Biology Study Notes Overview

Biology Study Notes

• Biology is the scientific study of life, examining its structure, function, growth, origin, evolution, and distribution.
• Characteristics of living things include: cellular organization; reproduction; growth and development; energy utilization; homeostasis; response to stimuli; adaptation.
• Evolution is the unifying theme in biology, explaining the unity and diversity of life, by proposing common ancestry.
• The three domains of life are Bacteria, Archaea, and Eukarya.
• Bacteria and Archaea are prokaryotic, lacking a nucleus and membrane-bound organelles.
• Eukarya is eukaryotic, containing a nucleus and membrane-bound organelles.
• Eukaryotic organisms include Animalia (animals), Plantae (plants), Fungi (fungi), and Protista (protists).
• Taxonomy, from most to least inclusive, is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
• Biological macromolecules include carbohydrates, lipids, proteins, and nucleic acids.
  • Carbohydrates: building blocks are monosaccharides (e.g., glucose), joined by glycosidic bonds.
  • Lipids: building blocks are glycerol and fatty acids, joined by ester bonds.
  • Proteins: building blocks are amino acids, joined by peptide bonds.
  • Nucleic acids (DNA/RNA): building blocks are nucleotides, joined by phosphodiester bonds.
• Water's properties (polarity, high specific heat, cohesion, adhesion, and acts as a universal solvent) are essential for life.
• pH is a measure of acidity or basicity (scale of 0-14, neutral is 7).
• The most basic unit of life is the cell.
  • Cell theory: all living organisms are composed of cells; the cell is the basic unit of structure and function; all cells come from pre-existing cells.
• Cell membranes: are a barrier separating cell interior and outside; composed of phospholipids and proteins; selectively permeable.
• Active transport moves molecules against the concentration gradient (requires energy).
• Passive transport moves molecules down the concentration gradient (no energy required).
• Diffusion is the movement of molecules from high to low concentration.
• Osmosis is the diffusion of water across a semipermeable membrane.
  • Isotonic solutions have equal solute concentrations inside and outside the cell.
  • Hypertonic solutions have higher solute concentrations outside the cell, causing water to move out.
  • Hypotonic solutions have lower solute concentrations outside the cell, causing water to move in.
• Endocytosis is the process of taking substances into a cell.
• Exocytosis is the process of releasing substances from a cell.
• Producers (autotrophs) make their own food (e.g., plants).
• Consumers (heterotrophs) obtain energy by consuming other organisms.
• The ultimate energy source is the sun;
• First law of thermodynamics: energy cannot be created or destroyed.
• Second law of thermodynamics: entropy (disorder) increases over time.
• Exergonic reactions release energy.
• Endergonic reactions absorb energy.
• Enzymes are proteins that act as biological catalysts, speeding up reactions and lowering activation energy.
• Photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2 (conversion of light energy to chemical energy; occurs in chloroplasts).
• Respiration: breakdown of glucose to release energy in the form of ATP (occurs in mitochondria).
• Fermentation is a metabolic process that occurs in the absence of oxygen, producing ATP.
• Central dogma: DNA → RNA → protein; genetic information flows from DNA, to RNA, to proteins.
• Transcription: DNA to RNA
• Translation: RNA to protein
• Cellular respiration: glycolysis, Krebs cycle and electron transport chain.
• Mitosis: cell division used for growth and repair (results in two identical daughter cells).
• Meiosis: cell division used for sexual reproduction (results in four genetically unique daughter cells).
• Cytokinesis: division of the cytoplasm to complete the cell division process
• Down syndrome: a genetic disorder caused by an extra copy of chromosome 21
• Autosomes are non-sex chromosomes; sex chromosomes determine the sex of an individual (e.g. X and Y in humans).
• Mendel's laws of inheritance describe patterns of inheritance, including segregation and independent assortment.
• Genotype is the genetic makeup.
• Phenotype is the observable characteristics.
• Homozygous: two identical alleles for a gene
• Heterozygous: two different alleles for a gene
• Alleles are different versions of a gene.