Biology

Cell Structure

Nucleus—Contains DNA, controls cell

Mitochondria—ATP production (energy)

Ribosome—Protein synthesis

Cell membrane—Phospholipid bilayer, selective

Endoplasmic reticulum (ER)—Rough: ribosomes; Smooth: lipids

Golgi apparatus—Packages & ships proteins

Lysosome—Digests waste (animal)

Chloroplast—Photosynthesis (plant)

Cell wall—Rigid support (plant, fungi)

Vacuole—Storage; large in plant cells

DNA, RNA & Protein Synthesis

DNA: deoxyribonucleic acid—Double helix

DNA bases: A-T, G-C—Adenine-Thymine, Guanine-Cytosine

RNA bases: A-U, G-C—Uracil replaces Thymine

mRNA: carries code from DNA—Transcription product

tRNA: brings amino acids—Has anticodon

rRNA: part of ribosome—

Codon: 3 bases = 1 amino acid—64 codons total

Transcription: DNA → mRNA—In nucleus

Translation: mRNA → protein—At ribosome

Start codon: AUG (Met)—

Stop codons: UAA, UAG, UGA—

Cell Division

Mitosis: 1 cell → 2 identical—Growth & repair

Phases: prophase, metaphase, anaphase, telophase—

Meiosis: 1 cell → 4 haploid—Gamete production

Meiosis has 2 divisions—Meiosis I & II

Crossing over in meiosis I—Genetic variation

Diploid (2n) → Haploid (n)—

Cell cycle: G1 → S → G2 → M—

Genetics

Genotype: genetic makeup (Aa)—

Phenotype: physical expression—

Dominant (A) masks recessive (a)—

Homozygous: AA or aa—

Heterozygous: Aa—

Punnett square: predict offspring—

Codominance: both alleles expressed—e.g., AB blood type

Incomplete dominance: blended—e.g., pink flowers

Photosynthesis & Respiration

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂—Photosynthesis

Light reactions: in thylakoids—Produce ATP, NADPH, O₂

Calvin cycle: in stroma—Fixes CO₂ into glucose

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O—Cellular respiration

Glycolysis: glucose → 2 pyruvate—2 ATP (cytoplasm)

Krebs cycle: in mitochondria—2 ATP, NADH, FADH₂

ETC: 34 ATP—Inner mitochondrial membrane

Total ATP per glucose ≈ 36-38—

Ecology

Producer → Primary → Secondary → Tertiary—Food chain

Ecosystem: biotic + abiotic—

Biome: large ecological area—e.g., tundra, desert

Symbiosis: mutualism, commensalism, parasitism—

Carbon cycle, nitrogen cycle, water cycle—Biogeochemical cycles

10% rule: energy transfer between levels—

Biodiversity: variety of life—

Body Systems

Circulatory: heart, blood—Transport

Respiratory: lungs—Gas exchange

Nervous: brain, nerves—Signals

Digestive: stomach, intestines—Nutrient absorption

Immune: white blood cells—Defense

Endocrine: hormones—Chemical signals

Muscular: movement—Skeletal, smooth, cardiac

Skeletal: bones, support—206 bones in adult

Excretory: kidneys—Waste removal

Reproductive—Produce offspring

Evolution & Classification

Natural selection—Survival of the fittest

Mutation: random DNA change—Source of variation

Adaptation: suited to environment—

Speciation: new species form—

Domain → Kingdom → Phylum → Class—

→ Order → Family → Genus → Species—Taxonomy hierarchy

Homologous structures: common ancestor—

Analogous structures: similar function—Not related

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