Cell biology

• What are eukaryotic cells?

  • Cells that contains genetic material in the nucleus
• what are prokaryotic cells?

  • Cells that does not contain genetic material enclosed in the nucleus
• What does the nucleus control?

  cell activity
• what does the cell memberane control?


  what goes in and out of cell
• what is mitochondria?


  site of aerobic respiration
• what is cytoplasm and what does it contain?

  where most chemical reactions occur

  (contains enzymes)
• what are ribosome?


  site of proteinsynthesis
• What are the differences between eukaryotic and prokaryotic cells?

  • eukaryotes is larger whereas prokaryotes are smaller
  • Eukaryotes contains nucleus whereas prokaryotes doesnt, they contain plasmids which are small rings of dna
  • Eukaryotes are found in plants and cells whereas prokaryotes are found in bacteria cells
• What does plant cells contain that animal cells don‘t?

  • vacuole: contains cell sap and keeps the cell rigid
  • Cell wall: made of cellulose and supports and strengthens the cell
  • Chloroplast: site of photosynthesis and contains chlorophyll
• what is resolution?


  ability to distinguish between 2 points
• how do you calculate magnification?

  image size/ real size
• what are the differences between light and electron microscope?

  • in a light microscope you can see cell in 2d whereas in an electron microscope you can see cells in 3d
  • in a light microscope, you can see cell in colours whereas in an electron microscope you cant see
  • in a light microscope there is a lower resolution/magnification whereas in an electron microscope you cant see a higher resolution/ magnification
• viewing onion cells

  • add drop of water onto clean side and cut an onion and separate out into layers
  • use tweezers to peel of epidermal tissue from the bottom of one of the layers
  • using tweezers place epidermal tissue onto the clean side and add a drop of iodine solution to stain and highlight cell and place transparent cover slip
  • carefully tilt and lower it so it covers the specimen
• Using light microscope

  • clip slide and select lowest powered objective lens and use coarse adjustment knob to move the stage up to just below objective lens
  • look down at eyepiece and use coarse adjustment knob to move the stage downwards until image is roughly in focus
  • adjust focus with fine adjustment knob until clear image of what’s on slide
• Conversions

  km-m= x1000

  m-cm= x100

  cm-mm= x10

  mm- um= x1000

  Um- nm= x1000
• what is cell differentiation?

  process of cells becoming specialised to carry out its job
• Cell differentiation in animal cells?

  • Ability to differentiate is lost at an early stage after they have become specialised
• cell differentiation in plant cells?

  dont ever lose ability to differentiate
• what are sperm cells specialised for?

  reproduction
• what is the function of sperm cells?

  • To get male dna to female dna
  • Has long tail and streamlined head to help swim to egg cell
  • Lots of mitochondria to generate energy
  • Carries enzyme in head to digest through egg cell membrane
• what is nerve cells specialised for?

  rapid signalling
• what is the function of nerve cell?

  • to carry electrical signals from one part of body to another
  • They are long to carry more distance
  • Have branched connections at the end to connect to other nerve cells and form a network throughout the body
• what is muscle cell specialised for?

  contraction
• what is the function of muscle cells?

  • To quickly contract
  • Long to have space to contract
  • Contains lots of mitochondria to generate energy for contraction
• what is root hair cells specialised for?

  water and minerals absorption
• what is the function of root hair cells?

  • give plants big surface area for water and mineral ion absorption from soil
  • grow into long hair and stick out into soil
• what are phloem and xylem cells specialised for?

  Transporting substances
• what is the function of phloem and xylem tubes?

  • transport substances such as food and water around plants
  • to form tubes, cells are longer and joined end to end
  • xylem cells are hollow in the centre
  • phloem cells have very few subcellular structures so that stuff can flow through them
• what does phloem carry and describe the process

  • they carry glucose
  • translocation- living cells have end plates with holes flows in both directions
• what does xylem carry and describe the process

  • Carry water and minerals
  • Transpiration- dead cells cell walls toughened by lignin flows in one direction
• what are chromosomes?

  • colied up lengths of dna molecules
  • they contain genetic information in the nucleus
  • 23 chromosomes are collected from each parent
• what is mitosis?

  • cell cycle stage where cell divides
  • Needed for growth, development and repair
• describe cell cycle

  • Cell grows and increases amount of subcellular structures
  • DNA duplicates so there is one copy for each new cell
  • DNA is copied and forms x shaped chromosomes
• describe mitosis

  • chromosomes line up at the centre of the cell and cell fibres pull them apart
  • 2 arms of each chromosomes go to opposite ends of the cell
  • memberanes forms around each of the sets of chromosomes which become the nuclei of 2 new cells as nucleus has divided
  • cytoplasm and cell memberane divide
  • 2 new identical daughter cells are formed
• describe process where prokaryotic cells are replicated by binary diffusion

  • circular dna and plasmids replicate
  • cell gets bigger and circular dna strands move to opposite poles of the cell
  • cytoplasm begins to divide and new cells walls begin to form
  • cytoplasm divides and 2 daughter cells are produced
• what are stem cells and where are they found

  • Undifferentiated cells that are capable of giving rise to many more cells of the same type
  • No stucture, can only become another cell
  • Found in human embryos (pluripotent)
  • Also in adult bone marrow (multipotent)
  • Also found in meristem of a plant
• What can stem cells do?

  • Can produce clones
  • Can differentiate into specialised cells to use in medicine or research
• what does embryonic stem cells do?

  • can be used to replace faulty cells in sick people by making insulin-producing cells for people with diabetes, nerve cells for people paralysed by spinal injuries
• therapeutic cloning

  • an embryo can be made to have some genetic information as the patient
  • This means stem cells produced from it would also contain same genes and not be rejected by patients body if used to replace faulty cells
  • stem cells grown in lab can become contaminated with a virus which could pass onto patient making them even sicker
• stem cells in bone marrow (a spongy tissue found in centre of some bones)

  • Can turn into different types of blood cells, red blood cells (carries oxygen around the body), white blood cells (helps fight infection), platelets ( helps to stop bleeding)