Photosynthesis & Cellular Respiration Ch. 8 & 9

All Living Things Require Energy 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 autotrophs produce chemical energy 6CO 2 + 6H 2 O chlorophyll C 6 H 12 O 6 + 6O 2 Light energy Carbon dioxide + Water glucose + oxygen

Respiration- breaks down glucose & release energy C 6 H 12 O 6 + 6O 2 Respiration uses what photosynthesis makes and vice versa Both photosynthesis & cellular respiration happen in a series of steps called biochemical pathways. 6CO 2 + 6H 2 O + ATP energy

The energy released in respiration is in the form of 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, an enzyme ATPase breaks the bond between the 2 nd & 3 rd phosphate groups A-P~P~P A-P~P +P + energy ATP ADP ATPase

To Add P to ADP is called Phosphorylation 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…. Light Reaction (occurs in light) –Energy in sunlight is trapped –O 2 is released –ATP is formed –NADPH 2 is formed –Occurs in the thylakoids of the chloroplast Dark Reaction/Calvin Cycle (occurs in light or dark) –CO 2 is fixed into organic compounds –ATP and NADPH 2 act with CO 2 C 6 H 12 O 6 (glucose) –Happens in the stroma of the chloroplast

Chloroplast-where photosynthesis takes place 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)

Respiration 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 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 Fermentation Lactic Acid- –Occurs in animal cells and causes muscle fatigue Alcoholic- –Occurs in plant cells and in yeast –Produces ethyl alcohol

Aerobic Respiration Releases a lot more energy than anaerobic respiration (38 ATP’s) C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + 38ATP’s Occurs in the cell’s mitochondria

Aerobic Resp. happens in a series of steps 1 st -glycolysis-glucose is broken down into pyruvic acid 2 nd conversion of pyruvic acid to acetyl-CoA 3 rd (Krebs Cycle or Citric Acid Cycle)- completes the breakdown of glucose 4 th Electron transport chain- more ATP is produced

Aerobic Respiration =38 ATP’s Fermentation (anaerobic) = 4 ATP’s