Flashcards in Metabolism Review Dr. Tuohy Deck (99):
glucose synthesis and glucose degradation occur in the
cytosol = glycolysis and gluconeogenesis
fatty acid synthesis occurs in the
the 3 pathways that occur in the cytosol are
glucose and fatty acid synthesis, and glycolysis
Oxidative phosphorylation occurs in the
fatty acid degradation (beta oxidation) occurs in the
TCA cycle occurs in the
3 things that happen in the mitochondria
fatty acid degradation
allosteric modification is covalent or non covalent?
covalent modification of enzymes are fast/slow processes
speed of a reaction depends on
the amount of activation energy
Most enzyme-catalyzed reactions proceed from ___times faster than uncatalyzed reactions.
(10)^3 - 10^8 x faster
enzymes affected by
temperature pH and cofactors
Holoenzyme is an Enzyme with its
Apoenzyme is the __ portion of the haloenzyme
__is a tightly bound coenzyme that does not dissociate
pyruvate dehydrogenase coenzyme is
monoamine oxidase coenzyme
flavin adenine nucleotide
lactate dehydrogenase coenzyme
nicotinamide adenine dinucleotide (NAD)
glycogen phosphorylase coenzyme
acetyl coA carboxylase coenzyme
coenzyme A (coA)
pyruvate carboxylase coenzyme
methylmalonyl mutase coenzyme
thymidylate synthase coenzyme
carbonic anhydrase coenzyme
1. cofactors are not proteins
2. if the cofactor is organic, it is called more specifically a
in michaelis-menten kinetics what are the y and x axis
y = initial velocity
x = substrate concentration
in michaelis-menten kinetics the curve is what shape
in michaelis-menten kinetics, how do you find Km
you find 1/2 Vmax and then go down to x axis
the top of the curve in michaelis-menten kinetics is the
in the hyperbolic shape, the initial reaction velocity is first/zero order?
in the hyperbolic shape, as we approach Vmax the reaction becomes _ order
if you increase the enzyme concentration in the reaction what will change? Vmax/Km
Vmax will change but not the Km
the rate of reaction is directly proportional to the enzyme/substrate concentration?
enzyme concentration at any substrate concentration
if enzyme concentration is halved then the initial velocity will be
covalent modification of enzymes vs allosteric modification of enzymes. Reversible inhibitors bind enzymes through _ bonds
the 2 most common inhibition
competitive and non competitive
methotrexate used in cancer therapy is an example of what kind of inhibition
competitive. binds dihydrofolate reductase that is the enzyme needed to make tetrahydrofolate (THF). when it binds it wont the appropriate substrate in, so we don't make THF, so the cell cant make nucleotides, so the cell dies. Kills the cancer cells.
what are the axis of the lineweaver burk plot?
1/V is the y
1/[S] is x
lineweaver burk plot is a __ plot
double reciprocal plot
the vmax is more easily found on the lineweaver burk plot or the michaelis menten curve?
lineweaver burk plot
what is the vmax in the lineweaver burk plot
the intercept of the y axis is 1/vmax
on a lineweaver burk plot if your vmax has gone higher up on the y axis has your vmax increased or decreased?
decreased ==> bc reciprocal plot
the intercept on the x axis of the lineweaver burk plot is
lineweaver burk plot: as your x intercept approaches the origin, does your Km increase or decrease?
covalent modification = irreversible inhibition
give examples of GI enzymes
proinsulin ==> insulin
adding phosphates, sugars, OH groups
pepsinogen ==> pepsin
ibuprofen (Advil) binds reversibly or irreversibly to COX
reversibly = therefore not covalent modification
aspirin binds reversibly or irreversibly to COX
irreversibly = aspirin adds acetyl group to the COX enzyme = covalent modification
any non protein molecule that assists an enzyme is called a
cofactors can be metal ions or organic molecules. if a cofactor is organic it is specifically called a
Which is true:
all cofactors are coenzymes or
all coenzymes are cofactors?
all coenzymes are cofactors
not all cofactors are coenzymes
Km is a constant/or will it change
same = constant no matter how much enzyme you have
Vmax is a constant?
no it is not a constant it can change depending on how much enzyme you have. if you have more enzyme your vmax will be higher
changing enzyme concentration will affect Vmax or Km?
proteins that go all the way through the plasma membrane are called
proteins that are attached to one side or the other of the plasma membrane are called
integral proteins/peripheral proteins needs a detergent to isolate?
