Unit 5: Cell Respiration

Question 1

Equation for Cell Respiration

Answer 1

C6H12O6 +6 O2 —> 6CO2+ 6H2O

Question 2

Cell Respiration Location

Answer 2

Mitochondria

Question 3

Cellular Respiration Purpose

Answer 3

A gradual process of breaking down glucose into usable energy (ATP).

Question 4

Cell Respiration Main Steps

Answer 4

Glycolysis - glucose begins to break down + some ATP is produced

Krebs - pyruvic acid breaks down - more ATP is produced

Electron Transport Chain (ETC) - more carbon-compounds are broken - generating A LOT of ATP

Question 5

Meaning of Anaerobic and Aerobic

Answer 5

Anaerobic: “without air”, ex: glycolysis
Aerobic: “in air”, ex: krebs + ETC

Question 6

Purpose of Glycolysis + Location

Answer 6

A series of reactions that break down glucose (C61H1206) into 2 (C3H403) pyruvic acid molecules.

Location: Cytoplasm

Question 7

Process of Glycolysis

Answer 7

1) 2 ATP molecules (energy) are used to start the process

2) When glucose breaks down into the 2 pyruvate, its electrons that were in its bonds get carried away by an electron carrier, NAD+ , which turns into NADH (eventually carries high - energy electrons to the ETC)

3) While this glucose is broken down, 4 ADP molecules turn into 4 ATP molecules - NET GAIN OF 2 ATP

Question 8

Krebs Location

Answer 8

Mitochondrial Matrix.

Question 9

Electron Transport Chain Location

Answer 9

Inner membrane of Mitochondria.

Question 10

Molecules That are NEEDED for + CREATED in the Krebs Cycle

Answer 10

Molecules Needed: Pyruvic acid, NAD+ and FAD (electron carriers), ADP

Molecules Created: CO2, NADH, FADH2, 2ATP

Question 11

Molecules are NEEDED for + CREATED in the ETC

Answer 11

Molecules Needed: NADH + FADH2 (electron carriers), O2

Molecules Created: NAD+, FAD, H20

Question 12

ETC Process

Answer 12

• NADH and FADH bring high-energy electrons to the ETC - which provides energy to allow H+ ions to ACTIVELY pass through the protein pumps
• At the end of the ETC, H+ ions combine w/ O2 to create H20
• Finally, the H+ ions that went through the inter-membrane space PASSIVELY diffuse through ATP synthase, allowing it to generate 32 ATP.

Question 13

Comparison of Cellular Respiration + Photosynthesis

Answer 13

review more - study guide answer

• energy in CR and Photosynthesis flow in opposite directions

Their impact on the exchange of CO2 and O2 gasses:
- Photosynthesis REMOVES C02; CR puts it back
- CR REMOVES O2; Photosynthesis puts it back

Question 14

Why is it NOT effective for a cell to simply repeat Glycolysis in the absence of oxygen?

Answer 14

• NAD+ turns into NADH during glycolysis (+ in the the Krebs cycle)
• If the ETC isn’t happening (since it requires this O2), NADH doesn’t turn back into NAD+, so glycolysis CANNOT happen forever.

Therefore it needs a new pathway (AKA: Fermentation).

Question 15

How Lactic Acid and Alcoholic Fermentation can be used to generate ATP w/o the presence of O2

Answer 15

Lactic Acid Fermentation (used by humans): After glucose turns into the 2 pyruvate molecules during Glycolysis, pyruvate is converted into Lactic Acid. Once this happens, it allows NADH to turn back into NAD+

ALSO: making Lactic Acid creates 2 ATP each time
_____________________________________
Alcoholic Fermentation (used by bacteria): After glucose breaks down into the 2 pyruvate molecules during Glycolysis, the pyruvate then breaks down into both CO2 and ethanol (a type of alcohol) with the help of yeast. NADH then turns back into NAD+

ALSO: making Lactic Acid creates 2 ATP each time