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Biochem weeks 3-4 > Carbohydrate structure and glycolysis > Flashcards

Carbohydrate structure and glycolysis Flashcards

1
Q

which organs / tissues need a constant supply of glucose (need glucose at both high and low blood glucose levels)?

A

brain (neurons) & RBCs (erythrocytes)

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2
Q

stereoisomers have …

A

same chemical formula, different 3D structure

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3
Q

of isomers for a molecule =

A

2^ (# C atoms - 2)

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4
Q

enantiomers are …

A

mirror images of each other

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5
Q

anomers are specific to …

A

ring structures of monosaccharides

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6
Q

L-enantiomer has the OH group …

A

on the left

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7
Q

D-enantiomer has the OH group …

A

on the right

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8
Q

epimers have …

A

same chemical formula AND same 3D structure, BUT asymmetric around one carbon

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9
Q

the 4 most important disaccharides

A

lactose
sucrose
maltose
isomaltose

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10
Q

glycosidic bond is between …

A

OH group on anomeric carbon (on monosaccharide 1)

free OH group (on monosaccharide 2)

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11
Q

lactose

A

galactose beta(1 - 4) glucose

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12
Q

sucrose

A

glucose alpha(1 - 2) fructose

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13
Q

maltose

A

glucose alpha(1 - 4) glucose

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14
Q

isomaltose

A

glucose alpha(1 - 6) glucose

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15
Q

GLUT transporters are …

A

monosaccharide transporters

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16
Q

3 sources of glucose for glycolysis

A

glycogenolysis (during exercise in muscle)
dietary intake (during FED state)
glycogenolysis gluconeogenesis (during fasting / starvation)

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17
Q

what are 3 polysaccharides of glucose?

A

glycogen
starch
cellulose

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18
Q

glycogen structure

A

highly branched

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19
Q

starch structure (contains 2 components) and what does it supply humans?

A

amylose
amylopectin

dietary fuel from plants

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20
Q

cellulose (another name, origin, structure, behavior in humans)

A

aka fiber

from plants

UNbranched

not digestible, but has health benefits

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21
Q

draw GLUT transporter concept map out

A
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22
Q

draw glycolysis overview on whiteboard

A
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23
Q

what is the first irreversible step in glycolysis? what else is true about it?

A

glucose –(hexo-/glucokinase)–>
glucose-6P

committed, regulated step
NOT key step bc it’s not unique

24
Q

what kind of rxn is glucose-6P –> fructose-6P?

A

reversible,
not regulated

25
what is the second irreversible step in glycolysis? what else is true about it?
fructose-6P --(PFK-1)--> fructose-1,6-BP - 1 ATP KEY and regulated step
26
what is the last rxn in glycolysis?
PEP --(pyruvate kinase)--> pyruvate + 2 ATP / per glucose regulated step
27
irreversible rxn =
regulated
28
reversible rxn =
NOT regulated
29
what are the 3 phases of glycolysis?
investment splitting energy generation
30
where does pyruvate go after glycolysis?
to mitochondria for TCA cycle
31
where does 2 NADH produced go after glycolysis?
to mitochondria for ETC
32
net production of glycolysis / per glucose
+ 2 pyruvate - 2 ATP + 2 NADH + 4 ATP
33
what is the first step of glycolysis in fasting / starvation? what tissue(s) does this occur?
glucose / fructose / galactose | {through GLUT 1 or GLUT 3} | (hexokinase) | V glucose-6P [- 1 ATP] all tissues
34
what is the first step of glycolysis in fed state? what tissue(s) does this occur?
glucose | {through GLUT 2} | (glucokinase) | V glucose-6P [- 1 ATP] only liver and pancreas
35
draw hexokinase vs glucokinase comparison list
36
what does Vmax mean for an enzyme?
capacity / amount of binding that the enzyme can handle
37
what does Km mean for an enzyme?
the concentration of substrate required for enzyme to reach half of its Vmax
38
what does a low Km indicate about binding affinity?
HIGH affinity for its substrate, bc it gets saturated quickly
39
what does a high Km indicate about binding affinity?
LOW affinity for its substrate, bc it does not get saturated quickly
40
what are the 3 stages of metabolism?
1. digestion & absorption in GI tract 2. glycolysis 3. oxidation of Acetyl-CoA in TCA
41
what are the products of anaerobic glycolysis? when does anaerobic glycolysis occur?
+ 2 lactate / per glucose +2 ATP absence of oxygen; in cells without mitochondria
42
how does NADH get to the ETC in the liver / heart?
malate-aspartate shuttle takes e- from cyto. NADH, takes it into mito., converts it to NADH recycles cyto. NAD+ into cytoplasmic pool cyto. NADH -> mito. NADH
43
how does NADH get to the ETC in the brain / muscle?
glycerol-3P shuttle takes e- from cyto. NADH, takes it into mito., converts it to FADH2 recycles cyto. NAD+ into cytoplasmic pool cyto. NADH -> mito. FADH2
44
arsenate can cause poisoning by inhibiting what rxn in glycolysis?
first rxn in energy production phase glyceraldehyde-3P <--> 1,3-BP
45
what can inhibit the rxn that produces PEP in glycolysis?
fluoride ions (ex. toothpaste)
46
what 3 enzymes are alloesterically regulated in glycolysis?
hexokinase PFK-1 pyruvate kinase
47
what is hexokinase allosterically inhibited by?
glucose-6P
48
what is PFK-1 allosterically stimulated by during FED state?
AMP fructose-2,6-BP (only in liver)
49
what is PFK-1 allosterically inhibited by during fasting / starvation state?
ATP citrate fructose-2,6-BPase (only in liver)
50
what is pyruvate kinase allosterically stimulated by?
fructose-1,6-BP
51
what is pyruvate kinase allosterically inhibited by?
ATP
52
where does hormonal regulation of glycolysis occur?
only in the liver
53
what is pyruvate kinase hormonally inactivated by? what does this prevent? where does PEP go now? in what state does this occur?
glucagon signaling PK inhibition prevents PEP from being converted to pyruvate PEP goes to gluconeogenesis instead in fasting / starvation state
54
why is glycolysis only on during fed state?
bc in fed state, liver is a glucose consumer + liver wants to store glucose
55
why is glycolysis off during fasting / starvation states?
bc in fasting / starvation, liver is a glucose producer for all other cells in body via glycogenolysis / gluconeogenesis if glycolysis is off then all glucose generated would just be wasted
56
what is pyruvate kinase deficiency? what happens in glycolysis if it is severe?
mutation in enzyme encoding pyruvate kinase 0 PK activity = ATP produced during glycolysis is half of normal amount
57
why can pyruvate kinase deficiency by catastrophic for RBCs?
RBCs only get ATP from glycolysis RBCs use ATP to maintain membrane shape without enough ATP -> become echinocytes (spikey cells) echinocytes are digested by body = causes HEMOLYTIC ANEMIA

Biochem weeks 3-4 (5 decks)

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