cellular respiration

Question 1

why do we breakdown our food stepwise and not just combust it?

Answer 1

we’re interested in energy storage- when we break it down stepwise, we produce ATP, which we can use to store energy

Question 2

what are the 2 ways to make ATP?

Answer 2

• 2 ways to make ATP:
  
  • 1. Chemiosmotic synthesis- happens more at end of process
  • 2. Substrate level phosphorylation- this is just the enzyme step that makes ATP

Question 3

what is chemiosmotic synthesis?

Answer 3

an enzymatic reaction process to make ATP where the energy comes from a proton concentration gradient. this is the pumped hydro of energy production, utilizes a rotor to place p’s on ADP’s

Question 4

how is ATP synthase related to chemiosmosis?

Answer 4

ATP synthase is the enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane and uses the free energy difference to phosphorylate adenosine diphosphate (ADP), making ATP.

Question 5

how do you get chemiosmotic synthesis going?

Answer 5

• in mitochondria, have a bunch of protons in intermembrane space. Low concentration gradient inside makes protons flow in.

Question 6

substrate level phosphorylation

Answer 6

Enzyme destabilizes bond with inorganic phosphate and substrate to remove the substrate and add the extra phosphate to ADP to create ATP. the delta G of removing P from PEP is so negative, that it drives the positive delta G of adding P to ADP.

Question 7

what is the big picture behind cellular respiration? why do we do it?

Answer 7

1. Take sugars with O2 and oxidize it in a bunch of small steps to get carbon dioxide and water
2. Do it in small steps to harvest the energy and use it for other purposes
3. GOAL: convert all the energy from small steps into creating ATP which can be used everywhere in the body

Question 8

high level- what is glycolysis, why is it crucial to evolution? where in cell does it occur?

Answer 8

A series of steps to break down the large macromolecules into their subunits. Present in all living things (evidence of one common ancestor.) Can occur without oxygen so we think it evolved before our atmosphere had free oxygen.

1. Happens in the cytoplasm of cells

Question 9

in glycolsis, what do you start with and what do you end with?

Answer 9

INS: Glucose, NAD+, 2 ADP

OUTS: 2 Pyruvate, 2 Net ATP, 2 NADH

Question 10

draw out glycolysis process starting from glucose and including correct end processes

Answer 10

Question 11

describe how the cell can regulate cell resp? and is this competitive or non competitive?

Answer 11

1. If there is a lot of ATP around, it can inhibit (turn down) the phosphofructokinase enzyme
2. If there is a lot of ADP and Citrate, it can turn up the phosphorfructokinase enzyme
3. This is non-competitive inhibition (allosteric)—the inhibitor changes the form of the enzyme

Question 12

where does chemiosmotic synthesis occur?

Answer 12

in the mitochondria

Question 13

why would humans use a process of fermentation?

Answer 13

When you exert yourself you do not supply oxygen fast enough to break down pyruvate : begin to pile them all up . You also use up all the NAD+ you make too

Question 14

what does fermentation allow us to do?

Answer 14

Fermentation allows us to use organic molecule to accept electrons from NADH so we can regenerate NAD+ so glycolysis can continue to run

Question 15

what are the phases of cellular respiration and the options?

Answer 15

1. glycolysis (doesn’t require O2).
2. with O2: pyruvate oxidation , krebs cycle, ETC, chemiosmosis
3. without O2: fermentation, -> glycolysis

Question 16

theoretical total and % yield of ATP for all of cellular respiration?

Answer 16

36 ATP

1. 38% efficiency in converting heat to energy

Question 17

what is our energy % yield through glycolysis

Answer 17

2%

Question 18

Q: If after glycolysis, oxygen is present, additional breakdown continues in the ____

Answer 18

mitochondrion

Question 19

The entire goal for a yeast cell is to recycle ___ into ____to continue glycolysis

Answer 19

NADH into NAD+

Question 20

inputs and outputs pyruvate oxidation

Answer 20

ins: 2 pyruvate, 2 NAD+
outs: 2 acetyl coA, 2 CO2, 2 NADH

Question 21

describe pyruvate oxidation and where it occurs

Answer 21

1. Once it enters mitochondrial matrix, Oxidation of pyruvate by pyruvate dehydrogenase (removes electrons which is an oxidation step)
   
   1. Pyruvate dehydrogenase is a multi-subunit enzyme complex

Question 22

in the presence of oxygen, pyruvate is converted to:

Answer 22

acetyl CoA

Question 23

a large, multi-subunit enzyme complex that links glycolysis and the citric acid cycle under aerobic conditions:

Answer 23

pyruvate dehydrogenase

Question 24

acetyl CoA is:

Answer 24

• the fuel for the citric acid cycle

Question 25

in the absence of oxygen (anaerobic conditions), pyruvate is converted into:

Answer 25

- lactic acid or ethanol

Question 26

pyruvate is converted into acetyl CoA usually in: (what kind of activity? what kind or organism?)

Answer 26

resting muscle activity in higher organisms

Question 27

the citric acid cycle takes place in what part of the cell?

Answer 27

in the mitochondria

Question 28

where must pyruvate be transported to be aerobically metabolized?

