U1 KA2- Structure Of DNA Flashcards
What form is genetic code?
The base sequence of DNA
What is stored by genetic code?
Instructions for making proteins
Name all of the components in a nucleotide
- A phosphate
- A deoxyribose sugar
- A base
What are the 4 DNA bases and their pairs?
- Adenine’s complementary base pairs is thymine
- Cytosins’s complimentary base pair is guanine
What forms the sugar phosphate backbone of DNA?
The phosphate of one nucleotide is joined to the deoxyribose sugar of the
next nucleotide
What shape is a DNA molecule?
A double helix
Describe the strands of a double helix
Anti parallel (they run in the opposite direction from each other)
What are the two DNA strands held together by?
Weak hydrogen bonds between complementary bases
What are chromosomes composed of?
Tightly coiled DNA
What is at the 3’ end of DNA?
A deoxyribose sugar
What is at the 5’ end of DNA?
A phosphate
What are the requirements for DNA replication?
-DNA template
-free nucleotides
-ATP
-DNA primers
-enzymes
What is the first step of DNA replication?
The DNA helix is unwound as hydrogen bonds between bases break to form two template strands
What is a primer?
A short strand of nucleotides
In DNA replication, how is the leading strand synthesised and how is the lagging strand synthesised?
The leading strand is replicated continuously while the lagging strand is replicated in fragments
State the two enzymes used in DNA replication
DNA polymerase, and ligase
State the role of ligase in DNA replication
To join together the fragments of DNA on the lagging strand
In what direction does DNA polymerase add DNA nucleotides?
3’ to 5’
State the role of DNA polymerase in DNA replication
Adds nucleotides and proofreads
Where does PCR occur?
In vitro
What is PCR?
A technique used to create many copies of a piece of DNA
PCR ______ a piece of DNA
Amplifies
What are the requirements for a PCR?
-DNA template
-Complementary primaries to target DNA sequence
-Free nucleotides
-Buffer solution to maintain PH
-Heat tolerant polymerase (Taq polymerase)
What allows PCR to be very specific to a particular sequence of DNA?
The primer used is selected to be complementary to a specific target sequence
State some practical applications of PCR
-Forensics (amplifying samples from crime scene)
-Medical (diagnosis of genetic disorders and diseases)
-Paternity testing