biology 20: unit c textbook: pages 202-233hillabybiology20.yolasite.com/resources/bio 20 chapter 7...

Biology 20: Unit C

Textbook: Pages 202-233

A series of chemical reactions that breaks down

glucose to release energy

The energy is then stored in a molecule that the

cell can use to do work

This molecule is called ATP

Cellular respiration takes place in all Eukaryotic

cells

Has the same format as a combustion reaction

Is different from a combustion reaction because:

It is a slower reaction

The energy released in steps (otherwise spontaneous combustion would be the result)

The energy released is stored in ATP

The cell then uses ATP energy to carry out reactions that require energy

How does ATP store energy?

Each ATP molecule holds about 1% of the energy of a glucose molecule

~36% of the energy of glucose is stored as ATP after cell respiration

~64% is lost as heat

This heat maintains body temperature

ATP formation ATP

reactants

oxidation - energy

reduction from

reaction reaction

products ADP + Pi

High

energy

Low

energy

Refer to chemical reactions where electrons are transferred

Oxidation = loss of electrons (LEO)

Na Na+ + e-

Reduction (GER)

Na+ + e- Na

In biological systems energy is associated with the movement of electrons

Electrons can be pulled away from a molecule

Hydrogen atoms are usually lost from a molecule during oxidation

Hydrogen atoms are usually gained by a molecule during reduction

NAD+ is reduced

NADH is an electron carrier

NADH can also lose electrons

NADH NAD+ + 2e- + H+

NADH is oxidized

Occurs when NADH is in contact with a molecule

that has a strong attraction for electrons

NAD+ Is recycled

Is an important electron carrier

NAD+ can attract electrons

NAD+ + 2e- + H+ NADH

1. Glycolysis in cytoplasm

2. Transition Step In mitrochondria

3. Kreb’s cycle in matrix of mitochondria

4. Electron Transport Chain and

Chemiosmosis inner membrane of mitochondria

Remember

This !!!

Energy, Cells, and ATP

Label the diagram

choosing from the

following words or

phrases:

•Transport protein

•ATP

•ADP

•P X 4

•Phosphorylated

•Protein releases solute

outside cell

•Phosphate detaches

from protein

Glucose and ATP

Label the diagram

choosing from the

following words or

phrases:

•100 %

•About 40 %

•25 %

•Energy released from

glucose banked in ATP

•Gasoline converted to

movement

•“Burning” glucose in

cellular respiration

•Burning glucose in an

experiment

Cell Anatomy

Identify the plant cell;

identify the animal cell.

Label the diagram

choosing from the

following words or

phrases:

•Mitochondria

•Cytoplasm

Mitochondria Anatomy

Use Nelson page 214

Label the diagram choosing

from the following words or

phrases:

•Inner membrane

•Mitochondrion

•Outer membrane

•Cristae

•Intermembrane space

•Matrix

Takes place in the cytoplasm of

the cell

A 6-carbon glucose molecule is

split into two molecules of

pyruvate (3 carbons each)

Is an anaerobic process (does

not require oxygen)

In glycolysis, two ATP molecules

are needed to start the reaction

Four ATP molecules are

produced

There is a net gain of 2 ATP

molecules

Glucose (6C)

2 Pyruvate

molecules (3C)

4 ADP + P

2 NAD

4 ATP

2 NADH

2 ADP

2 ATP

NADH (2) molecules are also produced

Glucose is oxidized

NAD+ is reduced

Note: Pyruvic acid = Pyruvate

Pyruvate enters the next phase of cellular

respiration (transition Step)

NADH is used in chemiosmosis and electron

transport

ATP is used by the cell to carry out biological

work Glycolysis Overview

Animation:

http://www.science.smith.ed

u/departments/Biology/Bio23

1/glycolysis.html

http://www.science.smith.edu/departments/Biology/Bio231/glycolysis.html



Before the Kreb’s cycle begins, pyruvate is

modified

This takes place in the mitochondria

One carbon is lost (in the form of CO2) to form an

acetyl molecule

Acetyl joins to a carrier called coenzyme A to

form acetyl Co-A

One NADH forms

Glycolysis

2 ATP per glucose

2 NADH per glucose

Transition Step

1 NADH per pyruvate (2 NADH per glucose)

Per glucose:

2 ATP

4 NADH

Read Pages 202-212 in your textbook

Complete Practice Problems 1-5 – pages 205, 207

Complete Section 7.1 Questions 1-5 on page 209

Complete Section 7.2 Questions 1-3 on page 212

Glycolysis



phrases:

•A fuel molecule is

energized, using ATP.

