Download Unit 1: The Cell

Unit 2 Review
The Cell
(except Cell Cycle, Ch 12!)
Break down the points on this essay question:
Prokayrotic and eukaryotic cells are physiologically
different in many ways, but both represent functional
collections of living matter.
A.It has been theorized that the organelles of eukaryotic
cells evolved from prokaryotes living symbiotically within a
larger cell. Compare & contrast the structure of the
prokaryotic cell with eukaryotic cell organelles, and make
an argument for or against this theory.
B.Trace the path of a protein in a eukaryotic cell from its
formation to its excretion from the cell.
CHAPTER 6
AN INTRODUCTION TO
METABOLISM
Section A: Metabolism, Energy, and Life
1. The chemistry of life is organized into metabolic pathways
2. Organisms transform energy
3. The energy transformations of life are subject to two laws of
thermodynamics
4. Organisms live at the expense of free energy
5. ATP powers cellular work by coupling exergonic reactions to endergonic
reactions
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• Energy conversion:
– child operates muscles to move limbs:
• P.E. (chemical)  K.E. (muscle/body movement)
– climbing to the top of a slide:
• K.E.  P.E. (altitude)
– sliding down:
• P.E.  K.E. (movement)
– friction for slowing/stopping:
• K.E.  heat energy
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Fig. 6.2
• Free energy (G): portion of a system’s
energy able to perform work.
– “Free” is a
terrible name for this,
think “available” instead.
Fig. 6.5
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• exergonic reaction:
– releases free energy
– G is negative.
– can be spontaneous
– released energy can
perform work
Fig. 6.6a
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– Cellular respiration equation:
• C6H12O6 + 6O2  6CO2 + 6H2O + energy
• G = + or - ?
– -686 kcal/mol of glucose…
• What is that 686 kcal/mol used for?
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• ATP  ADP + Pi
• G is -7.3 kcal/mol. This is exothermic
• Each phosphate group has a neg charge.
• Their repulsion creates instability.
Fig. 6.8b
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• ATP regeneration: endergonic process
requiring investment of energy: G = 7.3
kcal/mol.
• In a working muscle cell the entire pool of
ATP is recycled each minute (over 10
million ATP).
Fig. 6.10
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CHAPTER 6
AN INTRODUCTION TO
METABOLISM
Section B: Enzymes
1.
2.
3.
4.
Enzymes speed up metabolic reactions by lowering energy barriers
Enzymes are substrate specific
The active site in an enzyme’s catalytic center
A cell’s physical and chemical environment affects enzyme activity
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• Active site: a pocket or groove on the
surface of the protein into which the
substrate fits.
• induced fit definition? causes?
• conformation change to “hug” & stress substrates
• bonding with enzyme R-groups
• H-bonding with enzymes N-C-C backbone
Fig. 6.14
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1. EA.
• Enzymes speed reactions by lowering
3. Red
2. Black
Fig. 6.13
4. Enzyme names end in ???
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1.
5.
Bonus
4.
2.
3.
Fig. 6.15
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• What determines the rate of an enzyme
catalyzed reaction?
– Substrate concentrations: sufficient for
enzyme saturation?
– Enzyme Concentration
– Temp effects?
– Anything that
fouls up the
shape!
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Denaturation?
Causes?
-excessive temp
-wrong pH
-wrong salinity…
– Competitive inhibition: inhibitor binds to the
active site.
1.
Fig. 6.17a, b
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– Noncompetitive inhibition:
• binds somewhere other than active site, but
alters the active site.
1.
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• Most allosterically regulated enzymes are…
– constructed of two or more polypeptide chains.
– have an active site on each subunit
– allosteric sites are often located where
subunits join.
1.
Fig. 6.18a
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• Red line
represents?
Fig. 6.19
– negative
feedback…
– inhibits synthesis
when product is in
good supply!
• Bonus!! What are
threonine &
isoleucine?
– Amino Acids
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1.
• cooperativity:
when substrate binding at
one site activates other active sites.
– amplifies the response of enzymes to
substrates
Fig. 6.20
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CHAPTER 7
A TOUR OF THE CELL
Section A: How We Study Cells
1. Microscopes provide windows to the world of the cell
2. Cell biologists can isolate organelles to study their function
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• characteristics of ALL cells:
– plasma membrane: surrounds ALL cells
– cytosol: semifluid substance within the
membrane
– chromosomes: long DNA molecules containing
genes.
– ribosomes: tiny organelles that make proteins.
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Fig. 7.4 The prokaryotic cell is much simpler in structure, lacking a nucleus and the other
membrane-enclosed organelles of the eukaryotic cell.
