AP Bio Unit 4 - Cellular Respiration

summary equation

glucose + oxygen → (cytoplasm/mitochondria) carbon dioxide + water + ATP

oxidation

loss of electrons

reduction

gain of electrons

two main electron carriers in cellular respiration

NAD+ and FAD+

which has more potential energy, NAD+ or NADH? why?

NADH b/c it has more hydrogen and more hydrogen = more energy

function of dehydrogenase

removes hydrogen ions from substrates and delivers them to electron carriers

phosphorylation

add phosphate groups

phosphorylation in the context of cellular respiration

the addition of a phosphate group to ADP to form ATP

substrate-level phosphorylation

enzyme powers the addition of phosphate to ADP to form ATP

oxidative phosphorylation

the loss of an electron powers ATP synthesis from ADP and P

explain the steps of glycolysis IN DETAIL

1. energy from 2 ATP breaks glucose up into two GAPs (energy investment phase)

energy yielding phase:

1. 4 ATP are produced with the help of an enzyme (substrate-level phosphorylation)

2. 2 NAD+ are reduced to 2 NADH with the help of an enzyme

3. 2 pyruvates (3-carbon compounds are produced

inputs of glycolysis

2 ATP, 1 glucose, 2 NAD+

outputs of glycolysis

4 ATP

2 pyruvate

2 NADH

location of glycolysis

cell’s cytoplasm

explain the steps of the acetyl CoA prep step IN DETAIL PER PYRUVATE

1. NAD+ is reduced to NADH

2. CO2 is lost since whenever NADH is lost, so is CO2

3. CoA is inputted, forming acetyl CoA

happens again for the other pyruvate

inputs of link step PER GLUCOSE

2 pyruvate

2 CoA

outputs of link step PER GLUCOSE

2 NADH

2 CO2

2 acetyl CoA

location of link step

matrix

explain the steps of the Kreb’s cycle PER ACETYL COA IN DETAIL

1. CoA serves as a ticket to begin Kreb’s cycle, so it detaches from the acetyl group and returns to the prep step. acetyl group sits on oxaloacetate, forming citrate.

2. CO2 and NADH (reduced from NAD+) are lost from the citrate

3. repeat of step 2. oxaloacetate is back.

4. oxaloacetate changes shape, which releases energy in the form of GTP. GTP is converted to GDP + P and the phosphate group merges with ADP to form ATP.

5. shape change again; FAD+ is reduced to FADH2

6. shape change again; NAD+ is reduced to NADH

7. shape change to oxaloacetate; cycle can repeat

inputs of Kreb’s cycle PER GLUCOSE

2 acetyl CoA

outputs of Kreb’s cycle PER GLUCOSE

6 NADH, 2 FADH2, 4 CO2, 2 ATP

location of Kreb’s cycle

matrix

explain the steps of the Electron Transport Chain IN DETAIL

1. electron carrier is oxidized (NADH or FADH2)

2. the resulting H+ is pumped across its concentration gradient through a protein

3. H+ falls down a concentration gradient through ATP synthase, an enzyme built like a turbine. H+ turns this turbine to power the synthesis of ATP from ADP and P (oxidative phosphorylation)

4. O2 acts as the last electron acceptor; picks up 2 protons to neutralize the negative charge of electrons, forming H2O

what carriers does ETC start with?

the ones with most potential energy (like NADH) and goes to carriers with less potential energy (like FADH2)

chemiosmosis

H+ is pumped across its concentration gradient; when it falls back down, it powers the synthesis of ATP

inputs of ETC

10 NADH, 2 FADH2

outputs of ETC

32 - 34 ATP
H2O

overall # of ATP produced by cellular respiration

36 - 38 ATP

what takes place in the absence of O2 to produce ATP? where does this process take place?

fermentation, in the cell’s cytoplasm

explain the steps of alcohol fermentation

1. glycolysis as normal

2. Pyruvate is converted to acetylaldehyde, releasing CO2

3. electron from NADH powers the conversion of acetylaldehyde to ethanol, thereby recycling NAD+

organisms that carry out alcohol fermentation

yeast, brewing/winemaking

explain the steps of lactic acid fermentation IN DETAIL

1. glycolysis as normal

2. electron from NADH powers the conversion of pyruvate to lactate, thereby recycling NAD+