Page 11 - CB1.3 Genetic Varation sciPAD

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CB 1.3 GENETIC VARATION
PRINCIPLES OF GENETIC VARIATION
Some Important Proteins
Keratin (skin, hair, nails, etc.).
Collagen (ligaments, tendons, muscles and bones).
Elastin (ensures your body resumes
its shape after moving).
Haemoglobin (transports oxygen in your blood).
Numerous hormones and antibodies.
DNA to Protein
DNA contains the genetic code for making proteins. Proteins play a
significant structural and biochemical role in organisms. Proteins are
the building blocks for most of your body. In the same way that a wall is
made mostly of bricks, your body is made mostly of protein. In our cells,
proteins (in the form of enzymes) do most of the work. For example,
proteins help break down food to release energy. They also help to
organise the transport of useful chemicals among cells.
The bases that make up a gene are arranged in groups of three (called
a triplet). Each triplet carries the code for a specific amino acid. A
protein is simply a long chain of amino acids folded into a specific shape.
1. Outline why proteins are considered to be ‘important biological molecules’. 


2. Describe the relationship between:
(a) a ‘triplet’ and an ‘amino acid’. 


(b) an ‘amino acid’ and a ‘protein’. 


3. Use the word list to complete the paragraph below.
functions amino acids base sequence proteins triplets building blocks
DNA contains the instructions for linking . These amino acids
bond together to make . Proteins are important because
they are the of our body and carry out many
important within the body. The
of DNA can be broken down into (three-base sequences).
Each triplet carries the code for a specific amino acid.
G C G G
A T G G A A
T
T G C C C
T A C A G A A
T
T
C
G
C G C C
T A
T
A
C C T A
A G G G
C
G
T G T C T T
A
T
A
A
Serine Cysteine Glutamate Valine Histidine Arginine Proline Tyrosine
Methionine
T A C
Amino Acid
Each three-letter code (triplet) carries
the code for an amino acid. In this
case “T-A-C” codes for methionine.
Peptide Bonds
In proteins, amino acids are joined together by
peptide bonds forming a long chain (known as a
‘polypeptide chain’). This polypeptide then folds into
a specific shape known as a protein.
This diagram is a simplification. There are a
number of processes that occur between
reading DNA and producing a protein.
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