Topic 1 Revision - Inside Living Cells - GCSE Edexcel B2

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Preview of Topic 1 Revision - Inside Living Cells - GCSE Edexcel B2

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B2 Topic 1 Revision­ Inside Living Cells
DNA Structure and Function
DNA structure
Chromosomes are made up of genes
Genes are made up of DNA
The DNA molecule is two strands coiled together to form a
The sides of the ladder are made of a sugar called deoxyribose
and phosphate groups.
The strands are linked by a series of paired bases:
DNA function
DNA contains the genetic code
The genetic code tells the cell to make particular proteins
A gene is a length of DNA that gives the instructions for making a certain protein
Only one side of the ladder acts as the code for making proteins: this is called the coding strand
Proteins are made up of long chains of amino acids, the order of which is different for each protein
and is decided by DNA.
Examples of proteins include the hormone INSULIN and enzymes.
Protein Synthesis
A type of organelle (the name for any part of the cell with a specific function)
In ribosomes, proteins are assembled in the cytoplasm
1. DNA unwinds along a small length
2. Complimentary base pairs match up

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For example:
DNA coding strand sequence:
mRNA sequence:
3. mRNA made
4. mRNA leaves nucleus
Stage 2: Translation
1. mRNA attaches to a ribosome
2. tRNA anticodons pair up with complimentary mRNA codons (a triplet of bases)
3. There is a specific tRNA for each of the 20 different amino acids
4.…read more

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FERMENTATION ­ using microorganisms to break down nutrients into useful products, for example:
penicillin, Quorn, soy sauce.
Sections of DNA coding for specific proteins can be transferred into microorganisms, which are then
cultivated in fermenters to produce useful substances, for example: HUMAN INSULIN
Aseptic Conditions
Maintained by:
o The inside of the tank and pipes are cleaned and sterilised by very hot steam under high
pressure between batches.…read more

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Aerobic Respiration
Provides the energy for work (e.g.: muscle contraction, building proteins and sending messages through
DIFFUSION = movement of molecules from an area where they are at a high concentration to an
area where they are at a lower concentration.
1. Glucose and oxygen diffuse from capillaries into respiring cells
2. Carbon dioxide diffuses from respiring cells into capillaries
3. Capillary walls are only one cell thick, so substances can diffuse through them easily.…read more



A well presented set of notes with good detail and some annotated diagrams.These would be useful for most GCSE Biology specifications. As they are not in colour highlighting key words might be helpful. Team these up with a quiz or  a set of flashcards to test your knowledge.

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