Who am I, and how am I special?
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1.
2.
5.
1-5 are parts
of the ______
assembly line
3.
4.
6.
8.
7.
Fig. 7.7
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What’s new here?
Fig. 7.8
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Golgi Apparatus:
nucleus & ER
Fig. 7.12
cis face
trans face
cell membrane
•
During transit from cis  trans, products from the ER are
modified to reach their final state.
•
ex: modification of oligosaccharide portion of glycoproteins.
Now, can you explain the roles of each part of the
endomembrane system in the synthesis & processing of
membrane & proteins in the cell?
1.
Fig. 7.16
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• motor 1.
proteins pull protein fibers past each
other, causing:
• undulations of cilia & flagella;
• muscle cell contraction.
• movement of vesicles/organelles along microtubule
“monorails”
1.
Fig. 7.21
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1.
Fig. 7.24
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• Microfilaments:
– thinnest class of the cytoskeletal fibers
– two chains of actin subunits twisted together.
– resist tension.
– form a 3-D network inside the plasma
membrane.
– help cause cell contractions.
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• muscle cell contraction: myosin motor molecules “walk”
past actin microfilaments.
Fig. 7.21a
3.
Fig. 7.21b
• amoeboid movement:
actin-myosin
contractions squeeze
cytosol into expanding
pseudopodia.
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ECM:
What is this
extracellular
called?
matrix
Fig. 7.29
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CHAPTER 8
MEMBRANE STUCTURE AND
FUNCTION
Section A: Membrane Structure
1.
2.
3.
4.
Membrane models have evolved to fit new data
Membranes are fluid
Membranes are mosaics of structure and function
Membrane carbohydrates are important for cell-cell recognition
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• fluid mosaic model:
proteins “float”
1.
– hydrophobic region
stays “buried” in the
membrane
– hydrophilic regions
protrude
1.
Fig. 8.2b
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1. Membranes are fluid
• Why are flip flops rare?
Fig. 8.4a
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• Which is more fluid?
• What causes the kinks?
• When would you need “kinky H-C tails”?
Fig. 8.4b
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• cholesterol molecules (steroids) can do what
TWO things?
– dampen effects of warming and cooling on
membrane fluidity
• reduce fluidity at warm temperatures by restraining
movement of phospholipids.
• maintain fluidity at cool temperatures by preventing
tight packing.
Fig. 8.4c
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• Differences between
inner/outer surface of cell
membrane?
– may differ in lipid
composition
– proteins have a clear
direction.
– outer surface has carbs
attached.
• This begins during
synthesis of new
membrane in the …
– ER.
Fig. 8.8
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Purposes of Membrane proteins??
Fig. 8.9
• Ability of molecules to pass the membrane
depends on?
– Hydrophobic molecules (hydrocarbons, CO2, O2)
dissolve in the lipid bilayer and cross easily.
– Large molecules, ions (Na+, Cl-, Ca+2) and polar
molecules (H2O, glucose) pass through with
difficulty, Who can help?
• transport proteins can assist these molecules.
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4. Cell survival depends on
balancing water uptake and loss
3.
4.
5.
1.
6. What’s best for animal cells?
2.
7. What’s best for plant cells?
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ψw = ψs + ψp
ψp = 0 or positive.
ψs = 0 or negative.
• H2O will move
towards lowest
ψ until dynamic
equilibrium is
reached.
• What causes High ψ? Low ψ?
– High [H2O] or high pressure cause high ψw
– Solutes and/or low pressure can cause low ψw
• Facilitated Diffusion
via gated channels:
open or close due to a
physical or chemical
stimulus.
– Where would this
example occur?
• at a synapse!
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Na+
• Facilitated Diffusion via “translocation”
– transport proteins change shape to help a
solute diffuse.
– What solutes need this pathway?
Fig. 8.14b
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2.
1.
3.
Fig. 8.16 Both diffusion and facilitated diffusion are forms of passive transport of molecules down their
concentration gradient, while active transport requires an investment of energy to move molecules
against their concentration gradient.
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• Cotransport
– drives active transport of amino acids, sugars,
and other nutrients.
Fig. 8.18
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• Endocytosis (ex: phagocytosis):
– cell ingests macromolecules/particles by
forming vesicles from its plasma membrane.
• What is needed to digest the “prey”?
– fuses with lysosome
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CHAPTER 9
CELLULAR RESPIRATION:
HARVESTING CHEMICAL ENERGY
Section A: The Principles of Energy Harvest
1. Cellular respiration and fermentation are catabolic, energy-yielding
pathways
2. Cells recycle the ATP they use for work
3. Redox reactions release energy when electrons move closer to
electronegative atoms
4. Electrons “fall” from organic molecules to oxygen during cellular
respiration
5. The “fall” of electrons during respiration is stepwise, via NAD+ and an
electron transport chain
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• Two main catabolic processes for sugar
metabolism?
