Lecture 22 Flashcards Preview

MB 351 > Lecture 22 > Flashcards

Flashcards in Lecture 22 Deck (51):
1

Metabolism is highly connected vis these __________ ?

central metabolic "highways" (glycolysis, Krebs, etc). in plants, animals and bacteria.

2

Most microbes oxidize _________ as their primary source of cellular respiration. What is this called?

carbohydrates

carbohydrate catabolism

3

______ is the most common carbohydrate energy source used by cells.

glucose

4

To get energy from glucose, microbes use these two general processes?

cellular respiration and fermentation

5

First step of cellular respiration and fermentation?

glycolysis

6

Three principal steps of cellular respiration?

Embden-Meyerhof pathway is what?

1. Glycolysis (Embden-Meyerhof pathway)
2. Krebs cycle
3. ETC

7

Steps in fermentation?

1. Glycolysis
2. Fermentative pathways

8

Glucose (a 6 carbon sugar) is broken down into two 3-carbon sugars

what happens during this process? and what is formed?

glycolysis

These sugars are oxidized (losing electrons), releasing energy and their atoms are rearranged to form two molecules of pyruvic acid.

9

Glycolysis does not require what?

oxygen; it can occur whether oxygen is present or not

10

The generation of ATP in glycolysis is due to what?

substrate-level phosphorylation (SLP)

11

The oxidation of glucose to pyruvic acid produces what?

ATP and NADH

12

What is ATP made up of?

ATP is generated during certain _________ rxns, consumed in _______ rxns.

nucleoside adenosine to which 3 phosphate molecules are bonded in series. It is the prime energy currency in all cells

-exergonic rxns, endergonic rxns

13

Oxidation reduction (redox) rxns in microbes typically involves rxn between one or more intermediates called _______ ?

Carriers

14

Electron carries can be divided into 2 classes:

those that are freely diffusible (coenzymes) and those that are firmly attached to enzymes in the cytoplasmic membrane (prosthetic groups)

15

The fixed carriers function in membrane associated e- transport rxns that we'll see in ______ ?

the ETC

16

Common diffusiblecarriers include the ?

coenzymes Nicotinamide adenine dinucleotide (NAD+) and NAD- Phosphate (NADP+)

17

NAD+ and NADP+ are e- + ______ carriers, transporting _______ ?

proton carriers, transporting 2e-s and 2H+ at a time.

18

The electrons from the oxidation of glucose are temporarily stored by ______ ? Which is also generated during the Krebs cycle

NADH

19

If NAD+ gets reduced it is picking up ________ and producing _______ .

two hydrogen atoms, and producing NADH + H+

20

NADH is a good _______ and NAD+ a good ______ .

electron donor, electron acceptor

21

Glycolysis begins with a __________ or ________ __________ stage. And what happens?

preparatory stage, or energy investment stage

-glucose enters the cell and is phosphorylated

22

Preparatory Stage of Glycolysis: order of events?

1 . requiring the expenditure of 1 ATP to produce Glucose-6-phosphate.
2. This molecule is isomerized (rearranged) to fructose-6-phosphate
3. a second phosphorylation leads to the production of fructose 1,6-diphosphate
4. the enzyme aldolase splits this molecule to form 3-carbon molecules: glyceraldehyde 3-phosphate (GP) and its isomer, dihydroxyacetone phosphate (DHAP), which is readily converted to GP as GP is consumed in the next step.

23

During the preparatory stage of glycolysis, all rxns proceed without what?

redox (oxidation-reduction) changes

24

Preparatory stage of glycolysis

______ are used

Glucose is split to form _________

- 2 ATP are used (Phosphorylation)

-2 glucose-3-phosphate

25

Energy - Conserving Stage of Glycolysis -- steps?

Comes right after preparatory stage

1. enzyme converts each GP to 1,3 diphosphoglyceric acid (2 of these molecules form given two GP's from preparatory stage)

2. High energy P is moved to ADP, forming ATP, the first ATP production of glycolysis via SLP.

3. An enzyme relocates the remaining phosphate of the 3-phosphoglyceric acid to make 2-phosphoglyceric acid in preparation for the next step

4. by the loss of a water molecule, 2 phosphoglyceric acid is converted to phosphoenolypyruvic acid or PEP. In the process the phosphate bond is upgraded to a high energy bond.

5. This high energy bond is transferred from PEP to ADP to form ATP. So for each individual glucose molecule, 2 ATP and 2 molecules of 3-C compound called pyruvic acid would be formed during this step)

26

How is GP oxidized during the first step of energy-conserving stage of glycolysis? The enzyme (GP dehydrogenasease) couples this reaction with?

