6.1.5 - DNA structure Flashcards
(16 cards)
What is DNA?
A polymer made from 4 different nucleotides.
What does a nucleotide consist of?
A common sugar and phosphate group with one of four different bases attached to the sugar.
What are the 4 bases and their pairings?
A-T
C-G
What does a sequence of 3 bases code for?
A particular amino acid.
What does the order of bases control?
The order in which amino acids are assembled to produce a particular protein.
DNA is the polymer. What is the monomer?
Nucleotide unit
Describe protein sysnthesis
Proteins are synthesised on ribosomes, according to a template. Carrier molecules bring specific amino acids to add to the growing protein chain in the correct order.
When the protein chain is complete, it folds up into a unique shape which enables the protein to do their job as enzymes, hormones or forming structures in the body such as collagen
Explain simply how the structure of DNA affects the protein made
The sequence of bases affects the sequence of amino acids, which in turn affects the protein that is synthesised.
What is a mutation?
A change in the DNA base sequence
Are mutations common
Yes, they spontaneously happen in our cells continually
2 things increase risk of mutations
- carcinogens - harmful chemicals
- Certain types of radiation e.g. x-rays
What is non-coding DNA
DNA that isn’t part of a gene, so doesn’t code for a specific protein
It is only important for gene expression
3 types of mutation
- insertion
- substitution
- deletion
substitution mutation
One base is substituted for another random base
Changes amino acid
Insertion
Extra base inserted into the sequence - worse than substitution as all subsequent amino acids moved along so more amino acids change
Deletion
All subsequent amino acids shift so more amino acids changed
