Human Bio

• science inquiry


  IV: change/test

  DV: measure

  Hyp: if IV then DV

  Controlled: same

  Improve Reliability - suggest more controlled

  Improve validity - suggest higher sample, repeat trails/whole experiment

  Graph(s):

  - Title (IV+DV)

  - Axis (labelled/units) dv side, lv bottom

  - Continuous (line graph, 2 sets of numbers)

  - Discrete (column graph, words/numbers)
• the cell theory


  in 1800s the german scientists, Schleiden, Schwann and Virchow, put forward the cell theory

  
  

  - all living things are composed of cells

  - cells are the basic unit of structure and function in living things

  - all cells are produced from other cells
• cell structure


  cells are mad up of ORGANELLES which are structures suspended in the cytoplasm that carry out a particular function
• cell membrane


  location: surrounding the cell separating extracellular fluid from intracellular fluid

  description: made of phospholipid bilayer

  function: controls which substances enter and leave the cell
• cytoplasm


  location: inside the cell

  description: thick-watery fluid that suspends cell organelles

  function: contains dissolved ions, salts &c carbohydrates, some chemical reaction take place
• nucleus


  location: inside the cell

  description: contains the genetic material/DNA

  function: contains the DNA which codes for protein production in the cell

  NUCLEOLUS: suspended in nucleoplasm, contains RNA

  NUCLEAR MEMBRANE: separates nucleus from cytoplasm
• mitochondria


  location: inside the cell

  description: contains folded membrane to increase surface area

  function: where cellular respiration occurs to release energy for the cell
• endoplasmic reticulum


  location: inside the cell

  description: series of flattened, sac-like membranes that extend throughout the cytoplasm

  ROUGH ER: lined with ribosomes

  SMOOTH ER: no ribosomes

  function: transports proteins around the cell and involved in the manufacture of lipids
• ribosomes


  location: lining the rough endoplasmic reticulum or free in the cytoplasm

  description: small organelles

  function: where proteins are constructed from amino acids
• golgi body


  location: positioned near nucleus an surrounded by vesicle

  description: consists of parallel smooth membranes

  function: packages proteins, lipids and carbohydrates into vesicles for export from the cell
• vesicles


  location: inside the cell

  description: membrane bound organelle

  function: stores materials for secretion from the cell
• lysosomes


  location: inside the cell

  description: membrane bound vesicles

  function: contains digestive enzymes to break down foreign material in the cell
• centrioles


  location: inside the cell

  description: tube like structures and 90 degrees to one another

  function: produce spindle fibres which assist in separation of chromosomes during cell division
• microtubules


  location: inside the cell

  description: rod-like structures

  function: keep organelles in place or move them around the cell
• Function of the cell membrane

  hint 3Regulates what enters and leave cell

  - selectively permeable

  sensitivity

  - first part of the cell affected by any changes in the extracellular fluid

  Support

  - attached to cytoskeleton
• Cell membrane structure 1

  "Fluid Mosaic model"

  fluid- molecules constantly moving

  mosaic- made of different molecules
• cell membrane structure 2

  Main structure is made of PHOSPHOLIPID molecules (lipids attached to a phosphate group) Arranged in a "BI-LAYER"

  Hydrophilic head and Hydrophobic tail 'Hydro' - Water,

  'philic' - 'loving' 'phobic' - 'hating
• Cell membrane proteins


  CHANNEL PROTEINS - Form a channel through the membrane for smaller molecules to pass through. Used for simple diffusion CARRIER PROTEINS -Bind to larger molecules and help them move across the membrane. Used for Facilitated diffusion or Active transport

  RECEPTOR PROTEINS - Molecules outside the cell can bind with receptor proteins to cause a change within the cell, only bind with particular molecule. SPECIFIC - "LOCK AND KEY MODEL"

  RECOGNITION PROTEINS - Have a carbohydrate group projecting out of the cell which act as ID tags, allowing the cell to be recognised as "self" or a foreign cell, "non-self".
• cell transport


  CELL TRANSPORT refers to the movement of molecules across the membrane, from one side to the other.

