CB1

• Animal and plant cells are eukaryotic
• Bacterial cells are prokaryotic
• Bacterial cells have a cell wall, cell membrane, cytoplasm and a singular strand of DNA
• The nucleus contains DNA
• The cytoplasm is the liquid substance in which chemical reactions occur
• The cell membrane controls what enters and leaves the cell
• The mitochondria is where aerobic respiration occurs.
• The ribosomes are where protein synthesis occurs
• The chloroplasts are the sit of photosynthesis. They contain chlorophyll pigment which harvest the light needed for photosynthesis
• The vacuole contains cell sap and improves the cell’s rigidity
• The cell wall is made of cellulose and provides strength to the cell
• The cell wall of bacterial cells is made out of peptidoglycan.
• As bacterial cells have no nucleus the chromosomal DNA floats in the cytoplasm
• Plasmids are small rings of DNA in bacterial cells
• Flagella are long thin tails which help the bacterial cell to move
• Sperm cells adaptions:

  • Streamlined head
  • Long tail
  • Many mitochondira
  • Acrosome
• sperm cells have a streamlined head and a long tail to aid swimming
• Sperm cells have lots of mitochondria which supply the energy to allow the cell to move
• The acrosome (top of head) of a sperm cell has digestive enzymes which break down the outer layers of the membrane of the egg cell, helping with fertilisation.
• sperm cells are specialised to carry the males DNA to the egg cell for successful reproduction
• Egg cells are surrounded by a special cell membrane which can only accept one sperm cell, and becomes impermeable following this
• Egg cells have lots of mitochondria to provide an energy source for the developing embryo
• Egg cells are specialised to accept a single sperm cell and develop into an embryo
• Ciliated cell adaptions:

  • long hair like projections, known as cilia
• Ciliated cells have long hair-like projections called cilia, which waft bacteria trapped by sticky mucus (mucus is produced by goblet cells) down to the stomach, where they are killed by stomach acid
• Root hair cells are specialised to take up either water by osmosis and mineral ions by active transport from the soil, and are found in the tips of the roots
• Root hair cells adaptions:

  • Large surface area
  • Large vacuole
  • Mitochondria
• Root hair cells have a large surface area due to long projections, meaning that more water can move in via osmosis
• Mitochondria in the root hair cell provide energy from respiration for the active transport of mineral ions into the root hair cell.
• Root hair cells do not have chloroplasts because they are in the roots, so they cannot absorb sunlight
• Eyepiece - part of microscope we look through to view specimens
• Barrel - upper part of the microscope that can be moved up or down to focus the image
• Turret - Part of the microscope that is rotated to change the magnification
• Lens - The lens increases the magnification of the specimen
• Stage - the flat surface on which we place the specimen
• Using a light microscope:

  • place the slide on the stage and look through the eyepiece lens
  • turn the focus wheel to obtain a clear image
  • start with the lower objective lens magnification
  • increase the magnification of objective lens and refocus
• Preparing a slide for microscopy:

  • Take thin layer of cells from sample By peeling or using cotton bud
  • add small amount of stain. Stain is used to make parts of specimen more visible
  • apply cells to glass slide
  • put coverslip on slide, avoiding air bubbles
• Enzymes are biological catalysts
• Enzymes increase the rate of reaction without being used up
• Lock and key theory:

  • The shape of a substrate is complementary to the shape of the active site, so when it bonds it forms an enzyme-substrate complex.
  • Once bound, the reaction takes place the products are released from the enzyme