Photosynthesis & Respiration

Cell Energy

(Photosynthesis and Respiration)Energy:•Energy for living things comes from food. Originally, the energy in food comes from the sun.

• Organisms that use light energy from the sun to produce food—autotrophs (auto = self)Ex: plants and some microorganisms (some bacteria and protists)

• Organisms that CANNOT use the sun’s energy to make food—heterotrophs - must eat their foodEx: animals and most microorganisms

Adenine Ribose 3 Phosphate groups

Cell Energy:•Cells usable source of energy is called ATP•ATP stands for adenosine triphosphate

• ADP stands for adenosine diphosphate

Adenine Ribose 2 Phosphate groups

• All energy is stored in the bonds of compounds—breaking the bond releases the energy

• When the cell has energy available it can store this energy by adding a phosphate group to ADP, producing ATP

• ATP is converted into ADP by breaking the bond between the second and third phosphate groups and releasing energy for cellular processes.

Importance of ATP!

1. ALL organisms release ATP from the break down of glucose during cellular respiration

2. ATP powers the activities of the cell and allows living things to do work

3. ATP/ADP is a cycle that releases/stores energy for cell processes

4. ATP is used to actively transport material across the cell membrane

Photosynthesis•Photosynthesis is the process by which the energy of sunlight is converted into the chemical energy of glucose

• Photosynthesis occurs in the chloroplasts of plants

• Light absorbing compound is a pigment• pigments absorb some wavelengths of light and reflect

others• the color our eyes see is the color that the pigment

reflects

• Chlorophyll is the pigment inside the chloroplast the absorbs light for photosynthesis

As the chlorophyll in leaves decays in the autumn, the green color fades and is replaced by the oranges and reds of carotenoids.

•General formula for photosynthesis:

carbon dioxide + water —> glucose + oxygen

6CO2 + 6H2O —> C6H12O6 + 6O2

sunlight

sunlight

Light Reaction

Takes place in the thylakoid membrane

• (contains chlorophyll)

Reactants needed for the light reaction:• Water, Light, ADP, NADP+

Products made from light reaction and USED in dark reaction:

• ATP energy to make sugar• NADPH supplies e- and H to make C6H12O6

Oxygen is released into the air

Dark Reaction (Calvin Cycle)

Takes place in the stroma

Reactants needed for the dark reaction:• CO2, ATP, NADPH

Products made from the dark reaction USED in light reaction are:

• ADP returns to the light reaction to make more ATP• NADP returns to the light reaction to pick up more

electrons and Hydrogens

Glucose is made in the dark reaction for use throughout the organism.

Summary:

Light Reaction•H2O is broken down and

light energy is stored temporarily in ATP and NADPH.

•Oxygen released.

Calvin Cycle (Dark Reaction)•energy is transferred

from ATP and NADPH to the organic compound glucose

Location Reactants Products Release

Light Reaction

Thylakoid H2O

Light

ADP and NADP from dark reaction

ATP – energy to make sugar

NADPH – electrons and Hydrogen to make glucose

O2 to the air

Dark Reaction – Calvin Cycle

Stroma

CO2

ATP and NADPH from light reaction

ADP and NADP back to light reaction

GLUCOSE

•Diagram Reactants

Products

LightH2O CO2

O2C6H12O6

Glucose

Chloroplast

LightDependent

Reaction

Calvin Cycle

NADP

ADP + P

ATPNADPH

Cellular Respiration•Process where energy of glucose is released in the cell to be used for life processes (movement, breathing, blood circulation, etc…)

• Respiration occurs in ALL cells • Takes place in the mitochondria• Can take place either with or without oxygen present.

Aerobic Respiration•requires oxygen•occurs in the mitochondria•Net total of 36 ATP produced

•Formula

C6H12O6 + 6O2 6 CO2 + 6H2O + 36 ATP

glucose + oxygen carbon dioxide + water + energy

Human cells contain a specialized structure – the

mitochondrion – that generates energy.

STEP 1: Glycolysis

-First pathway of respiration - ALL organisms perform this (aerobic AND anaerobic)

-Takes place in the cytoplasm on enzymes

-Splits glucose in half to form 2 pyruvic acid (pyruvate)

-Gives off enough energy to make 2 ATP

STEP 2: Krebs Cycle-Also called the Citric Acid Cycle

-pyruvic acid is broken down and CO2 is released

-Occurs in matrix of mitochondria

STEP 3: Electron Transport Chain-electrons from Krebs Cycle converts ADP into ATP

-Occurs along inner membrane (cristae) of mitochondria

• Diagram - Cellular Respiration

Glucose GlycolysisElectron

Transport Chain

2

Krebs Cycle

Mitochondria

In Cytoplasm

2 32

Electrons carried in NADH

electrons carried in

NADH

Summary:3 steps: 1st glycolysis

2nd Krebs cycle3rd Electron Transport Chain (ETC)

Anaerobic Respiration or Fermentation: - pathway organisms use when no oxygen is available to the cell - Mostly unicellular organisms (low energy requirement)- Much less ATP produced than in aerobic respiration- Goes through glycolysis first, which makes 2 ATP- 2 kinds: Lactic Acid and Alcoholic

Glucose 2 Pyruvate + 2 ATP

Lactic acid

Ethyl alcohol + CO2

Glycolysis

Animals &

some Bacteria

Bacteria & Yeast

Lactic Acid Fermentation

pyruvic acid lactic acid

-Performed by muscle cells (animals)

-Lactic acid is produced in the muscles during rapid exercise, when the body cannot supply enough oxygen to the tissues

-causes a burning sensation in muscles

-Also occurs in some bacteria

-Used to create food products like yogurt and cheese

Alcohol fermentationPyruvic acid ethyl alcohol + carbon dioxide

-occurs in bacteria and yeast

-Process used by baking and brewing industry

-yeast produces CO2 gas during fermentation to make dough rise and gives bread its holes

Cellular Respiration Diagram

glycolysis

Anaerobic Respiration

Alcoholic fermentationBacteria, Yeast 2 ATP

Lactic acid fermentationMuscle cells 2 ATP

Aerobic Respiration36 ATP ETC

Mitochondria

Krebs Cycle

Cytoplasm

C6H12O6

glucose

Products of one reaction are the Reactants of the other (and vice versa)

Photosynthesis and Respiration

• Cells require a constant source of energy for life processes, but keep only a small amount of ATP on hand. Cells can make more ATP by using the energy stored in foods, like glucose.

• The energy stored in glucose by photosynthesis is released by cellular respiration and repackaged into the energy of ATP.

Energy Flow: Producers photosynthesize and provide glucose for consumers

Carbon Cycle: Producers remove CO2 from atmosphere while consumer replaces CO2 during respiration

Water Cycle: Producers take water out of ecosystem and consumers produce water during respiration (also O2 removed by producer and returned by consumer)