BIO130 - Exam 2 - Lecture 4

Heterotrophs

Gets energy from eating other animals or plants

Autotrophs

creates its own food using simple inorganic substances and an external energy source

Phototrophs

Capture and use light as their primary energy source.

Photosynthesis

CO2 + H2O + light (energy) —> C6H12O6 (glucose) + O2

Viable light

electromagnetic radiation

different colors have different wavelengths

Light

Wave nature and particle nature (protons)

carry energy

Pigment

A molecule that is capable of absorbing wavelengths of light and reflects others

Light-Harvesting Complexes

Chlorophylls (harness energy) and carotenids (dispose energy) are arranged into light-harvesting complexes as part of photosystems.

Light Dependent Reactions

Overview - H2O + Protons → O2 + ATP + NADPH

Photons strike pigments, which raise energy of chlorophylls, this gets passed from one chlorophyll to another until it reaches the reaction center chlorophyll

RC delivers high energy e- through an e- transport chain

High energy e- passed through a series of carriers, generates ATP

low energy e- arrive at Photosystem I’s RC Chlorophyll

Photons excite P1 chlorophyll and moves to RC chlorophyll

High energy e- used to reduce NADP+ to NADPH (e- carriers)

Light Independent Reactions

Overview: CO2 + ATP + NADPH —> Glucose

Occurs in “stroma”

An enzyme called RuBisCO performs carbon fixation by attaching CO2 to Ribulose
ATP + NADPH used to reduce 3-PGA to glyceraldehyde 3-phosphate

ATP used regenerated Ribulose Biphosphate from some G3P

In Cytoplasm, G3P used to build amino acids, lipids, sugars
- converted to glucose through glycolysis