SBI4UI - Cellular Respiration Review

kinetic vs potential energy

kinetic: the energy possessed by a moving entity

potential: stored energy that will be released when a chemical reaction occurs

exergonic vs endergonic reactions

exergonic: reactions that release free energy

endergonic: reactions that absorb energy

catabolic vs anabolic pathway

catabolic: complex molecules are broken down into simpler compounds — exergonic rxn

anabolic: builds complex molecules from simpler ones — endergonic rxn

how do our cells harness energy? (3)

macromolecules fuel chemical reactions → contributes to making of energy.

harnessed by:

1. forming new bonds as new compounds are created

2. moving electrons between different molecules (using electrons to help complete chemical reactions)

3. making & breaking down ATP

what is ATP

main source of energy

what does phosphorylation mean?

the gaining of a phosphate group

reduction reaction

molecules that gain electrons are reduced

oxidation reaction

molecules that lose electrons are oxidized 

what do our cells use ATP for? (3)

1. chemical reactions — helps complete an endergonic reaction

2. movement, motion, mechanical work — helps move cell parts, chromosomes, & muscle fibre contraction

3. moves substrates into & out of the cell

what happens during substrate level phosphorylation?

enzyme transfers a phosphate group to an ADP directly. ADP → ATP

where does substrate level phosphorylation occur?

glycolysis: cytoplasm

krebs cycle: mitochondria matrix

pros and cons of substrate level phosphorylation

pro: simple process (fast)

con: very few ATP made

what happens during oxidative phosphorylation (chemiosmosis)?

multi-step chemical reactions which uses energy harnessed in electrons (from redox reactions)

where does oxidative phosphorylation occur?

mitochondria

pros and cons of oxidative phosphorylation

pro: produces a lot of ATP

con: very complex

what is the purpose of glycolysis?

• to break down a 6 carbon molecule into 2 smaller pyruvate molecules (3 carbon molecules)

where does glycolysis occur?

cytoplasm

what is coming and going during glycolysis?

input: glucose, 2 ATP

output: 2 pyruvate molecules, 2 NADH, 2 ATP

Products of glycolysis (what is the function/destiny of each product)

2 pyruvate molecules → mitochondria for pyruvate oxidation

2 NADH → Electron transport chain

2 ATP → net

what is the purpose of pyruvate oxidation?

• break down 3 carbon pyruvate molecules into 2 carbon Acetyl CoA molecule to release all available energy

where does pyruvate oxidation occur?

mitochondrial matrix

what is coming and going out at each step during pyruvate oxidation?

input: 2 pyruvate molecules, NAD⁺, 2 CoA (added to acetyl molecule)
output: 2 Acetyl CoA, 2 CO₂, 2 NADH

Products of pyruvate oxidation (what is the function/destiny of each product)

2 Acetyl CoA → enters kreb’s cycle

2 CO₂ → gets released as waste

2 NADH → electron transport chain

what is the purpose of krebs cycle

complete oxidation of Acetyl CoA made during pyruvate oxidation

where does krebs cycle occur

mitochondrial matrix

what is going in and out during the krebs cycle

input: 2 Acetyl CoA

output: 6 NADH, 2 ATP, 2, FADH₂, 4 CO₂ gets released as waste

krebs cycle — major molecules: what happens to Acetyl CoA, what is oxaloacetate & citrate

Acetyl-CoA (2C) + Oxaloacetate (4C) → Citrate (6C)

Products of Krebs cycle (what is the function/destiny of each product)

4 CO₂ → exhaled

6 NADH, 2 FADH₂ → electron transport chain

2 ATP → useable energy

where does the electron transport chain occur

mitochondrial matrix

across the inner mitochondrial membrane

what is the purpose of the electron transport chain

to harness energy from NADH and FADH₂ to pump H⁺ and drive ATP production.

what is coming in and out of the electron transport chain

input: 10 NADH, FADH₂, O₂, H⁺,

output: ATP, H₂O, NAD⁺, FAD

what are the steps of the electron transport chain?

(where electrons come from and are transferred to)

as electrons from NADH and FADH₂  move through the components of the ETC, energy is released

what are the steps of the electron transport chain?

(how do the electrons drive hydrogen movement)

the energy release from electrons pumps H⁺ across the INNER membrane space → INTER MEMBRANE space

what are the steps of the electron transport chain?

(why is hydrogen movement important)

the high amounts of H⁺ create a H⁺ gradient, which drives ATP production

how does chemiosmosis work?

H⁺ ions move down their concentration gradient back into the matrix through AN ATP synthase channel. 

ATP synthase produces ATP by phosphorylation (ADP + Pi → ATP)

what are the products of electron transport?

ATP, H₂O, NAD⁺, FAD

how many ATP is produced per 1 electron carrier?

H⁺ = 1 ATP

1 NADH → 3 H⁺ → 3 ATP

1 FADH₂ → 2 H⁺ → 2 ATP

what is the role of oxygen in cellular respiration (4)

1. no final acceptor of electrons

2. no new electrons can go in

3. inhibits electron flow

4. NAD cannot be NADH (vice versa) & FAD cannot be FADH₂ (vice versa)

what is the role of water in cellular respiration

produced when O₂ combines with electrons + H⁺.

what is protein catabolism?

what is the waste product and what happens to the remaining molecule

the break down of amino acids for energy via cellular respiration

NH₃ → waste product & remaining amino acid enters cellular respiration pathways

what is lipid catabolism?

what happens to the glycerol backbone? what happens to the fatty acids?

glycerol → glyceraldehyde-3-phosphate and continues through the cellular respiration pathway

fatty acids → Acetyl + CoA → Acetyl CoA

how is aerobic respiration regulated?

regulated by oxygen.

No O₂ = no final electron acceptor = electrons entering & exiting = inactive ETC = no ATP

anaerobic processes — what is fermentation?

uses an organic molecule as a final electron acceptor but does not use an electron transport chain so it is not considered a form of respiration

anaerobic respiration — what is lactate fermentation?

glucose stays in glycolysis stage & regenerates NAD+

NADH transfers its electrons directly to pyruvate

generates lactate as product

anaerobic respiration — what is ethanol fermentation?

yeast and alike organisms produce energy without oxygen and generates CO₂ and ethanol as a product

Aerobic vs. anaerobic

what is required and what they produce

aerobic uses oxygen and produces 32 ATP and water