bio unit 3 (photosynthesis & enzymes)

metabolism

All of the chemical reactions that occur within an organism

metabolic pathway

A series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds.

catabolic pathways

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.

anabolic pathways

Metabolic pathways that consume energy to build complicated molecules from simpler ones.

energy

the ability to do work

kinetic energy

energy of motion

thermal energy

energy associated with the movement of atoms and molecules

potential energy

stored energy

chemical energy

potential energy available for release in a chemical reaction

Thermodynamics

the study of energy transformations in matter

1st law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

2nd law of thermodynamics

energy transformation increases the entropy (disorder) of the universe, some energy is unusable and lost as heat

free energy

energy that is available to do work

energetically favorable

spontaneous

exergonic reaction

A chemical reaction that releases energy

endergonic reaction

Reaction that absorbs free energy from its surroundings.

mechanical work

movement

transport work

the pumping of substances across membranes against the direction of spontaneous movement

chemical work

synthesis of complex molecules

Phosphorylation

the released phosphate moves to another molecule to give energy

Enzymes

macromolecules that speed up reactions by lowering the activation energy

induced fit

enzymes will change the shape of their active site to allow the substrate to bind better

the rate of enzyme activity ____ with temperature before it eventually denatures

increases

cofactors

nonprotein enzyme helpers

Holoenzyme

enzyme with its cofactor attached

coenzymes

organic cofactors

enzyme inhibitors

reduce the activity of specific enzymes

permanent enzyme inhibitor

inhibitor binds with covalent bonds (ex: toxins/poisons)

reversible enzyme inhibitor

inhibitor binds with weak interactions

competitive inhibitors

Reduce the productivity of enzymes by blocking substrates from entering active sites.

noncompetitive inhibitor

bind to an area other than active site (allosteric site) which changes shape of active site preventing substrates from binding

How cells regulate metabolic pathways

controls where and when enzymes are active

allosteric regulation

The binding of a regulatory molecule to a protein at one site that affects the shape and function of the protein at a different site.

allosteric activator

substrate binds to allosteric site and stabilizes the shape of the enzyme so that the active sites remain open

allosteric inhibitors

substrate binds to allosteric site and stabilizes the shape of the enzyme so that active sites are closed

cooperactivity

substrate binds to one active site (on an enzyme with more than one active site) which stabilizes the active form

Photosynthesis

Conversion of light energy from the sun into chemical energy.

Autotroph

An organism that makes its own food

Heterotroph

An organism that cannot make its own food so they live off of other organisms

Cyanobacteria

early prokaryotes capable of photosynthesis; oxygenated the atmosphere of early earth

prokaryotic photosynthetic pathways

foundation of eukaryotic photosynthesis

chloroplast

Site of photosynthesis; found in mesophyll

stomata

pores in leaves that allow CO2 and O2 out

stroma

aqueous internal fluid

thylakoids

form stacks known as grana

chlorophyll

green pigment in thylakoid membrane

redox reaction

reaction involving complete or partial transfer of one or more electrons from one reactant to another

Oxidation

loss of electrons

reduction

gain of electrons

two stages of photosynthesis

light reactions and calvin cycle

light

electromagnetic energy made of photons, travels in waves

wavelength

the distance from the crest of one wave to the crest of the next

short wavelengths

higher energy

long wavelength

lower energy

chlorophyll a

primary pigment, involved in light reactions, blue/green pigment

chlorophyll b

accessory pigment, yellow/green pigment

carotenoids

broaden the spectrum of colors that can drive photosynthesis, yellow/orange pigment

photoprotection

carotenoids absorb and dissipate excessive light energy that could damage chlorophyll or interact with oxygen

thylakoid (location)

light reactions occur in the

light reactions function

converts solar energy to chemical energy

NADPH and ATP

2 forms of chemical energy in light reactions

Photosystems

reaction center and light capturing complexes

reaction center

a complex of proteins associated with chlorophyll a and an electron acceptor

light capturing complexes

pigments associated with proteins

photosystem 2

reaction center P680; buildup of H+ ions, generates protein gradient. occurs first

photosystem 1

reaction center P700; electrons are re-excited to create NADPH. occurs second

3 phases of calvin cycle

carbon fixation, reduction, regeneration

Inputs of Calvin Cycle

CO2, ATP, NADPH

Outputs of Calvin Cycle

ADP, NADP+, G3P

Photorespiration

on hot days plants close their stomata to stop water loss, causes less CO2 to be present and more O2 to be present

C4 plants

separates light and dark cycle

C3 plants

everything occurs spontaneously (at same time)

photon

A particle of electromagnetic radiation with no mass that carries a quantum of energy

Rubisco

enzyme that converts inorganic carbon dioxide molecules into organic molecules during the final step of the Calvin cycle

spatial

pertaining to space on the Earth's surface; sometimes used as a synonym for geographic.