Biology- Cell Structure

    Cards (64)

    • Types of cells
      • Eukaryotic (plant and animal)
      • Prokaryotic (bacteria)
    • Differences between eukaryotic and prokaryotic cells
      • Prokaryotic cells are much smaller than eukaryotic cells
      • Eukaryotic cells contain membrane bound-organelles and a nucleus containing genetic material, while prokaryotes do not
    • Prokaryotic cell wall
      Composed of peptidoglycan
    • Genetic information storage in prokaryotic cells

      Found free within the cytoplasm as chromosomal DNA (single large loop of circular DNA) and plasmid DNA
    • Plasmids
      Small, circular loops of DNA found free in the cytoplasm and separate from the main DNA, carrying genes that provide genetic advantages e.g. antibiotic resistance
    • Order of magnitude
      A power to the base 10 used to quantify and compare size
    • Centimetre (cm)
      1 x 10-2 metres
    • Millimetre (mm)

      1 × 10-3 metres
    • Micrometre (µm)

      1 × 10-6 metres
    • Nanometre (nm)
      1 x 10-9 metres
    • Difference in order of magnitude between a human hair (length = 100 µm) and the HIV virus (length = 100 nm)

      100 µm = 10-4 m, 100 nm = 10-7 m, -4-(-7) = -4 + 7 = 3
    • Components of both plant and animal cells

      • Nucleus
      • Cytoplasm
      • Cell membrane
      • Mitochondria
      • Ribosomes
    • Additional cell components found in plant cells
      • Chloroplasts
      • Permanent vacuole
      • Cell wall
    • Function of the nucleus (other than storing genetic information)
      Controls cellular activities
    • Structure of the cytoplasm
      Fluid component of the cell, containing organelles, enzymes and dissolved ions and nutrients
    • Function of the cytoplasm
      Site of cellular reactions e.g. first stage of respiration, transport medium
    • Function of the cell membrane
      Controls the entry and exit of materials into and out of the cell
    • Function of the mitochondria
      Site of later stages of aerobic respiration in which ATP is produced
    • Function of the ribosomes
      Joins amino acids in a specific order during translation for the synthesis of proteins
    • Composition of the plant cell wall

      Cellulose
    • Function of the plant cell wall
      Provides strength, prevents the cell bursting when water enters by osmosis
    • Contents of the permanent vacuole
      Cell sap (a solution of salts, sugars and organic acids)
    • Function of the permanent vacuole
      Supports the cell, maintaining its turgidity
    • Function of chloroplasts
      Site of photosynthesis
    • Adaptations of sperm cells in animals
      • Haploid nucleus contains genetic information
      • Tail enables movement
      • Mitochondria provide energy for tail movement
      • Acrosome contains enzymes that digest the egg cell membrane
    • Adaptations of nerve cells in animals
      • Long axon allows electrical impulses to be transmitted all over the body from the central nervous system
      • Dendrites from the cell body connect to and receive impulses from other nerve cells, muscles and glands
      • Myelin sheath insulates the axon and speeds up the transmission of impulses along the nerve cell
    • Adaptations of muscle cells in animals
      • Arrangement of protein filaments allows them to slide over each other to produce muscle contraction
      • Mitochondria to provide energy for muscle contraction
      • Merged cells in skeletal muscle allow muscle fibre contraction in unison
    • Adaptations of root hair cells in plants
      • Large surface area to absorb nutrients and water from surrounding soil
      • Thin walls that do not restrict water absorption
    • Adaptations of xylem cells in plants
      • No upper or lower margins between cells to provide a continuous route for water to flow
      • Thick, woody side walls strengthen their structure and prevent collapse
    • Adaptations of phloem cells in plants
      • Sieve plates let dissolved amino acids and sugars be transported up and down the stem
      • Companion cells provide energy needed for active transport of substances along the phloem
    • Cell differentiation
      The process by which cells become specialised
    • Importance of cell differentiation
      Allows production of different tissues and organs that perform various vital functions in the human body
    • Most animal cells differentiate early in their life cycle
    • Plant cells retain the ability to differentiate throughout their entire life cycle
    • Purpose of cell division in mature animals

      Repair and replacement of cells
    • Changes a cell goes through as it differentiates
      Becomes specialised through acquisition of different sub-cellular structures to enable a specific function to be performed by the cell
    • Magnification
      The number of times bigger an image appears compared to the size of the real object
    • Throughout their entire life cycle
    • Resolution
      The smallest distance between two objects that can be distinguished
    • How a light microscope works

      Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed