Photosynthesis Photosynthesis & Cellular & Cellular

RespirationRespiration

Ch. 8 & 9Ch. 8 & 9

All Living Things Require All Living Things Require Energy to SurviveEnergy to Survive

• Photosynthesis- is the process that converts the radiant energy of sunlight into chemical energy (glucose)

• Respiration-the process that releases chemical energy for use by the cell (in the form of ATP)

• Autotrophs–Are plants and other organisms that make their own food

–Ex. Green plants

• Heterotrophs–Cannot make their own food.

–Ex. animals

Photosynthesis- how Photosynthesis- how autotrophs produce chemical autotrophs produce chemical

energyenergy

• 6CO2 + 6H2O chlorophyll C6H12O6 + 6O2 Light energy

• Carbon dioxide + Water glucose + oxygen

Respiration- breaks down Respiration- breaks down glucose & release energyglucose & release energy

• C6H12O6 + 6O2

• Respiration uses what photosynthesis makes and vice versa

• Both photosynthesis & cellular respiration happen in a series of steps called biochemical pathways.

6CO2 + 6H2O + ATP energy

The energy released in The energy released in respiration is in the form of respiration is in the form of

adenosine triphosphate (ATP)adenosine triphosphate (ATP)• An ATP

molecule has 3 parts.– Adenine +

Ribose = adenosine

– 3 phosphate groups

• A-P (AMP) = adenosine + 1 phosphate

• A-P~P (ADP) = adenosine + 2 phosphate

• A-P~P~P (ATP) = adenosine + 3 phosphates

~ = high energy bonds

When a cell needs energy, When a cell needs energy, an enzyme ATPase breaks an enzyme ATPase breaks the bond between the 2the bond between the 2ndnd & 3& 3rdrd phosphate groups phosphate groups

A-P~P~P A-P~P +P + energy ATP ADP

ATPase

To Add P to ADP is called To Add P to ADP is called PhosphorylationPhosphorylation

• The enzyme ATP synthetase has to be present for this

A-P~P + P A-P~P~P ADP + P ATP

ATP synthetase

Photosynthesis occurs in….Photosynthesis occurs in….

• Light Reaction (occurs in light)– Energy in sunlight is

trapped

– O2 is released

– ATP is formed

– NADPH2 is formed

– Occurs in the thylakoids of the chloroplast

• Dark Reaction/Calvin Cycle (occurs in light or dark)– CO2 is fixed into organic

compounds

– ATP and NADPH2 act with CO2 C6H12O6

(glucose)– Happens in the stroma

of the chloroplast

Chloroplast-where Chloroplast-where photosynthesis takes photosynthesis takes

placeplace

• Inner membrane = discs called thylakoids

• Thylakoids are surrounded by fluid called stroma

• Sunlight travels in waves.• Short waves have more energy than long• Pigments absorb lightwaves• 5 different kinds of chlorophyll (a pigment)

– Chlorophyll a & b are most common (absorbs many lightwaves and reflects green.

– Carotenoids also absorb lightwaves (yellow, orange, brown)•Carotenes•Xanthophylls

– Phycobilins (red and blue)

RespirationRespiration

• Releases the energy stored in the chemical bonds of glucose.

• 2 kinds of respiration• Both begin with glycolysis-occurs in

cytoplasm– Breakdown of glucose into 2 pyruvic

acid molecules.– Results in the production of 4 ATP

molecules

2 Kinds of Respiration2 Kinds of Respiration• Fermentation-

pyruvic acid is broken down without the use of oxygen

• Glycolysis + fermentation = anaerobic respiration

• Aerobic respiration-pyruvic acid is broken down with the use of oxygen.

2 Kinds of Fermentation2 Kinds of Fermentation• Lactic Acid-

– Occurs in animal cells and causes muscle fatigue

• Alcoholic-– Occurs in plant cells

and in yeast– Produces ethyl

alcohol

Aerobic RespirationAerobic Respiration

• Releases a lot more energy than anaerobic respiration (38 ATP’s)

• C6H12O6 + 6O2 6CO2 + 6H2O + 38ATP’s

• Occurs in the cell’s mitochondria

Aerobic Resp. happens in a Aerobic Resp. happens in a series of stepsseries of steps

1st-glycolysis-glucose is broken down into pyruvic acid

2nd conversion of pyruvic acid to acetyl-CoA

3rd (Krebs Cycle or Citric Acid Cycle)- completes the breakdown of glucose

4th Electron transport chain- more ATP is produced

• Aerobic Respiration = 38 ATP’s

• Fermentation (anaerobic) = 4 ATP’s