USABO Cell Biology

gooey space connecting primary walls of adjacent plant cells; made of pectin/hemicellulose

middle lamella

30S and 50S; 70 Svedberg units in total

prokaryotic ribosome sedimentation

40S and 60S; total 80S

eukaryotic ribosome sedimentation

how fast a ribosome/partial moves during sedimentation assay or when exposed to centrifugal force

sedimentation coefficient

The ______ synthesizes lipids, detoxifies poisons, stores calcium ions

Smooth ER

The _____synthesizes proteins and membrane phospholipids

Rough ER

The Golgi Apparatus entrance is called the?

cis face

complex protein that coats the molecules retrograde from the Golgi Apparatus to rough ER

COPI

complex protein that coats the molecules from ER to the Golgi Apparatus

COPII

moves molecules from the Golgi to plasma membrane

Clathrin vesicles

pH of a lysosome

4.5

special type of perixosome that converts lipids to starch in plant germination

glyoxysomes

____ are proteins found on the membrane of transport vesicles.

Bind to target proteins to form a SNARE Complex that pulls the membranes together, enabling exocytosis.

V-SNARE

V-Snares that consist of an arginine core

R-Snare

_____are located on a plasma membrane/target membrane. Provides a stable subcomplex for initiating the fusion of two membranes.

T-SNARE

A type of T-Snare with a core of glutamine

Q-SNARE

The main energy currency of the cell, composed of adenine, ribose, and three phosphate groups. Energy is released when phosphates are broken, forming ADP or AMP.

ATP

Adenosine triphosphate with one less phosphate, formed when ATP releases energy.

ADP

ATP or ADP with only one phosphate remaining.

AMP

The free phosphate group released from ATP breakdown.

Orthophosphate

Two phosphate groups linked together.

Pyrophosphate

ATP production via an enzyme-catalyzed reaction.

Substrate level phosphorylation

ATP production via the electron transport chain (ETC) using O₂.

Oxidative phosphorylation

ATP production during photosynthesis.

Photophosphorylation

Nicotinamide adenine dinucleotide; an electron carrier that accepts H− to become NADH.

NAD+

Reduced form of NAD+ that carries electrons to the ETC to generate ATP.

NADH

Gain of electrons; e.g., NAD+ → NADH.

Reduction

Loss of electrons; e.g., NADH → NAD+.

Oxidation

Essential for NAD+ production.

Vitamin B3

Flavin adenine dinucleotide; electron carrier that accepts 2H to become FADH2.

FAD

Reduced form of FAD used in the ETC to generate ATP.

FADH2

Essential for FAD production.

Vitamin B2

Nicotinamide adenine dinucleotide phosphate; electron carrier in photosynthesis, used to generate glucose.

NADP+

Facilitated diffusion proteins that transport glucose into the cell.

GLUT transporters

Enzyme that adds a phosphate group to a substrate.

Kinase

Enzyme that removes hydrogen (H−) from a substrate, producing NADH or FADH2.

Dehydrogenase

Enzyme that converts a molecule into its isomer form.

Isomerase

Cytoplasmic process that converts glucose into 2 pyruvate, producing ATP and NADH.

Glycolysis

3-carbon sugar produced during glycolysis; substrate for energy payoff phase.

G3P

3-carbon molecule produced during glycolysis; can be converted to G3P.

DHAP

High-energy 3-carbon molecule formed from 2-phosphoglycerate; substrate for pyruvate kinase.

PEP

Enzyme that adds a phosphate to glucose to form glucose-6-phosphate, trapping glucose in the cell.

Hexokinase

Enzyme that converts glucose-6-phosphate into fructose-6-phosphate.

Phosphoglucoisomerase

Rate-limiting enzyme of glycolysis; adds phosphate to fructose-6-phosphate to form fructose-1,6-bisphosphate.

Phosphofructokinase

6-carbon molecule with two non-adjacent phosphates, split into DHAP and G3P.

Fructose-1,6-bisphosphate

Enzyme that converts DHAP to G3P.

Triose phosphate isomerase

Enzyme that converts G3P to 1,3-bisphosphoglycerate and produces NADH.

G3P dehydrogenase

Enzyme that converts 1,3-bisphosphoglycerate to 3-phosphoglycerate and produces ATP.

Phosphoglycerate kinase

Enzyme that converts 3-phosphoglycerate to 2-phosphoglycerate.

Phosphoglycerate isomerase

Enzyme that removes water from 2-phosphoglycerate to form PEP.

Enolase

Enzyme that converts PEP to pyruvate, producing ATP.

Pyruvate kinase

End product of glycolysis; 3-carbon molecule used in the intermediate step.

Pyruvate

Conversion of pyruvate to acetyl CoA in the mitochondria; produces CO2 and NADH.

