Structure and Replication of DNA (2) Flashcards
What is DNA composed of?
Genes
What does DNA code for?
The production of proteins
Why is it important for none of the information to be lost from DNA?
It is very important that all of the genetic information remains as the proteins have to be replicated exactly otherwise the protein will not perform its function and the faulty information will be transferred to the next generations
Why must DNA replication take place before a cell divides?
This is done to ensure that two identical copies of the DNA are produced and that each daughter cell receives a full set of chromosomes
How many chromosomes do gametes contain compared to body cells?
Gametes contain half the mass of DNA when compared to body cells with red blood cells being an exception as they don’t have a nucleus.
What structure does DNA have?
Has a double stranded helix structure
What is the double helix composed of?
It is composed of two strands/chains of nucleotides.
What joins nucleotides together?
The nucleotides are joined together by strong deoxyribose sugar-phosphate bonds.
Why do the sugar and phosphates join?
To form the backbone.
What is a nucleotide composed of?
A phosphate, base and a sugar (deoxyribose in DNA)
How can the carbons in the deoxyribose sugar be numbered?
The end which connects to the phosphate is the 5’ end and the opposite of it is the 3’ end and is where the the other nucleotide would connect via the sugar phosphate bond.
What 4 different bases does DNA have?
Adenine, Thymine, Guanine and Cytosine meaning there are four different kinds of nucleotides.
In which specific manner do the bases form pairs?
Adenine - Thymine
Guanine - Cytosine
This is known as complementary base pairing.
What holds the base pairs?
Hydrogen Bonds.
What makes the 3’ end on the deoxyribose sugar distinct?
The chain is only able to grow by adding nucleotides to the 3’ end.
What is the arrangement of 2 strands with a sugar phosphate backbone running in opposite directions called?
Antiparallel.
What is a group of 3 bases on a DNA strand called?
Triplet.
What does a triplet of bases code for?
Amino acids.
What is DNA except for the fact that it carries all the genetic data?
It is a molecule of inheritance that has the ability to replicate itself.
What must be present for DNA to replicate?
DNA (template)
Primers
Enzymes (polymerase and ligase)
Four different nucleotide types
ATP (energy)
Prior to cell division DNA is replicated by?
DNA Polymerase.
What does DNA Polymerase need before it can start replicating?
Primers
What is a primer?
A primer is a a short strand of nucleotides which bind to the 3’ end of the DNA template, allowing DNA polymerase to add nucleotides.
What does the process of DNA replication produce?
Two identical DNA molecules with each double helix containing a newly synthesised strand and an original strand ensuring that the daughter cells have the same genetic information.
