ATP, Photosynthesis, and Cellular Respiration: Energy in a Cell

ATP, Photosynthesis, and Cellular Respiration:

Energy in a Cell

I. Background information

A. What is energy? --the ability to do work

B. Why is it needed?--Cells need energy to maintain homeostasis

and carry out life functions.

C. Heterotrophs get energy from _______ .

Ex: animals, fungi, some protists, some bacteria

D. Autotrophs get energy by __________.

Ex: plants, some protists, some bacteria

E. The chemical bonds in food are broken down to release the chemical energy stored in them.

F. However, NOT all of the energy is used at once. Some of it has to be stored.

II. ATP—adenosine triphosphate—an energy-storing molecule

phosphate bondsATP is made of:3 phosphates1 sugar1 adenine

A. Energy is stored in the phosphate bonds.

B. Energy is released when the phosphate bonds are broken.

C. When energy is released from ATP, a phosphate is released and ADP is left.

D. ADP—adenosine diphosphateADP is made of: 2 phosphates

1 sugar 1 adenine

Let’s look at this reversible reaction

in

3 different ways…

ATP ADP + phosphate + energy

ATPenergy

energy

ADP + phosphate

+ + energy

ADP + phosphate + energy ATP

III. Photosynthesis

photo—means lightsynthesis—means to make

*Photosynthesis is the process in which autotrophs use light energy to make food.

*Chemosynthesis is a similar process in which some bacteria use inorganic compounds to make food.

chemo—means chemical

*Equation for Photosynthesis:

CO2 + H2O light energy C6H12O6 + O2

carbon dioxide + water light energy glucose + oxygen

Note:Chemical equation at topWord equation on bottom

A. Where does photosynthesis take place?

1. in the chloroplasts, which contain the green pigment chlorophyll

2. In plants it mainly occurs in the leaves.

B. Requirements for Photosynthesis:

1. water (H2O)2. carbon dioxide (CO2)

3. sunlight (or light energy)4. chlorophyll (which is

already present in the plant)

Stoma (stomata-plural) of a leaf

C. Products:

1. Main Product—glucose (C6H12O6)

2. Waste Product or by-product—oxygen (O2)

D. Two Stages:1. Light reactions (light-dependent)-

--involves Photosystem I and II

a. Chlorophyll absorbs light energy and uses it to split water.

b. photolysis—splitting of water

c. Take place in the grana or thylakoids

Chloroplast Structure

2. Dark reactions or Calvin Cycle

(light-independent; Calvin-Benson Cycle)

a. Do NOT require light!

b. Glucose is produced.

c. Take place in the stroma

Overview of Photosynthesis

IV. Cellular Respiration *a process in which

organisms (heterotrophs AND autotrophs) break down food to release energy

*There are 2 types of respiration:aerobic – using Oxygenanaerobic – Not using Oxygen

*Equation for Aerobic Respiration:

C6H12O6 + O2 CO2 + H2O + ATP

glucose + oxygen carbon dioxide + water + energy

Mitochondrion Structure

Mitochondrion

1. Aerobic respiration involves 3 processes:

a. glycolysis—splitting of glucose

- doesn’t require oxygen

- occurs in the cytoplasm

- 2 ATPs to start, produces 4 ATP = Net’s 2ATP

- produces 2 Pyruvate molecules

b. citric acid cycle (Krebs cycle)

- 2 pyruvate enter

- in Matrix of Mitochondria

- CO2 waste product

- small amounts of ATP, FADH, NADH produced

c. electron transport chain

- inner membrane of Mitochondria

- Go In: O2and Energy Carrying molecules

- Water, Heat, and 34 – 36 ATP produced

• TOTAL ATP: Glycolysis (2) + ETC (34) = 36 ATP!

2. Anaerobic Respiration

1. Does NOT require oxygen

2. Produces only 2 ATP’s total

3. Takes place in the cytoplasm

4. Also called fermentation

5. Begins with glycolysis

C. Types of Fermentation (Anaerobic Respiration):

1. Lactic acid fermentation—

a. takes place in animals

b. Lactic acid is the waste product.

c. Lactic acid builds up in muscles, causing muscle fatigue.

2. Alcoholic fermentation—

a. takes place in some microorganisms such as yeast

b. Ethyl alcohol and carbon dioxide are the waste products.

c. Process used in making alcoholic beverages

D. Both types of Respiration:

Main product=energy (ATP)

E. For Aerobic:

Waste products=carbon dioxide and water

F. Contrasting TableCategory Photosynthesi

sRespiration

Organelle Chloroplast Mitochondrion

Energy Required Produced

Glucose (food) Produced Required

Oxygen Produced Required

Carbon dioxide Required Produced