Metabolism

Question 1

Which two fundamental tasks must cells accomplish in order to grow?

Answer 1

1. Synthesize new components
   ~ Need carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, etc.
2. Harvest energy

Question 2

What is metabolism?

Answer 2

The sum total of chemical reactions of biosynthesis and energy-harvesting

Question 3

What are the 3 central metabolic pathways?

Answer 3

1. Glycolysis
2. Pentose phosphate pathway
3. Tricarboxcylic acid cycle

Question 4

What are the 3 things that central pathways provide?

Answer 4

1. Energy in the form of ATP
2. Reducing power (electrons bound to carriers)
3. Precursor metabolites

Question 5

What is glycolysis?

Answer 5

The oxidizing of glucose to two molecules of pyruvate

Question 6

Which 3 tasks does the Pentose phosphate pathway accomplish?

Answer 6

1. Breaks down glucose
2. Produces molecules for biosynthesis
3. Works in conjunction with glucose degrading pathways

Question 7

How many times does the TCA cycle turn for each molecule of Glucose that enters glycolysis?

Answer 7

Twice

Question 8

When does pyruvate enter a transition step?

Answer 8

Between glycolysis and the TCA cycle.

Question 9

What are the 3 electron carriers used in respiration?

Answer 9

1. Nicotinamide adenine dinucleotide - NAD+
2. Flavin adenine dinucleotide - FAD+
3. Nicotinamide adenine dinucleotide phosphate - NADP+

Question 10

When are Electron carriers reduced?

Answer 10

when they pick up electrons

Question 11

Reduced electron carriers bonds contain a form of what?

Answer 11

Usable energy

Question 12

What does NAD+ carry?

Answer 12

2 electrons and a proton

NAD+ + 2e- + 2H+ ↔ NADH + H+

Question 13

What does FAD+ carry?

Answer 13

2 electrons and 2 protons

FAD+ + 2e- + 2H+ ↔ FADH2

Question 14

What does NADP+ carry?

Answer 14

2 electrons and a proton

NADP+ + 2e- + 2H+ ↔ NADPH + H+

Question 15

If glucose was oxidized all at once, what would be the form of the released energy?

Answer 15

Heat and light

Question 16

Why are electrons passed from carrier to carrier through the Electrom Transport Chain?

Answer 16

To release the energy gradually, so that energy can be used to make ATP.

Question 17

What is the Electron Transport Chain?

Answer 17

A group of membrane-embedded electron carriers that accept electrons and pump protons across (cytoplasmic) membrane.

Question 18

How is a proton motive force created?

Answer 18

Some carriers accept electrons only and some accept electrons and protons, so protons are effectively pumped out of the membrane, creating a concentration gradient.

Question 19

How does a cell utilize proton motive force?

Answer 19

to synthesize ATP, actively transport substances, or rotate a flagella

Question 20

What is the “Final Destination” of the electrons in aerobic respiration?

Answer 20

oxygen– making water

Question 21

Waht are the end products of fermentation?

Answer 21

1. Lactic acid
   ~ if pyruvate itself serves as the final destination of the electrons
2. Other acids or alcohols
   ~ if pyruvate is first converted to another chemical
   ~ ex. propionic acid and CO2
   ~ ex. Ethyl alcohol and CO2

Question 22

What can the end products of fermentation be used for in the lab?

Answer 22

identification of microorganisms

Question 23

Name 3 anaerobic terminal electron acceptors.

Answer 23

1. nitrate (NO2-)
2. from glucose to sulfate
   ~ sulfate reducers (Obligate anaerobes)
3. from hydrogen gas to carbon dioxide
   ~ methanogens

Question 24

Which releases more energy: aerobic respiration or anaerobic respiration?

Answer 24

Aerobic

Question 25

What does anaerobic respiration use as the terminal electron acceptor in the electron transport chain?

Answer 25

An inorganic chemical other than oxygen

Question 26

What does aerobic respiration use as the terminal electron acceptor?

Answer 26

Oxygen

Question 27

What does fermentation use as the terminal electron acceptor?

Answer 27

An organic compound

Question 28

What do Photosynthetic organisms harvest energy from?

Answer 28

Sunlight

Question 29

What are “light capturing pigments”?

Answer 29

Chlorophyll or similar molecules

Question 30

What are the steps of photosynthesis?

Answer 30

1. Electrons are stripped from water 2. Added to chlorophyll 3. Raised in energy by light energy ~ Redox reaction is thus oxidation of (excited) chlorophyll and reduction of chlorophyll.

Question 31

What is the production of Oxygen in photosynthesis called?

Answer 31

Oxygenic photosynthesis

Question 32

Where do electrons come from in anoxygenic photosynthesis?

Answer 32

hydrogen gas, hydrogen sulfide, or organic compounds

Question 33

Can photosynthesis electrons generate a proton motive force similar to how the electron transport chain does?

Answer 33

Yes.

Question 34

Which color of bacteria are Anoxygenic Phototrophs, and where do they live?

Answer 34

Purple and Green bacteria often inhabit bogs and upper layers of mud

Question 35

What is the earliest Oxygenic Phototrophs and where do they live?

Answer 35

Cyanobacteria thought to be earliest, and they inhabit a wide range of environments (aquatic to terrestrial)

Question 36

What is the most common pathway of carbon fixation?

Answer 36

The Calvin Cycle

Question 37

How is carbon dioxide converted to organic carbon? How much energy does it consume?

Answer 37

Through carbon fixation, which consumes a great deal of energy