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biochemistry exam 2
Terms in this set (109)
km is the measure of ____?
the affinity of ENZYME for SUBSTRATE
the LARGER the value of Km, the ____ the affinity of enzyme and substrate
glycoproteins typically have.....
multiple sugars attached at a SINGLE glycosylation site
true/false: ethanol can be converted into acetaldehyde by alcohol dehydrogenase in humans
feedback inhibition is ____
is a common means of regulation of metabolic pathways
pepsin is ... 2 things
1) a protease
2) found in the stomach
[NOT activated in the small intestine]
when [S]<< Km, you can measure ____
enzymes affect the ____
rate of a reaction
what does a catalyst do?
lowers activation energy of a reaction
D fructose exists in solution primarily in the ___ form
FAD is ____? 2 things
1) the OXIDIZED form of the cofactor
2) can be involved in oxidizing a carbon-carbon single bond to a carbon-carbon double bond
as dela G*' becomes more negative, K'eq becomes ____
[delta G= +, Keq= -]
delta G= -RTlnKeq
phosphofructokinase (PFK) is activated by a higher ___/____ ratio
glyceraldehyde-3-phosphate dehydrogenase [reduces], with appropriate substrates and cofactors.... 2 things
1) OXIDIZES glyceraldehyde-3-phosphate
2) produces a high energy intermediate of glycolysis
_____ is a potent ACTIVATOR of PFK
fructose 2,6 bisphosphate (F26BP)
know how to make MM graphs and LB graphs (Axes) and km and vmax and intercepts
competitive inhibition: definition, graph, vmax, km, slope, more substrate
uncompetitive inhibition: definition, graph, vmax, km, slope, product
uncompetitive inhibition: definition, graph, vmax, km, slope, more substrate added
draw the structure of sucrose
draw the structure of lactose
list a few differences between the structures cellulose and glycogen
discuss the process of digestion for a lipids or carbohydrates or proteins, starting from the mouth and ending in the enterocytes of the small intestine. please mention key enzymes and what happens in each organ
discuss the allosteric regulation of pyruvate kinase in the liver
discuss the steps in glycolysis where ATP is utilized or produced. discuss, don't just list them.
do it 1, 3, and 10
draw the structure of ATP/AMP/ADP
discuss the structure and function of chlyomicrons
have hydrophobic cores ad transport exogenous lipids and cholesterol esters through the blood. they are packages of lipoproteins
draw the structure of both liner and cyclic forms of glucose. circle the anomeric carbon.
true/false: an enzyme lowers the activation energy of a reaction
the synthesis of complex molecules in living organisms from simpler ones together with the storage of energy
what enzyme catalyzes the phosphorylation of fructose in the liver?
delta G= + and it is NONspontaneous
RXN will not occur
delta G= - and it is spontaneous
will occur WITHOUT the input of energy
how can you convert the change in free energy of a reaction to the equilibirum constant?
how is galactose converted into glucose?
name the enzyme that converts glyceraldehyde 3 phosphate to 3 phosphoglycerate. what cofactor is required?
glyceraldehyde 3 phosphate dehydrogenase.
cofactor required: NAD+
glycolysis takes place in the ______
true/false: enzymes usually speed up a reaction
discuss several allosteric affectors of PFK
1) in eukaryotes PFK is activated by fructose 2,6-bisphosphate
2) a high ratio of ATP to ADP will inhibit PFK
write out the MM equation and define each term
Km= substrate concentration at 1/2 Vmax
is fructose a reducing sugar? yes/no and WHY
yes, because it has an aldose that can turn into a ketose
discuss the allosteric control of pyruvate kinase in the liver
what do proteolytic enzymes do?
catalyze the hydrolysis of peptide bonds. they also illustrate the range of enzyme specificity
trypsin is an example of a proteolytic enzyme. it is produced in the ___ and moves in duoderum, where it cuts up ___
produces in the pancreas and cuts up peptides
what are cofactors, and what are the 2 main classes?
small molecules that some enzymes require for activity.
1) coenzymes- organic molecules derived from VITAMINS
what is an enzyme WITH the cofactor called?
what is an enzyme WITHOUT the cofactor called?
equation for free energy delta G
delta G=delta H- T*deltaS
what does the delta G of a RXN depend on?
the free energy difference between reactants and products
equation for delta G *'
delta G *'= -RTlnKeq
the more ____ a RXN is, the LARGER the equilibrium constant
the more ____ a RXN is, the SMALLER the equilibrium constant
enzymes alter the ____ ____ but not the RXN equilibirum
enzymes facilitate the formation of the __ state
what is activation energy?
energy required to form the transition state from the substrate
enzymes _____ activation energy
what is an active site?
particular region of the enzyme that contains an enzyme-substrate complex
allosteric enzymes catalyze the ____ step of reactions. they are sigmoidal
allosteric enzymes depend on alterations in _____ strcuture
enzymes activity can be modulated by: 3 things
1) temperature (enhances the rate of enzyme-catalyzed RXNs)
3) inhibitory molecules
what can irreversible inhibitors be used for? and what is an example of one?
mapping the active site. ex) chymotrypsin
what are monosaccharides and examples?
simplest carbohydrates. aldehydes/ketones that contain 2+ OH groups
aldehyde reacts with an alcohol to form a ?
ketone reacts with an alcohol to form a ?
sugars that react with oxidizing agents are called ____ sugars
what are thee 2 storage forms for glucose?
