AS Biology Cells and living processes

Well presented clear notes on :

  • The importance of the cytoskeleton (how it aids transport and enables cell movement)
  • Undulipodia and cilia
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  • Created on: 18-09-10 08:44
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Biology
Unit 1: Cells, exchange and transport
Module 1: Cells and living processes
Characteristics of living things
MRSNERG
Movement, respiration, sensitivity, nutrition, excretion,
reproduction, growth
Some bacteria do not respire ­ use other chemical reactions to
obtain energy
Organelles and ultrastructure
Ultrastructure (fine structure) ­ the detailed structure of the
internal components of cells as revealed by the electron
microscope
Organelles ­ structure inside a cell, each organelle has a specific
function
Division of labour
Each type of organelle has specific role within the cell = division of
labour
Movement and stability in cells
Cytoskeleton
Cells contain a network of fibres made of protein ­ fibres keep the
cell's shape stable ­ provide an internal framework ­ cytoskeleton
Some of the fibres (called actin filaments) similar to muscle fibres ­
able to move against each other ­ they cause the movement seen
in some white blood cells ­ they also move some organelles around
in cells
Other fibres = microtubules ­ cylinders 25nm in diameter ­ made
of a protein called tubulin
Microtubules may be used to move a microorganism through a
liquid or to waft a liquid past the cell
Other proteins present on the microtubules move organelles and
other cell contents along the fibres ­ how chromosomes are
moved during mitosis ­ how vesicles move from the endoplasmic
reticulum to golgi apparatus ­ proteins known as microtubule
motors and they use ATP to drive movements

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Biology
Unit 1: Cells, exchange and transport
Module 1: Cells and living processes
Flagella (undulipodia) and cilia
In eukaryotes flagella (undulipodia) and cilia are structurally the
same
Hair-like extensions which stick out from the surface of cells
Each made up of a cylinder containing 9 microtubules arranged in a
circle ­ also two microtubules in a central bundle
Undulipodia are longer than cilia
The undulipodium that forms the tail of a sperm cell can move the
whole cell
Trichomonas causes urinary infections ­ the whip-like…read more

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Biology
Unit 1: Cells, exchange and transport
Module 1: Cells and living processes
Vesicles and vacuoles
Vesicles ­ membrane-bound sacs found in cells ­ used to carry
many different substances around cells
In plant cells, large cell vacuole maintains cell stability ­ filled with
water + solutes so pushes cytoplasm against cell wall ­ makes cell
turgid
Turgid plant cells support plant ­ important for non-woody plants
Plant cell walls
Are on the outside of plant cell plasma membranes (cell surface
membranes)
Made of cellulose…read more

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