  Cell transport processes can be PASSIVE (doesn't require energy) or ACTIVE (requires energy)
• cell transport (3 processes)

  Simple diffusion - diffusion and osmosis - both passive

  
  

  Facilitated transport - facilitated diffusion - passive

  carrier-mediated transport - active

  
  

  Vesicular transport - active
• Diffusion


  the movement of liquids and gases from an area of higher concentration to an area of lower concentration (along the gradient until equilibrium)
• Simple diffusion


  refers only to the movement of lipid-soluble substances that can diffuse between the phospholipids of the membrane.

  Eg. Oxygen, carbon dioxide, fatty acids,
• Osmosis


  movement of H20 molecules from high concentration to low concentration until equilibrium is obtained
• Osmosis - tonicity


  Tonicity is a measure to compare the concentration of water in two different solutions
• Osmosis - hypertonic


  the concentration of solute outside the cell is more than inside the cell.

  Water moves out of hypertonic envrionment to make it more concentration
• Osmosis - hypotonic


  the concentration of solute outside the cell is less than inside the cell

  water moves into hypotonic environment to dilute it
• Osmosis - isotonic


  the concentration of solute outside the cell is the same as the inside the cell

  no movement
• Facilitated transport


  is the use of channel or carrier proteins to move molecules across the membrane, usually larger molecules
• facilitated diffusion - water molecules


  water molecules cannot pass through the phospholipid bilayer as the hydrophobic tails repel water, they must pass through channel proteins
• carrier-mediated transport


  can be CARRIER PROTEINS only open on one side of the cell membrane. Molecules bind to the binding site open side, the protein then changes shape and then opens on the other side to release the molecule. They are specific. Can be used to move substances 'with' (facilitated diffusion) or 'against' (active transport) the concentration gradient
• Active transport (carrier-mediated transport)

  requires energy, which comes in the form of ATP
• Vesicular transport


  is the movement of substances into and out of the cell enclosed in VESICLES
• vesicular transport - endocytosis

  is bringing material into the cell

  cell membrane surrounds and encloses extracellular material.

  vesicle pinches off and suspends in cells cytoplasm.

  Two subtypes: Phagocytosis - for solids, 'cell eating' Pinocytosis - for liquids, 'cell drinking'

  e.g. white blood cells use phagocytosis to engulf bacteria
• vesicular transport - exocytosis

  where contents of a vesicle are pushed out of the cell

  vesicle is formed inside the cell, migrates tot the cell membrane and fuses with it, contents are passed out

  e.g. digestive enzymes from lining of S.I
• Summary of cell transport (table)

  on cell transport pp.
• metabolism


  biochemical processes including anabolic and catabolic reactions in the cell, are controlled in the presence of specific enzymes
• catabolism and anabolism


  Catabolism

  - breaks large molecules into smaller ones

  - releases energy

  e.g. cellular respiration

  Anabolism

  - builds smaller molecules up into larger ones

  - requires energy

  e.g. protein synthesis
• cellular respiration


  process by which organic molecules are broken down in the cells to release energy for the cells activities

  there are 2 forms of cellular respiration:

  > aerobic respiration - requires oxygen

  > anaerobic respiration - occurs in the absence of oxygen

  (both forms begin with the process of glycolysis)
• complete cellular respiration (aerobic) equation

  glucose + oxygen -> 38 ATP + carbon dioxide + water

  C6H12O6 + O2 -> 38ATP + 6CO2 + 6H20
• Glycolysis


  In a series of ten steps one glucose molecule is broken down to form 2 molecules of pyruvate . During this process bonds are broken and energy is released, and 2 ATP molecules are formed. Glycolysis occurs in the cytoplasm and does not require oxygen.