a degree
that stops
cellular
metabolism.
2. Mesenchymal Cell Types and Connective Tissues
Figure 23-52 Molecular Biology of the Cell (© Garland Science 2008)
The Fibroblast
Loose Connective Tissue
Dense Irregular CT
Dense Regular CT
Elastic Connective Tissue
The dermis is as
complex as the
epidermis and
contributes greatly to
skin function
Cartilage and the Chondrocyte
Lacunar Structure of the Hyaline Cartilage
Extremely low blood flow
Osteoblasts
Lacunar structure of the long bone
Cortical Bone vs. Spongy Bone
Cell Types of the Bone
Marrow of
Long Bones
has Stem
Cells
Start out as cartilage models built by chondrocytes
Chondrocytes hypertrophy, calcify and die
Osteoblasts and osteoclasts finish up
The Adipocyte
Mesenchymal
Stem Cells are a
continuous
source of
adipocytes
3. Contractile Tissue
Figure 23-47a Molecular Biology of the Cell (© Garland Science 2008)
Arteries, veins
Lymphatic vessels
Gastrointestinal tract
Respiratory tract
Urinary bladder
Reproductive tract
Urinary tract
Iris of the eye
Erector pili of skin
4. Nervous Tissue
Nerve Bundles