key concepts of bio 1

Amino acid

Building block of proteins.

Peptide bond

Link between two amino acids.

Polypeptide

Chain of many amino acids.

Dipeptide

Molecule of two amino acids joined together.

Primary structure

The sequence of amino acids.

Secondary structure

Coiling or folding of the chain (e.g. alpha-helix, beta-sheet).

Tertiary structure

3D shape of a single polypeptide.

Quaternary structure

3D shape formed by multiple polypeptides.

Globular protein

Round, water-soluble protein.

Fibrous protein

Long, structural, and insoluble protein.

Denaturation

Loss of protein shape due to heat or pH.

R-group (side chain)

Variable group on an amino acid that determines its properties.

Enzyme

Protein that speeds up reactions.

Substrate

Molecule the enzyme acts on.

Active site

Part of the enzyme where the substrate binds.

Enzyme-substrate complex

Temporary pairing of enzyme and substrate.

Product

Result of the enzyme reaction.

Catalyst

Substance that speeds up a reaction without being used up.

Activation energy

Energy needed to start a reaction.

Lock and key model

Enzyme fits exactly with the substrate.

Induced fit model

Enzyme changes shape slightly to fit the substrate.

Optimum temperature

Temperature where the enzyme works best.

pH

Measure of acidity or alkalinity.

Substrate concentration

Amount of substrate in a solution.

Competitive inhibitor

Molecule that blocks the active site.

Non-competitive inhibitor

Molecule that changes the enzyme's shape.

Aerobic respiration

Uses oxygen to make ATP.

Anaerobic respiration

Makes ATP without oxygen.

Glycolysis

First stage of respiration; breaks glucose into pyruvate.

Pyruvate

End product of glycolysis.

Krebs cycle

Second stage; produces energy carriers.

Electron transport chain (ETC)

Transfers electrons to make ATP.

ATP (adenosine triphosphate)

Main energy molecule of cells.

NAD⁺ / NADH

Electron carrier (oxidized/reduced forms).

FAD / FADH₂

Another electron carrier.

Mitochondria

Organelle where respiration happens.

Cristae

Folds of inner mitochondrial membrane.

Matrix

Inner fluid of the mitochondrion.

Oxidative phosphorylation

Making ATP using ETC and oxygen.

Decarboxylation

Removing carbon dioxide from a molecule.

ATP synthase

Enzyme that makes ATP.

Chemiosmosis

Flow of protons that powers ATP production.

Proton gradient

Difference in proton concentration across a membrane.

Chloroplast

Organelle where photosynthesis occurs.

Thylakoid

Membrane discs in the chloroplast.

Grana

Stacks of thylakoids.

Stroma

Fluid inside chloroplast.

Chlorophyll

Green pigment that captures light.

Light-dependent reactions

First stage using light to make energy carriers.

Light-independent reactions (Calvin cycle)

Second stage; uses energy to build sugar.

Photolysis

Splitting of water using light.

ATP

Energy molecule made in light-dependent reactions.

NADP⁺ / NADPH

Electron carrier (oxidized/reduced forms).

Carbon fixation

CO₂ is attached to another molecule.

G3P (glyceraldehyde-3-phosphate)

3-carbon sugar from Calvin cycle.

Rubisco

Enzyme that fixes CO₂.

Electron transport chain

Moves electrons to create energy.

Starch

Storage form of glucose in plants.

Limiting factors

Things that slow down photosynthesis when in short supply.

DNA

Molecule that carries genetic instructions.

Double helix

Two strands twisted into a spiral.

Nucleotide

DNA building block.

Sugar-phosphate backbone

The "sides" of the DNA ladder.

Adenine (A)

Nitrogen base that pairs with T.

Thymine (T)

Base that pairs with A.

Cytosine (C)

Base that pairs with G.

Guanine (G)

Base that pairs with C.

Complementary base pairing

A pairs with T, C pairs with G.

Helicase

Enzyme that unzips DNA.

DNA polymerase

Enzyme that adds new nucleotides.

Semi-conservative replication

One old strand, one new strand.

Replication fork

Area where DNA is being copied.

Origin of replication

Starting point for copying DNA.

Leading strand

Copied continuously.

Lagging strand

Copied in fragments.

Okazaki fragments

Short segments on the lagging strand.

Ligase

Enzyme that joins fragments together.

Gene

DNA section that codes for a protein.

Transcription

Making RNA from DNA.

Translation

Making protein from RNA.

RNA (ribonucleic acid)

Single-stranded nucleic acid.

mRNA (messenger RNA)

Carries code from DNA to ribosome.

tRNA (transfer RNA)

Brings amino acids to ribosome.

rRNA (ribosomal RNA)

Part of the ribosome.

RNA polymerase

Enzyme that builds RNA from DNA.

Promoter

DNA sequence where transcription starts.

Codon

Three RNA bases that code for one amino acid.

Anticodon

tRNA bases that match the codon.

Start codon

Signals the start of translation.

Stop codon

Signals the end of translation.

Ribosome

Site of protein synthesis.

Peptide bond

Link between amino acids.

Polypeptide chain

Chain of amino acids.

Exon

Coding part of a gene.

Intron

Non-coding part of a gene.

Splicing

Removing introns from RNA.

Mutation

Change in DNA.

Gene mutation

Mutation affecting a single gene.

Point mutation

Change in one base.

Silent mutation

No change in protein.