Studied by 3 peoplethe most basic function of the cell cycle is to duplicate accurately the vast amount of...
DNA in the chromosomes
DNA duplication occurs during which phase
S phase
how long does S phase take
8-12 hours
After S phase chromosome segregation and cell division occur in what phase
M phase
M phase involves a series of dramatic events that begin with
mitosis
where does DNA polymerase begin
origin of replication
how many strands open forming the replication forks
2
where do new strands for dna ploymerase grow
the forks
what is a helicase
enzyme which catalyze the unwinding and separation (breaking H- Bonds) of the parental double helix.
what are single strand binding proteins
proteins which attach and help keep the separated strands apart
what is topoisomerase
enzyme which relieves stress on the DNA molecule by allowing free rotation around a single strand
what do rna primers do
start the addition of new nucleotides
what is primase
enzyme that polymerizes the rna primer
DNA polymerase catalyzes the...
stepwise addition of a deoxyribonucleotide to the 3'-OH end of a polynucleotide chain
The growing primer strand that is paired to...
an existing template strand
The newly synthesized DNA strand therefore polymerizes in which direction
5' to 3'
DNA polymerase is driven by a large favorable free energy change caused by the release of
pyrophosphate and its subsequent hydrolysis to two molecules of inorganic phosphate
the DNA synthesized on the lagging strand must be made initially as a series of short DNA molecules, called
okazaki fragments
On the lagging strand, the Okazaki fragments are synthesized sequentially, with those nearest the fork
being the most recently made
in eukaryotes rna primers are made at intervals spaced by about how many nucleotides
200
each rna primer is approximately how many nucleotides long
10
this primer is erased by a special dna repair enzyme...which recognizes and rna strand in an rna/dna helix and fragments it
RNAse H
what does unwinding do
forms replication fork
what does primase do
synthesizes rna primer
continuous synthesis is what strand
leading
discontinuous synthesis is what strand
lagging
do silent mutations have phenotypic effect
no
do missense mutations have phenotypic effects
yes or no
do nonsense mutations have phenotypic effects
yes
The oxidation of long-chain fatty acids to... is a central energy-yielding pathway in many organisms and tissues
acetyl-coa
in mammalian...it provides as much as 80% of the energetic needs under all physiological circumstances
heart and liver
The acetyl-CoA produced from the fatty acids... completely oxidized to CO2 in the citric acid cycle, resulting in further energy conservation
may be
In some species and in some tissues, such as in liver... may be converted to...water-soluble fuels exported to the brain and other tissues when glucose is not available
acetyl-coa ketone bodies
The repetitive four-step process, called... by which fatty acids are converted into acetyl-coa
what is the first step for the complete oxidation of fatty acids to CO2 and H20
Oxidation of long-chain fatty acids to two-carbon fragments, in the form of acetyl-CoA ( b-oxidation)
what is b-oxidation
fully saturated fatty acids with an even number of carbon atoms is degraded to acetyl-coa
The enzymes of fatty acid oxidation in animal cells are located in the...
mitochondrial matrix
The fatty acids with chain lengths of... carbons enter the mitochondria without the help of membrane transporters
12 or fewer
Those with 14 or more carbons, which constitute the majority of the FFA obtained in the diet or released from adipose tissue, cannot pass directly through the mitochondrial membranes—they must first undergo
the three enzymatic reactions of the carnitine shuttle
the first of three enzymatic reactions of the carnitine shuttle is catalyzed by what
acyl-CoA synthetases
Fatty acyl–CoA esters formed at the cytosolic side of the...can be transported into the mitochondria and oxidized to produce ATP, or they can be used in the cytosol to synthesize
outer mitochondrial membrane
Fatty acyl–CoAs, like acetyl-CoA, are high-energy compounds; their hydrolysis to FFA and CoA has a large, what free energy change
negative standard free energy change
Conversion to the carnitine ester commits the fatty acyl moiety to the...
oxidative fate and it is a regulation point
fatty acyl-Coa will go to two organelles what are they
mitochondria for ATP and cytosol to synthesize membrane lipids
for the oxidation of fatty acids the 16 carbon palmitic acid undergoes how many passes though the oxidative sequence
7
throughout each pass of the oxidative sequence two carbon atoms are lost as what
acetyl coa
at the end of 7 cycles the last two carbon atoms (C-15,C-16) remain as what
acetyl coa
The overall result is the conversion of the 16-carbon chain of palmitate to
eight two-carbon acetyl groups of acetyl coa molecules
stage 1 of the oxidation of fatty acids
A long-chain fatty acid is oxidized to yield acetyl residues in the form of acetyl-CoA. This process is called oxidation
stage 2 of the oxidation of fatty acids
The acetyl groups are oxidized to CO2 via the citric acid cycle
stage 3 of the oxidation of fatty acids
Electrons derived from the oxidations of stages 1 and 2 pass to O2 via the mitochondrial respiratory chain, providing the energy for ATP synthesis by oxidative phosphorylation
The single bond between methylene (CH2) groups in fatty acids is
relatively stable
The b-oxidation sequence is an elegant mechanism for destabilizing and
breaking these bonds
in each pass through this... step sequence of the b-oxidation
4
one acetyl residue (shaded in pink) is removed in the form of ... —in this example palmitate (C16), which enters as palmitoyl-CoA
acetyl-CoA from the carboxyl end of the fatty acyl chain
Six more passes through the pathway yield ... , the seventh arising from the last two carbon atoms of the 16-carbon chain. Eight molecules of acetyl-CoA are formed in all
seven more molecules of acetyl-CoA
for the b-oxidation sequence 1 molecule of NADH and FADH2 give mow many molecules of ATP
3 and 2
Transfer of electrons from NADH or FADH2 to O2 yields one
H2O per electron pair
Reduction of O2 by NADH also consumes one
H+ per NADH molecule
The overall equation for the oxidation of palmitoyl-CoA to...
