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Human Physiology > Homeostasis, metabolism, and bioenergetics 2 > Flashcards

Homeostasis, metabolism, and bioenergetics 2 Flashcards

1
Q

bioenergetics

A

study of flow of energy through biological systems

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2
Q

ATP

A

adenosine triphosphate
special carrier for free energy
provides most of the energy for cell functions
made of adenine, ribose, and three linked phosphates
made by adding a phosphate group to an ADP molecule

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3
Q

which bonds in ATP are the high energy bonds

A

two outer most phosphates - they have the most amount of stored energy

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4
Q

ATP-PC system

A

anaerobic pathway that occurs in the cytoplasm
most rapid way of making ATP because it’s only a one enzyme reaction
ADP + phosphocreatine (PC) -> ATP + Creatine

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5
Q

explain the anaerobic glycolysis pathway for glucose

A

1.) glucose molecule enters cell
2.) glucose is phosphorylated to become glucose-6-phosphate by hexokinase
-1 ATP
3.) glucose-6-phosphate is rearranged into fructose-6-phosphate by glucose-6-phosphate isomerase
4.) fructose-6-phosphate is phosphorylated to form fructose-1,6-biphosphate by phosphofructokinase
-1 ATP
5.) fructose-1,6-biphosphate molecule splits into two glyceraldehyde-3-phosphate molecules (G3P)
6.) each G3P molecule is converted to pyruvate

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6
Q

two main aerobic pathways

A

citric acid cycle (Krebs cycle)
electron transport chain

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7
Q

cellular respiration

A

metabolic pathway where organic molecules are oxidized and disassembled in a controlled manner by a series of enzymes

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8
Q

what enzyme breaks down ATP

A

ATPase

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9
Q

why don’t we store a lot of ATP

A

the molecule is large and would make us large
only storing a little causes us to make more as soon as we need it (ex. starting to exercise)

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10
Q

which enzyme donates the phosphate group of phosphocreatine to create an ATP molecule

A

creatine kinase

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11
Q

why can we not solely use the ATP-PC system to make ATP

A

we do not have an unlimited amount of phosphocreatine

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12
Q

what is the limiting factor in the anaerobic glycolysis of glucose

A

phosphfructokinase (enzyme that phosphorylates fructose-6-phophate)

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13
Q

what are the products of the anaerobic glycolysis of glucose

A

4 ATP (net 2)
2 NADH+ + 2H+
2 pyruvate or lactate

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14
Q

why must glucose be phosphorylated after entering the cell

A

phosphorylation prevents it from leaving the cell through the glucose channel
prevents the build up of glucose in the cell and maintains the chemical gradient

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15
Q

what does a hexokinase do

A

adds phosphate group

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16
Q

explain the anaerobic glycolysis pathway for glycogen

A

1.) glycogen already in the cell is converted to glucose-6-phosphate
2.) glucose-6-phosphate is rearranged into fructose-6-phosphate by glucose-6-phosphate isomerase
3.) fructose-6-phosphate is phosphorylated to form fructose-1,6-biphosphate by phosphofructokinase
-1 ATP
4.) fructose-1,6-biphosphate molecule splits into two glyceraldehyde-3-phosphate molecules (G3P)
5.) each G3P molecule is converted to pyruvate

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17
Q

what are the products of the anaerobic glycolysis of glycogen

A

4 ATP (net 3)
2 NADH+ + 2H+
2 pyruvate or lactate

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18
Q

where is glycogen stored

A

in liver and skeletal muscle

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19
Q

what happens to pyruvate if there is sufficient oxygen present

A

the pyruvate will be changed to acetyl CoA where it can start the Krebs cycle

20
Q

what happens to pyruvate if there is not sufficient oxygen present

A

pyruvate is converted to lactic acid because we don’t want pyruvate building up

21
Q

what is the equation for converting pyruvate to lactic acid

A

pyruvate + NADH + H+ -> lactic acid + NAD+
then

lactic acid -> lactate + H+

22
Q

what enzyme catalyzes converting pyruvate into lactic acid

A

lactate dehydrogenase (LDH)

23
Q

explain the preparatory phase of pyruvate of acetyl-CoA

A

occurs in the mitochondria
pulls off a carbon group and adds a CoA group by pyruvate dehydrogenase complex (PDC) - irreversible
NAD+ is also converting back and forth to NADH + H+ to send electrons to the electron transport chain

