Transcript A&P I Exam 2 Review Slides Spring 2014 Lectures 5-8 Ch. 2, 3, and 24 (cell resp.)

A&P I Exam 2 Review Slides
Spring 2014
Lectures 5-8
Ch. 2, 3, and 24 (cell resp.)
Cell Membranes
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
2
Passage of Materials through the Cell Membrane
Carrier/channel
proteins required
for all but fatsoluble molecules
and small
uncharged
molecules
oxygen, carbon
dioxide and other
lipid-soluble
substances diffuse
freely through the
membrane
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Cellular Transport Review
TRANSPORT
PROCESS
IS
ENERGY
NEEDED?
CONCENTRATION
GRADIENT
GENERAL
DESCRIPTION
EXAMPLE
IN
HUMANS
SIGNIFICANCE
SIMPLE
DIFFUSION
NO
[HIGH]
TO
[LOW]
spreading out of
molecules to
equilibrium
O2 into cells; CO2
out of cells.
Cellular
Respiration
FACILITATED
DIFFUSION
NO
[HIGH]
TO
[LOW]
Using a special carrier
protein to move
something through the
cell membrane (cm)
Process by which
glucose enters
cells
OSMOSIS
NO
[HIGH]
TO
[LOW]
water (solvent) moving
through the cell
membrane to dilute a
solute
maintenance
of osmotic
pressure.
Same
FILTRATION
NO
[HIGH]
TO
[LOW]
using pressure to push
something through a cell
mmembrane (sprinkler
hose)
manner in which
the kidney filters
things from blood
Separates small
from large
molecules using
hydrostatic pressure
ACTIVE
TRANSPORT
YES
[LOW]
TO
[HIGH]
opposite of diffusion at
the expense of energy
K+-Na+-ATPase
pump
maintenance of the
resting
membrane
potential
Cellular Transport Review
TRANSPORT
PROCESS
IS
ENERGY
NEEDED?
CONCENTRATION
GRADIENT
GENERAL
DESCRIPTION
EXAMPLE
IN
HUMANS
ENDOCYTOSIS
YES
[LOW]
TO
[HIGH]
bringing a
substance
into the cell
that is too
large to
enter by
any of the
above
ways;
Phagocytosi: cell
eating;
Pinocytosis: cell
drinking.
Phagocytosed
(foreign)
particles
fuse with
lysosomes
to be
destroyed
help fight infection
EXOCYTOSIS
YES
[LOW]
TO
[HIGH]
expelling a
substance
from the
cell into
ECF
Exporting
proteins;
dumping
waste
Same
SIGNIFICANCE
Osmotic Pressure/Tonicity
Osmotic Pressure (Osmolarity) – ability of solute to generate
enough pressure to move a volume of water by osmosis
*Osmotic pressure increases as the number of nonpermeable
solutes particles increases
0.9% NaCl
• isotonic – same
5.0% Glucose
osmotic pressure as a
second solution
• hypertonic – higher
osmotic pressure
• hypOtonic – lower
osmotic pressure
Crenation
The O in
o
hyp tonic
Cellular Organelles
Table 1 of 2
CELL COMPONENT
DESCRIPTION/
STRUCTURE
FUNCTION(S)
CELL MEMBRANE
Bilayer of phospholipids with proteins
dispersed throughout
cell boundary; selectively permeable
(i.e. controls what enters and
leaves the cell; membrane
transport)
CYTOPLASM
jelly-like fluid (70% water)
suspends organelles in cell
NUCLEUS
Central control center of cell; bound
by lipid bilayer membrane;
contains chromatin (loosely
colied DNA and proteins)
controls all cellular activity by
directing protein synthesis (i.e.
instructing the cell what
proteins/enzymes to make.
NUCLEOLUS
dense spherical body(ies) within
nucleus; RNA & protein
Ribosome synthesis
RIBOSOMES
RNA & protein; dispersed throughout
cytoplasm or studded on ER
protein synthesis
ROUGH ER
Membranous network studded with
ribosomes
protein synthesis
SMOOTH ER
Membranous network lacking
ribosomes
lipid & cholesterol synthesis
GOLGI
“Stack of Pancakes”; cisternae
modification, transport, and packaging
of proteins
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Cellular Organelles
Table 2 of 2
CELL COMPONENT
DESCRIPTION/
STRUCTURE
FUNCTION(S)
LYSOSOMES
Membranous sac of digestive enzymes
destruction of worn cell parts
(“autolysis) and foreign particles
PEROXISOMES
Membranous sacs filled with oxidase
enzymes (catalase)
detoxification of harmful substances
(i.e. ethanol, drugs, etc.)
MITOCHONDRIA
Kidney shaped organelles whose inner
membrane is folded into “cristae”.
