CELL ENERGY Photosynthesis & Cellular Respiration (Chapter 5)

PHOTOSYNTHESIS is converting light energy into chemical energy (= carbs = FOOD). –Done by PLANTS Things that can make their own food are called “AUTOTROPHS”. Auto- = self - troph = feeding – Autotrophs are “self-feeding:” mostly plants, also cyanobacteria (green bacteria), & some protists (like algae & plankton)

Photosynthesis in Plants Photosynthesis is made possible by the green chlorophyll pigments found within chloroplasts in plants. Chlorophyll a & b can ABSORB the energy from most wavelengths of light (but they reflect green & yellow light). (There are other pigments [carotenoids] that absorb different wavelengths of light. You see these in Fall leaves).

Pigment Graphs

Inside each Chloroplast There are structures that look like “stacks of coins”. These are THYLAKOIDS, and the chlorophyll is actually in them.

Gases (O 2, CO 2 ) enter or exit leaves through holes called “stomata” Sugars go to storage (as simple sugars in fruits, starches in tubers, etc.)

Photosynthesis Chemistry Basic formula (*know this!): CO 2 + H 2 O - light -> C 6 H 12 O 6 + O 2 “Carbon dioxide and water, in the presence of light, produce glucose and oxygen.” ____ = Carbon dioxide _______ = glucose ____ = water __ = Oxygen The balanced equation is: ___CO 2 + ___H 2 O - light -> __C 6 H 12 O 6 + ___O 2

Photosynthesis Chemistry Basic formula (*know this!): CO 2 + H 2 O - light -> C 6 H 12 O 6 + O 2 “Carbon dioxide and water, in the presence of light, produce glucose and oxygen.” CO 2 = Carbon dioxide C 6 H 12 O 6 = glucose H 2 O = water O 2 = Oxygen The balanced equation is: 6 CO H 2 O - light -> C 6 H 12 O O 2

Just be glad I’m not asking you to memorize each step!

PHOTOSYNTHESIS happens in the CHLOROPLASTS of PLANTS THE REST happens in the MITOCHONDRIA of PLANTS and of ANIMALS that eat plants. (happens in ALL eukaryotes, really)

CELLULAR RESPIRATION Is using energy from food to make ATP, which gives cells the energy needed to live (= metabolism). Plants make the food (glucose) during photosynthesis, and they use some of it to fuel their own lives (they are autotrophs). Animals cannot make their own food, and must eat plants to get it (or eat animals that ate plants) Animals are heterotrophs (“hetero” means “mixed”, “troph” = feeding)

2 Main TYPES of Cell. Resp. AEROBIC = “needing oxygen” –More efficient than anaerobic –Produces more ATP than anaerobic (makes a gain of 36 ATP overall) ANAEROBIC = “without oxygen” –Less efficient (produces only 2 ATP) –Done by muscles that run out of oxygen = LACTIC ACID FERMENTATION” = muscle soreness –Done by yeast = “ALCOHOLIC FERMENTATION”

In the Mitochondria There are 2 membranes, and the inner one has lots of folds (= more surface area for cellular respiration to happen).

Cellular Respiration Chemistry Basic formula (*know this!): C 6 H 12 O 6 + O 2 - enzymes -> CO 2 + H 2 O+ energy “Glucose and oxygen, in the presence of enzymes, produce carbon dioxide, water, and energy (ATP).” Remember: CO 2 = Carbon dioxide C 6 H 12 O 6 = glucose H 2 O = water O 2 = Oxygen The balanced equation is: __C 6 H 12 O 6 + ___O 2 - enzymes -> ___CO 2 + ___H 2 O + energy

Cellular Respiration Chemistry Basic formula (*know this!): C 6 H 12 O 6 + O 2 - enzymes -> CO 2 + H 2 O+ energy (ATP) “Glucose and oxygen, in the presence of enzymes, produce carbon dioxide, water, and energy (ATP).” Remember: CO 2 = Carbon dioxide C 6 H 12 O 6 = glucose H 2 O = water O 2 = Oxygen The balanced equation is: C 6 H 12 O O 2 - enzymes -> 6 CO H 2 O + energy (ATP)

Again, it could be worse! The whole process:

So basically, it’s all a big energy cycle. What photosynthesis makes is used in cellular respiration, & What cellular respiration makes is used by photosynthesis!

Another overview:

Image credits bs-cycle.jpg head.com/index/images/stories/photosynthesis.jpg ogy/AnimalPhysiology/Anatomy/AnimalCellStructur e/Mitochondria/mitochondria.jpg