Exam 1: Cell respiration - metabolism Flashcards
1
Q
Metabolism
A
- all reactions in body that involve energy transformations
- catabolism + anabolism
2
Q
catabolism
A
- breaks down molecules & releases energy
- Is primary source of energy for making ATP
3
Q
anabolism
A
- makes larger molecules & requires energy
- Source of body’s large energy-storage compounds
4
Q
Aerobic cellular respiration
A
series of chemical reactions whereby glucose (or other molecules) and oxygen are converted into carbon dioxide and water in the process of making adenosine triphosphate (ATP)
5
Q
Under Aerobic cellular respiration 1 glucose molecules can be made into how many ATP molecules
A
30-38
6
Q
Anaerobic cellular respiration
A
series of chemical reactions whereby glucose (or other molecules) is converted into carbon dioxide and water in the process of making (ATP)
7
Q
Under Anaerobic cellular respiration 1 glucose molecules can be made into how many ATP molecules
A
2 atp molecules
8
Q
Both aerobic and anaerobic respiration begin with
A
glycolysis
9
Q
glycolysis
A
metabolic pathway by which glucose (C6H12O6 ) is converted to 2 pyruvates = pyruvic acid (C3H4O3 );
10
Q
glycolysis occurs where
A
occurs in cytoplasm and does not require oxygen
11
Q
overall net equation of glycolysis is
A
Glucose + 2NAD + 2ADP + 2Pi 2 pyruvates + 2NADH + 2 ATP
12
Q
what is NAD
A
Nicotinamide adenine dinucleotide = electron carrier
13
Q
Glycolysis produces net gain of?
A
2ATPs & 2NADHs
14
Q
The 9 steps of Glycolysis :
1st Step
A
- Glucose is activated with ATP (phosphorylation) before energy can be obtained; phosphorylation traps glucose inside cell by forming glucose 6-phosphate
15
Q
The 9 steps of Glycolysis :
2nd Step
A
.2. glucose 6-phosphate is converted to its isomer fructose 6-phosphate
16
Q
The 9 steps of Glycolysis :
3rd Step
A
.3. Another ATP is used to form fructose 1,6-biphosphate
17
Q
The 9 steps of Glycolysis :
4th Step
A
. fructose 1,6-biphosphate is converted into two 3 C molecules = 3-phosphoglyceraldehyde
18
Q
The 9 steps of Glycolysis :
5th Step
A
- 2 pairs of H’s are removed and added to NAD forming NADH and Pi is added to form 1,3-biphosphoglyceric acid
19
Q
The 9 steps of Glycolysis :
6th Step
A
- a phosphate is removed from each 1,3-biphosphoglyceric acid forming 2 ATP and 3-phosphoglyceric acid
20
Q
The 9 steps of Glycolysis :
7th Step
A
- 3-phosphoglyceric acid is changed to the isomer 2-phosphoglyceric acid
21
Q
The 9 steps of Glycolysis :
8th Step
A
- 2-phosphoglyceric acid is changed to the isomer phosphoenolpyruvic acid
22
Q
The 9 steps of Glycolysis :
9th Step
A
- last phosphate is removed from phosphoenolpyruvic acid forming 2 more ATP and pyruvic acid
23
Q
Glycolysis end
A
2ATPs added & 4 are produced for a net gain of 2 ATP
24
Q
In order for glycolysis to continue, what must happen
A
there must be sufficient NAD available to accept hydrogens from glucose,
- needs to be more NAD for step 5 of glycolysis
25
What needs to happen to avoid end-product inhibition
NADHs produced in glycolysis need to give Hs away
26
anaerobic respiration
= lactic acid fermentation
| - happens in the absence of O2
27
What happens in absence of O2
NADH gives its Hs to pyruvate creating lactic acid, which makes muscles feel fatigued and can cause cell death in excessively high concentrations
28
When NADH gives its Hs to pyruvate (rather than taking them to the mitochondira), what is created?
lactic acid
29
what uses only lactic acid pathway and why
RBCs because they dont have mitochondria
30
lactic acid occurs where?