Site of Cellular Respiration;
“Powerhouse of Cell”
FLAGELLA
long, tail-like extension; human sperm
locomotion
CILIA
short, eyelash extensions;
human trachea & fallopian tube
to allow for passage of substances
through passageways
MICROVILLI
microscopic ruffling of cell membrane
increase surface area
CENTRIOLES
paired cylinders of microtubules at
right angles near nucleus
aid in chromosome alignment and
movement during metaphase,
anaphase, and telophase of mitosis
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A Closer Look at Mitochondria
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
(Impermeable to charged or polar molecules)
Mitochondria
• membranous sacs with
inner partitions
• contain their own DNA
• generate energy
Strategically
placed in cell
where ATP
demand is high
Concentration of enzymes in the matrix is so high that there is
virtually no hydrating water. Enzyme-linked reactions and
pathways are so crowded that normal rules of diffusion do not apply!
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Overview of Cellular Respiration
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Anaerobic
ATP
e-
*Most ATP from here
Cellular
respiration
(aerobic)
e-
ETS
+ e-
e-
ATP
• Structural – Functional Relationship - Inner membrane:
• Contains Matrix where TCA cycle takes place
• Has enzymes and molecules that allow Electron Transport System to be carried out
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Overview of Glucose Breakdown
NAD+
NADH
NAD+
NADH
NAD+, FAD
NADH
FADH2
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Figure from: Hole’s Human A&P, 12th edition, 2010
Anaerobic Glycolysis & Lactic Acid
During glycolysis, if O2 is not
present in sufficient quantity,
lactic acid is generated to keep
glycolysis going so it continues
to generate ATP (even without
mitochondria)
Figure from: Hole’s Human A&P, 12th edition, 2010
NOTE what happens with and
without O2 being available…
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Summary Table of Cell Respiration
Where it takes
place
Products Produced
Purpose
What goes on
GLYCOLYSIS
TCA
ETC
Cytoplasm
Mitochondria
Mitochondria
ATP
NADH
Pyruvate
Breakdown of glucose
(6 carbons) to 2
molecules of pyruvate
(3 carbons)
1. Glucose is
converted to pyruvate,
which is converted to
acetyl CoA when there
is sufficient O2
present.
2. Acetyl CoA enters
the TCA cycle.
3. If O2 is not present,
pyruvate is converted
to lactic acid to
replenish the supply of
NAD+ so glycolysis
can continue to make
ATP
ATP
NADH,FADH2
CO2
Generation of energy
intermediates (NADH,
FADH2, ATP) and CO2
ATP
NAD+,FAD
H2O
Generation of ATP and reduction
of O2 to H2O (Recall that
reduction is the addition of
electrons)
1. The energy in acetyl CoA 1. Chemiosmosis (that drives
is trapped in activated
oxidative phosphorylation) uses
carriers of electrons (NADH, the electrons donated by NADH
FADH2) and activated
and FADH2 to eject H+ from the
carriers of phosphate groups matrix of the mitochondria to the
(ATP).
intermembrane space.
2. The carries of electrons
that trap the energy from
2. These H+ then flow down
acetyl CoA bring their high
their concentration gradient
energy electrons to the
through a protein (ATP synthase)
electron transport chain.
that makes ATP from ADP and
phosphate.
3. During this process, the H+
that come through the channel in
ATP synthase are combined with
O2 to make H2O.
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Cell Nucleus
• control center of cell
• nuclear envelope
(membrane)
• porous double membrane
• separates nucleoplasm from
cytoplasm (*eukaryotes only)
• nucleolus
• dense collection of RNA and
proteins
• site of ribosome production
• chromatin
• fibers of DNA and proteins
• stores information for synthesis
of proteins
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson
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The Cell Cycle
• series of changes a cell
undergoes from the time it
forms until the time it divides
• stages
• interphase
• mitosis
• cytoplasmic division
• differentiation
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson
Differentiated cells may spend all their time in ‘G0’ (neurons, skeletal muscle, red
blood cells). Stem cells may never enter G0
Why the Cell Cycle Must Have Controls
1. DNA/Cell replication must not proceed unless a ‘signal to
proceed’ is received
2. DNA must be completely and correctly replicate before
mitosis takes place otherwise it should not occur.
3. Chromosomes must be correctly positioned during mitosis
so they are separated correctly
What are the Controls of the Cell Cycle?