Intermediate step

Multi-enzyme complex that converts pyruvate to acetyl CoA, releases CO2, and produces NADH.

Pyruvate dehydrogenase

2-carbon molecule that enters the Krebs cycle; formed from pyruvate and Coenzyme A.

Acetyl CoA

Carrier molecule that attaches to acetyl groups; requires Vitamin B5 (pantothenic acid).

Coenzyme A

Mitochondrial cycle that oxidizes acetyl CoA to produce NADH, FADH2, ATP, and CO2.

Krebs Cycle

4-carbon molecule that combines with acetyl CoA to form citrate in the Krebs cycle.

Oxaloacetate

6-carbon molecule formed from OAA + acetyl CoA in the Krebs cycle.

Citrate

Enzyme that converts citrate to D-isocitrate via cis-aconitate.

Aconitase

Isomer of citrate; converted to α-ketoglutarate by isocitrate dehydrogenase.

D-Isocitrate

Enzyme converting D-isocitrate to α-ketoglutarate; produces NADH and CO2.

Isocitrate dehydrogenase

5-carbon molecule in the Krebs cycle; converted to succinyl-CoA by α-ketoglutarate dehydrogenase.

α-Ketoglutarate

Enzyme converting α-ketoglutarate to succinyl-CoA; produces NADH and CO2.

α-Ketoglutarate dehydrogenase

4-carbon molecule in the Krebs cycle; converted to succinate, producing GTP/ATP.

Succinyl-CoA

Enzyme converting succinyl-CoA to succinate; produces GTP/ATP.

Succinyl-CoA synthetase

4-carbon molecule converted to fumarate by succinate dehydrogenase.

Succinate

Enzyme converting succinate to fumarate; produces FADH2.

Succinate dehydrogenase

4-carbon molecule converted to malate by fumarase.

Fumarate

Enzyme converting fumarate to malate.

Fumarase

4-carbon molecule converted to OAA by malate dehydrogenase.

Malate

Enzyme converting malate to oxaloacetate; produces NADH.

Malate dehydrogenase

10 molecules per glucose (2 glycolysis + 2 intermediate step + 6 Krebs cycle).

NADH

2 molecules per glucose (from Krebs cycle).

FADH2

30-32 molecules per glucose depending on efficiency.

ATP

6 molecules per glucose (2 intermediate step + 4 Krebs cycle).

CO2

Chain of proteins that transport electrons from one to another, using energy differences to pump protons across the inner mitochondrial membrane.

Electron Transport Chain (ETC)

The tendency of an atom or molecule to attract electrons toward itself.

Electronegativity

A gradient formed by differences in proton concentration and charge across a membrane.

Electrochemical gradient

Movement of protons down their electrochemical gradient through ATP synthase, driving ATP production.

Chemiosmosis

The energy stored in the proton gradient that drives rotation of ATP synthase to make ATP.

Proton-motive force

Multi-subunit enzyme complex that produces ATP using proton flow; composed of F0 rotor in the membrane and F1 stator in the matrix.

ATP synthase

Membrane-embedded part of ATP synthase that rotates with proton flow.

F0

Matrix-facing part of ATP synthase that synthesizes ATP; contains the rotating gamma subunit and the stationary alpha-beta hexamer.

F1

Accepts electrons from NADH and pumps protons.

Complex I (NADH dehydrogenase)

Initial electron acceptor in Complex I that accepts electrons from NADH.

FMN

Iron-sulfur clusters in Complex I, II, and III that shuttle electrons between proteins.

Fe-S clusters

Accepts electrons from FADH2; does NOT pump protons.

Complex II

Lipid-soluble mobile electron carrier shuttling electrons from Complexes I & II to III.

Ubiquinol

Accepts electrons from Q and passes them to cytochrome c.

Complex III

Water-soluble protein that transfers electrons from Complex III to Complex IV.

Cytochrome c

Transfers electrons to O2, producing water.

Complex IV

ATP generation driven by electron flow through the ETC.

Oxidative phosphorylation

Process by which cells regenerate NAD+ without oxygen to continue glycolysis.

Fermentation

Converts pyruvate to ethanol and CO2 while regenerating NAD+.

Alcohol fermentation

Converts pyruvate to acetaldehyde, releasing CO2.

Pyruvate decarboxylase

Converts acetaldehyde to ethanol, regenerating NAD+.

Alcohol dehydrogenase

Converts pyruvate to lactic acid without producing CO2; regenerates NAD+.

Lactic acid fermentation

Uses an electron transport chain without O2; alternative final electron acceptors like sulfate (SO4²⁻) generate products like H2S.

Anaerobic respiration

Formation of glucose from non-carbohydrate sources.

Gluconeogenesis