Unit 2

Cards (95)

  • what are the differences between prokaryotic (P) and eukaryotic cells (E) ?
    P are smaller - E are larger
    P has circular DNA - E has linear DNA
    only E has DNA associated with histones
  • what is the function of the nucleus
    contains genetic information and has the nucleolus which makes ribosomes
  • what is the function of ribosomes
    site of protein synthesis
  • what is the function of the smooth endoplasmic reticulum
    make and store lipids
  • what is the function of the Golgi apparatus
    package and modify proteins / lipids into vesicles by adding carbohydrates
    make lysosomes
  • what is the function of the rough endoplasmic reticulum
    where proteins are made and stored
    have ribosomes on their surface
    proteins packaged into vesicles for transport
  • explain the advantage of using an electron microscope
    electrons have a shorter wavelength than light so electron microscopes have a higher resolution
  • how are antibodies produced in the body following a viral infection
    the virus contains an antigen
    the T-cells detect the antigen and release cytokines
    cytokines stimulate b-cells
    clonal selection b-cells divide by mitosis to produce clones
    plasma cells and b-memory cells produces antibodies
    antibodies are specific to the antigen
    antibody-antigen complex formed
  • name the components that form the nucleus
    nuclear envelope
    nucleolus
    nucleoplasm
    chromatin
  • Give structures found in all prokaryotic cells and in all eukaryotic cells.
    cell membrane
    ribosomes
    cytoplasm
    DNA
  • what is an antigen
    foreign protein that stimulates an immune response / production of an antibody
  • Contrast the structure of a bacterial celland the structure of a human cell.
    bacteria is smaller
    bacteria have a cell wall human cells dont
    bacteria has plasmids but human cells have nucleus
    bacterial lacks membrane-bound organelles but human has membrane-bound organelles
    bacterial have 70S ribosomes whereas human have 80S ribosomes
  • Cristae
    extensions of the inner membrane
    extend across the whole width of mitochondria
    provides large surface area for attachment of enzymes involved in respiration
  • Define "resolution"
    The minimum distance apart that two objects can be in order for them to appear as seperate items
  • Define monoclonal antibodies
    Antibodies produced from a single clone of B cells
  • Describe active transport.
    carrier proteins
    against concentration gradient
    using ATP
  • Describe binary fission in bacteria.
    circular DNA and plasmids are replicated
    cytoplasm divides
    each daughter cell has : one copy of circular DNA and a variable number of plasmids
  • Describe the function of cholesterol in the cell membrane
    reduces lateral movement of other molecules including phospholipids
    makes the membrane less fluid at high temperatures
    prevent leakage of water and dissolved ions from the cell as it is hydrophobic
  • vacuole
    fluid filled ( cell sap )sac bound by a single membrane called the tonoplast
    provides structure to plant cell
  • what is the cell wall of prokaryotic cells made of
    murein
  • describe the structure of all viruses
    attachment proteins
    capsid
    genetic material e.g. mRNA or DNA
  • define magnification
    how many time larger the size of the image is than the size of the object
  • what are the features of a solution used for ultracentrifugation
    cold - prevent enzyme activity that may break down the organelles
    isotonic - prevents osmosis of water into organelles causing the organelles to burst as the water potential of the solution is equal to the water potential of the organelles
    buffered - maintain pH to prevent enzymes denaturing
  • describe the process of ultracentrifugation
    homogenise the cells to break them open
    filter
    ensure the solution is cold isotonic and buffered
    centrifuge then remove nuclei
    centrifuge the supernatant at higher speed
    heaviest / most dense organelles will be at the bottom of the tube
  • what property of cell organelles allow them to be centrifuged
    different densities
  • how does a light microscope produced an image
    beam of light is shone through the specimen
  • how does a TEM produce an image
    electromagnet focuses a beam of electrons onto specimen
    beam passes through the thin section of the specimen
    parts of the specimen that let electrons pass through appear light and the parts that absorb the electrons appear dark
    image photographed using microphotograph
  • how does an SEM produce an image
    beam of electrons shone on surface of a metal-salt stained specimen
    electrons scattered onto the surface of the surface of the specimen
    electrons reflect back onto the detector
    computer analyses the pattern of scattered electrons
    3D image
  • why use electron microscopes instead of light microscope
    electrons have a shorter wavelength than light
    so electron microscopes have a higher resolution
  • disadvantages of TEM
    needs vacuum to be used - living specimens cannot be viewed
    images are black and white
    complex staining process
    only produces 2D images
    image may have artefacts
    specimen sample has to be thin
  • disadvantages of SEM
    needs vacuum to be used - living specimens cannot be viewed
    images are black and white
    complex staining process
    image may have artefacts
    lower resolution than TEM
    cannot view the internal structure of samples e.g. organelles inside a cell
  • describe the process of co-transport
    sodium ions are actively transported out of epithelial cell into the blood in capillaries
    concentration of sodium ions in the epithelial cell decreases
    sodium ions diffuse from the lumen down the concentration gradient into epithelial cells
    glucose attach to the co-transporter protein and are actively transported into the epithelial cell against their concentration gradient
    glucose moves by facilitated diffusion from the epithelial cell into the blood
  • what are the stages of interphase
    G1 and G2
    S phase
  • what occur during interphase
    protein synthesis
    chromosomes are uncondensed so not visible
    DNA unwound as chromatin so genes are accessible for transcription
    grows and makes enough organelles for two cells
  • what occurs during S phase
    DNA replication
    DNA checked for errors to prevent mutations being passed on
  • chromatin vs chromosomes
    chromatin - unwound DNA allows DNA replication
    chromosomes - condensed , tightly packed DNA
  • describe the structure of an antibody and label the diagram
    produced by b-cells
    4 polypeptide chains
    chains joined by disulphide bridges
    unique 3D shape
    A) light chain
    B) heavy chain
    C) constant region
    D) variable region
    E) antigen binding sites
  • what is an antibody
    a protein / immunoglobin specific to an antigen
    produced by b-cells
  • compare passive (P) and active (A)immunity
    A requires exposure to an antigen P does not
    P protection is immediate
    A memory cells are produced
    A protection is long term as antibodies are produced in response to the complementary antigen being present in the body
    P protection is short term as antibodies are broken down
  • describe give examples of active immunity
    immune system makes antibodies in response to an antigen
    natural - immune after catching a disease
    artificial - immune after vaccination