L-6 Energy Balance and Metabolism I Flashcards
(69 cards)
1
Q
describe the energy production
A
- oxidation; make ATP
1) proteins
2) Carbs
3) fats
2
Q
describe the energy utilization
A
consume ATP
- active ion transport
- muscle contraction
- synthesis of molecules
- cell division and growth
3
Q
describe the delta G
A
- std free energy difference
= difference in free energy when 1 mole of each reactant is converted to 1 mole of each product at 1 atm pressure at 25 degrees C
4
Q
what becomes the final common pathway for the transport of almost all the carbs to the tissue cells?
A
glucose
5
Q
T/F: galactose, glucose, and fructose are all interconvertible
A
true
6
Q
what two hexoses can be converted to fructose-6-phosphate to enter the glycolytic pathway?
A
galactose and glucose
7
Q
describe the two type of glucose uptake
A
via active sodium-glucose co-transport and facilitated transport
8
Q
where does sodium-glucose co-transport occur? describe it
A
GI tract and renal tubules
- active transport of sodium provides energy for absorbing glucose against a concentration gradient
9
Q
where does facilitated transport occur? describe it
A
most tissues
- only transported from higher to lower concentration
- presence of insulin increases glucose transport x10
- phosphorylation of glucose prevents diffusion out of cell
10
Q
in what tissues can the phosphorylation be reversed?
A
- phosphorylation can be reversed in liver, renal, and intestinal cells
11
Q
what 3 important enzymes are involved in glycogenesis and glycogenolysis? what do they do?
A
- glucokinase - transfers phosphate from ATP
- phosphatase (removes phosphate)
- phosphorylase (catalyzes production of glucose-1-phosphate from glycogen)
12
Q
what factors can activate phosphorylase?
A
- epinephrine (from adrenal medulla)
- glucagon (from alpha cells of pancreas)
13
Q
what are the effects of phosphorylase?
A
- promotes conversion of glycogen to glucose
- glucose can then be released into blood
14
Q
in glycolysis, what are the end products?
A
- 2 pyruvic acid
- 4 hydrogens (released via dehydrogenase)
- 2 ATP (net)
15
Q
what are the end products of converting pyruvate to acetyl-CoA?
A
- 2 Acetyl-CoA
- 4 Hydrogen
- 2 CO2
16
Q
describe the citric acid cycle and its end products
A
- occurs in the mitochondrial matrix
- 16 H’s
- 2 ATPs
- 4 CO2
17
Q
what is the net reaction of the citric acid cycle?
A
2 Acetyl-CoA + 6H20 + 2ADP –> 4 CO2 + 16 H + 2 CoA + 2 ATP
18
Q
where does oxidative phosphorylation occur?
A
mitochondrial cristae
19
Q
what is the fate of hydrogen atoms from previous cycles?
A
- note that hydrogens are removed in pairs
- one member of each pair becomes a H ion
- the other member combines with NAD+ –> NADH
20
Q
what is the fate of electrons removed from H ions?
A
- enter ETC
21
Q
what are the major components of the ETC?
A
- flavoprotein
- several ion sulfide proteins
- Ubiquinone (Q)
- cytochrome A3 (cytochrome oxidase) // located on inner membrane; can give up two electrons to oxygen
22
Q
number of ATPs formed per glucose molecule:
A
- glycolysis: 2 ATP
- CAC: 2 ATP
- oxidative phosphorylation: 34 ATP
23
Q
what is the max number of ATPs per glucose molecule?
A
38 ATP
24
Q
what is the efficiency?
A
66%
456,000/686,000 = 66%
25
what is the pentose phosphate pathway?
the ppp is a cyclical pahtway in which one molecule of glucose is metabolized for each revolution of the cycle
26
describe some details about it
- for every 6 molecules of glucose that enter the pathway, 5 molecules of glucose are resynthesized
27
what is this pathway used for?
mostly used for the synthesis of fats and other substances
| -
28
Where are the hydrogens generated from this pathway bound to?
NADP+ instead of NAD+
29
what can be used for the synthesis of fats from carbohydrates? NADP or NAD?
NADP+ (as NADPH)
30
how is glucose broken down when theres an excess of glucose in liver?
PPP; producing excess NADPH
31
what does this NADPH participate in?
