Bio 2 Flashcards Preview

MCAT > Bio 2 > Flashcards

Flashcards in Bio 2 Deck (89):
1

What 5 things can gluconeogenesis make glucose from?

pyruvate
lactate
Krebs cycle intermediates
glycerol
carbon skeleton of glycogenic amino acids

2

What is one cell respiration molecule that can NOT be used for gluconeogenesis?

acety-CoA

3

Where does gluconeogenesis occur in the body? Where does it occur in cells?

can start in the mitochondrial matrix, but its mostly in the cytoplasm
major organ is the liver, kidney can also do some

4

What is required for gluconeogenesis?

ATP

5

Does gluoconeogenesis use the same enzymes as glycolysis?

yes except for the 3 irreversible steps

6

What enzyme converts G6P to glucose in gluconeogenesis?

glucose-6-phosphatase

7

What enzyme converts F1,6P to F6P in gluconeogenesis?

F 1,6 biphosphatase

8

What does pyruvate carboxylase do? What does it use?

converts pyruvate to OAA
requires ATP (one for each pyruvate)

9

What does PEP carboxy kinase do? What does it require?

converts OAA to PEP
requires GTP (one for each OAA)

10

What does PFK2 do?

converts F6P to F26P (regulatory molecule)

11

What regulates PFK2?

decrease in blood sugar
gives increase in glucagon
gives increase in cAMP
activates PKA
PKA inhibits PFK2

insulin stimulates PFK2

12

What does F-2,6-bisphosphatase do?

coverts F-2,6-P to F6P

13

How is F-2,6-bisphosphatase regulated?

PKA stimulates it (low blood sugar>glucagon>cAMP>PKA)
insulin inhibits it

14

What does F-2,6-bisphosphate do?

stimulates PFK and inhibits F-1,6-bisphosphatase

15

What effects does citrate concentration have on metabolism?

high citrate concentration inhibits glycolysis and stimulates gluconeogenesis

16

What effects do AMP and ADP concentration have on metabolism?

high AMP and ATP stimulate glycolysis and inhibit gluconeogenesis

17

What effects does ATP concentration have on metabolism?

high ATP inhibits glycolysis (and PFK) and stimulates gluconeogenesis

18

Describe the regulation of phosphofructokinase

stimulated by F2,6P and AMP
inhibited by ATP

19

Describe the regulation of fructose-1,6-bisphosphatase

inhibited by F-2,6-P and AMP

20

Describe regulation of isocitrate dehydrogenase

stimulated by ADP
inhibited by ATP and NADH

21

Where is glycogen found?

muscle and liver cells

22

What kind of bonds does glycogen have?

alpha 1,4 bonds with alpha 1,6 branches
(glucose polymer)

23

When do glycogenesis and glycogenolysis occur?

glycogenesis occurs when blood sugar is high
glycogenolysis occurs when blood sugar is low

24

What is the key enzyme in glycogenesis? How is it regulated?

glycogen synthase
stimulated by insulin
inhibited by glucagon and epinephrine

25

What is the key enzyme in glycogenolysis? How is it regulated?

glycogen phosphorylase
stimulated by glucagon and epinephrine
inhibited by insulin

26

What are the steps in beta-oxidation? What is produced?

oxidation-FADH2 produced
hydration
oxidation-NADH produced
cleavage

27

Where does beta-oxidation occur?

in the mitochondrial matrix

28

Where does fatty acid activation occur for lipid catabolism?

at the outer mitochondrial membrane?

29

How are activated fatty acyl-CoA molecules transported into the mitochondrial matrix for beta-oxidation?

via the carnitine shuttle

30

Where does lipolysis occur? How do fatty acids move through the blood and into target cells?

lipolysis occurs in adipocytes
fatty acids move through the blood bound to carrier protein i.e. albumin and then diffuse into target cell

31

If an 18 carbon fatty acid chain went through bet-oxidation what would the resulting molecules be?

8 FADH2
8 NADH
9 acetyl-cow which would make (in Krebs cycle):
27 NADH
9 FADH2
9 GTP

32

What is produced in the final cleavage of a fatty acid undergoing beta-oxidation?

NADH
FADH2
2 acetyl-CoA

33

Describe how unsaturated fatty acids are dealt with in lipid catabolism

if there is more than one cis double bond it is reduced by reductase using NADPH (makes NADP+)
when there is only one cis bond left isomerase coverts it into a trans bond
molecule then enters step 2 of beta-oxidation (hydration)

34

Where does lipid anabolism occur?

cytoplasm

35

What is the "committed" step in lipid anabolism? What enzyme performs this step? What is the reaction?

activation is the committed step
acetyl-CoA carboxylase performs it
turns acetyl-CoA into malonyl-CoA

36

What does malonyl-CoA regulate?

carnitine shuttle, so that fatty acids can't go into the mitochondrial matrix

37

What are the 4 steps in biosynthesis of fatty acids? What enzyme is used? What molecule are used/produced?

enzyme = fatty acid synthase
1) elongation
2) reduction- uses NADPH and makes NADP+
3) dehydration
4) reduction- uses NADPH and makes NADP+

38

How does an increase in blood glucose affect fatty acid synthesis?

increase in blood glucose causes insulin to be released
which increases transcription and translation of both acetyl-CoA carboxylase and fatty acid synthase

39

How does a decrease in blood glucose affect fatty acid synthesis?

decrease in blood glucose causes glucagon and epinephrine to be released
which causes an increase in cAMP
which activates PKA
which inhibits acetyl-CoA carboxylase and stimulates lipase (for catabolism)

