Cells

• What is the cell-surface membrane?

  Consists of a phospholipid bilayer with proteins, antigens and others.

  Controls entry and exit of substances.
• What is the nucleus?

  Contains genetic information (DNA).

  This combines with histones (proteins), forming chromatin.

  Chromatin is coiled and super-coiled to form chromosomes.
• What is the nuclear envelope?

  Surrounds the nucleus and has many gaps or pores.
• What are mitochondria?

  The site of aerobic respiration, and therefore adenosine triphosphate (ATP).
• What are ribosomes?

  The site of protein synthesis.

  Use information coded in mRNA to assemble the correct order of amino acids in a protein, called translation.
• What is the smooth endoplasmic reticulum?

  No attached ribosomes

  Responsible for making, storing and transporting lipids and some carbohydrates
• What is the rough endoplasmic reticulum?

  Attached ribosomes make proteins

  These proteins usually are for outside of the cell or to be incorporated in the plasma membrane

  They are then folded, packaged and transported in the RER to the Golgi apparatus
• What is the Golgi apparatus?

  Stack of flattened sacs (cisternae)

  Each is surrounded by a membrane and filled with fluid

  Modifies proteins from RER, for example by adding carbohydrates
• What are Golgi vesicles?


  These package modified proteins from the Golgi apparatus for transport

  Formed when the ends of cisternae are pinched off

  Can form lysosomes, and secretory vesicles, which carry their contents to the plasma membrane to be released
• What are lysosomes?

  Worn-out cell components are moved into these

  Digestive enzymes in the lysosome break them down into their constituents

  Also involved in the digestion of invading pathogens
• What are centrioles?

  Made of protein tubulin

  Involved in spindle formation in mitosis, which separates chromosomes during cell division
• What are erythrocytes and how are they specialised?

  Red blood cells

  No nucleus to hold more haemoglobin

  Flattened biconcave shape for increased surface area, allowing for more efficient diffusion

  Elastic plasma membrane allows cell to change shape to squeeze through capillaries
• What are neurones and how are they specialised?

  Nerve cells

  Has a myelin sheath for insulation and therefore allows for faster signal traveling

  Is long to give it the best possible chance to connect with other nerve cells

  Many dendrites for a wide range in connecting with other nerve cells
• What are squamous epithelial cells and how are they specialised?

  Found in the skin surface tissue, respiratory and digestive tracts and in the lining of hollow organs in the body

  They are flattened, making them well suited for exchange surfaces
• What are sperm cells and how are they specialised?

  Male gametes

  Less cytoplasm to reduce mass for swimming

  Acrosome (front of head) contains enzymes used to penetrate the egg cell

  Flagellum (tail) to allow for fast swimming

  Streamlined head for easier swimming

  Many mitochondria for energy in the middle piece
• What are ova and how are they specialised?

  Female gametes

  Larger than most cells to allow for multiple division of zygote without an overall increase in size

  Surrounded by a gel layer and a layer of cells from the ovarian follicle
• What are striated muscle cells and how are they specialised?

  Make up the skeletal muscles

  Multiple nuclei means that protein synthesis is more efficient

  Long cells allow them to contain the proteins involved in muscle contraction
• How would you calculate magnification?

  mangification = image size / actual size