Answer 28

into the mitochondria

Question 29

why is glycolysis inefficient?

Answer 29

it captures only a fraction of the energy inherent in a glucose molecule as ATP

Question 30

what does the pyruvate dehydrogenase complex produce and capture?

Answer 30

it produces CO2 and captures high-transfer-potential electrons in the form of NADH

Question 31

the citric acid cycle processes:

Answer 31

the two-carbon acetyl unit to 2 molecules of CO2 while generating high-energy electrons that can be used to form ATP

Question 32

the high-potential electrons produced in the citric acid cycle are transferred to oxygen to form water in a series of oxidation-reduction reactions called the:

Answer 32

electron transport chain

Question 33

the electron transport chain is highly (ender/exergonic) allowing it to produce \_\_\_

Answer 33

exergonic, and the released energy is used to synthesize ATP (oxidative phosphorylation)

Question 34

the conversion of pyruvate into acetyl CoA consists of 3 steps:

Answer 34

1) decarboxylation 2) oxidation 3) the transfer of the resultant acetyl group to CoA

Question 35

describe start to end cellular respiration

Answer 35

The process that releases energy (ATP) by breaking down glucose. cytoplasm: glucose -\> 2 pyruvate, 2 ATP, 2 NADH via **glycolysis** Mitochondrial membranes: pyruvate -\> acetyl coA via **pyruvate oxidation** Pyruvate Dehydrogenase, a large multi-subunit enzyme complex Mitoochondrial membranes: **krebs cycle** -\> 1 turn generates 3 NADH, 1 GTP, 1 FADH2, 2 molecules CO2 note: FAD is just Another electron-carrying cofactor **ETC:** uses NADH to produce ATP, O2, H2O

Question 36

Alcoholic Fermentation

Answer 36

Type of anaerobic respiration used by organisms such as yeast to recycle products of glycolysis. Alcohol and Carbon Dioxide made, NO additional ATP made. Used in making beer, bread and wine

Question 37

glycolysis- photo- where is it, what's coming out?

Answer 37

Question 38

describe how DNP worked in Racker's experiment

Answer 38

used DNP to create a channel in the mitochondrial matrix that ruined the proton gradient so chemiosmotic synthesis of ATP didn’t work (DNP is **uncoupling agent** because it uncouples protons gradient from ATP synthase) 1. Convert potential energy of gradient into kinetic energy of moving protons, you create heat instead of using the energy to make ATP 2. Less ATP available so metabolic rate ramps up so you break down more macromolecules to get more ATP, so you break down fat more rapidly and lose weight 3. DNP also overheats you which also ramps your metabolism and KILLS YOU

Question 39

pyruvate

Answer 39

3 carbon sugar produced when glucose is split during glycolysis

Question 40

which molecule feeds the ETC?

Answer 40

FADH

Question 41

how many turns does the kreb cycle do?

Answer 41

2. once per pyruvate

Question 42

oxidation of NADH in ETC forms what products?

Answer 42

NAD+, H2O

Question 43

describe what happens in the intermembrane space/mitochondrial matrix during ETC

Answer 43

proton pump (converting NADH-\> NAD+) creates gradient of H+'s pushing them out into IMS, then H+'s get sucked back into matrix to do chemiosmosis , forming ATP, H2O

Question 44

what provides the energy to pump protons across membrane in ETC?

Answer 44

electrons harvested from NADH provide this energy to create and pump H+ protons across , forming gradient

Question 45

what was Racker's hypothesis?

Answer 45

proton gradient can generate ATP . does experiment using photonabsorbing bacteria to prove it

Question 46

what's DNP and why was it used as a weight loss drug?

Answer 46

DNP uncouples synthesis of ATP from proton flow. It generates heat instead of ATP. Then ATP wont synthesize because gradient is missing. People started taking DNP as weight loss to increase metabolic rate.

Question 47

white fat versus brown fat? what do they do are where are they found? what does brown fat do that is so special?

Answer 47

1. White fat: storage form of fat in body 2. Brown fat: mitochondrial rich, found in a few designated spots in body, present in newborn humans (less in adult humans) and small mammals 1. Produces an uncoupling agent called thermogenin (protein that acts as channel in membrane to short circuit ATP making so it is designed to produce heat)

Question 48

when proteins are broken down in cellular resp, what do they turn into?

Answer 48

ammonia and urea

Question 49

what happens to fats who get cut down for cellular respiration?

Answer 49

1. Fatty acids get cut into acetyl CoA and get fed into Krebbs cycle

Question 50

describe the Endosymbiont Hypothesis

Answer 50

1. Fusion event of an ancient bacterium that can do oxidative respiration (mitochondria) with primitive eukaryotic cell 2. Became advantageous to both for the eukaryote to provide a home and nutrients for the bacterium and not eat it (this morphed into the mitochondria within eukaryote cells)

Question 51

draw out and describe oxidative phosphorylation

Answer 51

between the 2 phospholipid bilayers of Mito, you have 2 processes running at the same time: ETC to produce the gradient using NADH, FADH2, and then chemiosmosis to use the gradient to produce ATP . byproducts of this process are H2O and it requires O2.