Unit 6- Cell Energy- Photosynthesis & Cellular Respiration

6b- Cellular Respiration

Bellwork

• Explain the Calvin Cycle using these words: CO2 , RuBP, PGA, ATP & NADPH, PGAL.– How is it a cycle?– What is the final product of the Calvin Cycle?– Where does it occur?

• What three factors affect the rate of photosynthesis?

Bellwork1) – CO2 combines with RuBP, new molecule splits into

PGA.– PGA combines with ATP/NADPH to become PGAL.– PGAL makes glucose, leftover PGAL becomes RuBP

to start cycle again.

2) Final product= glucose! 3) Occurs in the stroma.

4) Temperature, amount of CO2, amount of sunlight.

Cellular Respiration• Goal of Cellular Respiration: to convert the chemical

energy in food to chemical energy stored in adenosine triphosphate (ATP)– ATP can then release the energy for cellular metabolic processes,

such as active transport, protein synthesis, & muscle contraction

• Any organic molecule can be broken down into smaller molecules & then used as a source of energy to produce ATP molecules.

• Occurs in both autotrophs & heterotrophs

Stages of Cellular Respiration • The process is generally represented using a

balanced chemical equation…– C6H12O6 + 6O2 6CO2 + 6H2O + energy (ATP)

• However, to transfer the energy stored in glucose to ATP, a cell must break down glucose slowly in a series of steps and capture the energy in stages. – 2 Stages (when oxygen is present)

• Glycolysis– Anaerobic – does not require oxygen

• Aerobic Respiration– Aerobic- requires oxygen

Glycolysis1. Glycolysis-

• A series of reactions catalyzed by enzymes• Occurs in the cytoplasm of the cell• Anaerobic- Does not require oxygen

• In the process of glycolysis, a glucose molecule is broken down into pyruvic acid molecules and two ATP molecules– Glucose pyruvic acid + ATP (small amount)

Aerobic Respiration

• If oxygen is available, the 2-stage process of aerobic respiration occurs after glycolysis. – The two aerobic reactions are

• the Krebs Cycle (aka Citric Acid Cycle) • the Electron Transport Chain

– Occurs in the mitochondria of the cell

Krebs Cycle (Citric Acid Cycle)• The pyruvic acid, produced by glycolysis, travels to the

mitochondria where it is broken down in a cycle of chemical reactions – Occurs in the mitochondrial matrix- space inside

mitochondria– Produces carbon dioxide, ATP, & electron carriers (NADH &

FADH2)– Pyruvic acid CO2 + ATP (small amount) + electron carriers

Krebs CycleCO2 is released

Pyruvic acid from Glycolysis fuels the cycle

CO2 is released

ATP is released

Electron carriers are released

Electron Transport Chain• A series of chemical reactions in which energy is

transferred to form a large number of ATP molecules – Located in the inner membrane of the mitochondria– Uses the electron carriers (NADH and FADH2) to pass electrons

down the protein chain & slowly release energy that is used to form ATP

Electron Transport Chain• At the end of the chain oxygen

combines with hydrogen & the electrons to form water. – Why is oxygen required?

• ATP can only be synthesized if electrons continue to move along the ETC.

• The last molecule in the chain must pass the electrons to a final electron acceptor. Otherwise, the process would stop.

Checkpoint: try to fill in the blank!• The steps of Cellular respiration:• Glycolysis

– Produces what?– Needs or does not need oxygen?

• Aerobic Respiration: – Needs or does not need oxygen?– What does it use in the Krebs cycle?– What does it produce in the Krebs cycle?– After the Krebs Cycle, the Electron Transport

Chain. What is produced?

Cellular Respiration

Glycolysis

Citric Acid Cycle (Krebs Cycle)

Electron Transport Chain

1 Glucose

2 Pyruvic Acid

2 ATP

2 Pyruvic Acid

CO2

2 ATP

34 ATP NADH

and FADH2

NADH and FADH2

Oxygen

Water

Cellular Respiration Equation

C6H12O6 + 6O2 6CO2 + 6H2O + energy

Water – released

from Electro

n Transpo

rt Chain

Oxygen from the

atmosphereUsed in

Electron Transport

Chain

Carbon Dioxide –

waste product of the Krebs cycle

ATP released from

Glycolysis, Krebs Cycle, & Electron Transport

Chain

Up to 38 ATP molecules are made from the breakdown of one glucose molecule: 2 from glycolysis & up to 36 from aerobic respiration.

Most of the energy released by respiration, that is not used to make ATP, is released in the form of heat.

Glucose made in

photosynthesis by

plants or consumed by animals

Used in Glycolysis