Cellular Respiration

Ms. LowrieBiology 11

Energy Transformation

Chemical energy in food converted into energy that cells can use Glucose to ATP

Occurs in plants and animals

Figure 3 (pg 60)

Cellular Respiration

Photosynthesis

Light energy

Carbondioxide

Water Glucose Oxygen Water

Compare the Equations

Glucose Oxygen Carbondioxide

EnergyWater

+

Photosynthesis

Cellular Respiration

Sunlight

Heat

PhotosynthesisCellular

respiration

The Exchange of Chemicals

Note: Products from one process are reactants for the other.

Breathing

Lungs

Musclecells

Cellularrespiration

Cellular Respiration & Breathing

Breathing Exchanges these

gases between blood and outside air

Cellular respiration Requires cells to

exchange gases with surroundings

Remember …

Why does energy need to be transferred from glucose to ATP?

Glucose has TOO much energy Therefore, unusable

ATP – usable energy for cell

Water

Cellular Respiration

Summary Equation

Glucose Oxygen Carbondioxide

EnergyWater

+

Three Steps

1. Glycolysis Occurs in cytoplasm

2. Kreb’s cycle3. Electron transport

system

Can occur with oxygen (aerobic) or without oxygen (anaerobic)

Occurs in mitochondria

Cytoplasm(cytosol) Mitochondrion

GlycolysisKrebsCycle

ElectronTransport

Step 1 – Glycolysis

Location: Cytoplasm

Does NOT require oxygen Anaerobic phase

Plants -> Bacteria -> Humans!

Glycolysis

Glucose is broken down into 2 PGAL Uses 2 ATP molecules

Each PGAL is converted into pyruvate

a.k.a. pyruvic acid

glucose

PGAL

PGAL

pyruvate

pyruvate

Glycolysis – Glucose Breakdown

Glycolysis

2 NAD+ (hydrogen carrier) gain hydrogen & electrons Creates 2 NADH

4 ATP are produced 2 ATP replace those used to initiate Net gain of 2 ATP molecules

Glucose

2 Pyruvic acid

Cytoplasm

NADH

Glycolysis

Glucose2

Pyruvate

Kreb’s Cycle & Electron Transport System

Location: Mitochondria

DO require oxygen Aerobic

Step 2 – Kreb’s Cycle (Citric Acid Cycle)

CoA

1

2

3Pyruvic

acid

Aceticacid

Coenzyme A

Acetyl-CoA(acetyl-coenzyme A)

CO2

Pyruvate changed into usable form Acetyl coenzyme A (coA)

Kreb’s Cycle

Acetyl-coA goes through a series of reactions with water Uses water from atmosphere

Then enters Kreb’s Cycle Glucose (C6H12O6) finishes breaking

down

Carbon & Oxygen create CO2

Which is released to atmosphere

Hydrogen & electrons Picked up by NAD+ or FAD (hydrogen

receptors) to form NADH or FADH2

Net gain is 2 ATP 1 from each pyruvate

Kreb’s Cycle

Input

Acetyl coA

ADP

3 NAD

FAD

KrebsCycle

Output

3 CO2

Cycle Repeats Twice

Cytoplasm

Mitochondria

NADH NADH & FADH2

Glycolysis

Glucose2

PyruvateKrebsCycle

2 Acetyl coA

Step 3 – Electron Transport System

Uses hydrogen from NADH & FADH2

Hydrogen (and its electrons) are passed down a “stairway” of reactions Energy is released with each step

Oxygen = final hydrogen electron acceptor “Catches” hydrogen Combines with two hydrogen Forms water

Net gain is 34 ATP

Electron Transport System

ElectronStairway

Hydrogen electrons “falling”

Creates energy at each step

1/2

(from food via NADH)

2 H 2 e

Energy forsynthesis

of

Electro

n tran

spo

rt chain 2 e

2 H1/2

Cytoplasm

Mitochondria

NADH NADH & FADH2

Glycolysis

Glucose2

PyruvateKrebsCycle

ElectronTransport

2 Acetyl coA

Adding Up Aerobic ATP

Glycolysis 2 ATP

Kreb’s + 2 ATP

Electron Transport + 34 ATP 38 ATP

Adding Up Aerobic ATP

Cytoplasm

Mitochondria

Glycolysis

Glucose2

Pyruvate

2Acetyl-

CoA

KrebsCycle Electron

Transport

Maximumper

glucose:

Glucose Oxygen Carbondioxide

Water Energy

Summary Equation

Water

+

Glucose Oxygen Water Energy

Balanced Equation – Note Water

Task – Electron Transport System

Use notes & pages 62 & 63

Answer: #3, 4

(page 64)

#3 – Electron Transport System

Series of hydrogen (electron) acceptors As hydrogen moves, energy is released

What if energy from glucose was released all at once? Too quick Cause cell damage

#4 – Energy in Electron Transport

Results in: 34 ATP Water

The process of mitochondria breaking down glucose to produce ATP is …

a) Photosynthesis

b) Cellular respiration

c) Glycolysis

d) Calvin cycle

The stages, in order, of cellular respiration are …

a) Carbon fixation, Calvin cycle, Citric acid cycle

b) Light reactions, Kreb’s cycle, Electron transport system

c) Glycolysis, Kreb’s cycle, Electron transport system

d) Citric acid cycle, Glycolysis, Electron transport system