6.1 dna and inheritance

Question 1

genes definition

Answer 1

a short sequence of dna that codes for a specific sequence of amino acids to make a protein responsible for a specific characteristic

Question 2

4 bases

Answer 2

adenine
thymine
cytosine
guanine

Question 3

mutations

Answer 3

changes in the sequence of base in the dna
silent mutation—no effect, a change in dna base sequence means the the new triplet still codes for the same amino acid
dramatic effect - a change in DNA base sequence codes for a different amino acid—shale of protein is different, e.g. active site is no longer complementary to substrate

Question 4

protein synthesis

Answer 4

when a particular protein is required, the section of the dna forming the gene is copied by making a mRNA copy
as only the code for one gene and not the whole dna has been copied it is small enough to tracel out of the nucleus
it binds to a ribosome which is where the protein eill be made
the order of bases on the mRNA is ‘read’ in groups of 3 letters by rhe ribosomes. each triplet is then used by the ribosome to guide the correct amino acids into place

The amino acids are carried to the ribosome by a carrier molecule called transfer RNA (tRNA). Each tRNA carries only one specific amino acid.

The amino acids join together to form a protein, which then folds to form a unique 3D shape that allows it to carry out its particular function e.g. it may fold to form the active site of an enzyme, the specific shape of a hormone or form long fibres in structural proteins such as collagen.