BSCI Exam 3

Metabolism

the sum of all anabolic and catabolic reactions in a cell, connected in a network of reaction pathways

Anabolic Reactions

make things, endergonic (use energy), takes energy from catabolic reactions

Metabolism

the sum of all anabolic and catabolic reactions in a cell, connected in a network of reaction pathways

Anabolic Reactions

make things, endergonic (use energy), takes energy from catabolic reactions

Catabolic Reactions

break things, exergonic (release energy), gives energy to anabolic reactions

Energy

Capacity to do work (potential and kinetic)

1st Law of Thermodynamics

Energy can be converted, but not created or destroyed

2nd Law of Thermodynamics

Entropy always increases, but we want it to decrease

Entropy

Disorder, things breaking or getting dispersed (does not mean lack of equilibrium!!!)

Free Energy (G)

is chemical energy available to do work and is expressed as the difference between enthalpy (total energy) and entropy

-Delta G

• Catabolic
• Lower G products
• Increase entropy
• Exergonic
• Spontaneous

+Delta G

• Anabolic
• Higher G products
• Decrease entropy
• Endergonic
• Non-spontaneous

Main Role of Enzymes

lower activation energy (the hump)

Enzymes

A type of protein where the function depends on the shape

Substrates

interact with enzymes at the active site, forming an enzyme-substrate complex with a close interaction through induced fit

Allosteric effectors

bind somewhere other than the active site (called the allosteric site) and alter the shape of the protein to either inhibit or activate enzyme function

Reaction coupling

Makes positive delta G reactions work by combining multiple reactions together (comines positive and negative reactions together to form a net negative reaction)

most common is hydrolysis and ATP

Enzyme Optima

The optimal conditions for an enzyme to work

Oxidation

Loss of electrons between molecules (looks like loosing an H)

Reduction

The gaining of electrons between molecules (looks like gaining an H)

Photosynthesis

transforms light energy into chemical energy

Light Reaction

energy carriers, generate high energy electrons (light dependent)

Dark Reaction

CO2 (light independent)

Stroma

Space outside chloroplasts (cytoplasm)

Thylakoid Membrane

hollow membrane disks (separator)

Thylakoid Lumen

Space inside disks

Photosystem 2

• absorbs light

• splits water (photolysis)

• reduces PQ to PQH2 (gives electron to PQ)

Cytochrome Complex

• Uses energy from e- to pump H+ creating an H gradient

• Electrons reduce to PC

Photosystem 1

• Absorbs light, exciting electrons

• reduces ferredoxin, which delivers electrons to NADP+ reductase then to NADPH

ATP Synthase

Uses H+ gradient to power turning ADP + Pi into ATP

By Products of Photosynthesis

H+ and Oxygen

Calvin Cycle

turns CO2 into G3P in a never ending loop, involves both ATP and NADPH

Carbon Fixation

1st phase of the calvin cycle, CO2 (1C) is added to RuBP (5C) by rubisco which breaks turning into 2× 3C molecules

Reduction

2nd phase of the calvin cycle, 3C molecules reduced to form G3P (3C)

Regeneration

3rd phase of calvin cycle, 5x G3P are recycles into 3x RuBP

Use of G3P

used to synthesis carbohydrates, fatty acids, and amino acids

Carbohydrates

Sugar polymers used for fuel (ex, CH2O) can be monosaccharides, disaccharides, or polysaccharides