– fermentation – yields PARTIAL breakdown.
– cellular respiration: uses oxygen to complete the
breakdown of many organic molecules.
• more efficient and widespread
• Most steps occur in mitochondria.
?
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Really Big Picture:
• Photosynthetic organisms
store energy in organic
molecules.
– These are available to…
• themselves, and …
• others that eat them.
Fig. 9.1
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• Redox rxns often produce change in electron
sharing:
– Contrast high and low energy electron positions.
Fig. 9.3
high energy e- positions
low energy e- positions
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CHAPTER 9
CELLULAR RESPIRATION:
HARVESTING CHEMICAL ENERGY
Section B: The Process of Cellular Respiration
1. Respiration involves glycolysis, the Krebs cycle, and electron transport: an
overview
2. Glycolysis harvests chemical energy by oxidizing glucose to pyruvate: a
closer look
3. The Krebs cycle completes the energy-yielding oxidation of organic
molecules: a closer look
4. The inner mitochondrial membrane couples electron transport to ATP
synthesis: a closer look
5. Cellular respiration generates many ATP molecules for each sugar molecule
it oxidizes: a review
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1. Respiration involves glycolysis, the
Krebs cycle, and electron transport:
an overview
1.
2.
3.
Fig. 9.6
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• A little ATP is generated in glycolysis and the
Krebs cycle by substrate-level
phosphorylation.
– How is this different
from oxidative
phosphorylation?
• no e- transport
chain.
Fig. 9.7
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Glycolysis:
• Net Production?
– 2 ATP + 2 NADH
– 2 pyruvate
• NOT used?
– O2
Fig. 9.8
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For each pyruvate
that goes in...
• What high energy
electron carriers are
produced?
– Net of 2 NADH
– 1 FADH2
• How much ATP?
– one
• Where next??
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Fig. 9.12
Who’s the final
electron accepter?
+ 2 H+
Fig. 9.15
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Where is this
happening?
• ATP synthase
– What kind of
molecule is it?
– What does it do?
– What powers it?
• Push of H+ gradient
powers ATP synthase
• Chemiosmosis:
using a chemical’s
“push”
Fig. 9.14
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• lactic acid fermentation:
– Lactic acid fermentation by some fungi and bacteria is
used to make cheese and yogurt.
– Muscle cells switch from aerobic respiration to lactic
acid fermentation to generate ATP if O2 is scarce.
• lactate is converted
back to pyruvate in
the liver.
Fig. 9.17b
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CHAPTER 10
PHOTOSYNTHESIS
Section A: Photosynthesis in Nature
1. Plants and other autotrophs are the producers of the biosphere
2. Chloroplasts are the site of photosynthesis in plants
Formula for photosynthesis?
6CO2 +6H2O  C6H12O6 + 6O2
What was left out?
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• Water is split
– electrons & H+ from water reduce CO2 to sugar.
• polar covalent bonds are converted to
nonpolar bonds.
–this boosts the potential energy of electrons
Fig. 10.3
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• What’s this about?
Fig. 10.8b
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• What’s a photosystem?
– chlorophyll a, chlorophyll b, and carotenoid molecules.
– acts like a light-gathering “antenna complex”
• Lost electrons are replaced by:
– H2O  2H+ + O + 2e-
Fig. 10.11
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1.
2. What comes out?
Where to with these?
Fig. 10.4
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With the pieces in place, can
you explain each step?
Fig. 10.16
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• Mitochondria generate ATP from food…
2.
1.
• Chloroplasts generate ATP from light3.
Fig. 10.14
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enzyme
Fig. 10.17.3
•
C3 plants (most plants) suffer photorespiration
on hot, dry days. Here’s how:
1. stomata close to conserve H2O
2. Calvin cycle drops CO2 levels.
3. O2 levels rise as light reaction
cracks H2O molecules.
4. rubiscos start adding O2
instead of CO2 (BAD)
5. RuBP splits into a 3-C piece and
a 2-C piece.
6. 2-C piece leaves the chloroplast
& is degraded to CO2
7. no ATP or additional organics
are produced
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Fig. 10.18
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• carbon
fixation and
the Calvin
cycle are:
– spatially
separated in
C4 plants.
– temporally
separated in
CAM plants.
Fig. 10.19
Here’s a quick review of chapters 9 and 10, KNOW IT:
2
1
3
4
9
5
6
7
8