Cell Energy:

Photosynthesis & Respiration

Today’s Learning Goals

In plants, chlorophyll (found in chloroplasts) captures energy from the sun in order to make food during photosynthesis (Review)

Cells release energy from food through either cellular respiration or fermentation

Why it matters: Understanding how plants & animals get energy to grow & develop is an important part of biology.

How Does a Plant Make Its Own

Food? (REVIEW)

Plants use carbon dioxide (CO2), water (H2O), and

sun’s energy to make food.

This is called “photosynthesis”

The food gives plants energy

Animals get the

energy stored in

plants when they

eat them.

How Do Plants Get Energy From Sun?

(REVIEW)

Plants have pigments that

absorb energy from light

Chlorophyll (found in

chloroplasts) is the pigment

used in photosynthesis

What “Food” do Plants Make? (REVIEW)

The “food” plants

make is a sugar

called glucose

(C6H12O6).

Glucose and oxygen

(O2) are made during

photosynthesis.

How Do Organisms Get Energy

From Food?

Animals cannot make their own food like plants can.

But, BOTH plants and animals must break down

(digest) food in order to get energy from it (so they

can live, grow, & develop)

Cells do this 2 ways: cellular respiration and

fermentation

Cellular Respiration Produces

ATP Energy obtained from food must be transferred

into ATP.

This is done through cellular respiration.

Oxygen speeds up the process = AEROBIC

Can be done without oxygen = ANAEROBIC

Cellular Respiration

Cellular Respiration =

chemical process that

happens in cells

In prokaryotes, it

happens in the cell

membranes

In eukaryotes, it

happens mostly in the

mitochondria

Cellular Respiration has 3 Main

Stages

1. GLYCOLYSIS

2. CITRIC ACID CYCLE (KREB’S CYCLE)

3. ELECTRON TRANSPORT CHAIN

STAGE 1 - GLYCOLYSIS

Glycolysis = Glucose is broken down in the

cytoplasm of the cell.

ATP is made.

Glycolysis uses two ATP molecules but it

produces four ATP molecules = net gain of

two ATP molecules.

STAGE 1 – GLYCOLYSIS

Glycolysis can occur WITH or WITHOUT oxygen

WITH OXYGEN

AEROBIC (Produces more ATP than without)

WITHOUT OXYGEN = FERMENTATION

ANAEROBIC (Small amounts of ATP produced)

So most eukaryotes

(ex: plants & animals)

get their energy through

cellular respiration

In Stage 2, More ATP is Made by

Aerobic Respiration

Krebs Cycle = A series of reactions that

produce ATP

Aerobic = Oxygen

AKA = Citric Acid Cycle

www.progressivegardens.com

Stage 3: Electron Transport

Chain

Makes ATP

Occurs in the membranes of mitochondria

Aerobic Respiration

No oxygen? Then Fermentation

follows Glycolysis

Two kinds of fermentation

1. Lactic Acid Fermentation

2. Alcoholic Fermentaion

Fermentation

Happens when cells cannot

get the oxygen they need for

cellular respiration

Fermentation is a way to get

energy when oxygen isn’t

available

Ex: In short, fast races you

might get a burning feeling

in you leg muscles because of

a build up of lactic acid (made

during fermentation)

Lactic Acid Fermentation

Vigorous exercise produces a build up of

pyruvate in muscles

Pyruvate converts to lactate in the absence of

oxygen

ATP is still produced in glycolysis BUT you

will likely be sore due to a build up of lactate.

http://www.uic.edu/classes/bios/bios100/su

mmer2002/alchferm.gif

Alcoholic Fermentation

In other organisms, pyruvate is broken down into

alcohol.

Can be done by yeast

Two step process:

1. Pyruvate is broken down which releases CO2.

2. Electrons are transferred and ethanol is produced.

http://www.uic.edu/classes/bios/bios100/su

mmer2002/alchferm.gif

Summary

https://eapbiofield.wikispaces.com/Chapter+9+Cellular+Respiration-Harvesting+Chemical+Energy+AK

Photosynthesis vs Respiration

http://www.kensbiorefs.com/cellchem.html

Facts

Human body uses 1 million molecules of ATP

per cell per second.

Much of the body’s energy is released as heat.

Skunk cabbage generates heat when it flowers

in Feb/Mar. How is this helpful?

http://www.pathcom.com/~wgbz/xv01209z.jpg

Review of Cellular Respiration

Food (glucose) is broken down into CO2 and H2O and

energy is released

C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy (ATP)

This energy can be used for:

Keeping a constant body temperature

Storage (ATP) - to be used later for things like growth

What Do You Notice?

Check It Out!

Did you notice

that cellular

respiration is just

the opposite of

photosynthesis?

Pop Quiz

1) Plants use carbon dioxide (____), water (____), and the sun’s energy to make food.

CO2 and H2O

2) What type of cell has chloroplasts?

PLANT CELL

3) BOTH plants and animals must break down food in order to get ________from it.

ENERGY

4) How are respiration and photosynthesis related?

THEY ARE THE REVERSE (OPPOSITE) OF EACH OTHER.

5) Fermentation is a way to get energy when ______ isn’t available.

OXYGEN

Gotta Get that ATP

https://www.youtube.com/watch?v=V_xZuCPI

Hvk

Gotta Get that ATP Answers

1. ATP

2. Energy

3. Glycolysis

4. Mitochondria

5. Electron Transport Chain

Today’s Learning Goals

In plants, chloroplasts capture energy from the sun in order to make food during photosynthesis

Cells release energy from food through either cellular respiration of fermentation

Why it matters: Understanding how plants & animals get energy to grow & develop is an important part of biology.