- in the conversion of Acetyl-CoA into fatty acid chains
- glucose is preferentially stored as glycogen until the storage cells (liver and muscle) are saturated
- excess glucose is then converted into fat (liver and fat cells) and stored in fat cells
32
describe what happens when triglyceride absorption occurs from intestinal lumen
- most triglycerides are digested into monoglycerides and fatty acids
- intestinal epithelial cells resynthesize these into triglycerides that enter the lymph as chylomicrons
- apoprotein B is adsorbed to the chylomicron surfaces
33
how are chylomicrons transported to the venous system?
via the thoracic ducts
34
what tissues are chylomicrons especially removed from (from their blood)?
- adipose tissue
- skeletal muscle
- heart
35
what do these last three tissues synthesize?
- lipoprotein lipase, which:
= is transported to surface of capillary epithelial cells
= hydrolyzes chylomicron triglycerides, releasing fatty acids and glycerol
36
some more fun facts about neutral fats
- fatty acids can be used for fuel or again synthesized into triglycerides
- 50% of the plasma fatty acid is replaced every 2-3 minutres
- therefore, all normal energy requirements of the body can be provided by the oxidation of fatty acids without using carbs or proteins as an energy source
37
under what conditions is there an increase in utilization of fat for energy?
- starvation
| - diabetes mellitus
38
what type of lipoprotein is synthesized by intestinal cells/
chylomicrons
39
what kinda lipoproteins are synthesized by the liver?
- very low density lipoproteins (VLDLs)
- intermediate DLs
- low DLs
- High DLs
40
describe the lipid transport in the blood via VLDLs
- high concentration of triglycerides and moderate amounts of cholesterol and phospholipids
- transport lipids mainly from liver to adipose tissue
41
LDLs
- high concentration of cholesterol and moderate concentration of phopsholipids
42
HDLs
- high concentration of proteins and low concentration of cholesterol and fatty acids
43
what are the principal functions of the liver in lipid metabolism?
text***
44
under what conditions do large quantities of triglycerides appear in the liver?
text***
45
what are triglycerides hydrolyzed into? (in regards to energy source)
- into fatty acids and glycerol, which are transported in blood to tissue
46
what two type of cells dont use fatty acids for energy?
brain cells and RBCs
47
what is glycerol converted to?
G3P
48
what are fatty acids converted to? and where?
Acetyl-CoA; in mito
49
via what process? elaborate
via beta-oxidation
- carnitine is used as a carrier molecule into the mitochondria
- Acetyle CoA enters the citric acid cycle by binding to oxaloacetic acid
- hydrogens enter the chemoismotic oxidative system
50
what are the products from beta-oxidation of one molecule of stearic acid?
- 9 ACA molecules
| - 146 molecules of ATP
51
what happens to fatty acids in liver not used for metabolism?
releases many ACAs
- 2 ACAs condense to form acetoacetic acid
- some of the acetoacetic acid is converted to: b-hydroxybutyric acid and acetone
52
T/F: acetoacetic acid is a keto acid
True
53
what are considered ketone bodies?
- acetoacetic acid
- beta-hydroxybutyric acid,
- acetone
54
what happens to ketone bodies during ketosis?
- diffuse back into cells and are converted into ACA
55
how does ketosis occur/
if concentration of ketone bodies increase above normal in blood
56
what conditions favor ketosis?
- starvation
- diabetes
- diet composed almost entirely of fat
57
how many steps are involved in synthesis of fatty acids? what do they involve?
2;
- involves malonyl-CoA
- NADPH
58
why is fat synthesis important?
- more fat can be stored in tissues than carbs
| - weight-for-weight, fat contains about 2.5x the energy of carbs
59
why are fats poorly synthesized during insulin insufficiency?
text
60
why are carbs preferred over fats for energy?
text
61
describe the development of atherosclerotic plaque
- damage to vascular endothelium
- circulating monocytes and LDLs accumulate at injury site
- monocytes
62
describe damage to vascular endothelium
- incr the expression of adhesion molecules
| - decreases release of NO and other substances that prevent adhesion of macromolecules and cells
63
describe monocytes
- cross endothelium
- enter intima
- become macrophages
64
describe macrophages
- ingest lipoproteins
- become foam cells
- form visible fatty streaks
65
describe fatty streaks
- grow larger
| - coalesce
66
surrounding fibrous and smooth muscle tissues
- proliferate
| - form large plaques
67
descirbe the large plaques
- may occlude lumen
- may become sclerotic or fibrotic
- may become calcified
68
what are the basic causes of atherosclerosis?
- increased LDLs
| - familial hypercholesterolemia (defective LDL receptors)
69
note about HDLs
they may be able to absorb cholesterol crystals that are beginning to be deposited in arterial walls
