High yield - bio

What does a catalyst do?

Lowers activation energy (by stabilizing transition state) without changing ΔG or equilibrium.

What is the rate-limiting step?

The slowest step in a pathway that determines overall rate.

What does Km represent?

Substrate concentration at 1/2 Vmax (affinity indicator).

High Km means what?

Low enzyme-substrate affinity.

What does Vmax depend on?

enzyme concentration.

What kind of molecules are enzymes?

Mostly proteins (some RNA = ribozymes).

what determines protein structure?

Amino acid sequence (primary structure)

What bonds stabilize secondary structure?

hydrogen bonds

What bonds stabilize tertiary structure?

Hydrophobic interactions, disulfide bonds, ionic bonds.

What amino acid forms disulfide bonds?

cysteine

What makes an amino acid acidic?

Carboxyl side chain (Asp, Glu)

What makes an amino acid basic?

Amine side chain (Lys, Arg, His)

What is the isoelectric point (pI)?

pH where net charge = 0.

what happens at pH < pI?

Protein is positively charged

What happens at pH > pI?

Protein is negatively charged.

Where does glycolysis occur?

cytoplasm

Net ATP from glycolysis?

2 ATP

Net NADH from glycolysis?

2 NADH

Rate-limiting enzyme of glycolysis?

Phosphofructokinase-1 (PFK-1).

What inhibits PFK-1?

ATP, citrate.

What activates PFK-1?

AMP, ADP

What enzyme converts pyruvate to acetyl-CoA?

Pyruvate dehydrogenase.

What is produced when an enzyme converts pyruvate to acetyl-Coa

NADH + CO₂.

Where does TCA occur?

Mitochondrial matrix.

What is produced per acetyl-CoA?

3 NADH, 1 FADH₂, 1 GTP.

Where does ETC occur?

Inner mitochondrial membrane.

What is the final electron acceptor in the ETC

Oxygen → forms water.

What drives ATP synthase?

proton gradient

What enzyme unwinds DNA?

helicase

What enzyme builds DNA?

DNA polymerase

Direction of DNA synthesis?

5' → 3'.

What strand is continuous?

leading strand

What strand is discontinuous?

Lagging strand (Okazaki fragments).

What enzyme seals fragments?

DNA ligase

Where does transcription occur?

nucleus

What enzyme is used in transcription

RNA polymerase

Where does translation occur?

ribosome (cytoplasm)

Start codon?

AUG

Stop codons?

UAA, UAG, UGA.

What organelle makes ATP?

mitochondria

What organelle modifies proteins?

Golgi apparatus.

Rough ER function?

Protein synthesis.

Smooth ER function?

Lipid synthesis, detox.

Lysosome function?

degradation

What type of hormones are fast acting?

peptide hormones

What type of hormones are slow acting?

steroid hormones

where do peptide hormones bind?

Cell surface receptors.

Where do steroid hormones bind?

Intracellular receptors.

What does cAMP do?

Second messenger that activates protein kinase A.

What activates GPCRs?

Ligand binding → G protein activation.

What does phosphorylation usually do?

Activates or deactivates proteins.

What separates proteins by size?

SDS page

What separates DNA?

Gel electrophoresis.

What technique amplifies DNA?

PCR

What technique detects specific proteins?

western blot

What is the Hardy-Weinberg equation?

p² + 2pq + q² = 1

p- dominant

r- recessive

Conditions for Hardy-Weinberg equilibrium?

No mutation, no selection, large population, random mating, no migration.

What is a missense mutation?

changes one amino acid

What is a nonsense mutation?

Creates a stop codon.

What is a silent mutation?

No amino acid change.

What is a frameshift mutation?

Insertion/deletion altering reading frame.

What carries electrons in metabolism?

NAD⁺ → NADH, FAD → FADH₂.

Which produces more ATP: NADH or FADH₂?

NADH, because it enters ETC earlier → more proton pumping.

What type of molecule crosses membrane easily?

small, nonpolar molecules.

What is facilitated diffusion?

Passive transport via protein.

What is active transport?

Requires ATP, moves against gradient.

What is hypertonic solution?

Higher solute outside → cell shrinks.

What is osmosis?

Movement of water across membrane.

What is hypotonic solution?

Lower solute outside → cell swells.

Why does DNA replication need primers?

DNA polymerase cannot start synthesis.

What enzyme makes primers?

primase

What enzyme removes primers?

DNA polymerase I (prokaryotes).

What prevents DNA from unwinding too much?

Topoisomerase.

What is an operon?

Group of genes under one promoter.

What does a repressor do?

blocks transcription

Lac operon activated when?

Lactose present, glucose low.

Trp operon activated when?

tryptophan low

What does ELISA detect?

Antigens or antibodies.

What is chromatography used for?

Separation based on polarity/size.

What does Southern blot detect?

DNA

What does Northern blot detect?

RNA

What produces antibodies?

B cells

What activates B cells?

helper T cells

What do cytotoxic T cells do?

CD8/MHC 1: - kill infected cells

What is MHC I?

CD8- Found on all nucleated cells.

What is MHC II?

CD4-Found on antigen-presenting cells.

Prokaryotes vs eukaryotes key difference?

No nucleus or mitochondria in prokaryotes.

Where is DNA in prokaryotes?

nucleoid region

Where does ETC occur in prokaryotes?

cell membrane

What bond links monosaccharides?

glycosidic bond

What bond links fatty acids?

ester bond

Saturated vs unsaturated fats?

Saturated = no double bonds; unsaturated = double bonds.

What is the purpose of the urea cycle?

remove ammonia

where does the urea cycle occur

liver

High ATP →

inhibits glycolysis

Low energy (AMP) →

activates glycolysis

What happens during protein denaturation?

Loss of secondary, tertiary, quaternary structure (NOT primary).

What happens to enzyme activity when denatured?

Decreases or stops.

What causes denaturation?

Heat, pH changes, chemicals.

What is energy coupling?

Using exergonic reactions (ATP hydrolysis) to drive endergonic ones.