24
Q

what enzyme catalyzes the conversion of pyruvate to acetyl-CoA

A

pyruvate dehydrogenase complex (PDC)
multi-enzyme complex

25
Q

what 5 things can be converted to acetyl-CoA

A

pyruvate, amino acids, fatty acids, glycerol, and ketone bodies

26
Q

explain the citric acid cycle (Krebs cycle)

A

occurs in the mitochondria
1.) acetyl group is transferred to oxaloacetate to form citrate
2.) citrate is eventually converted back into oxaloacetate
3.) oxalocetate is converted back to citrate to continue the cycle as long as there is sufficient intermediates

27
Q

what enzyme transfers an acetyl group to oxaloacetate to form citrate

A

citrate synthesis

28
Q

what is the reaction for the transfer of an acetyl group to oxaloacetate

A

acetyl-CoA + oxaloacetate -> citrate + CoA

29
Q

what is the rate limiting enzyme of the citric acid cycle

A

isocitrate dehydrogenase

30
Q

what are the products for one turn of the Krebs cycle

A

1 ATP
3 NADH + H+
1 FADH2
2 CO2

*double the quantities for one glucose molecule

31
Q

explain the electron transport chain

A

occurs in the mitochondria
1.) NADH + H+ and FADH2 are brought to the electron transport chain from previous processes and release high energy electrons
2.) NAD+ and FAD are recycled to go get more
3.) pairs of high energy electrons move across the ETC to create energy
4.) this energy created fuels the cytochrome pumps
5.) pumps pump H+ from mitochondrial matrix to the mitochondrial intermembrane space, thus creating an electrochemical gradient
6.) H+ move down the concentration gradient through the protein ATP synthase
7.) ATP synthase transfers the kinetic energy into ATP from ADP and phosphate
8.) 1 ATP for every 3 H+
9.) high energy electron pairs that come to the end of the ETC combines with H+ and oxygen to form water

32
Q

what is the equation for the high energy electrons to become water

A

2H+ + 1/2O2 + 2e- -> H2O

33
Q

what enzyme catalyzes the creation of water from high energy electrons

A

cytochrome oxidase

34
Q

what is the rate limiting enzyme of the electron transport chain

A

cytochrome oxidase - if we don’t have enough of this enzyme, we cannot do the conversion of electrons to H2O which stops the electron transport chain

35
Q

what is oxygen’s role in the electron transport chain

A

final acceptor of electrons

36
Q

how much ATP is made from each NADH + H+ and FADH2 molecule that goes through the electron transport chain

A

NADH + H+ = 2.5
FADH2 = 1.5

37
Q

what is the grand total of net ATP from one glucose molecule (explain how you got to the number)

A

32 ATP

38
Q

what is the grand total of net ATP from one glycogen molecule (explain how you got to the number)

A

33 ATP
(one more ATP molecule from glycolysis)

39
Q

explain how fatty acids are used for energy

A

go through beta oxidation to yield ATP
occurs in the mitochondria

40
Q

what are the products of each round of beta oxidation

A

1 acetyl-CoA (except for last round which yields 2)
1 NADH + H+
1 FADH2

41
Q

what is the equation to determine the number of rounds of beta oxidation a fatty acid will go through

A

of carbons / 2 -1
ex. 14 carbon fatty acid will go through 6 rounds

42
Q

what is the equation to determine the number of acetyl-CoA molecules you will get out of a fatty acid

A

of carbons / 2
ex. 14 carbon fatty acid will make 7 acetyl-CoA molecules

43
Q

why are amino acids (proteins) not usually a major source of energy

A

we need proteins for so many other things that we only use them as fuel when absolutely necessary
ex. long starvation

44
Q

what is the amino acid structure

A

amino group, carboxyl group, alpha carbon with attached H, and R group (variant)

45
Q

what are the 3 ways to use proteins as an energy source

A

1.) convert them to glucose via gluconeogenesis
2.) convert them to acetyl-CoA
3.) convert them to citric acid cycle intermediates

46
Q

what is ATP cycling

A

formation and breakdown of ATP
ATP is formed when energy is released (exergonic reactions)
ATP is oxidized to aid in exergonic reactions

Human Physiology (19 decks)

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