Genetic information, variation and relationships between organisms-Genetic diversity can arise as a result of mutation or during meiosis

Question 1

What is a Gene?

Answer 1

 a section of DNA that codes for a protein
 made out of intron and exon
 intron = non-coding DNA (function e.g. turns gene on or off)
 exon = coding DNA (codes for protein)

Question 2

How does a Gene/Exon code for a Protein?

Answer 2

 made out of a sequence of bases
 each 3 bases code for 1 amino acid (called triplet code)
 therefore,
 sequence of bases
 determines sequence of triplet codes
 which determine the sequence of AAs
 = polypeptide chain/primary structure (folds to secondary, then to tertiary/quaternary)

Question 3

Properties of triplet code?

Answer 3

 degenerate = each AA has more than one triplet code
 non-overlapping = each base is read only once
 stop codes = occur at end of sequence – do not code for an AA

Question 4

How does a mutation lead to a non-functional enzyme?

Answer 4

 change in base sequence
 change in sequence of triplet codes
 change in sequence of AAs
 change in primary structure
 change in tertiary structure 
 change in active site shape
 can no longer form enzyme-substrate complex

Question 5

How is a protein assembled?

Answer 5

 by transcription and translation
 transcription = production of a single stranded complementary copy of a gene (called mRNA)
 translation = use sequence of codons on mRNA to assemble protein (tRNA brings in AAs)