integral only. the peripheral do not need a detergent bc they fall off the membrane
name the 3 types of lipids in the plasma membrane
glycerophospholipids, sphingolipids and cholesterol
aka glycerophospholipids are made up of
they have a glycerol backbone and 2 fatty acids,and a phosphate and an R group
the R groups differ in the glycerophospholipids what are the 5 phospholipids found in our membranes
sphingolipids are made by?
sphingosine (hydrocarbon with an amino group) + Fatty acid ==> ceraminde ===> ceramide + sugar = glycosphingolipid
sphingosine + FA ==>
sphingosine + FA + phosphocholine ==>
sphingosine + FA + glucose ==>
sphingosine + FA + oligosaccharide ==>
sphingomyelin found in many
nerve cell membranes
an inability to break down gangliosides give us what disease
Tay Sachs disease
1. Tay–Sachs disease is a rare autosomal recessive genetic disorder. it causes a progressive deterioration of nerve cells and of mental and physical abilities that begins around ___of age and usually results in death by the age of __.
2. The disease occurs when harmful quantities of cell membrane components known as gangliosides accumulate in the brain's nerve cells, eventually leading to the premature death of the cells.
death = four years old
A ganglioside is a form of sphingolipid, which makes Tay–Sachs disease a member of the sphingolipidoses. There is no known cure or treatment.
cholesterol is important in maintaining the appropriate _ of the membrane
Fluidity, strength, thickness, permeability and curvature of membrane
cholesterol has how many carbons and how many rings
27 carbons, 4 rings
cholesterol's role is __ dependent
temperature and concentration dependent
the more UNSATURATED/SATURATED fatty acids you have in a membrane the more fluid?
unsaturated fatty acids = more fluidity
simple diffusion needs
only a concentration gradient, small non polar O2 CO2 -----water is not non polar!! so it does not do simple diffusion
facilitated diffusion needs
membrane helper and concentration gradient
glucose gets into cell by
glucose transported = facilitated diffusion
primary active transport
moving against gradient, need ATP to fuel it and you need a protein helper
secondary active transport
moving against gradient, but do need ATP to fuel it and you need a protein helper. you use an established gradient
Epinephrine glucagon and ACTH are all stimulatory/inhibitory hormones for signal transduction pathways.
stimulatory = bind receptor = activates the G protein (Gs) = binds adenylyl cyclase ==> makes cAMP ==> makes protein kinase A
PGE1 and Adenosine are stimulatory/inhibitory hormones for signal transduction pathways.
inhibitory: bind receptor = activates the inhibiotry G protein (Gi) = which binds adenylyl cyclase ==> does not make cAMP ==>does not make protein kinase A
adenosine in our brain is responsible for
lack of motivation, tired. its receptors are blocked by caffeine
when cyclic AMP binds protein kinase A where does it bind and what happens
cyclic AMP binds the 2 regulatory units of PKA, which makes it release the catalytic units = ACTIVE PKA
what does protein kinase A do?
it adds phosphates = remember all kinases add phosphates
what enzyme degrades cAMP
what can block the receptor in signal transduction?
insulin uses a __ receptor
a catalytic tyrosine kinase receptor (RTK = receptor tyrosine kinase). it is a dimer, it binds insulin and acts like an enzyme on the cytoplasmic side. DOES NOT USE G PROTEIN
thyroid hormones and steroid hormones bind their receptors
inside the cell.
Growth hormone activates a cascade that activates
protein kinase C
neurotransmitter linked to ion channel. AcH binds receptor --> activates G protein which hits a potassium channel and opens it (directly activates the channel)
nitric oxide (gases) pathway uses
cGMP and protein kinase G
cGMP are broken down by
phosphodiesterase that breaks down cGMP so that there is more vasodilation
you have to have free glucose (monosaccharide) to pass into blood from intestinal cells: where is the low/high concentration- in the intestines or in the enterocyte cell?
enterocyte cell has higher glucose than inside the small intestine. Na+ is higher in the intestine than in the enterocyte, so sodium comes in down its gradient and glucose piggybacks in = Na+ glucose cotransporter
the Na+ glucose cotransporter is called __ and is __ transport
SGLT1 = Sodium Glucose Transporter 1, secondary transport, brings glucose that we ate into the intestinal cell.
glucose inside the enterocyte crosses into the blood using which transporter and is _ transport
GLUT2 transport protein = facilitated transport bc going down its concentration gradient
Na/K pump keeps
high potassium inside the cells and high sodium outside the cell. 3Na+ out, 2K+ in.