AP Biology Cellular Energetics

Kreb’s Cycle

Oxidation of the pyruvate in the mitochondrial matrix

• Outputs: 2 ATP, 2 FADH2, 8 NADH, 6CO2

Aerobic

Reactions that require oxygen to survive

Anaerobic

Reactions that don’t require oxygen to survive

Oxidative Phosphorylation

The connected reactions of the E.T.C and the flow of h+ back through ATP Synthase

• Cristae/Thylakoid membrane

Alcohol Fermentation

Pyruvate —> ethanol + CO2 (Anaerobic)

• Recycle NADH to NAD+

Lactic Acid

Pyruvate —>Lactic Acid

• Recycle NADH to NAD+

Acetyl CoA

Molecule that carries an acetyl group into the Krebs cycle

• Formed by breakage of a pyruvate

Cellular Respiration

Process in which cells breakdown glucose to convert it to ATP

Redox Reactions

ATP Synthase

Enzyme in the E.T.C that facilitates the flow of H+ to synthesize ATP

Oxidation

Substance loses electrons

Glycolysis

Breaking down glucose into two pyruvates

Catabolism

Breaking down complex molecules into simpler ones

Reduction

Gaining electrons

Chemiosmosis

The flow of H+ protons down their concentration gradient through ATP synthase

NAD+/NADH

Coenzyme that carries electrons

• Catabolic reactions (Glycolysis, Krebs, E.T.C)

• Breaking down

Proton Motive Force

Lots of H+ pushed up in the E.T.C

Proton Gradient

Gradient difference between H+ in membrane (E.T.C)

Photosynthesis

Light energy is converted into chemical energy in the form of glucose

Autotrophs

An organism that produces its own food

Heterotrophs

An organism that eats other things for energy

Chlorophyll

Green pigment found in the chloroplasts of plants

• Essential for photosynthesis

Absorption Spectrum

A graph that shows the relative amount of light a pigment absorbs across a range of wavelengths.

Mesophyll Cells

Cells in the middle of a plant leaf where most of photosynthesis takes place

Chlorophyll a

Primary photosynthetic pigment that absorbs best in red and blue wavelengths

• Least in green

Rubisco

Enzyme which fixes carbon from air

• Most important enzyme on planet

Stomata

Tiny pores on the surface of a plant leaf that regulate gas exchange

Action Spectrum

Graph that plots the rate of photosynthesis at different wavelengths of light

C3 plants

Utilize normal Calvin cycle but suffer from photorespiration

Stroma

The “gel” that fills the inner space of the chloroplast

• Site of Calvin Cycle

Chlorophyll b

An accessory pigment what works with chlorophyll a to absorb light for photosynthesis

Photorespiration

Oxygen levels within a plant get too high and Rubisco begins binding O2 instead of CO2

Light reactions

(Light dependent reactions) first stage of photosynthesis

• Thylakoid membrane of chloroplast

• Produce ATP and NADH for Calvin Cycle

Accessory pigments

Pigments with different structures to absorb different wavelengths of light that chlorophyll a can’t absorb

C4 plants

Physically separate carbon fixation from Calvin cycle

• Decreases photorespiration

Calvin cycle

turning Co2 into glucose

• Stroma of chloroplasts

Bundle-sheath cells

tightly packed cells in C4 plants around xylem and phloem

• Protective sheath

NADP+/NADPH

Electron carriers for photosynthesis

Reaction center chlorophyll

Chlorophyll molecules located in thylakoid membrane (of photosystem 1 or 2) that converts light energy to chemical energy

Photophosphorylation

The process of using light energy to add a phosphate group to make ATP

• Thylakoid membrane of chloroplast

Carbon fixation

Organisms convert carbon into a carbohydrate through the help of Rubisco

PEP Carboxylase

Enzyme that fixes carbon to a 4c compound in C4 and CAM plants

Photosystem 1

Structure for Cyclical photophosphorylation

Photosystem 2

Structure for Non-cyclical photophosphorylation

CAM Plants

Separate carbon fixation for Calvin cycle by time

• Night: Opens stomates and fixes carbon to 4c

• Day: Release carbon from 4c to Calvin cycle

Thylakoid membrane

Internal membrane within a chloroplast

• Where light rxs and photosynthesis take place

Substrate-level Phosphorylation

Transfer of a phosphate group from a substrate to ADP to create ATP

• Kinase

• No oxygen required

• Mitochondrial Matrix (Krebs)

• Cytoplasm (Glycolysis)

Non-cyclic photophosphorylation

One way flow of a electron from PS2 to PS1

• Creates ATP 

• NADPH  

• Releases O2

• Thylakoid membrane

Cyclic Photophosphorylation

Electron flows in a circle to make ATP only is PS1

• No O2 or NADPH 

• Only ATP made 

• Thylakoid membrane (chloroplast)

Used only when Calvin cycle needs more ATP