Endosymbiont Theory, Mitochondria, Glycolysis, Krebs Cycle, ETC, Photosynthesis, Cytoskeleton, and Cilia: Key Concepts for Biology Students

What features support the endosymbiont theory?

Circular DNA, 70S ribosomes, double membrane, fission

Why is the inner mitochondrial membrane impermeable?

Maintains proton gradient

What is the purpose of glycolysis?

Produces ATP, NADH, pyruvate

Which enzyme commits glucose to glycolysis?

Hexokinase

Which enzyme is rate-limiting in glycolysis?

PFK-1

What activates PFK-1?

AMP or F2,6BP

What inhibits PFK-1?

ATP

Which enzyme produces NADH in glycolysis?

GAP dehydrogenase

Which enzymes produce ATP in glycolysis?

Phosphoglycerate kinase and pyruvate kinase

What converts pyruvate to acetyl-CoA?

Pyruvate dehydrogenase

Where does the Krebs cycle occur?

Mitochondrial matrix

Major products of the Krebs cycle?

NADH, FADH2, ATP(GTP), CO2

What enters the Krebs cycle?

Acetyl-CoA

What is oxidative phosphorylation?

ATP synthesis using ETC proton gradient

Where does the ETC occur?

Inner mitochondrial membrane

Where do NADH electrons enter?

Complex I

Where do FADH2 electrons enter?

Complex II

What does Complex IV reduce?

Oxygen to water

What inhibits Complex IV?

Cyanide

What inhibits ATP synthase?

Oligomycin

What drives ATP synthase?

Proton motive force

What is chemiosmosis?

Proton gradient drives ATP synthesis

What is heteroplasmy?

Different mtDNA types in one cell

What is a mitochondrial presequence?

Matrix-targeting sequence

What does TOM do?

Translocates proteins across outer membrane

What does TIM do?

Translocates proteins across inner membrane

Where do light reactions occur?

Thylakoid membrane

Where does the Calvin cycle occur?

Stroma

What donates electrons to PSII?

Water

Main product of the Calvin cycle?

G3P

What does Rubisco do?

Fixes CO2

What is cyclic electron flow?

Makes extra ATP

What are TOC/TIC?

Chloroplast import complexes

What is a transit peptide?

Chloroplast targeting sequence

Building block of microfilaments?

Actin

Building block of microtubules?

Tubulin

Building block of intermediate filaments?

Coiled-coil proteins

Sizes of MF, IF, MT?

7 nm, 10 nm, 25 nm

Which cytoskeleton element has no polarity?

Intermediate filaments

What nucleates actin filaments?

Arp2/3

What severs actin?

Cofilin

What stabilizes actin?

Tropomyosin

What bundles actin?

Fimbrin

What is dynamic instability?

Rapid MT growth/shrink

What is catastrophe?

Sudden MT depolymerization

What stabilizes MTs in neurons?

Tau

What generates ciliary bending?

Axonemal dynein

Axoneme structure?

9+2

What is the MTOC?

Centrosome

Kinesin direction?

#NAME?

Dynein direction?

#NAME?

Sarcomere I band change?

Shortens

What releases myosin from actin?

ATP binding

What triggers myosin power stroke?

Pi release

What is a nucleosome?

DNA + histone octamer

Why are histones positive?

Bind DNA phosphate

What is euchromatin?

Active chromatin

What is heterochromatin?

Condensed inactive chromatin

What loosens chromatin?

Acetylation

What tightens chromatin?

Deacetylation/methylation

What synthesizes RNA?

RNA polymerase

What does sigma factor do?

Promoter recognition

What is a promoter?

Transcription start region

What is polycistronic mRNA?

mRNA encoding multiple proteins

What is wobble?

Flexible 3rd base pairing

What charges tRNA?

Aminoacyl-tRNA synthetase

Translation direction?

5' to 3'

Protein synthesis direction?

N to C

What binds signal peptides?

SRP

What does signal peptidase do?

Cleaves signal

ER modification?

N-linked glycosylation

What is ERAD?

ER degradation of misfolded proteins

ER retention signal?

KDEL

Lysosome targeting signal?

M6P

What maintains lysosome acidity?

V-type proton pump

Rab protein function?

Vesicle targeting

SNARE protein function?

Membrane fusion

What is receptor-mediated endocytosis?

Specific uptake via receptors

Coat protein used in RME?

Clathrin

Fluid mosaic model?

Proteins float in membrane

Amphipathic meaning?

Hydrophobic + hydrophilic

What increases membrane fluidity?

Unsaturated fatty acids

What decreases fluidity?

Saturated fatty acids

Cholesterol at low temp?

Increases fluidity

Cholesterol at high temp?

Decreases fluidity

What diffuses freely across membrane?

Small nonpolar molecules

What requires transport proteins?

Ions, large polar molecules

Facilitated diffusion?

Protein-mediated passive transport

Active transport?

Requires energy

Na/K pump function?

3 Na out, 2 K in

What drives depolarization?

Na influx

What drives repolarization?

K efflux

What is hyperpolarization?

Excess K efflux

What restores gradients after AP?

Na/K pump

Ligand-gated channel?

Opens when ligand binds

Voltage-gated channel?

Opens when membrane potential changes

Miller-Urey experiment showed?

Organic molecules form spontaneously

Stromatolites?

Fossilized microbial mats

Why RNA first?

Catalytic and informational

What are iPSCs?

Induced pluripotent stem cells