40

Where does ketogenesis occur?

in the mitochondrial matrix in the liver

41

What organs use ketone bodies made by the liver? When do they use them?

heart and central nervous system
use them during starvation or when glucose can't enter cells i.e. type 1 diabetes mellitus

42

Name 3 ketone bodies

aceton
acetoacetate
beta-hydroxybutyrate

43

What are ketone bodies made from in the liver?

acetyl-CoA

44

How are ketone bodies metabolized?

transported through the blood
go into the mitochondria
are oxidized back to acetyl-CoA
enter the Kreb's cycle

45

Can amino acids be stored or excreted?

no not as is

46

What is another name for protein anabolism?

translation

47

Where does deamination occur? What are the products?

in the liver
produces alpha-keto acids and NH3

48

What happens to NH3 produced by the deamination of amino acids?

go into the urea cycle
produce urea
are then excreted in the urine

49

What can alpha-keto acids be turned into?

glucogenic amino acids or ketogenic amino acids

50

Describe what the body does with glycogenic amino acids that it produces

they are turned into pyruvate or Kreb's cycle amino acids
they then can go into cell respiration or gluconeogenesis

51

Describe what happens to ketogenic amino acids that the body produces

they are turned into acetoacetate then acetyl-CoA or directly into acetyl-CoA
they then go into fatty acid biosynthesis, ketogenesis or the Kreb's cycle

52

Can ketogenic amino acids ever be turned into glucose?

no

53

Where does the pentose phosphate pathway occur?

in the cytoplasm

54

What are the products of the pentose phosphate pathway?

ribose-5-phosphate, NADPH, CO2 and metabolic intermediates

55

What is G6P dehydrogenase?

enzyme that catalyzes the oxidation of G6P in the pentose phosphate pathway, using NADP+ and making NADPH

56

What is a nucleoside?

sugar and base

57

What is a nucleotide?

sugar and base and phosphate

58

What holds DNA strands together?

H-bonds between bases
intermolecular forces between bases
hydrophobic interactions between bases

59

What is Tm?

the temperature at which a solution of DNA molecules is 50% denatured/melted

60

What would attaching the phosphate oxygens along a DNA double helix to methyl groups do to its Tm?

it would increase Tm because the charged phosphates repel each other

61

Describe a telomere

6-8bp that are repeated 50-1000 times
need special replication
have ~300 nucleotides ss at the end which loop around or bind proteins

62

What are centromere made of? What surrounds them?

made of heterochromatin repeats
surrounded by kinetochores

63

Which arm of the chromosome is q? Which one is p?

q is the long arm
p is the short arm

64

Describe the shape of viruses, prokaryotes and eukaryotes genomes

viruses- linear or circular
prokaryotes- 1 circular chromosome
eukaryotes- many linear chromosomes

65

How do the sizes of genomes of viruses, prokaryotes and eukaryotes compare?

viruses- 3200 to 1.6 million bp
prokaryotes- 10^6 bp
eukaryotes- 10^9 bp

66

How does the density of viral, prokaryotic and eukaryotic genomes compare?

viruses- very high density
prokaryotes- high density
eukaryotes- low density

67

How are viral genomes packed?

they have minimal packing

68

How are prokaryotic genomes packed?

they are supercoiled using DNA gyrase which requires ATP

69

How are eukaryotic genomes packed?

they are wrapped around histones to form nucleosomes which are then packed into chromatin and then chromosomes

70

What are tandem repeats?

short regions go variable length that repeat 3-100 times
useful in DNA fingerprinting
can cause disease if they are too many etc
ie Huntington's

71

What is metacentric centromere positioning?

in the middle, both arms are the same size

72

What is submetacentric centromere positioning?

centromere is a bit closer to one end than the other, one set of arms is slightly smaller

73

What is acrocentric centromere positioning?

centromere is a lot closer to one end, one set of arms are much smaller than the other

74

What is telocentric centromere positioning?

centromere is at one end, there is only one set of arms

75

What do the simplest transposons have? What can they do?

inverted repeats, encode a transposase in the middle
after transcription and translation of the transposase, it can cut the transposon out of the genome and paste in another spot

76

What does a complex transposon contain?

inverted repeats with a transposase and gene(s) in the middle

77

What is a composite transposon?

when there are 2 transposons with inverted repeats on either side of a "central region" (part of the genome)

78

What is the start codon?

AUG (codes for Met)

79

What are the stop codons?

UAA
UAG
UGA

80

What is a balanced translocation? Unbalanced?

balanced translocation is when no info is lost
unbalanced is when some genetic info is lost or degraded

81

What effects can transposons have on DNA?

insertion mutations
deletions or inversions during recombination if there are 2 beside each other

82

What type of viruses can cause mutations?

lysogenic because they insert into the genome

83

What is direct reversal?

some bacteria and plants can directly reverse mutations i.e. pyrimidine dimers via photoreactivation

84

What are the two types of homology-dependent DNA repair?

excision repair
mismatch repair

85

When does excision repair occur?

during replication
cut out defective nt and replace with the right one

86

When does mismatch repair occur?

during or after replication
identify new vs old strands
cut out defective nts on old strand and replace

87

What are the two types of double-stranded break repair?

homologous recombination and non-homologous

88

What is homologous recombination? When does it occur?

occurs while cells are growing and dividing
uses sister chromatids to make a joint molecule and repair double-stranded break

89

What is non homologous recombination? When does it occur?

occurs when cells are not dividing
stabilize and ligate nonspecific DNA fragments