BIOLOGY 101

• Cell membrane


  2 lipid layer with one protein layer sandwiched in between. It is selectively permeable
• Nucleus


  Contains genetic material (chromosomes)
• Cytoplasm


  Contains water and dissolved substances e.g. glucose, minerals, vitamins
• Ribosome


  Small grains found scattered in the cytoplasm, some may be attached to endoplasmic reticulum
• Ribosome


  • Responsible for protein formation
  • Site for protein synthesis
• Mitochondrion


  Surrounded by 2 membranes, inner membrane has folds. Where energy is released by the process of aerobic respiration
• Cell wall


  Made of a carbohydrate called cellulose. Protects cell against mechanical damage and gives plant a definite shape
• Vacuole


  Has concentrated solution made of salts, glucose. It is selectively permeable. Stores the cell sap. Regulate pH and in balance within the cell. Maintain turgor pressure
• Cell membrane


  • Controls the movement of substances in and out of a cell. It selects substances entering and leaving the cell
• Nucleus


  • Controls all chemical reactions taking place in a cell. Regulates cell activities
• Cytoplasm


  • Where biochemical reactions take place e.g. protein synthesis, photosynthesis, respiration
• Cell membrane


  A thin barrier that surrounds all cells in your body and is composed of two layers of lipid molecules with a layer of protein molecules sandwiched in between. It is selectively permeable, allowing certain molecules to pass through while blocking others.
• Lipid layers


  Two layers of lipid molecules, which are fat-like molecules that do not dissolve in water, that make up the cell membrane.
• Protein layer


  A layer of protein molecules, which are large complex molecules that perform various functions in the cell, that is sandwiched in between the two lipid layers of the cell membrane.
• Selectively permeable


  The ability of the cell membrane to allow certain molecules to pass through while blocking others, which is crucial for maintaining the internal environment of the cell and regulating the exchange of materials between the cell and its surroundings.
• Lipid layers


  Composed of phospholipid molecules, which have a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophilic heads face outwards and the hydrophobic tails face inwards, creating a barrier that is impermeable to most polar and charged molecules.
• Phospholipid molecules


  Molecules that make up the lipid layers of the cell membrane and have a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophilic heads face outwards and the hydrophobic tails face inwards, creating a barrier that is impermeable to most polar and charged molecules.
• Hydrophilic heads


  The water-loving heads of phospholipid molecules that face outwards in the lipid layers of the cell membrane.
• Hydrophobic tails


  The water-fearing tails of phospholipid molecules that face inwards in the lipid layers of the cell membrane.
• Bilayer structure


  The arrangement of phospholipid molecules in the lipid layers of the cell membrane, with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards, creating a barrier that is impermeable to most polar and charged molecules.
• Polar and charged molecules


  Molecules that are unable to pass through the lipid layers of the cell membrane due to their polar or charged nature.
• Impermeable


  The property of the lipid layers of the cell membrane that prevents most polar and charged molecules from passing through.
• Non-polar molecules


  Molecules that are able to pass through the lipid layers of the cell membrane due to their non-polar nature.
• Biology


  A branch of Science which involves the study of form and function of living things and their interrelationships with the environment
• Cell


  The basic unit of life from which all living things are built. Each cell is capable of carrying out life processes
• Types of cells


  • Eukaryotic
  • Prokaryotes
• Eukaryotic cells


  • Contain membrane bound organelles, have a well defined nucleus, with cytoplasm
• Prokaryotic cells


  • Do not have any membrane bound organelles, have no defined nucleus
• Cell structures


  • Cell membrane
  • Nucleus
  • Cytoplasm
  • Ribosome
  • Mitochondrion
  • Cell wall
  • Vacuole
• Cell membrane


  2 lipid layer with one protein layer sandwiched in between, selectively permeable
• Nucleus


  Contains genetic material (chromosomes), controls all chemical reactions and regulates cellular activities
• Cytoplasm


  Contains water & dissolved substances e.g. glucose, minerals, vitamins, where biochemical reactions take place. A site for anaerobic respiration
• Ribosome


  Responsible for protein formation, site for protein synthesis
• Mitochondrion


  Where energy is released by the process of aerobic respiration
• Cell wall


  Made of cellulose, freely/fully permeable, protects cell against mechanical damage & gives plant a definite shape
• Vacuole


  Has concentrated solution made of salts, glucose, stores the cell sap
• Specialized cells


  • Red blood cells
  • Muscle cells
  • Sperm cells
  • Ovum
  • White blood cells
  • Root hair cells
  • Xylem cells
  • Nerve cells
  • Guard cells
  • Palisade cells
  • Phloem
  • Ciliated cells
• Red blood cells


  • Biconcave structure to have large surface area to absorb oxygen, spongy cytoplasm to compress in small blood vessels, absence of nucleus to increase space for oxygen transport, presence of haemoglobin to bind and carry oxygen
• Muscle cells


  • Long with numerous protein fibres in the cytoplasm to help shorten the cell when there is energy, can contract and relax to move parts
• Sperm cells


  • Streamlined head to move towards ovum with less friction, have a tail to swim towards the ovum, have many mitochondria to release energy for movement