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183 Cards in this Set

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Three major types of cytoskeleton:
microtubules, microfilaments, intermediate filaments
Microtubules are made of:
tubulins
tubulin
rigid tubes within cells that form microtubules
alpha + beta tubulin =
tubulin heterodimer
heterodimers link end to end to form a:
protofilament
protofilaments are arrange into:
a ring w/ 13 strands
How large are microtubules?
25 nm in diameter (they're the largest)
What is the function of microtubules?
Serve as tracks along which other cell components move (e.g., vesicles, organelles, chromosomes)
most microtubules originate from the:
centrosome/MTOC
What are the ends of microtubules referred to as?
minus and plus ends
When are microtubules rearranged? What do they form?
mitosis; mitotic spindle
mitotic spindle
separates chromosomes during mitosis
Microfilaments are a polymer of
protein actin
Microfilaments size?
7 nm across
The microfilaments structure is:
flexible, thin
Microfilaments function:
>serves as a cable holding parts together
>cell movement
>cell shape
What do amoeba use to crawl?
Microfilaments
In non muscle cells _______ have a dynamic polymerization and
depolymerization cycle that gives cell shapes
Microfilaments
What gives shape to the microvilli in intestinal epithelial cells?
microfilaments
microfilaments serve what role in cytokinesis?
pinching cells in two
Intermediate filaments are made of...
made of several types of proteins, e.g., keratin
Intermediate filaments size:
10 nm
Intermediate filaments structure:
not dynamic, fixed
Intermediate filaments function:
strong cables, giving strength to tissues
epithelial sheets get their strength from:
intermediate filaments
molecular motors
interact with the cytoskeleton
Kinesin and dynein move along _____________
microtubules
kinesin moves towards:
plus end
dynein moves towards:
minus end
molecular motors require:
use of ATP --> ADP + Pi
molecular motors are responsible for:
the placement and movement of organelles and vesicles inside the cell
molecular motors cause:
heads to release, move forward and rebind
during mitosis, motors are responsible for:
pulling the sister chromatids apart
ATP hydrolysis walks...
the motor heads along the microtubules.
Myosin
similar in function as the microtubule motors, but is used to walk along
the microfilaments.
Heads walk along
actin fiber, use ATP for energy
molecular motors are responsible for
muscle contraction & cell shape
sperm tails are
flagella
lungs use ____ to remove debris
cilia
___ line the fallopian tube
cilia
in the fallopian tube, ____ move eggs from the ovaries
cilia
cilia are composed of:
9 outer doublet microtubles, two central singlet microtubules
In cilia, the protein dynein causes:
one set of outer doublet microtubules to move along another, bending the structure and creating a whip-like movement
1st law of thermodynamics
energy in a reaction is neither created nor destroyed
2nd law of thermodynamics
disorder tends to increase - essentially states that not all energy in the system is
available for work
Enthalpy
total energy = H
Gibbs free energy
energy available for work = G
Entropy
energy that is disorganized for work = S
H=
G + S
entropy increases
with:
temperature
ΔG =
ΔH − TΔS (T = the absolute temperature)
In a chemical reaction, if ΔG is positive, the reaction is
endergonic and will require
energy input
If ΔG is negative, then the reaction is
exergonic and will release energy.
Catabolic reactions
exergonic: complex molecules --> free energy + small molecules
Anabolic reactions
endergonic: free energy + small molecules --> complex molecules
The formation of phosphate bonds between the
phosphates requires _______and serves as a _____ for energy in the cell.
energy; storage unit
Pi
inorganic phosphate
Breakage of these bonds to release ADP + Pi (inorganic phosphate) or
AMP + PPi (pyrophosphate) releases approximately ______ of energy.
7.3 kcal/mol
Luciferin + O2 + ATP -->
oxyluciferin + AMP + PPi + light
at rest, an average person produces and
hydrolyzes ______ of ATP in a day.
40 kilograms
the average ATP molecule cycles
between ADP and ATP ______ times a day
10,000
we really only have ___ of ATP
turning over in a person
4 grams
Pumps and molecular motors are driven by:
ATP
enzymes
catalyze reactions
The reason why all exergonic reactions don't go to completion automatically even though
the products have less free energy than the reactants is because :
the transition state
between the two is a high energy state.
The role of a catalyst is to:
lower the energy for the transition state of a reaction.
The free
energy of the reactants and products don't change, but the ability to get from one state to
the other is enhanced by _____
a catalyst.
Proteins serve as catalysts by:
having binding sites on their surfaces for the reactants that
can bring the reactants in close proximity to each other and stabilize the transition states
as covalent bonds are broken and formed.
The summary of a glycolysis reaction:
C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O
In glycolysis, ΔG =
-686 kcal per mole
Glycolysis
breakdown of glucose produces ATP, which is the key energy currency.
ADP + Pi --> ATP, ΔG =
+7.3 kcal per mole
Optimal yield of glycolysis:
36 - 38 ATP
Efficiency of glycolysis:
40% efficiency
NADH carries:
two high-energy electrons
NAD+ 2 e- + H+ -->
NADH
When bonds are broken down, high energy electrons are transferred to ____ along with
a ____ to make ____. These are fed into the _______ to produce more
____.
NAD+; H+; NADH; electron transport chain; ATP
Extracting energy from glucose consists of 4 phases…
1.Glycolysis
2. Pyruvate Oxidation
3. Citric Acid Cycle
4. Electron Transport Chain/ATP synthase
Does glycolysis occur in virtually all organisms?
Yes.
Glycolysis pathway has how many steps?
ten
phosphorylated
has phosphates added to it
pyruvate has how many carbons?
three
In glycolysis, glucose (6 carbons) is ________, rearranged and
broken down to yield two 3 carbon molecules of _____.
phosphoylated; pyruvate
Glucose - 6C is broken down into how many pyruvates?
two pyruvates
How many ATP are required to start glycolysis?
Two (for steps 1 and 3) -- used to make initial phosphoylated intermediates
Net yield of glycolysis:
2 ATPs and 2 NADH
Anaerobic organisms can get all of their ATP from _______
glycolysis
Anaerobic organisms
organisms that don't require O2
In fermentation, further ATP production after pyruvate requires ____, if ____ is low, then you get
______
O2;O2; anaerobic metabolism
One problem with glycolysis is that
NAD+ gets quickly used up (reduced to NADH).
NAD+ is present at low concentrations in the
cytoplasm
How to get the electrons off of NADH to recover NAD+ in humans :
Pyruvate + NADH --> lactic acid + NAD+
How to get the electrons off of NADH to recover NAD+ in yeast:
Step one: Pyruvate --> acetylaldehyde + CO2

