CH3 DNA replication Flashcards
1
Q
Why do cells divide
A
To produce more cells needed for growth or repair of tissues
2
Q
Why is DNA replication described as semi conservative
A
Each new molecule of DNA contains one new strand and one old strand of DNA
3
Q
What enzymes are involved in DNA replication
A
- DNA helicase to seperate strands of DNA
- DNA polymerase to form phosphodiester bonds between nucleotidees
4
Q
What are the stages of DNA replication
A
- enzyme DNA helicase causes two strands of DNA to unzip
- free nucleotides are attracted to their bases
- once nucleotides are lined up, they are joined together by DNA polymerase
5
Q
What is continuous replication
A
- occurs on leading strand
- DNA polymerase can only bind to 3’ and travels 3’ to 5’
- strand can be continuously replicated as unzipped
6
Q
What is discontinuous replication
A
- occurs on lagging strand
- unzipped from 5’ end so polymerase has to wait for a section to be unzipped and then work back along
- causes DNA to be produced in sections called Okazaki fragments
7
Q
What is a consequence of replication errors
A
Mutation
8
Q
Why is DNA described as genetic code
A
- proteins are the foundation of living things
- DNA codes for a sequence of amino acids
9
Q
What is a gene
A
A section of DNA that contains the complete sequence of bases for an entire protein
10
Q
How is an amino acid coded for
A
Three bases called a codon
11
Q
What is a degenerate code
A
- there are 64 different base triplets or codons possible
- only 20 amino acids
- many amino acids can be coded for by more than one codon