8 molecules of acetyl coa
In hibernating animals, fatty acid oxidation provides metabolic
energy heat water
One of the most pronounced adjustments of fat metabolism occurs in
hibernating grizzly bears
Hibernating grizzly bears use... as their sole fuel source
body fat
Fat oxidation yields sufficient energy for maintenance of
body temperature active synthesis of amino acids and proteins
The glycerol released by degradation of triacylglycerols is converted into blood glucose by
gluconeogenesis
Urea formed during breakdown of amino acids is reabsorbed in
the kidneys and recycled
Acetyl-CoA Can Be Further Oxidized in the
citric acid cycle
in aerobic respiration how much ATP comes from 1 molecule of glucose
32-36
in aerobic respiration 1 NADH and 1 NADH2 yield how much ATP
2-3 and 1-2
cancer cells are defined by 2 heritable properties
(1) they reproduce in defiance of the normal restraints on cell growth and division, and (2) they invade and colonize territories normally reserved for other cells.
As long as the neoplastic cells have... invasive the tumor is benign
not invaded surrounding tissues
a tumor is considered a true cancer if it is malignant this is when its cells have the ability to
invade surrounding tissue
it is generally... that kill cancer patients
metastases
the doubling time of a typical breast tumor is about how many days
100
Knudsons two hit hypothesis
TSG mutation in a normal cell leading to a sporadic cancer
TSG mutation in a cell with a germline mutation leading to familial cancer
Tumor progression involves a large element of... and takes many years
chance
At each stage of cancer progression, some individual cell acquires an
additional mutation or epigenetic change
additional mutations or epigenetic changes in cancer cells give it a selective advantage over... making it better able to thrive in this environment
its neighbors
The environment inside a tumor, may be harsh,
with low levels of oxygen, scarce nutrients, and the natural barriers to growth
cancer cells have an altered sugar metabolism and ...
Warburg effect
Given sufficient oxygen, normal adult tissue cells will generally... in the glucose
fully oxidize almost all the carbon
a growing tumor needs...to provide the building blocks to...
nutrients in abundance , make new macromolecules
tumor cells consume ... avidly importing it from the blood at a rate that can be as much as 100 times higher than neighboring normal cells
glucose
in cancer cells, only a small fraction of this imported glucose is used for... by oxidative phosphorylation
production of ATP
since cancer cells only use a small fraction of glucose for ATP production a large amount of what is produced
lactate
what is the warburg effect
the tendency of cancer cells to de emphasize oxidative phosphorylation while taking up large quantities of glucose
in cancer cells many of the remaining carbon atoms derived from glucose are diverted for use as raw materials for the synthesis of... required for tumor growth
proteins, nucleic acids, and lipids
In the interior of a large solid tumor, cell... occurs on a massive scale
death
in tumor cells the living conditions are brutal with severe competition among the cancer cells for ...
oxygen and nutrients
many cancer cells will die but typically more die from ... than apoptosis
necrosis
large rates of cancer cell death are the reason for what
the time it takes for a tumor to double in size can be far longer than the cell cycle time of the tumor cells
cancer cells spread and multiple at new sites in the body through a process called
metastasis
what is the most deadly and least understood aspect of cancer which is responsible for 90% of cancer associated deaths
metastasis
Metastasis is a multistep process:
cancer cells first have to invade local tissues, move through circulation, leave the vessels and then establish colonies
the types of accidents that can convert a proto-oncogene into an oncogene from good to bad are what
deletion or point mutation in coding sequence
regulatory mutation
gene amplification
chromosome rearrangement
what systems does cystic fibrosis affect
respiratory and digestive
cystic fibrosis most seriously affects ... cells which increases the risk of infection by bacteria
lung
what are two distinct forms of cell death
necrosis and apoptosis
cells in ... seem to have exploded while cells in ... have condensed but relatively intact
necrosis apoptosis
characteristics of necrosis
inflammatory response, ATP independent
Note
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