Biology

• LEVELS OF BIOLOGICAL ORGANIZATION

  (from smallest to biggest)

  1. individual
  2. population - all individuals of the same species in an area
  3. community - all populations in an area
  4. ecosystem - all communities and their environment
  5. biosphere - all ecosystems on Earth
• MODERN CELL THEORY

  1. The cell is the most basic unit of life
  2. All organisms are made up of cells
  3. All cells arise from other cells
  4. All cells have similar biomolecules and biochemical reactions
  5. All cells contain genetic material which is passed on from one cell to another
  6. All chemical and physiological processes in the body happen in the cell
• ORGANELLE FUNCTIONS

  • cell membrane - cell communication and transport
  • genetic material - storage of genetic information
  • ribosomes - protein synthesis
  • nucleus - command center
  • Golgi apparatus - transportation of proteins and other cellular components
  • endoplasmic reticulum - protein synthesis and lipid production
  • mitochondria - ATP synthesis
  • lysosome - cellular digestion
  • chloroplast - photosynthesis
  • vacuole - storage of food and other cellular components
  • cell wall - structural support, protection, controls cell transportation
  • centrioles - production of spindle fibers during cell division
• ORGANELLES PRESENT ONLY IN PROKARYOTES

  • nucleoid region
  • capsule
  • plasmid - extra, circular DNA
  • pilli
• ORGANELLES PRESENT IN BOTH PROKARYOTES AND EUKARYOTES

  • ribosomes
  • cytoplasm
  • cell membrane
  • genetic material
• MITOSIS

  1. prophase - chromosomes become distinct in diploid cell
  2. metaphase - chromosomes line up
  3. anaphase - sister chromatids head towards opposite poles
  4. telophase - cell splits; 2 diploid cells formed
• MEIOSIS

  1. Prophase I - chromosomes become distinct
  2. Metaphase I - chromosomes line up by pairs
  3. Anaphase I - chromosome pairs move towards each pole
  4. Telophase I - cell splits; 2 haploid cells form
  5. Prophase II - 2 haploid cells ready for division
  6. Metaphase II - chromosomes line up
  7. Anaphase II - sister chromatids head towards each pole
  8. Telophase II - each cell splits; 4 haploid cells formed
• Metabolism 


  general term for all chemical reactions of a cell, consists of anabolism (building-up) and catabolism (breaking-down)
• PHOTOSYNTHESIS

  CO2 + H2O -[with sunlight and chlorophyll]-> C6H12O6 + O2
• STEPS IN PHOTOSYNTHESIS

  1. Light-dependent Reactions - conversion of light energy and water to chemical energy and oxygen
  2. LIght-independent Reactions/Calvin cycle - formation of carbohydrate molecules from carbon dioxide using the chemical energy produced from light-dependent reactions
• RESPIRATION (opposite of photosynthesis)

  C6H12O6 + O2 --> CO2 + H2O + energy
• STEPS IN RESPIRATION

  1. Glycolysis - conversion of glucose to pyruvate
  2. Oxidation of pyruvate - conversion of pyruvate to acetyl CoA
  3. Citric Acid/TCA/Krebs Cycle - a 10-step cycle that produces oxaloacetate from acetyl CoA; leads to the formation of ATPs, NADHs, FADH2s
  4. Oxidative Phosphorylation - consists of the electron transport chain and chemiosmosis; synthesis of ATPs using ATP synthase
• Fermentation - anaerobic respiration; replaces Krebs cycle and electron-transport chain if oxygen is absent

  1. Lactic acid fermentation - converts glucose into lactic acid (C3H6O3)
  2. Ethanol fermentation - converts glucose into ethyl alcohol (C2H5OH)
• ACTIVE TRANSPORT - uses ATP; e.g. phagocytosis ("cell-eating"), pinocytosis ("cell-drinking"), uptake of glucose in the intestine
• GENETICS

  • alleles - gene forms for a certain trait
  • homozygous - having two of the same allele; purebred
  • heterozygous - having two different alleles for a certain trait; half bred
  • recessive - hidden or masked gene
  • dominant - expressed gene
  • phenotype - an organism's physical characteristics
  • genotype - an organism's actual genetic composition