Exam 3 - Review Flashcards
what is a by product of light reactions?
oxygen
what are dark reactions?
The Calvin Cycle - Uses ATP, NADPH, and CO2 to produce hexose carbohydrates
what are light reactions?
transform light energy into: ATP and NADPH (biosynthetic reducing power)
where does photosynthesis take place?
in chloroplasts
what enzyme breaks down glycogen?
glycogen phosphorylase
what induces glycogen degredation?
epinephrine and glucagon
what does phosphoglucomutase do?
it takes glucose 1-phosphate and makes glucose 6-phosphate
why does liver contain glucose 6 - phosphatase?
glucose 6-phosphatase generates free glucose from glucose 6-phosphate
absent from muscle
How is glycogen phosphorylase regulated in the liver and muscle?
activated when phospharylated
primarily phosphorylated a in active R state in the liver
primarily unphosphorylated b state in the muscle
what does glucose regulate?
phosphorylation state
binds and inhibits the allosteric site
what does AMP, ATP, and glucose 6-phosphate do to the liver enzyme? the muscle enzyme?
AMP - low energy, activates glycogen phosphorylase
ATP - high energy, inhibits glycogen phosphorylase
glucose 6-phosphate - high energy, inhibits glycogen phosphorylase
what type of regulators are AMP, ATP, and glucose 6 - phosphate?
isoforms
what does phosphorylation do to each enzyme?
exists in two forms
b is less active
a is more active (has a phosphorylated serine residue)
which phosphorylase state is more active?
R state
which phosphorylase state is less active?
T state
which phosphorylase state is usually found in muscle?
T state
what does glucagon do during fasting?
signals low glucose levels in the blood to start gluconeogenesis
what is UDP-Glucose?
higher level energy precursor for glucose to be synthesized
what does phosphorylation do to glycogen synthase activity?
inhibits it
what does glycogen synthase kinase (GSK) do?
it phosphorylates glycogen synthase
inhibiting it
what does insulin do to GSK?
inhibits GSK to turn on glycogen synthase
what effects do glucagon and epinephrine have on glycogen synthase?
inhibits synthesis
what does high glucose do to insulin?
high glucose instigates the release of insulin from the pancreas to store FAs as TAGs
what is the pentose phosphate pathway?
source of biosynthetic reducing power (electrons) and produces ribose phosphates for DNA/RNA synthesis, neurotransmitter synthesis, etc.
In the oxidative phase of the pentose phosphate pathway, what is being oxidized?
glucose - 6 - phosphate
In the oxidative phase of the pentose phosphate pathway, what is being reduced?
NADPH
what is the oxidative phase of the pentose phosphate pathway?
Glucose - 6 - phosphate → 2 NADPH → Fatty Acid Synthesis, Cholesterol Synthesis, Nucleotide synthesis, Neurotransmitter synthesis
what is the non-oxidative phase of the pentose phosphate pathway?
glucose - 6- phosphate → 2 NADPH + Ribose 5 - phosphate → Glycolytic intermediates →glucose - 6- phosphate
and
glucose - 6- phosphate → 2 NADPH + Ribose 5 - phosphate → DNA, RNA, ATP, NAD, FAD, CoA
where are triacyclglycerols stored?
adipose tissue and muscle
what hormones activate triacylglycerol breakdown?
epinephrine and glucagon
what is the first step in the breakdown of fatty acids?
adding CoA to acyl group absorbed through intestines
where does fatty acid oxidation occur and how does it get there?
mitochondrial matrix by carnitine shuttle
what are the four steps in beta-oxidation?
- Oxidation (FAD)
- Hydration (H2O)
- Oxidation (NAD+)
- Thiolysis (CoA)
are there meaningful intermediates in the reactions of beta-oxidation of fatty acids?
yes, the reduced forms NAD and FAD
unsaturated fatty acids with odd numbers of double bonds need what enzymes?
only isomerase
unsaturated fatty acids with even numbers of double bonds need what enzymes?
isomerase and reductase
beta-oxidation of fatty acids with odd numbers of carbons generate what intermediates?
Propynol CoA (3 carbon chain)
becomes succinyl CoA
where does the intermediate of beta - oxidation end up?
Succinyl CoA → TCA Cycle
where does ketone body formation take place?
made from Acyl CoA
related to glucose levels
primarily in the liver
what organs normally use ketone bodies?
kidney and heart
what conditions generate abnormally high levels of ketone bodies?
diabetes → no insulin
chronic alcohol use
where does fatty acid synthesis occur in the cell?
cytosol
what are the three stages of fatty acid synthesis?
- Acyl CoA moves out of the mitochondria to Cytosol by citrate shuttle
- activate CoA to malonyl CoA
- addition of 2 carbon units to get to C16
what does the enzyme, acetyl CoA carboxylase do?
converts Acetyl CoA to malonyl CoA; regulatory enzyme
what do the following do to the activity of acetyl CoA carboxylase?
citrate, insulin, glucagon, epinephrine, ATP
citrate - partially activates acetyl CoA
insulin - activates acetyl CoA carboxylase
glucagon - inhibits acetyl CoA carboxylase
epinephrine - inhibits acetyl CoA carboxylase
ATP - downregulates (inhibits) acetyl CoA carboxylase
what enzyme phosphorylates CoA carboxylase and what does phosphorylation do to this enzyme?
AMP activated protein kinase
phosphorylation inhibits
what is the most detrimental intermediate in excessive alcohol use?
high levels of reduced NAD
glycolysis and FA breakdown
what is LDL?
bad cholesterol
distributes cholesterol throughout the body
what is HDL?
good cholesterol
less fatty acids and more good proteins
takes cholesterol back to the liver
The regulation of cholesterol synthesis is dependent on the activity of?
HMG CoA Reductase
cholesterol is a precursor for what hormones?
sex hormones (proestrogen, androgen, and estrogen)
glucocortisoids
mineralcorticoids
Vitamin D deficiency results in what condition?
rickets
what function does the glucose - alanine cycle serve?
way of getting rid of amino groups from branched amino acids
used in the urea cycle
what does the urea cycle do? where does it occur?
Urea Cycle gets rid of ammonia from the body
occurs in the liver cells (according to google)
what are glucogenic amino acids?
amino acids that can enter glucose synthesis pathways to create glucose
what are ketogenic amino acids?
only enter at acetyl CoA site
can’t make glucose
Leucine and Lysine
which amino acids are only ketogenic?`
leucine
lysine
how do we obtain nitrogen for the synthesis of biomolecules?
dietary sources → nitrogen fixing bacteria
needs to be fixed to ammonia
what is the difference between the de novo pathway of nucleotide synthesis and the salvage pathway?
de novo pathway - build from from scratch out of nucleotides
salvage pathway - nucleotides “gathered” and reused after cell is broken down
how are purines in the de novo pathway built?
purines are made on the ribose and then the ring is added
how are pyrimidines in the de novo pathway built?
pyrimidines connect to the ring then the ribose
what does the enzyme, ribonucleotide reductase do and how is it regulated?
takes ribose and reduces to get deoxy from reduced nucleotides
how is TMP synthesized?
de novo from dUMP
adds methyl group form methyl donor