GLYCOGEN and STARCH
what do you call a molecule when all of the monosaccs in the polysaccharide are the same?
what is the storage form of glucose in animal cells?
what is the storage form of glucose in plant cells? and what are the 2 forms
1) amylose- LINEAR polymer
2) amylopectin-BRANCHED polymer
what are the 4 reducing sugars?
glucose, lactose, maltose, ribose
what is the one non reducing sugar?
what are glycoproteins?
proteins with carbohydrates attached
what are the 3 main classes of glycoproteins?
1) glycoproteins-the protein is the largest component by WEIGHT
2) proteoglycans- carbohydrates are the largest component by WEIGHT
3) mucins/mucoproteins- predominately carbs too, but the protein is characteristically attached to the carbohydrate by N ACETYLGALACTOSAMINE
where do all glycoproteins' carbohydrates attach? 2 spots
1) N-linkage: [nitrogen atom of side chain of ASPARAGINE]
2) O-linkage: [oxygen atom of side chain of SERINE or THREONINE]
what glycoprotein is secreted by the kidney into the blood that stimulates the production of red blood cells?
generation of energy from food: 3 things
1) large molecules in food are broken don into smaller ones by digestion
2) small molecules are processed into key molecules of metabolism, mostly acetyl CoA
3) ATP is produced from the COMPLETE OXIDATION of the acetyl component o acetyl coA
digestion steps: 3
1) begins in mouth by chewing, which leads to a more digestible aqueous slurry
2) the acidic environment of the stomach DENATURES proteins, which renders them more susceptible to PROTEOLYTIC digestion in the intestine. [the stomach protease PEPSIN begins the digestion of proteins]
3) as the partially digested food moves into the SMALL INTESTINE [through secretin and CCK], the pancreas secretes SODIUM BICARBONATE to neutralize the acid, bile salts facilitate the digestion of FATS, and enzymes digest all types of FUEL molecules
what do proteases do?
digest proteins into amino acids and peptides
what does secretin do?
causes the release of bicarbonate (neutralizes stomach acid)
wha does cholecystokinin (CCK) do?
stimulates the release of digestive enzymes from the PANCREAS and BILE SALTS from the gall bladder
what is our primary source of carbohydrates?
dietary carbohydrates are digested by ____ ____
chylomicrons have ___ cores
cell signaling facilitates __ ___
what is caloric homeostasis?
the ability to maintain adequate but not excessive ENERGY STORES
what 2 things regulate long term control of caloric homeostasis?
where is LEPTIN secreted and where does it ACT?
secreted by adipocytes in direct proportion to fat stores and acts in the brain
insulin is secreted by __ cells of the pancreas and reports on carbohydrate availability
B-cells of the pancreas
ATP can be formed by the ____ of carbon fuels
catabolic metabolic pathways: what do they do and are energy ____
BREAKING UP: catabolic: combust carbon fuels to synthesize ATP
anabolic metabolic pathways: what do they do and are energy ____
CONSTRUCTING: anabolic: use ATP and REDUCING power to synthesize large biomolecules
what do you call pathways that can function as catabolic and anabolic?
what 2 criteria must be met in order to construct a metabolic pathway?
1) indivi. rxn must be SPECIFIC
2) pathway in TOTAL must by thermo. favorable
what are the 3 reasons that ATP has a high phosphoryl transfer potential?
1) charge repulsion
2) resonance stabilization
3) stabilization by dehydration
the more ____ a carbon atom is, the more free energy is RELEASED upon oxidation
[more reduced=more efficient]
the most ____ carbon compounds are FULLY SATURATED
what enzyme can transfer a phosphate group to ADP?
NADPH is involved in ___ biosynthesis
cholesterol is synthesized in the ___
glycolysis is an ____ reaction
what are the 3 products of glycolysis?
2 pyruvate, 2 ATP, 2 NADPH
where does glycolysis take place in the cell?
what is 1 way of recycling NAD+?
lactic acid fermentation
glycolysis in the muscle is regulated by __ ___
when ATP needs are high, __ ___ generates ATP from 2 ADP
___ depresses the ATP INHIBITED PFK
what regulator of PFK inhibits PFK?
low blood glucose= 2 things [of liver pyruvate kinase]
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