Step two: Acetylaldehyde + NADH --> ethanol + NAD+
In glycolysis, if O2 is available, then the high energy electrons can be given to O2 and much more
energy can be derived from _____.
pyruvate
When oxygen is unavailable for pyruvate, _____ occurs
fermentation
pyruvate oxidation reaction
Pyruvate + NAD+ + Coenzyme A --> CO2 + NADH + acetyl Coenzyme A
in pyruvate oxidation ___ high energy ____ are put on ____
two; electrons ; NAD+
breath out a CO2 molecule caused by
decarboxylation of glucose
Coenzyme A serves as a carrier for
acetyl
pyruvate oxidation takes place :
inside the mitochondrion
pyruvate oxidation takes pl ace in the:
mitochondrial matrix
the citric acid cycle takes place in the:
mitochondrial matrix
the citric acid cycle:
Uses the ____ group from acetyl CoA to make more ____
acetyl ; ATP
How many enzymes are used in the citric acid cycle?
eight
How many steps in the pathway are there in the citric acid cycle?
eight
In step one, 2C Acetyl group + 4C OAA -->
6C citrate in first step
In the citric acid cycle...

2 C + 4C --> 6 C -->
5 C + CO2 --> 4C + CO2
For each Acetyl CoA that goes in, the citric acid cycle produces
2 CO2, 1 ATP, 3
NADH and 1 FADH2
FADH2 serves as a
high energy electron carrier
NADH and FADH2 have high energy
electrons
For each glucose, Glycolysis, pyruvate oxidation and the citric acid cycle yield a total
of…
6 CO2
10 NADH
2 FADH2
4 ATP
NADH and FADH2 accumulated during glycolysis, pyruvate oxidation and the citric acid
cycle carry _____
high energy electrons
NADH + H+ + ½ O2 ------->