Occurs in skeletal (during heavy exercise ) regularly & heart muscle (vascular blockage) when oxygen supply falls below critical level only rarely
31
Cells cannot store a lot of separate glucose molecules because
the osmotic pressure would draw large amounts of water into cells
32
where is glucose stored as glycogen
some organs (liver, skeletal muscle, heart)
33
Glycogenesis
process of polymerizing glucose into glycogen
34
process of glycogenesis
glucose -> glucose 6-phosphate -> glucose 1-phosphate --> enzyme called glycogen synthase removes the phosphate as polymerization to glycogen
35
Glycogenolysis
glycogen (catalyzed by glycogen phosphorylase) -> glucose 1-phosphate -> glucose 6-phosphate; can be used for glycolysis by skeletal muscles
36
In glycogenolysis only liver has
glucose-6-phosphatase that removes phosphate groups from glucose 6-phosphate so glucose can be secreted into blood for use by other tissues/organs
37
cori cycle
2-way traffic between skeletal muscle and the liver
| **** must know 2 diagram
38
most of the lactic acid produced in anaerobic respiration is
eliminated by aerobic respiration where it is made into CO2 and H2O
39
Some of the lactic acid produced in anaerobic goes to
liver where it is converted back to pyruvate via lactic acid dehydrogenase and then to glucose 6-phosphate
40
what happens to glucose 6-phosphate after the lactic acid produced in anaerobic goes to liver where it is converted back to pyruvate
Glucose 6-phosphate can then be converted to free glucose or be used to make glycogen
41
Aerobic respiration; is preceded by
glycolysis (2 pyruvates, 2 ATP, 2 NADH)
42
Aerobic respiration has end products of
CO2, H2O, and ATP
43
Aerobic respiration begins when
when pyruvate enters mitochondria
44
in Aerobic respiration what happens to pyruvate after it enters mitochondira
Pyruvate is converted to acetyl coenzyme A (acetyl CoA = a 2 C molecule) via coenzyme A and C02
45
Energy in acetyl CoA is extracted during
aerobic respiration in mitochondria
46
where does CO2 goes
lungs
47
Why is lactic acid made
So glycolysis continue
| Nadh that was made during step 5 glycolysis has to be generated to NAD
48
During Aerobic respiration each pyruvate (3c) --> 1 acetyl CoA + CO2, therefore what is formed from 1 glucose
2 acetyl CoA + 2 CO2
49
During Aerobic Respiration Oxygen in CO2 is not from breathed O2 gas, its from?
glucose
50
Krebs cycle
= Citric Acid Cycle = Tricarboxylic Acid (TCA) Cycle
51
krebs cycle begins with
Begins with acetyl CoA (2 C) combining with oxaloacetic acid (4 C) to form citric acid (6 C)
52
krebs cycle:
| in a series of reactions citric acid converted back to?
oxaloacetic acid to complete the pathway
53
key point: Products of Krebs Cycle/ acetyl CoA : (x2 all)
1 GTP, which donates phosphate to ADP to produce ATP
3 NADH, & 1 FADH2, which carry electrons to Electron Transport Chain (ETC)
2 more CO2 = waste = byproduct
54
what is electron transport chain and how does it contribute to making of cellular energy
ETC is a link series of protein embedded in the cristae in the mitochondria which creates proton gradient that atp synthase uses as energy to make ATP
55
Why do we breathe o2
So O2 can server as the final electron acceptor for the electron transport chain
56
ETC
The electron transport chain (ETC) is a linked series of proteins on the foldings (cristae) of mitochondria
57
proteins of ETC include
flavin mononucleotide FMN, coenzyme Q, & iron containing pigments (cytochromes)
58
NADH & FADH2 from Krebs carry
electrons to ETC, which are then shuttled in sequence through ETC
59
NAD and FAD are regenerated to?
to shuttle more electrons from Krebs Cycle to ETC
60
As each protein in ETC accepts electrons
it is reduced
61
When protein in ETC gives electrons to next protein it is
oxidized
62
the process of accepting and giving electrons from and to protein is called?
exergonic
63
exergonic:
| energy gained is used to?
is used to phosphorylate ADP to make ATP
| Called oxidative phosphorylation
64
chemiosmotic theory
: energy gathered by ETC by the passage of e- is used to pump H+s (by the proteins of the ETC) into mitochondria outer chamber; this creates high H+ concentration f
65
As H+s diffuse down concentration & charge gradients thru ATP synthase, & back into inner chamber, their energy drives ATP synthesis by:
ADP + Pi = ATP
66
function of Oxygen in ETC
Electrons added to beginning of ETC by NADH and FADH2 and are passed along until they reach the last member of the ETC (cytochrome a3), which has to pass the e- on or the chain will stop
67
Where will the e- s be passed if we have reach the end of the chain??? ….A: THIS IS WHY YOU BREATH O2!!!