• cell division capacities vary greatly among cell types
• skin and bone marrow cells divide often
• liver cells divide a specific number of times then cease
• chromosome tips (telomeres) that shorten with each mitosis
provide a mitotic clock (cell senescence)
• cells divide to provide a more favorable surface area to
volume relationship
• growth factors and hormones stimulate cell division
• hormones stimulate mitosis of smooth muscle cells in uterus
• epidermal growth factor stimulates growth of new skin
• contact inhibition
• Cyclins and Cyclin-dependent kinases provide central control
• tumors are the consequence of a loss of cell cycle control
Mitosis and Meiosis
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Mitosis – production of two identical diploid daughter cells
Meiosis – production of four genetically varied, haploid gametes
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The Cell Cycle and Mitosis
• I (INTERPHASE)
• PASSED (PROPHASE)
• MY (METAPHASE)
• ANATOMY (ANAPHASE)
• TEST (TELOPHASE/CYTOKINESIS)
Interphase and Mitosis (IPMAT)
Interphase
Metaphase
Early Prophase
Anaphase
Late Prophase
Telophase/Cytokinesis
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Cell Death
• Two mechanisms of cell death
– Necrosis
– Programmed cell death (PCD or apoptosis)
• Necrosis
– Tissue degeneration following cellular injury or
destruction
– Cellular contents released into the environment
causing an inflammatory response
• Programmed Cell Death (Apoptosis)
– Orderly, contained cell disintegration
– Cellular contents are contained and cell is
immediately phagocytosed
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Stem and Progenitor Cells
Stem cell
• can divide to form two new stem cells
• can divide to form a stem cell and a progenitor cell
• totipotent – can give rise to any cell type (Embryonic stem
cells)
• pluripotent – can give rise to a restricted number of cell
types
Progenitor cell
• committed cell further along differentiation pathway
• can divide to become any of a restricted number of cells
• pluripotent
• *not self-renewing, like stem cells
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Some Definitions…
*Chromatin – combination of DNA plus histone proteins
used to pack DNA in the cell nucleus
Gene – segment of DNA that codes for a protein or RNA
- About 30,000 protein-encoding genes in humans
- DNA’s instructions are ultimately responsible for the
ability of the cell to make ALL its components
Genome – complete set of genes of an organism
- Human Genome Project was complete in 2001
- Genomes of other organisms are important also
Genetic Code – method used to translate a sequence of
nucleotides of DNA into a sequence of amino acids
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Structure of Nucleic Acids
Purines: Adenine and Guanine (double ring)
Pyrimidines: Cytosine, Thymine, and Uracil (single ring)
Figure from: Alberts et al., Essential Cell Biology, Garland Press, 1998
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Structure of DNA
5'
3'
A double-stranded
DNA molecule is
created by BASEPAIRING of the
nitrogenous bases
via HYDROGEN
bonds.
Notice the
orientation of the
sugars on each
stand.
5'
3'
*DNA is an antiparallel, double-stranded polynucleotide helix25
Structure of DNA
Complementary base pairing…
Base pairing in DNA is VERY specific.
- Adenine only pairs with Thymine (A-T)
- Guanine only pairs with Cytosine (G-C)
Note that there are:
- THREE hydrogen bonds in G-C pairs
- TWO hydrogen bonds in A-T pairs
- A purine (two rings)base hydrogen
bonds with a pyrimidine base (one ring)
Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001
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DNA Replication
5’
THINGS TO NOTE:
1. DNA is replicated in the
S phase of the cell cycle
3’
5’
3’
3. DNA polymerase has a
proofreading function
(1 mistake in 109
nucleotides copied!)
5’
3’
3’
5’
3’
Figure from: Martini, “Human Anatomy &
Physiology”, Prentice Hall, 2001
2. New strands are
synthesized in a 5’ to 3’
direction
5’
4. Semi-conservative
replication describes
pairing of postreplication strands of
DNA (1 new, 1 old) 27
RNA
• RNA is a polynucleotide with important
differences from DNA
– Uses Uracil (U) rather than Thymine (T)
– Uses the pentose sugar, ribose
– Usually single-stranded
• There are three important types of RNA
– mRNA (carries code for proteins)
– tRNA (the adapter for translation)
– rRNA (forms ribosomes, for protein synthesis)
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Transciption/Translation
• Transcription
– generates mRNA from DNA
– Occurs in nucleus of the cell
– Uses ribonucleotides and RNA polymerase to synthesize
mRNA
• Translation
– generates polypeptides (proteins) from mRNA
– Occurs in the cytoplasm of the cell
– Uses 3 components: mRNA, tRNA w/aa, and ribosomes
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The Genetic Code
1. Codon – group of three ribonucleotides found in mRNA that specifies an aa
2. Anticodon – group of three ribonucleotides found in tRNA that allows specific
hydrogen bonding with mRNA
3. AUG is a start codon and also codes for MET. UAA, UAG, and UGA are stop codons
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that terminate the translation of the mRNA strand.
Find the AMINO ACID SEQUENCE that corresponds to the following gene region on
the DNA:
Template -> C T A A G T A C T
Coding
-> G A T T C A T G A
tRNAs
Transfer RNAs (tRNA) function as
‘adapters’ to allow instructions in the
form of nucleic acid to be converted
to amino acids.
Figures from:
Martini,
Anatomy &
Physiology,
Prentice Hall,
2001
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Eukaryotic Genes
The template strand of DNA is the one that’s transcribed.
The coding strand of DNA is used as the complementary
strand for the template strand in DNA and looks like the
codons.
Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998
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Eukaryotic mRNA Modification
Newly made eukaryotic
mRNA molecules
(primary transcripts)
undergo modification in
the nucleus prior to
being exported to the
cytoplasm.
1. Introns removed
2. 5' guanine cap added
3. Poly-A tail added
Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998
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The Fate of Proteins in the Cell
• Breakdown of proteins regulates the amount of a given
protein that exists at any time.
• Each protein has unique lifetime, but the lifetimes of
different proteins varies tremendously.
• Proteins with short life-spans, that are misfolded, or that
become oxidized must be destroyed and recycled by the cell.
Enzymes that degrade proteins are
called proteases. They are hydrolytic
enzymes.
Most large cytosolic proteins in
eukaryotes are degraded by enzyme
complexes called proteasomes.
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