AP Bio Unit 1-6 Review

Carbohydrates

Organic molecules (C, H, O in 1:2:1) used for quick energy, energy storage, and structure

Monosaccharide

Single sugar unit; building block of carbohydrates (ex: glucose)

Disaccharide

Two monosaccharides joined by a glycosidic linkage

Structural carbohydrates

Cellulose (plant cell walls; rigidity)
Chitin (fungi cell walls; protection)

Storage carbohydrates

Starch (plants; glucose storage)
Glycogen (animals; short

Proteins

Polymers of amino acids that function as enzymes, structure, transport, movement, and signaling

Amino acid

Protein monomer with amino group, carboxyl group, R group (determines properties)

Peptide bond

Covalent bond formed by dehydration synthesis between amino acids

Primary structure

Specific amino acid sequence (determines all higher structure)

Secondary structure

Alpha helices or beta sheets from hydrogen bonding in backbone

Tertiary structure

Overall 3D shape from R-group interactions (H-bonds, ionic, disulfide)

Quaternary structure

Multiple polypeptide chains forming one functional protein

Nucleic acids

Polymers that store, transmit, and express genetic information

Nucleotide

Phosphate + pentose sugar + nitrogenous base

Phosphodiester linkage

Covalent bond between nucleotides forming sugar-phosphate backbone

DNA vs RNA bases

DNA: thymine (T)

RNA: uracil (U)

DNA vs RNA sugar

DNA: deoxyribose

RNA: ribose

DNA vs RNA structure

DNA: double-stranded

RNA: single-stranded

DNA orientation

Antiparallel strands running 5′ → 3′ (direction of synthesis)

Lipids

Nonpolar molecules used for long-term energy, membranes, insulation, hormones

Fats

Glycerol + three fatty acids; energy storage

Saturated fatty acids

No double bonds; straight chains; solid at room temp

Unsaturated fatty acids

One or more double bonds; bent chains; liquid at room temp

Phospholipids

Amphipathic molecules forming cell membranes

Steroids

Four fused rings; function as hormones (ex: testosterone)

Water polarity

Unequal electron sharing allows hydrogen bonding

Cohesion

Water sticks to water (surface tension)

Adhesion

Water sticks to polar surfaces (capillary action)

Universal solvent

Dissolves ionic and polar substances

High specific heat

Buffers temperature changes in organisms

Ice density

Hydrogen bonds form lattice → ice floats

Nucleus

Stores DNA; site of transcription; assembles ribosomal subunits

Ribosomes

Translate mRNA into polypeptides

Rough ER

Synthesizes proteins for secretion or membranes

Smooth ER

Lipid synthesis; detoxification; Ca²⁺ storage

Golgi apparatus

Modifies proteins (ex: glycosylation), sorts, and ships them

Mitochondria

Produces ATP through aerobic respiration

Krebs cycle

Matrix; breaks acetyl-CoA into CO₂, NADH, FADH₂

Oxidative phosphorylation

Cristae; ETC builds proton gradient → ATP

Chloroplast

Converts light energy to chemical energy

Light reactions

Thylakoid; water split → O₂, ATP, NADPH

Calvin cycle

Stroma; CO₂ fixed into G3P using ATP/NADPH

Lysosome

Intracellular digestion; recycling; apoptosis

Vacuole

Storage; water balance; maintains turgor pressure

Surface area-to-volume ratio

Higher ratio allows faster diffusion of materials

Plasma membrane

Fluid mosaic of phospholipids, proteins, carbs, cholesterol

Passive transport

Moves substances down concentration gradient without ATP

Simple diffusion

Small, nonpolar molecules cross membrane directly

Facilitated diffusion

Polar molecules use transport proteins; no energy

Active transport

Uses ATP to move substances against gradient

Ion pumps

Maintain electrochemical gradients (Na⁺/K⁺, Ca²⁺)

Endocytosis

Cell engulfs material into vesicles
(phago = solids, pino = liquids, receptor-mediated = specific)

Exocytosis

Vesicles fuse with membrane to release contents

Osmosis

Water moves from high to low water potential

Hypertonic

Water exits cell → shrinkage

Hypotonic

Water enters cell → swelling/lysis

Isotonic

No net water movement

Gibbs free energy

Energy available to drive cellular processes

Exergonic reaction

Releases energy; spontaneous (ATP hydrolysis)

Endergonic reaction

Requires energy input (ATP synthesis)

Enzymes

Proteins that lower activation energy by stabilizing transition state

Competitive inhibitors

Block active site; resemble substrate

Noncompetitive inhibitors

Change enzyme shape; reduce activity

Denaturation

Loss of shape → loss of function

Glycolysis

Cytosol; glucose → 2 pyruvate + ATP + NADH

ETC

Cristae; electrons power proton pumps

Final electron acceptor

Oxygen (forms water)

Chemiosmosis

Proton flow through ATP synthase → ATP

Photosynthesis

Stores light energy as chemical energy

Light reactions

Light + H₂O → ATP + NADPH + O₂

Calvin cycle

CO₂ → G3P (sugar precursor)

Signal transduction

Reception → signal amplification → response

Steroid hormones

Diffuse through membrane; regulate gene expression

Protein hormones

Bind surface receptors; trigger cascades

Secondary messengers

Amplify signal inside cell (cAMP, Ca²⁺)

G₁

Growth; organelle duplication

S

DNA replication

G₂

Final growth and error checking

Mitosis

Nuclear division (PMAT)

Cytokinesis

Cytoplasm divides

Mitosis outcome

2 genetically identical diploid cells

Meiosis outcome

4 genetically unique haploid cells

Crossing over

Homologous chromosomes exchange DNA (Prophase I)

Independent assortment

Random alignment of homologs (Metaphase I)

Complete dominance

Dominant allele fully masks recessive

Codominance

Both alleles fully expressed

Incomplete dominance

Heterozygote shows intermediate phenotype

Replication

DNA → DNA

Helicase unwinds; primase primes; DNA polymerase builds 5′ → 3′

Transcription

DNA → mRNA

RNA polymerase reads template strand and builds mRNA 5′ → 3′

RNA processing

5′ cap protects; poly-A tail stabilizes; introns removed via splicing

Translation

mRNA → polypeptide

Ribosome reads codons; tRNA brings amino acids; peptide bonds form

Operons

Gene clusters regulated together

Repressible operon (Trp)

Normally ON

Substrate: tryptophan

Product effect: tryptophan activates repressor → operon OFF

Inducible operon (Lac)

Normally OFF

Substrate: lactose

Product effect: lactose inactivates repressor → operon ON

Silent mutation

Codon change; same amino acid

Missense mutation

Codon change; different amino acid

Nonsense mutation

Codon becomes STOP → shortened protein

Frameshift mutation

Insertion/deletion shifts reading frame → major protein disruption