biochemistry exam 3

what 3 organic molecules are characterized by their low solubility in water?

fatty acids, triacylglycerol, cholesterol

are triacylglycerols hydrophobic or hydrophilic?

hydrophobic

what is a saturated fatty acid?

no double bonds between C in chain

what is a monosaturated fatty acid?

1 double bond between C in alkyl chain

what is a polyunsaturated fatty acid?

more than 1 double bond in alkyl chain

what 2 acids are dietarily essential for our diet?

lineoleic and a-linolenic acid

what is the relationship between solubility of fatty acid and chain length?

inverse

what is the relationship between melting point of FA and chain length?

direct

what is the relationship between the melting point of FA and number of double bonds?

inverse

what are lipids transported in the blood as?

chylomicrons

what does intestinal lipase do?

digests dietary fat in intestine

what does lipoprotein lipase do?

digest triacylglycerol in chylomicrons and VLDL particles

what does hormone sensitive lipase do?

cleaves stored triacylglycerol in fat cells and other cells

what is hormone sensitive lipase regulated by?

glucagon and epi

what is hormone sensitive lipase inhibited by?

insulin

what do FA have to convert to to be able to attach to phospholipids?

fatty acyl-CoA

what are fats degraded to in the cytoplasm of adipocytes?

FA and glycerol

where does B-oxidation of FA occur?

in the mitochondria

why is B-oxidation of FA essential?

provides energy

how are large FA transported?

acyl-carnitine/carnitine transporter

how much ATP does the complete oxidation of palmitate yield?

108 ATP

what does the catabolism of FA produce?

acetyl-CoA

reducing power- NADH, FADH2

where does the catabolism of FA take place?

in the mitochondria

what does the anabolism of FA require?

acetyl-CoA

malonyl-CoA

reducing power from NADPH

where does anabolism of FA take place in animals and plants?

cytosol in animals

chloroplast in plants

what is malonyl-CoA formed from?

acetyl-CoA and bicarbonate

what is malonyl-CoA activated by?

insulin

FA synthesis involves cycles of what 4 steps?

condensation

reduction

dehydration

reduction

what is the cost of FA synthesis?

3 ATP per 2-C unit

what is acetyl-CoA caroxylase feedback inhibited by?

palmitoyl-CoA

what is acetyl-CoA carboxylase activated by?

citrate

what are elcosanoids?

potent, short range hormones made from arachidonate

COX-1 catalyzes the synthesis of what?

prostaglandins that regulate gastric mucin secretion

COX-2 catalyzes the synthesis of what?

prostaglandins that mediate pain, imflammation, fever

what is COX-2 inhibited by?

NSAIDs

what kind of inhibitor is aspirin?

irreversible

what kind of inhibitor are ibuprofen and naproxen?

competitive

what is the target for statin drugs?

HMG-CoA

what do adrenal glands, testes, and ovaries convert cholesterol to?

steroid hormones

what is cholesterol used for in the liver?

bile acid synthesis

what does the brain convert cholesterol to?

hydroxycholesterols

what are the 4 major classes of lipoprotein particles?

chylomicrons

VLDL

LDL

HDL

what is a apolipoprotein?

protein part of lipoprotein particle

what are high LDL levels associated with?

artherosclerosis

what are low HDL levels associated with?

heart disease

what causes familial hypercholesterolemia?

genetic mutation in LDL receptor

what does the metabolism of AA in the liver make?

proteins

hormones, nucleotides

CAC intermediates/pyruvate

what is the function of white adipose tissue?

fuel storage

what do lipases hydrolyze to release FA?

TAGs

what does resting muscle rely on?

FA

what do active muscles use?

glucose and ketone bodies

what are the purine bases?

adenine

guanine

what are the pyrimidine bases?

cytosine

thymine

uracil

what bases are found in both DNA and RNA?

A,G,C

what base is found in DNA only?

T

what base is found in RNA only?

U

what are ribonucleotides?

structural units of RNA

what are deoxyribonucleotides?

structural units of DNA

what are the 3 regulatory nucleotides?

cAMP

cGMP

ppGpp

what is P-P bonds store?

chemical energy

when is ppGpp produced in bacteria?

during AA starvation

what end of the DNA/RNA strand is the phosphate?

5’

what end of the DNA/RNA strand is the hydroxyl?

3’

what are monomers joined by?

phosphodiester bond

what are antiparallel DNA strands linked by?

H-bonds

which bases go together in DNA?

C & G

T & A

what direction is DNA synthesized?

5’ to 3’

what is conservative DNA replication?

new DNA molecule made with 2 newly synthesized strands

what is semi-conservative DNA replication?

new DNA molecule made with 1 old strand from template DNA strand and 1 newly synthesized strand

what can cause denaturation of DNA strands?

heat or extreme pH

what does thermal stability of DNA increase with?

% (G+C)

what does base-pair stacking contribute to?

DNA stability

what are the 3 helical forms?

B-DNA

A-DNA

Z-DNA

what is the most common helical form in cells?

B-DNA

Hoogsteen positions and pairings occur in DNA structures with how many strands?

3

where do triplex DNAs form from?

Hoogsteen pairings

when do tetraplex DNAs occur?

when 4 DNA strands pair

what structures form from self-complementary within each strand?

hairpin

cruciform

what form is DNA mostly found in?

right handed B-form

what form is RNA mostly found in?

right handed A-form

what allows phosphates to come closer together and pack more tightly in the A-form?

C3’-endo sugar pucker

what is important for helix stability?

H-bonding and base stacking

what does monocistronic mean?

codes for only 1 polypeptide

what does polycistronic mean?

codes for 2+ different polypeptides

how many chromosomes do human somatic cells have?

46

what are chromatin?

eukaryotic chromosomal material composed of DNA,RNA and proteins

when are chromatin amorphous?

in G0 and interphase

what phase do amorphous DNA replicate to produce sister chromatids?

S phase of interphase

where do most of histone modifications occur?

in amino-terminal tails of histones

what do amino-terminal tails of histones play a key role in?

forming contacts between nucleosomes in chromatin

what does binding of histone core depend on?

local abundance of A=T base pairs

long noncoding RNAs play functional role in what?

defining chromosome structure

what are SMC proteins responsible for?

maintaining structure and integrity of chromosomes following replication

how do condensins stabilize DNA loops?

by binding at base of each one

what kind of mRNAs do prokaryotic genes give?

mono or polycistronic

what kind of mRNAs do eukaryotic genes give?

monocistronic

what shape is prokaryotic DNA?

circular

what shape is eukaryotic DNA?

linear

what is important in DNA packaging?

DNA supercoiling

what are the 2 parts of DNA polymerase active site?

insertion site

postinsertion site