Module 2 Section 3 - Polynucleotides And DNA Flashcards
Nucleotides join together to form
Polynucleotides
Where do nucleotides join up to make polynucleotide bonds
They join up between the phosphate group of one nucleotide and the sugar of another nucleotide
What type of reaction joins nucleotides together to make polynucleotides
Condensation reaction
What is the bond called between nucleotides in a polynucleotide
A phosphodiester bond
What does the phosphodiester bond consist of
The phosphate group and two ester bonds
What is the sugar-phosphate backbone
The chain of sugars and phosphates
How are polynucleotides broken down to nucleotides
by breaking the phosphodiester bonds using hydrolysis reaction
What do two polynucleotide strands join together to form
A double helix
How are DNA polynucleotide strands joined together by
Hydrogen bonding between bases
What is complementary base pairing
Each base can only join with one particular partner
What does adenine always pair with
Thymine
What does cytosine always join with
Guanine
A purine always…..
Pairs with a pyrimidine
How many hydrogen bonds are formed between A and T
2 hydrogen bonds
How many hydrogen bonds form between C and G
3 hydrogen bonds
What twists to form the DNA double helix
Two antiparallel polynucleotide strands
What does DNA do before cell division
It copies itself
What enzyme breaks the hydrogen bonds between the two polynucleotide DNA strands
Helicase
What happens to the helix after Helicase breaks hydrogen bonds
The helix unzips to form two single strands
What acts as a template for a new strand
Each original single strand
What do the free floating DNA nucleotides join to
The exposed bases on each original strand
the DNA nucleotides join to the exposed bases on each original template strand by….
Complementary base pairing. A with T, C with G
How are nucleotides of the new strand joined together by
The enzyme polymerase
What does the DNA polymerase form
Sugar phosphate backbone
Why is DNA replication called semi-conservative replication
Because half of the strands in each new DNA molecule are from the original piece of DNA
Why does DNA replication need to be accurate
Because it needs to make sure genetic information is conserved each time DNA is replicated
What is a mutation
A change to the DNA base sequence
How often do mutations occur
Randomly and Spontaneous
Do mutations always have an effect
Not always however they can alter the sequence of amino acids in a protein which causes an abnormal protein to be produced which may or may not function better than the normal.
