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• five kingdoms


  • Animals
  • Plants
  • Fungi
  • Protoctists
  • Prokaryotes
• eukaryotic organisms

  have a nucleus, membrane bound organelles, and a cell membrane. they can be single celled or multicellular.

  
• animal and plant cells 


  they are both eukaryotic cells

  
• Prokaryotic organism 


  Are in a separate kingdom. They are always single cells and do not contain a nucleus. instead the genetic material is found in the cytoplasm. The cells are substantially smaller than eukaryotic cells.
• Animals 


  They are multicellular.

  Their cells contain a nucleus with a distinct membrane.

  Their cells do not have cellulose cell walls.

  Their cells do not contain chloroplasts (so they are unable to carry out photosynthesis).

  They feed on organic substances made by other living things.

  They often store carbohydrates as glycogen.

  They usually have nervous coordination.

  They are able to move from place to place

  
• Nucleus 


  contains the genetic material (DNA) which controls the activities of the cell
• Cytoplasm


  A gel-like substance composed of water and dissolved solutes

  supports internal cell structures

  site of many chemical reactions, including anaerobic respiration.

  site of many chemical reactions, including respiration.
• cell membrane 


  holds the cell together, separating the inside of the cell from the outside

  controls which substances can enter and leave the cell
• ribosomes


  site of protein synthesis
• Mitochondria 


  site of most of the reactions involved in aerobic respiration, where energy is released to fuel cellular processes

  cells with high rates of metabolism(carrying out many different cell reactions) have significantly higher number of mitochondria than cells with fewer reactions taking place.
• Plants


  They are multicellular.

  Their cells contain a nucleus with a distinct membrane.

  Their cells have cell walls made out of cellulose. Their cells contain chloroplasts (so they can carry out photosynthesis).

  They feed by photosynthesis.

  They store carbohydrates as starch or sucrose. They do not have nervous coordination

  
• cell wall


  made of cellulose ( a polymer of glucose)

  gives the cell extra support, defining shape
• Chloroplast


  a plastid in green plant cells which contains chlorophyll and in which photosynthesis takes place.
• A permanent vacuole 


  contains cell sap; a solution of sugars and salts dissolved in water

  used fr storage of certain materials

  also helps support the shape of the cell
• They are usually multicellular but some are single-celled (e.g. yeast)

  Their cells contain a nucleus with a distinct membrane

  Their cells have cell walls made of chitin (chitinous cell walls)

  Their cells do not contain chloroplasts

  Some fungi are parasitic and feed on living material

  Some fungi store carbohydrates as glycogen

  They do not have nervous coordination

  Examples of fungi include: moulds, mushrooms, yeasts

  
• Multicellular Fungi 


  mainly made up of thread like structures known as hyphae that contain many nuclei and are organised into a network known as a mycelium
• saprotophic nutrition


  they feed by secreting extracellular digestive enzymes onto the food and then absorbing the digestive molecules.
• Protoctists


  They are mainly microscopic and single-celled but some aggregate into larger forms, such as colonies or chains of cells that form filaments

  Their cells contain a nucleus with a distinct membrane

  Some have animal cell features and some have plant cell features

  This means some protoctista photosynthesise and some feed on organic substances made by other living things

  They do not have nervous coordination

  Examples of protoctists include: amoeba, Paramecium, Plasmodium, Chlorella

  
• Bacteria

  They are microscopic single-celled organisms

  Possess a cell wall (made of peptidoglycan, not cellulose), cell membrane, cytoplasm and ribosomes

  Lack a nucleus but contain a circular chromosome of DNA that floats in the cytoplasm

  Plasmids are present in prokaryotes - these are small rings of DNA (also floating in the cytoplasm) that contain extra genes to those found in the chromosomal DNA

  They lack mitochondria, chloroplasts and other membrane-bound organelles found in eukaryotic cells

  
• Flagellum


  a slender threadlike structure, especially a microscopic appendage that enables many protozoa, bacteria, spermatozoa, etc. to swim.
• Specialised Cells 


  those which have developed certain characteristics in order to peform particular functions
• Differentiation


  the process by which cells develop the structure and characteristics needed to be able to carry out their functions
• Sperm cells


  role in reproduction

  the head contains the genetic material for fertilisation in haploid nucleus

  the acrosome in the head contains digestive enzymes so that a sperm can penetrate an egg cell wall

  the mid piece is packed with mitochondria to release energy needed to swim and fertilise the egg

  the tail enables the sperm to swim

  
• Ovum cell


  role in reproduction

  contains a lot of cytoplasm which has nutrients for the growth of an embryo

  haploid nucleus contains the genetic material for fertilisation

  cell membrane changes after fertilisation by a single sperm so that no more sperm can enter

  
• Ciliated epithelial cells


  role in wafting bacteria and other particles (trapped in mucus) up the throat or down the stomach

  movement of mucus in the trachea and bronchi

  extension of the cytoplasm at the surface of the cell form hair-like structures called cilia which beat to move particles

  
• Microscopy techniques


  have developed over time, increasing our understanding of cel structure and organelles and sub cellular structures.
• light microscopes 


  developed 17 century.

  The first cells (of a cork) were observed by Robert Hooke in 1665 using a light microscope

  Light microscopes use light and lenses to form a magnified image of a specimen

  has evolved increasing magnification and resolution to enhace the detail of what can be visualised
• modern light microscope


  see images of cells and large sub cellular structures (like nuclei and vacuoles), although stains are often required to highlight certain parts of cells

  The most powerful light microscopes today have a maximum magnification of approximately 1000 to 2000x
• first electron microscope


  developed in the first half of 20th century (1930)

  use beams of electrons rather than light

  the wavelength of beams is much smaller so the resolution is higher and the magnification
• electron microscope


  understand many more subcellular structures such as the mitochondria, chloroplasts and ribosomes

  They have also helped biologists develop a better understanding of the structure of the nucleus and cell membrane

  Electron microscopes have a maximum magnification of approximately 2,000,000x
• Magnification calculations


  does not have units

  
• Converting units 


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• Enzymes

  • Enzymes are proteins that act as biological catalysts to speed up the rate of a chemical reaction without being changed or used up in the reaction
  • They are biological because they are made in living cells
  • Enzymes are necessary to all living organisms as they allow all metabolic reactions to occur at a rate that can sustain life
• Lock and key theory


  the active site is specific to a complimentary substrate shape

  when the enzymes move into the active site the enzyme substrate complex is formed

  when the product leaves the active site the reaction is complete and it is free to take up another substrate
• Substrates cannot fit into denatured enzymes as the shape of their active site has been lost.
• Denaturation is irreversible – once enzymes are denatured they cannot regain their proper shape and the reaction they are catalysing will stop.
• Denaturation can occur due to high temperatures or extremes of pH.
• Enzymes work fastest at their 'optimum temperature'.
• In the human body, the optimum temperature for enzymes is about 37⁰C.
• Heating enzymes to high temperatures beyond the optimum will break the bonds that hold the enzyme together and the active site will lose its shape - denaturing.