GP is oxidized by the transfer of two hydrogen atoms to NAD+ to form NADH.

-couples with the creation of a high energy bond between the sugar and a phosphate

27

SLP - results in what?

Substrate level phosphorylation. Type of metabolic rxn that results in the formation of ATP

SLP is the generation of ATP where you directly transfer P to ADP from a reactive intermediate (PEP in this case) generated during enzymatic conversion of one organic compound to another

28

In the energy conserving stage of glycolysis, the two 3-carbon molecules (GP) are oxidized in several steps to two molecules of pyruvic acid. HOW?

In these rxns, two NAD+ are reduced to NADH in the first step of conserving.

Four molecules of ATP are made by SLP: 2 from step 2 and 2 from step 5 (where high energy phosphate bonds are)

**remember everything is double since this happens twice for every glucose molecule

29

Net ATP gain from glycolysis total from both GP molecules

2

30

Single GP molecule yields production of

One glucose molecule produces four ATP, two NADH, and two pyruvate molecules during glycolysis. ????

31

The acetyl group is attached to coenzyme A via a what?

high energy bond

32

Acetyl-CoA is a very common what?

intermediate, ex. oxidation of fats and amino acids

33

Bride/transition step produces what?

2 molecules CO2
2 molecules NADH
2 molecules of Acetyl-CoA

34

As Acetyl-CoA enters the Krebs cycle, the CoA does what?

detaches from the acetyl group

35

In cellular respiration, pyruvate is completely oxidized to ______ in the Kreb's cycle.

CO2

36

In fermentation, the pyruvate is reduced and converted into ________ products that are subsequently _________ .

fermentation products, subsequently excreted

37

First molecule of preparatory stage of glycolysis that uses ATP to form second molecule

glucose (6 carbons)

38

second molecule of preparatory stage of glycolysis

glucose-6-phosphate (ATP used to create this molecule)

39

in the third step of the preparatory stage of glycolysis, glucose-6-phosphate is _______ and becomes _______

isomerized, and becomes fructose-6-phosphate

40

in the fourth step of the preparatory stage of glycolysis, fructose-6-phosphate becomes phosphorylated again using _______ to produce _________

using ATP to produce fructose 1,6 - diphosphate

41

in the fifth step of the preparatory stage what splits fructose 1,6 - diphosphate? And what does this form?

the enzyme aldolase,

glyceraldehyde 3-phosphate (GP), and its isomer, dihydroxyacetone phosphate (DHAP), which is readily converted to GP.

GP is consumed in the next step.

42

During this stage all the reactions, including the consumption of 2 ATP proceed without any redox oxidation-reduction reactions

preparatory stage of glycolysis

43

Steps 6-10 in glycolysis are referred to as?

energy-conserving stage

44

step 6 of energy-conserving stage of glycolysis. Each GP is converted into?

1, 3 diphosphoglyceric acid

45

what allows for the high energy bond on 1, 3 diphosphoglyceric acid. What enzyme aids in this reaction?

GP is oxidized by the transfer of two hydrogen atoms to NAD+ to form NADH.

The enzyme GP dehyrogenase couples this reaction with the creation of a high energy bond between the sugar and a phosphate. The 3 carbon sugar now has 2 phosphate groups.

46

in the 7th step of glycolysis -- after the formation of 1,3 diphosphoglyceric acid, what happens? What molecule is formed in the process?

The high energy P is moved to ADP to form ATP. This is the first ATP production of glycolysis via SLP

3-phosphoglyceric acid

47

in the 8th step, an enzyme does what?

relocates the phosphate group on 3-phosphoglyceric acid to form a high energy bond on 2-phosphoglyceric acid

48

in the 9th step ______ is lost, so 2-phosphoglyceric acid is converted to ___________ with a ______ bond

water is lost, so it's converted into phosphoenolpyruvic acid (PEP), and the phosphate is upgraded to a high energy bond

49

the 10th step. what type of phosphorylation is occurring? what molecule is created in the process?

the high energy bond on phosphoenolpyruvic acid (PEP) is transferred to ADP to form ATP.

again this is SLP, and pyruvic acid is formed (3-carbon compound)

50

SLP

direct transfer of a phosphate group to ADP from a reactive intermediate (like PEP) generated during enzymatic conversion of one organic compound to another

51

What is ATP made of?

nucleotide adenosine with three phosphate molecules