•A redox reaction generates

NADH

•A six – carbon

intermediate splits into two

three – carbon

intermediates.

•ATP and pyruvic acid are

produced

•Glucose

•G3P

•Pyruvic acid

•ATP X 4

Pyruvate Oxidation



phrases:

•Pyruvic acid

•NADH + H+

•Coenzyme A

•CO2

•Acetyl CoA (acetyl

coenzyme A)

•NAD+

Also called the citric acid cycle

Takes place in the matrix of the mitochondria

Starts with Acetyl-CoA (2 per glucose)

Cycle goes around twice for every glucose molecule

that undergoes glycolysis

Acetyl-CoA is oxidized, NAD+ and FAD are reduced

2 carbons enter as

acetyl – CoA

2 carbons leave as CO2

(3) NAD+ are reduced to

form NADH

(1) FAD is reduced to

form FADH2

1 ATP is formed

NOTE: these numbers

double for a glucose

molecule

Overview animation:

http://www.science.smith.edu/departments/Biology/Bio231/krebs.html

http://www.science.smith.edu/departments/Biology/Bio231/krebs.html

The inner membrane of the mitochondria

contain proteins that can carry electrons

These proteins are called cytochromes

They take electrons from NADH and FADH2 that

are produced in glycolysis and the Kreb’s cycle

NAD+ and FAD

are recycled

and can be used

in glycolysis and

Kreb’s cycle

A small amount of energy is released as they are passed from protein to protein

This energy is used to move H+ into the intermembrane space

OXYGEN Is the final electron acceptor

Has a stronger attraction for electrons than any of the proteins in the membrane

It is reduced to form water

2 H+ + ½ O2 + 2e- H20

What happens to the ETC if there is no O2?

A lack of oxygen causes the system to back up all the way to glycolysis because the NADH and FADH2 can’t be recycled

A process that produces

most of the ATP for

cellular respiration

32 ATP are produced per

glucose in chemiosmosis

Chemiosmosis

requires…

A concentration gradient

of H+ ions

An ATP synthase channel which is found in the

inner membrane of the mitochondria

Remember that electron transport causes H+ to

build up in the intermembrane space

H+ ions are not allowed to

diffuse back into the

matrix

The ATP synthase

channel is the only place

permeable to H+

As hydrogen flow back

into the matrix from the

intermembrane space

energy is released

This energy is used to

make ATP

32 per glucose

Animation of ETC:

http://www.science.smi

th.edu/departments/Bio

logy/Bio231/etc.html

http://www.science.smith.edu/departments/Biology/Bio231/etc.html



2 ATP from glycolysis

2 ATP from Kreb’s

32 ATP from the electron transport and chemiosmosis

Total = 36 ATP per glucose

A Review of Cellular Respiration:

http://www.toppermost.biz/CellResp.html


Electron Transport and ATP Synthesis

http://bcs.whfreeman.com/thelifewire/content/

chp07/0702001.html

http://highered.mcgraw-

hill.com/olc/dl/120071/bio11.swf

http://www.science.smith.edu/departments/Biol

ogy/Bio231/etc.html

A Review of Cellular Respiration:


http://bcs.whfreeman.com/thelifewire/content/chp07/0702001.html

http://bcs.whfreeman.com/thelifewire/content/chp07/0702001.html

http://highered.mcgraw-hill.com/olc/dl/120071/bio11.swf






Read Pages 213-220 of textbook

Complete “Practice” problems 1-6, pages 215, 219

Compete Section 7.3 Questions 1-10 on page 220

Compete the Workbook supplementary diagrams

Refers to respiration without oxygen

Without oxygen NADH and FADH2 cannot get rid of their electrons

This means there is no NAD+ for glycolysis or Kreb’s cycle

When oxygen levels decrease…

NADH and FADH2 give their electrons to another acceptor instead of oxygen

This allows NAD+ and FAD to be available for glycolysis (which produces a small amount of ATP

Anaerobic respiration produces ethanol, and is

called fermentation

Fermentation has commercial uses: breweries,

bread making, wine making

Anaerobic respiration produces lactic acid

When cells are not receiving enough oxygen, muscles become cramped due to a build of lactic acid

When oxygen becomes available, lactic acid is converted back into pyruvate

Pyruvate then continues to Kreb’s cycle

Anaerobic respiration is useful because it provides a short burst of energy when oxygen is not available