ΔG =
NAD+ + H2O

ΔG = -53 kcal/mol
ΔG for ATP synthesis ADP + Pi --> ATP is about
7.3 kcal/mol
Peter Mitchell in 1961 proposed
"chemiosmotic hypothesis" based initially on studies
of bacteria, but later proven applicable to the inner membrane of mitochondria.
Electrochemical gradient is used to drive
ATP synthesis
Three main points of chemiosmotic hypothesis:
1-components of the electron transport chain are proton pumps
2- need closed vesicle to make ATP
3- H+ gradient is used to drive synthesis of ATP
Complexes I, III and IV are
H+ pumps driven by the moving electrons.
Complex II is
there to receive e- from
FADH2
Ubiquinone (Q) and cytochrome C
carry electrons from one complex to the next
In complex IV, the electrons are given to
O2 to form H2O. This is the lowest energy
state of the electrons.
RESULTS OF ELECTRON TRANSPORT
For each pair of electrons donated by NAD+,
3 to 4 H+ pumped out of matrix by
complexes I, III and IV.
How is the elctrochemical gradient used to make ATP?
The ATP synthase couples transport of H+ down electrochemical gradient to synthesis of
ATP.
ATP synthase constitutes _____ of the protein in the mitochondrial inner membrane
15%
f1 is made of
5 types of polypeptides and it synthesizes ATP.
f0 is made of
3 types of integral membrane proteins which form a proton channel.
Protons passing through the channel down their electrochemical gradient are used to
drive synthesis of ATP.
alpha and beta subunits
alternating three of each in ring in f1.
Gamma subunit
attached to c proteins in membrane which form a complex that spins as
electrons pass through the channel. This causes the gamma subunit to spin inside of alpha
and beta subunit ring when electrons flow.
gamma subunit spinning inside of alpha and beta subunits causes
conformational change
of beta subunits which drives ATP synthesis.
Beta subunits bind _____ and then a conformational change in beta subunit caused
by rotation of gamma subunit brings these close enough together to form ___.
ADP and Pi; ATP
beta subunit exists in _____ states and the position of the gamma subunit
rotating _____ through this process drives the production of ATP.
three ; 120°
f1 subunit
3 alpha,
2 beta and one gamma proteins
pyruvate/H+ symport
used to import pyruvate into the matrix
Pi/H+ symport
used to import Pi into the matrix
Antiports exist in inner membrane to
exchange ATP out for ADP into the mitochondrial
matrix
cell cycle
process by which a cell, which has arisen from the division of
two cells, grows, replicates its chromosomes, and divides in two to form two daughter
cells.
cancer is basically a disease that is caused when
the cell cycle is not
regulated
Cytokinesis
dividing the cell in two
M phase stands for
mitosis
mitosis
process by which the chromosomes are
separated into the two daughter cells and the two cells divide
S phase stands for
synthesis
S phase
phase of the cell cycle in which the DNA in the
genome is completely replicated. It is also the phase in which the centrosome
(microtubule organizing center) is duplicated.
G was initially used to stand for
gap since it was not clear initially what the cells were
doing during the G phases
Now people commonly refer to G as the
growth phases of the
cell.
G1 is the phase in which
most growth occurs
G2 is the phase
after the DNA is replicated
during which more growth can occur and in which the cell has twice as much DNA as it
does at the other times
G0
refers to cells that stop dividing
quiescence
G0
terminally differentiated cells
remain at G0 until they die
interphase
refers to cells in G1, S or G2 because they look the same
under the microscope; they have a nucleus.
How did S phase get discovered?
tritiated thymidine in pulse-chase experiments
Time of M phase Mitosis
1 -2 hours
Time of G1 phase Gap 1
~8 hours
Time of S phase synthesis
~8 hours
Time of G2 phase Gap 2
~5 hours
In a typical animal cell in culture, interphase lasts
21 hours
6 stages of mitosis:
1) prophase
2) prometaphase
3) metaphase
4) anaphase
5) telophase
6) cytokinesis
prophase
Chromosomes condense, centrosomes migrate and begin assembly of mitotic spindle
prometaphase
Nuclear envelope breaks down, chromosomes attach to spindle
metaphase
Chromosomes align at the equator
anaphase
Sister chromatids synchronously separate and are pulled slowly towards the
spindle poles
telophase
Chromosomes arrive at the poles, begin to decondense. Nuclear envelope
reassembles.
cytokinesis
Contractile ring pinches the cell in two.
chromosomes
long strands of DNA packed up in proteins
if our classroom is the size of a human nucleus, there would be ______ of DNA that
would have to be organized in it, completely replicated during _____, lined up at the
_______, and separated by the ______.
3000 miles; S phase; metaphase plate; mitotic spindle apparatus
chromatin
DNA and associated
proteins
DNA is wrapped ____ around:
2x; an octamer of proteins
called histones an octamer of proteins
called histones arranged in a structure called the nucleosome
histones
an octamer of proteins
arranged in a structure called the nucleosome
Approximately ______ of
DNA are found around one nucleosome and the spacer between the next one.
200 BP
mitotic spindle
a rearrangement and specialized function of the microtubule
organizing center
In mitosis, the microtubule network ____, the centrosome ________, and the microtubule networks______
breaks down; duplicates and migrates
to opposite sides of the nucleus ; grow out to form the
mitotic spindle apparatus
Minus ends of the microtubules are embed in the
centrosome
Plus ends grow...
out to the cell edge, towards the chromosomes and towards each other.
Polar microtubules
reach across the center and interact with microtubules from the other
pole
centromere
The constriction of the mitotic chromosome where the two sister chromatids are held
together
kinetochore
a protein plaque at the centromere
plus ends of some of the microtubules are attached to the
kinetochore
cohesins
proteins attaching the sister chromatids together at the
centromere
what happens to cohesins during anaphase?
destroyed and the daughter chromosomes separate.
daughters travel to
the poles of the mitotic spindle
PPi
pyrophosphate
Decarboxylation
a chemical reaction which releases carbon dioxide (CO2)