3B - Photosynthesis & Cellular Respiration

Question 1

What are the three stages of cellular respiration?

Answer 1

1. Glycolosis, breaks down glucose into two molecules of pyruvate
2. Pyruvate Oxidation / Citric Acid Cycle / Krebs Cycle (completes the breakdown of glucose)
3. Oxidative Phosphorylation/ ETC (accounts for most of the ATP synthesis)

Question 2

Define Aerobic

Answer 2

In the presence of oxygen

Question 3

What kind of reactions is CR

Answer 3

exothermic & redox

Question 4

Define Fermentation

Answer 4

Partial degradation of sugars in the absence of oxygen.

Question 5

What is the formula for CR

Answer 5

C6H12O6 + 602 -> 6CO2 + 6H20 + Energy (heat + ATP)

Question 6

In CR, what is being oxidized/is a reducing agent?

Answer 6

Glucose (C6H1206)

Question 7

In CR, what is being reduced/is an oxidizing agent?

Answer 7

Oxygen (O2)
it is also the final electron acceptor

Question 8

Define a Coenzyme.

Answer 8

an organic molecule that binds to the active sites of certain enzymes to assist in the catalysis of a reaction

substances that help a reaction go forward

proteins, compounds

Question 9

Define Anaerobic

Answer 9

In the absence of oxygen

Question 10

cellular respiration formula

Answer 10

C6H1206 + 602 -> 6CO2 + 6H2O + Energy (ATP + Heat)

Question 11

Where does glycolysis happen?

Answer 11

in the cytoplasm

Question 12

where does the Krebs cycle happen?

Answer 12

in the matrix

Question 13

where does oxidative phosphorylation happen

Answer 13

along the inner folds on the membrane/ cristae

Question 14

Wy does the inner membrane of the mito. fold?

Answer 14

to increase surface area without increasing volume

Question 15

What is the Net ATP gain in glycolysis

Answer 15

2 ATP.

2 ATP investment
4 ATP payoff

Question 16

What are 3 important things about Glycolosiys

Answer 16

Does NOT require oxygen
In the cytoplast
net gain of atp is 2

Question 17

What happens in glycolysis

Answer 17

1. glucose takes 2 phosphates from 2 ATP’s, turning them into 2 ADP’s, to break down glucose into an intermediate 3-carbon molecule: PGAL/G3P
2. These PGAL/G3P pick up extra phosphates and hands them off to ADP, making 4 total ATP’S so that PGAL/G3P can form pyruvate, a 3 carbon acid

Also, 2 NAD+ is reduced to produce 2 NADH

Question 18

From Glycolysis, what happens if there is no O2 Present, and is there is O2 present?

Answer 18

After glycolysis, two pathways are available. If no O2 is present, the pyruvate will undergo fermentation. If there is O2 present, the pyruvate will continue to KREBS CYCLE prep, the cycle, and oxidative phosphorylation after.

Question 19

How does pyruvate enter the mitochondria (Krebs cycle preparation)

Answer 19

the 3 carbon molecule becomes a 2 carbon molecule, having lost one as CO2.

NAD+ comes along and steals electrons for krebs, making it NADH

a coenzyme ‘coenzyme a’ attaches itself to the end of the molecule, helping it cross the membrane and into the matrix

Question 20

EXPLAIN THE KREBS CYCLE

Answer 20

• Acetyl CoA breaks back into a 2-carbon molecule and then is attached to a four-carbon chain.
• they break down, losing carbon as CO2 and getting electrons taken from them now they’re 5-carbon chains.
• yet another carbon is taken, it’s four now.
• 2 atp is made from each chain
• more electrons are stolen to make ATP NADH AND FADH2
• four carbon chains still, be used in the next cycle
• more electrons are taken

Question 21

explain oxidative phosphorylation

Answer 21

• Electron carriers (NADH & FADH2) bring their electrons to the ETC embedded in the cristae
• electrons are carried from one carrier to the next and they lose energy with each move
• energy released by e- is used to pump h+ ions across the inner membrane through ATP synthase, spinning it and this produces 30-32 ATP
• the O2 YOU BREATH IN, IS THE FINAL electron acceptor, pulls them in and h2o is made as a byproduct

Question 22

How many ATP is made in the entire of CR?

Answer 22

36 per oxidized glucose