O2 is reduced and serves as the final e- acceptor by accepting these electrons & combining with 4H+s to form H2O: O2 + 4 e- + 4 H+ 2 H20
68
cyanide is deadly b/c?
it blocks transfer of e- from cytochrome a3 to O2
69
Fats as energy source
Fats can be hydrolyzed to glycerol & fatty acids, which can be modified to run thru Kreb's to make ATP
70
Proteins as energy source
Proteins can be broken down to amino acids, which can be deaminated (removal of the amine group), converted into pyruvate & run thru Kreb's
71
Fats and protein pathways can be used to
interconvert carbohydrates, fats, & proteins into cellular energy
72
When more energy (ffod) is taken in that consumed (used to make heat and ATP)
ATP synthesis is inhibited;
| we do not store extra ATP
73
Glucose converted into glycogen & fat
can later be broken down (if needed) to form ATP
74
When glucose is going to be converted to fat
glycolysis 1st occurs forming pyruvate, which is converted to acetyl CoA
75
Acetyl CoA is a common substrate for energy & synthetic pathways because
it can be sent to Krebs cycle (to make ATP) or made into cholesterol, bile salts, steroid hormones, ketone bodies, and fatty acids
76
fat synthesis
lipogenesis
77
Acetyl CoA can be linked together to form
fatty acids
78
Fatty acids + glycerol =
Fat (triglycerides);
79
fat productions occurs mainly in
adipose & liver tissues when blood [glucose] are high (usually after a meal)
80
what is a major form of energy storage in body
fat
81
lipolysis
breakdown of fat into free fatty acids & glycerol via hydrolysis by lipase
82
Acetyl CoA from free fatty acids serve as
major energy source for many tissues
83
Lipolysis Acetyl CoA from Fat
Beta-Oxidation
84
lipolysis: equatioin
triglyceride glycerol + fatty acid chains
85
Some organs use glycerol to
form phosphoglyceraldehyde (glycolysis intermediate)
86
Most fatty acids are used in a process called
Beta (β) oxidation
87
Beta-oxidation uses fatty acid chains (long hydrocarbons with COOH at end) to
make acetyl CoA (2 C) until the chain is entirely converted to acetyl CoA
88
how many ATP total from 16 C fatty acid chain
108
89
brown fat
Major site for thermogenesis in the newborn and amount of brown fat greatest at time of birth
90
brown fat are mostly around
kidneys and adrenal glands and small amount around blood vessels, chest, and neck
91
brown fat kidneys and adrenal glands and small amount around blood vessels, chest, and neck
produces uncoupling protein
92
Uncoupling protein causing
H+ to leak out of inner mitochondrial membrane thus fewer H+ pass through ATP-synthase, thus less ATP is produced
93
in brown fat, lower ATP causes
electron transport system to be more active which generates heat instead of ATP
94
ketone bodies
Triglycerides are continually broken down forming glycerol and fatty acids & resynthesized to ensure blood will contain fatty acids for aerobic respiration by other organs
95
During fasting & diabetes
rate of lipolysis > fatty acid utilization
| blood [fatty acid] increases
96
Fat metabolites, occur normally, but in fasting conditions get:
too high in blood (ketosis) or in urine (ketonuria); also gives breath an acetone (sweet) smell b/c it is respired
97
Nitrogen (N) ingested primarily as
which is used in body as amino acids
98
excess N is excreted mainly as
urea
99
Nitrogen balance =
N ingested - N excreted
100
Positive N balance:
more N ingested than excreted b/c used in protein synthesis
101
Negative N balance:
: less N ingested than excreted b/c proteins are broken down
102
In healthy adults amount of N excreted =
amount ingested
103
Excess amino acids can be deaminated (have the amine group removed) converted into
carbohydrates & fat
104
Essential & Non-essential Amino Acids
20 amino acids used to build all proteins
12 can be produced by body (= nonessential amino acids)
8 for adults must come from diet (= essential amino acids)
105
New amino acids can be obtained by a process called
transamination
106
Transamination =
is addition of amine (-NH2) to pyruvate or Kreb's cycle acids called “keto acids”, which have a ketone functional group to make a new amino acid
107
transamination is catalyzed by
transaminase
108
gluconeogenesis
(formation of glucose from non-carbohydrates)
109
Main substrates for gluconeogenesis
alanine, lactic acid, and glycerol
110
Uses of Different Energy Sources
Different cells have different preferred energy substrates
Brain uses glucose as its major source of energy
Under fasting conditions, blood glucose is supplied mostly from liver via glycogenolysis and gluconeogenesis