However, it can only produce a small amount of ATP compared with aerobic respiration (2 ATP)

Exercise physiology

Branch of biology dealing with body’s biological responses

Most common question: shortage of energy by athletes

Athletic fitness

Measure of ability of heart, lungs, and bloodstream to supply O2 to cells of body

Other factors to athletic fitness:

Muscular strength, muscular endurance,

flexibility, body composition (ratio of fat to bone

to muscle)

A measure of body’s capacity to generate E required for physical activity

Treadmill exercise test is used to measure VO2 max

10 – 15 minute test

Animal is forced to move faster and faster on a treadmill

Expired air is collected and measured by a computer

VO2 max measures:

Volume of O2 (mL) that cells of body can remove from bloodstream in 1 minute per kg of body mass

While body experiences maximum exertion

VO2 max values:

Average: 35 mL/kg/min.

Athletes: 70 mL/kg/min.

VO2 max

Can be increased with more exercise

Genetic variation is also a factor

Decreases with age

Value of exercise intensity at which blood lactic acid

concentration begins to increase sharply

Exercising beyond threshold may limit duration of

exercise

Due to pain, muscle stiffness, and fatigue

Athletic training improves blood circulation and

efficiency of O2 delivery to body cells

Result:

Decrease in lactic acid production

Increase in lactic acid threshold

Untrained individuals reach a lactic acid threshold at

60 % VO2 max

Elite athletes reach threshold at or above 80 % VO2

max

Creatine phosphate

May serve as an E source by donating its

phosphate to ADP

Occurs naturally in body and many foods

Athletes consume compound to produce more ATP

in muscles

Compound may also buffer muscle cells and delay

onset of lactic acid fermentation

Potential harmful side – effects are possible

Some poisons interfere with the electron

transport chain

Causes death quickly because electron flow

stops, which stops all stages of cellular

respiration

Examples:

Cyanide

Hydrogen sulfide

Read pages 221 – 228 of your textbook

Complete “Practice” Problems 1-6, pages

222, 226

Complete Section 7.4 Questions – Page 228

#’s 1-6, 9

Simplistic View of

Krebs Cycle



phrases:

•CoA

•NADH

•ATP

•FADH2

Overview of Krebs

Cycle



phrases:

•Redox reactions generate

FADH2 and NADH

•Acetyl CoA stokes the

furnace.

•NADH, ATP, and CO2 are

generated during redox

reactions

•ATP

•NADH

•FADH2

•Krebs Cycle

Electron Transport

Chain and

Chemiosmosis

Use Nelson page 217

Label the diagram choosing from

the following words or phrases:

•Mitochondria matrix

•NADH

•ATP

•ADP + P

•½ O2 + 2H+

•H2O

•NAD+

Protein complex

•Electron carrier

•H+ X 5

•Electron Transport Chain

•ATP Synthase

Aerobic Respiration

Energy Balance Sheet

Use Nelson page 219

Label the diagram choosing from the

following words or phrases:

•Cytoplasmic fluid

•Glycolysis: glucose pyruvic acid

•2NADH X 2

•6 NADH

•2 FADH2

•+ 2 ATP X 2

•+ about 34 ATP

•By chemisosmotic phosphorylation

•About 38 ATP

•Krebs Cycle

•Electron Transport Chain and

Chemiosmosis

•Mitochondrion

•Electron shuttle across membranes

•2 Acetyl CoA

Alcohol Fermentation

Use Nelson page 221



•Glycolysis

•Glucose

•2 ATP

•2 NADH X 2

•2 pyruvic acid

•2 ethanol

•2 CO2 released

•2 ADP + 2 P

Lactic Acid

Fermentation

Use Nelson page 224



•Glycolysis

•Glucose

•2 ATP

•2 NADH X 2

•2 pyruvic acid

•2 lactic acid

•2 ADP + 2 P

Cellular Respiration

and Other Sources of

Energy



•Krebs cycle

•ATP

•Electron Transport Chain and

Chemiosmosis

Cellular Respiration

and Biosynthesis



•Krebs cycle

•ATP

•Cells, tissues, organisms

Unit C Review

Complete the following to help you prepare for

the upcoming unit final

Page 232 #1-8, 11-13

Page 234-235 # 1-10

biology 20: unit c textbook: pages 202-233hillabybiology20.yolasite.com/resources/bio 20 chapter 7...

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