Genome Projects and Gene Technology Flashcards
1
Q
What is a genome?
A
All the genes that an organism has.
2
Q
Why is the DNA heat to 95°C during PCR?
A
- Produce single stranded DNA
- Breaks weak hydrogen bonds between strands
3
Q
Why do you add primers during PCR?
A
- Attaches to start of the gene
- Replication of base sequence from here
- Prevents strands annealing
4
Q
Explain why ‘base-pairs’ is a suitable unit for measuring the length of a piece of DNA.
A
- DNA is 2 chains joined by linking of 2 bases
- Bases are a constant distance apart
- Each base-pair is same length
5
Q
Name one mutagenic agent.
A
- High energy radiation /ionising particles e.g. α, β, γ and X-rays
- Cosmic rays
- UV light
6
Q
Describe how DNA is replicated in a cell.
A
- DNA strands separate as weak hydrogen bonds broken
- Parent strand acts as a template
- Nucleotides line up by complementary base pairing (Adenine to Thymine, Cytosine to Guanine)
- DNA polymerase joins adjacent nucleotides on the developing strand via condensation and formation of phosphodiester bonds
- 5’ to 3’ direction
- Each new DNA molecule has 1 template and 1 new strand
- Formed by semi-conservative replication
7
Q
A deletion mutation occurs in gene 1. Describe how a deletion mutation alters the structure of a gene.
A
- Removal of one or more bases
- Results in a frameshift
8
Q
Describe the polymerase chain reaction.
A
- Heat DNA to 95°C to break weak hydrogen bonds/separate strands
- Add primers and add nucleotides
- Cool to 50°C to allow binding of nucleotides and primers
- Add heat-stable DNA polymerase
- Heat to 75°C
- DNA Polymerase joins nucleotides together
- Repeat cycle many times
9
Q
Why is the DNA polymerase used during PCR heat-stable?
A
So that it does not denature when the solution is heated.
10
Q
Describe the main stages in the copying, cutting and separation of the DNA.
A
- Heat DNA to 95°C so strands separate;
- Cool to 50°C so that primers bind to DNA
- Add DNA polymerase/nucleotides
- Use of restriction endonuclease enzymes to cut DNA at specific base sequence
- Use of gel electrophoresis
- Shorter fragments move further
11
Q
Describe a plasmid.
A
- Circular DNA
- Separate from main bacterial DNA
- Contains only a few genes
