AP Biology Unit 3 (photosynthesis & enzymes)

Photosynthesis

the conversion of light energy to chemical energy

Autotroph

organisms that produce their own food (organic molecules) from simple substances in their surroundings

Heterotroph

organisms unable to make their own food so they live off of other organisms

Cyanibacteria

early prokaryotes capable of photosynthesis (oxygenated the atmosphere of early Earth)

Chloroplasts

organelle for the location of photosynthesis (found in the mesophyll - the cells that make ip the interior tissue of the leaf

Stomata

pores in leaves that allow CO2 in and O2 out

Stroma

aqueous internal fluid

Thylakoid

form stacks known as grana

Chlorophyll

green pigment in thylakoid membranes

Simplified Formula of Photosynthesis

6CO2 + 6H20 + light energy -> C6H12O6 + 6O2

Redox Reaction

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

Light

electromagnetic energy (made up of particles called photons, travels in waves)

Wavelength

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

Short Wavelength

higher energy

Long Wavelength

lower energy

Chlorophyll a

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

Chlorophyll b

accessory pigment, yellow/green pigment

Carotenoids

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

Photoprotection

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

Light Reactions

occurs in the thylakoid membrane in the photosystems, converts solar energy to chemical energy

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 (antenna for the reaction centers)

Photosystem 2

reaction center P680, absorbs light at 680 nm

Photosystem 1

reaction center P700, absorbs light at 700 nm

Metabolism

all of the chemical reactions in an organism

Metabolic Pathways

series of chemical reactions that either build complex molecules or break down complex molecules

Catabolic Pathways

release energy by breaking down complex molecules into simpler compounds

Anabolic Pathways

consume energy to build complicated molecules from simpler compounds

Energy

the ability to do work

Kinetic Energy

energy associated with motion

Thermal Energy

energy associated with the movement of atoms or molecules

Potential Energy

stored energy

Chemical Energy

potential energy available for release in a chemical reaction

Thermodynamics

the study of energy transformations in matter

First Law of Thermodynamics

energy cannot be created or destroyed, energy can be transferred or transformed

Second Law of Thermodynamics

energy transformation increases the entropy (disorder) of the universe, during energy transfers or transformations some energy is unusable and often lost as heat

Exergonic Reaction

reaction that releases energy (reaction is spontaneous, ex. cellular respiration)

Endergonic Reaction

reaction that absorbs energy (reaction is not spontaneous, ex. photosynthesis)

Mechanical

movement (ex. beating cilia, movement of chromosomes, contention of muscle cells)

Transport

pumping substances across membranes against spontaneous movement

Chemical

synthesis of molecules (ex. building polymers from monomers)

Adenosine Triphosphate (ATP)

molecule that organisms use as a source of energy to perform work

Phosphorylation

the released phosphate moves to another molecule to give energy

Enzymes

macromolecules that catalyze (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

Enzyme Catabolism

enzyme helps break down complex molecules

Enzyme Anabolism

enzyme helps build complex molecules

The efficiency of enzymes can be affected by

temperature, pH, chemicals

Optimal Conditions

the conditions (temperature and pH) that allow enzymes to function optimally (at their best)

Cofactors

non protein molecules that assist enzyme function (inorganic cofactors consist of metals, can be bound loosely or tightly

Holoenzyme

an enzyme with the cofactor attached

Coenzymes

organic cofactors (ex. vitamins)

Enzyme Inhibitors

reduce the activity of specific enzymes

Permanent Inhibitors

inhibitor binds with covalent bonds (ex. toxins and poisons)

Reversible Inhibitors

inhibitor binds with weak interactions

Competitive Inhibitors

reduce enzyme activity by blocking substrates from binding to the active site

Noncompetitive Inhibitors

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

Allosteric Regulation

molecules bind (noncovalent interactions) to an allosteric site which changes the shape and function of the active site

Allosteric Activator

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

Allosteric Inhibitor

substrate binds to the allosteric site and stabilizes the enzyme shape is that the active sites are closed (inactive form)

Cooperativity

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

rubisco

enzyme that catalyzes CO2 and makes 3-phosphoglycerate