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BIOSCI 107 > (02) Harvesting Chemical Energy > Flashcards

(02) Harvesting Chemical Energy Flashcards

1
Q

how is ATP used to produce energy

A

the HYDROLYSIS of ATP to ADP + inorganic phosphate releases energy

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2
Q

describe the ATP cycle

A

transformation of ATP to ADP then back to ATP
energy transfer between complex and simple molecules in the body

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3
Q

define anabolic reactions

A

simple –> complex molecules
transfer energy from ATP to complex molecules

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4
Q

define catabolic reactions

A

complex –> simple molecules
transfer energy from complex molecules to ATP

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5
Q

name some simple molecules (involved in ATP cycle)

A

glucose
amino acids
glycerol
fatty acids

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6
Q

what is glycerol

A

a type of carbohydrate called a sugar alcohol (it’s a triol)
forms backbone of glycerides

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7
Q

name some complex molecules involved in the ATP cycle

A

glycogen (a stored form of glucose made up of many connected glucose molecules)
proteins
triglycerides

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8
Q

three major categories of “fuel” to generate ATP

A

Carbohydrates (–> simple sugars)
Protein (–> amino acids)
Fats (–> simple fats)

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9
Q

pathway that glucose takes into a cell

A

glucose in food / intestines –> bloodstream –> into a cell via insulin

then either:
storage
cellular respiration –> cellular work

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10
Q

how is glucose stored and released from storage

A

glucose in a cell can cross-link –> glycogen in liver and skeletal muscle

returns to the bloodstream via glucagon (then back to cell via insulin… etc)

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11
Q

how is homeostasis restored after in increase in blood glucose level

A

beta cells in pancreatic islets (receptors) respond by SECRETING INSULIN
which affects all body cells
–> increase rate of glucose transport, increased rate of glucose use and ATP generation, increased conversion of glucose to glycogen (to store)

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12
Q

how is homeostasis restored after a decrease in blood glucose level

A

alpha cells in pancreatic islets respond by secreting GLUCAGON
affects liver, skeletal muscle, adipose cells
–> increased breakdown of glycogen to glucose (liver, skeletal muscle)
–> increased breakdown of fat to fatty acids (adipose)

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13
Q

name the four main steps in the conversion of glucose to ATP

A

Glycolysis
Pyruvate oxidation
Citric acid cycle (Krebs cycle)
Electron transport chain

summarised in the eqn
glucose + 6O2 –> 6 CO2 + 6H2O + energy

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14
Q

in what part of the cell does glycolysis take place?

A

cytosol

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15
Q

net product of glycolysis

A

2 ATP and 2 NADH produced

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16
Q

inputs and outputs of glycolysis

A

input: glucose molecule
output: 2 pyruvic acid molecules (3C each)

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17
Q

where does pyruvate oxidation take place

A

the mitochondrial matrix

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18
Q

what is required for pyruvate oxidation

A

oxygen, duh

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19
Q

inputs and outputs of pyruvate oxidation

A

input: pyruvate molecule
output: Acetyl CoA + 1 CO2, 1 NADH
(so x2 per glucose molecule)

  • Acetyl CoA has 2C chain
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20
Q

what is the function of the acetyl CoA?

A

enables the 2-carbon acetyl group to enter the citric acid cycle

links the glycolysis and citric acid cycle

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21
Q

where does the citric acid cycle take place?

A

in the mitochondrial matrix

22
Q

Products of the citric acid cycle

A

2 ATP
6 NADH
2 FADH2
4 CO2
(per glucose molecule)

23
Q

what does the citric acid cycle require

A

oxygen - it is an aerobic process

24
Q

what are the electron donors in the electron transport chain?

A

NADH and FADH2

25
Q

define intermediates (in a cycle)

A

in a series of reaction, the product of one reaction is the substrate for the next

26
Q

how many ATP are produced per glucose in each of the first three stages of cellular respiration?

