All Notes Needed For OCR As Biology (F211 exam)

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  • Created by: Amy
  • Created on: 03-06-12 16:11


Magnification – the degree to which the size of an image is larger than the object itself.

Resolution - the degree to which it is possible to distinguish between two objects that are close together. The higher the resolution, the greater the detail that can be seen.

Light Microscope 

  • x1500 magnification
  • 200nm resolution

Scanning Electron

  • x100 000 magnification
  • 0.1nm resolution

Transmission Electron

  • x500 000 magnification
  • 0.1nm resolution

Staining- stains bind to specific structures increasing contrast and making different structures more visible.


Magnification = Image Size / Actual Size


Nucleus - controls activity of the cell.

Nucleolus – RNA synthesis.

Nuclear Envelope – controls movement of mRNA out of the nucleus.

Rough ER – transports proteins.

Smooth ER – makes and transports lipids.

Golgi Apparatus – modifies and packages proteins.

Ribosomes – protein synthesis.

Mitochondria – aerobic respiration.

Lysosomes – contain powerful digestive enzymes.

Chloroplasts – photosynthesis.

Plasma Membrane – controls entry and exit of molecules from the cell.

Centrioles – form the spindle (only in animal cells and some protoctists).

Flagella – spin using ATP to allow movement of bacterial cells.

Cilia – waft rhythmically, e.g. to move mucus form the lungs.

Protein Synthesis

Nucleus – hold the DNA for the protein.

Nucleolus – make an mRNA copy of the gene

Nuclear Envelope – mRNA moves out of the nucleus through one of the pores.

Rough ER – mRNA attaches to a ribosome on the rough ER.

Ribosomes – 'read' the code on the gene and uses the code to make the protein.

Golgi Apparatus – processes and packages protein into vesicles, these pinch off and move through the cytoplasm.

Cell Membrane – vesicle moves along the cytoskeleton and attaches to the cell membrane, releasing the protein outside the cell.


Actin Filaments – able to move against each other.

Microtubules – made from the protein tubulin.

  • used to move a micro-organism through a liquid or to waft a liquid past a cell.

Microtubule Motors – move organelles and other cell content along the fibres. e.g. vesicles.

- use ATP to drive the movement.

Eukaryotic Cells

  • Plasma membrane
  • DNA wrapped around Histone Proteins
  • Larger Ribosomes
  • Mitochondria

Prokaryotic Cells

  • No plasma membrane
  • Naked DNA
  • Smaller Ribosomes
  • Mesosomes

Animal Cells

  • Nucleus
  • Centrioles
  • Cell Membrane
  • Lysosomes

Plant Cells

  • Nucleus
  • Chloroplasts
  • Cell membrane and cell wall

Cell Membranes

Within Cells – control exchange of materials between organelles and cytoplasm.

  • provide separate areas for reactions (aerobic respiration in mitochondria).

  • isolate enzyme (lysosomes).

  • provide an internal transport system.

  • provide surfaces for reactions (chloroplasts & mitochondria).

Outside Cells – partially permeable barrier.

  • controls exchange of materials between the cell and its environment.

  • communicate by cell signalling.

  • receptor bind to specific hormones.

Phospholipids – forms the basic structure, acting as a barrier to lipid and protein molecules.

Cholesterol – gives the membrane mechanical stability.

Glycolipids – cell recognition and cell adhesion.

Proteins – act as receptors for cell signalling; transport specific molecules.

Glycoproteins –




awesome THANKS!



so good ! thanks!



what did you get for the exam? x



Thank youuuu!!! I have the exam tomorrow!!! X



Amazing. Thank you so much! :D

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