Biology Exam 3

Cell communication, enzymes, photosynthesis, cellular respiration, energy and metabolism

Autocrine Signaling

Cells produce a signal they receive

Gap Junction Signaling

Sends signals through the gap junction

Paracrine Signaling

A cell targets a nearby cell

Endocrine Signaling

A cell targets another cell through the bloodstream

Phosphorylation

Needs a phosphate group to activate

Kinase

Enzyme that transfers phosphate group from ATP to a protein

Phosphorylation Cascade

Chain reaction that starts with activating the relay molecule, can amplify the signal

Dephosphorylation

Deactivates the protein

Phosphatase

Enzyme that removes phosphate group from protein

2nd Messengers

Non-proteins that spread via diffusion

G-protein coupled receptor (GPCR)

Cell-surface transmembrane receptor that works with the help of a G-protein

G-protein

Peripheral protein attached to cytoplasmic side of membrane with GDP (inactive) or GTP (active) bound to it

Isolated System

Unable to exchange energy or matter with its surroundings

Closed System

Does not allow transfer of matter in or out

Open System

Can exchange energy and matter with surroundings

Free Energy

Measure of stability

Equilibrium

Maximum stability

Spontaneous Change

Free energy decreases and stability increases

Exergonic Reactions

Energy exits to provide free energy to the cell

Endergonic Reactions

Reactants have less potential energy than products

Catabolic Reaction

Large molecule breaking down into smaller molecules and energy

Anabolic Reaction

Small molecules and energy making up larger molecules

Competitive Inhibitors

Substrate binding is blocked, can be overcome with more substrate

Noncompetitive Inhibitors

Substrate can bind but reaction is blocked, cannot be overcome by changing substrate concentration

Allosteric Reaction

Regulatory molecule binding to the allosteric site, can activate or inhibit enzymes

Positive Allosteric Regulation Feedback

Amplifies response, self reinforcing loop

Negative Allosteric Regulation Feedback

Stabilizes enzyme, prevents overproduction

Chloroplast Envelope

Highly permeable outer membrane and much less permeable inner membrane

Stroma

Contains metabolic enzymes

Thylakoids

Third membrane folded into flattened disc-like sacs- contains light capturing systems, electron transport train, and ATP synthase that converts light energy to ATP

Oxidation Reduction Reaction

Reactions that involve the transfer of electrons from one species to another

Photosynthetic Mesophyll Cells

Where photosynthesis takes place

Palisade Mesophyll

Specialized for light capture

Spongy Mesophyll

Specialized for gas exchange

Stomata

Pores that allow gasses to enter leaf

Chlorophyll a

Reflects green, absorbs red/purple

Chlorophyll b

Reflects yellow green, absorbs red/blue

Carotenoids

Reflects orange, absorbs everything else

Cyclic Electron Flow

Excited electrons from PS1 cycles back through the ETC

Calvin Cycle

Reactions “fix” carbon, does not need light just CO2, ATP, and NADPH

Light-dependent Reactions

Takes place in the thylakoid membrane

Light-independent Reactions

Takes place in the stroma

Mitochondria Outer Membrane

Contains porins, permeable to most small molecules

Mitochondria Inner Membrane

Folds into cristae- contains transport proteins, the ETC, and ATP synthase

Mitochondria Inter-Membrane Space

Several enzymes, use ATP to phosphorylate nucleotides

Mitochondria Matrix

Highly concentrated mixture of hundreds of enzymes

Substrate-level Phosphorylation

An enzyme that transfers a phosphate group from a substrate to ADP generating ATP (does not require oxygen)

Anaerobic Respiration

Uses the ETC with different final electron acceptor, leads to less energy production

Fermentation

After glycolysis, uses substrate level phosphorylation instead of the ETC to generate ATP