Study Guide for Biology Midterm Exam (use with PowerPoints) Characteristics of Life –Cells, homeostasis, genetic code, energy/materials, grow/develop, evolve, reproduce, respond to stimuli –Prokaryotes = example bacteria, smaller, no nucleus –Eukaryotes = example plant/animal cells, larger, do have nucleus Scientific Method and Controlled Experiments –Ask a question, form a hypothesis, test hypothesis with a controlled experiment, record data, analyze results, form conclusion, publish results Controlled experiment: –Everything is the same except the independent variable (the condition you change—example: color of light). The dependent variable is the effect of your change (example: plant growth) –Experimental groups are changed, control groups get no change Chemistry –Atoms  molecules  macromolecules  cells –Chemical reactions change molecules releasing or absorbing energy (start with reactants, end with products) –pH = 0 to 14, 0—6.9 = acidic, 7 = neutral, 7.1—14 = basic. Stronger as you move away from 7 in both directions –Water is a polar molecule that forms hydrogen bonds with other water molecules Results in cohesion, adhesion, surface tension, excellent solvent

Macromolecules –Proteins Made of smaller units called amino acids Used for building muscle/bone, fighting infection, transport across cell membrane Enzymes are proteins that speed up chemical reactions by lowering activation energy –Substrate fits into active site like lock-and-key –Not changed and reusable –Affected by pH and temperature –Usually end with “-ase” –Carbohydrates Made of smaller units called monosaccharides (for immediate energy) Disaccharides = two-unit carbs Polysaccharides = many-unit carbs –Cellulose = cell walls of plant cells –Starch = energy storage in plant cells –Lipids Fats, oils, and waxes Hydrophobic Made of smaller units called glycerol and fatty acids Energy storage, heat insulation, cell membranes, waterproof coatings

Nucleic Acids –Made of smaller units called nucleotides –Store information about traits Transport –Cell membrane = selectively permeable phospholipid bilayer –Diffusion = high to low concentration with no energy –Facilitated diffusion = high to low concentration with transport protein and no energy –Active transport = low to high concentration with transport protein and ATP –Osmosis = water moves toward highest concentration Energy –ATP releases energy when 3 rd phosphate is removed (becomes ADP)—ATP is rechargable –Glycolysis = done by all cells, anaerobic (no oxygen) Glucose is split, costs 2 ATP, gain 4 ATP –Lactic acid fermentation = done by animal cells (no oxygen) Glucose is split, costs 2 ATP, gain 4 ATP Lactic acid is a product –Alcoholic fermentation = done by yeast cells (no oxygen) Glucose is split, costs 2 ATP, gain 4 ATP Alcohol and CO2 are products –Cellular respiration Done in the mitochondria of plant and animal cells Glucose + O2 = CO2 + H2O + 36 ATP

Photosynthesis –CO2 + H2O  C6H12O6 + O2 –Done in the chloroplasts of plant cells –Chlorophyll absorbs light energy (ROYGBIV) –Light reactions Light energy absorbed, H2O split, O2 made---ATP and NADPH made to power Calvin cycle –Calvin cycle ATP and NADPH used to turn CO2 into glucose (C6H12O6) Cell organelles –Membrane, cytoplasm, ribosomes, mitochondria, chloroplast (plant only), cell wall (plant, bacteria, fungi only), rough ER, smooth ER, vacuole (larger in plants), lysosome, Golgi Apparatus, cytoskeleton, nucleus, nucleolus DNA –Nucleotides (A, T, C, and G) linked together to form double-stranded double helix –A matches with T, C matches with G –Nucleotide = phosphate + sugar + nitrogenous base Sugar bonds with phosphate to form “backbone” of each strand Bases form hydrogen bonds in the middle

Protein synthesis –Instructions from gene (DNA) turned into protein (1 gene = 1 protein) –Gene to mRNA during transcription in the nucleus mRNA = single stranded with “U” instead of “T” –mRNA to polypeptide during translation at the ribosome mRNA codon = 1 amino acid Use codon letters in the codon chart for amino acid First amino acid always “MET” tRNA has an anti-codon, delivers amino acid Polypeptide is released with “stop” codon, then becomes functional protein –Mutations in a gene (insert, delete, or replace nucleotide) can change protein Insertions and deletions usually cause the most changes in amino acid sequence

Genetics –Mendel worked with pea plants to determine laws of dominance and segregation –One trait is dominant, one is recessive –For dominant trait, use capital letter to represent the gene (allele): Example “T” –For recessive trait, use lowercase letter to represent the gene (allele): Example “t” –Each cell has two alleles, one from each parent: Example TT, Tt, or tt –Same allele = homozygous, different alleles = heterozygous –Allele combination = genotype, trait they produce = phenotype –Gametes (haploid) deliver alleles during fertilization to produce diploid zygote –Punnett square used to determine probability of offspring