A

glycolysis: 2 ATP
Pyruvate oxidation: 0 ATP
Citric acid cycle: 2 ATP

27
Q

name the two types of phosphorylation

A

substrate phosphorylation
oxidative phosphorylation

28
Q

define substrate phosphorylation

A

ATP generated by direct transfer of phosphate group from a substrate to ADP

29
Q

which two steps in cellular respiration involve substrate phosphorylation?

A

Glycolysis and Citric acid cycle
both make ATP via substrate phosphorylation

30
Q

define oxidative phosphorylation

A

ATP is generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons

31
Q

what are the two processes involved in oxidative phosphorylation?

A

the Electron Transport Chain
Chemiosmosis

32
Q

in what specific part of the cell does the Electron Transport Chain take place?

A

in protein complexes in/on the inner membrane

33
Q

what type of reaction occurs in the electron transport chain?

A

it is oxidative phosphorylation, therefore OXIDATION occurs

34
Q

what happens at each transfer in the electron transport chain

A

at each transfer, each e- gives up a small amount of energy
enables H+ ions to be pumped into the Intermembrane space

35
Q

describe chemiosmosis in oxidative phosphorylation

A

after electrons are transported down the chain and H+ is released into the IMS, H+ rush down their concentration gradient
causes “turbine” within ATP synthase to turn
enables phosphorylation of ADP –> ATP

36
Q

products of chemiosmosis

A

26 or 28 ATP produced per glucose

37
Q

summarise the steps of oxidative phosphorylation

A

the bulk of ATP production occurs here
fall of e- down chain –> movement of H+ into IMS –> proton gradient –> ATP synthase turbine
O2 is the final e- acceptor, turns into water

38
Q

what molecule pulls electrons from the electron transport chain

A

oxygen, forming H2O

39
Q

in what form do fats, proteins and complex carbohydrates enter the cell to generate ATP?

A

as monomers: fatty acids, glucose, amino acids
3C chains (all)
or 2C chains (fatty acids and amino acids)

40
Q

what is the role of phosphofructokinase

A

an enzyme that catalyses a phosphorylation step in glycolysis
therefore controls the rate of glycolysis - positive / negative feedback mechanisms

41
Q

what is phosphofructokinase inhibited and stimulated by?

A

inhibited by citrate and ATP (the products of cellular respiration)
stimulated by AMP (which accumulates when ATP is being used rapidly)

42
Q

normal blood glucose level

A

4-6 mmol/L

43
Q

define hyperglycemia and steps to maintain homeostasis

A

hypER = exaggerated (as in hyperbole)
beta cells in pancreatic islets secrete insulin to increase rate of glucose –> ATP / glycogen

44
Q

define hypoglycemia and steps to maintain homeostasis

A

low blood glucose level
alpha cells in pancreatic islets secrete glucagon –> increased breakdown of glycogen in liver / skeletal muscle and fat in adipose tissue

45
Q

where are beta and alpha cells produced?

A

the Islets of Langerhans in the pancreas

46
Q

what is diabetes mellitus

A

impaired ability to produce or respond to insulin
results in abnormal metabolism of carbs and elevated levels of blood glucose (>7 mmol/L)

47
Q

describe the mechanism of diabetes mellitus

A

insulin hormone normally binds to receptor so the glucose receptor opens
either insulin not present or receptors not functional
no glucose in cells –> no ATP from glucose –> no stored glycogen

48
Q

describe type 1 diabetes

A

insulin-dependent diabetes
the body does NOT produce insulin as beta cells of pancreas are destroyed

less common
requires insulin replacement

49
Q

describe type 2 diabetes

A

non-insulin-dependent
body produces insulin but receptors are non-functional (insulin resistance)

more common, usually adults over age of 40

50
Q

what are the two main symptoms of diabetes mellitus and why?

A

significantly increased hunger
significant weight loss

because of a lack of functional insulin, glucose cannot get into cells to make ATP
body asks for more glucose from food and stores

BIOSCI 107 (22 decks)

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