Paper 1 biology

• Eukaryotic cells


  Complex cells, include plant and animal cells
• Prokaryotic cells


  Smaller and simpler cells, e.g. bacteria
• Cytoplasm


  Gel-like substance where most chemical reactions happen
• Cell membrane


  Holds the cell together and controls what goes in and out of the cell
• Cell wall


  Made of cellulose, supports and strengthens the cell
• Ribosomes


  Involved in translation of genetic material and synthesis of proteins
• Chloroplasts


  Found in plant cells, where photosynthesis happens to make food for the plant
• Chromosomal DNA


  Controls the cell's activities and replication in a bacterium
• Egg/sperm cell nucleus


  Haploid nucleus
• Acrosome


  Found at the front of the sperm cell, stores enzymes needed to digest the egg cell membrane
• Cilia


  In ciliated epithelial cells, move substances in one direction along the tissue surface
• Light microscope


  Magnifies images by passing light through the specimen
• Electron microscope


  Uses electrons rather than light
• Total magnification


  Eyepiece lens magnification x objective lens magnification
• Enzymes


  Biological catalysts
• Substrate


  The molecule changed in a chemical reaction
• Active site


  Joins on to the substrate to catalyse the reaction
• Factors affecting enzyme reaction rate

  • Temperature
  • pH
  • Substrate concentration
• Lipases


  Enzymes that break down lipids into glycerol
• Proteases


  Enzymes that convert proteins into amino acids
• Carbohydrases


  Enzymes that convert carbohydrates into simple sugars
• Glycogen synthase


  Enzyme that joins together glucose molecules to make glycogen (energy storage)
• Diffusion


  Net movement of particles from higher to lower concentration
• Active transport


  Movement of particles against a concentration gradient using energy from respiration
• Osmosis


  Net movement of water molecules from higher to lower water concentration
• Cell differentiation


  Process of cells becoming specialised for their job
• Cell division


  Process of a cell dividing into two new daughter cells (mitosis)
• Cell elongation


  When a plant cell expands, making the cell bigger and the plant grow
• Cancer


  Uncontrolled cell division due to changes in genes controlling cell division
• Stem cells


  Undifferentiated cells
• Synapse


  Connection between two neurons
• Zygote


  Cell formed when sperm and egg join together
• DNA


  Polymers made up of repeating units
• Complementary base pairs


  Adenine joins with thymine, cytosine joins with guanine, joined by weak hydrogen bonds
• Chromosomes


  Long, coiled up molecules of DNA
• Recessive alleles


  Shown with a small letter in genetic diagrams
• Genetic variation


  Caused by organisms having different alleles, and by sexual reproduction combining alleles
• Mutations


  Changes to the base sequences of DNA