Genetics - DNA and Mutations 151-155 Flashcards
what is DNA
3 points
1) deoxyribonucleic acid, the chemical that all the genetic material in a cell is made from
2) it contains coded information that puts an organism together
3) it’s a polymer that’s made up of two strands coiled together to form a double helix shape
where is DNA found
2 points
1) in the nucleus of animal and plant cells
2) in long structures called chromosomes
what is a gene
2 points
1) a small section of DNA found on a chromosome
2) each gene codes for a particular sequence of amino acids which are put together to make a specific protein
what is a genome
the entire set of genetic material in an organism
why is it important to understand the human genome
4 points
1) allows scientists to identify genes in the genome that are linked to different types of diseases
2) knowing this helps us to understand inherited diseases better helping to develop treatments
3) scientists can also use genomes to trace migrations of certain populations
4) all humans descend from a common ancestor in Africa, genomes help to see when new populations split off and migrated away from Africa
what is the structure of DNA
5 points
1) DNA strands are polymers of monomers called nucleotides
2) each nucleotide has a sugar, phosphate group and one ‘base’
3) the sugar and phosphate groups form a ‘backbone’ to the DNA strands, one of four bases- A, T, C, G - join to each sugar
4) each base links to a base on the opposite base, A links to T and C links to G
5) it’s the order of bases in a gene that decides the order of amino acids in a protein
how does a ribosome make DNA
3 points
1) they use the code in DNA, however the DNA code needs to get from the DNA to the ribosome
2) this is done by using a mRNA, which is made by copying the code from DNA
3) the mRNA acts as a messenger between DNA and the ribosome, the correct amino acids are brought to the ribosomes in the correct order
what are different types of protein and there functions
3 points
1) enzymes - act as biological catalysts to speed up chemical reactions in the body
2) hormones - used to carry messages around the body
3) structural proteins - they’re physically strong, e.g. collagen strengthens connective tissues
what is a mutation
a random change in an organism’s DNA
when do mutations occur
2 points
1) when a chromosome isn’t replicated properly
2) chance of a mutation is increased by exposure to certain substances or some types of radiation
what do mutations do
1) change the sequence of the DNA bases in a gene, which produces a genetic variant
2) they can sometimes lead to changes in the protein that it codes for
how can a mutation effect the proteins
4 points
1) most mutations have very little or no effect
2) some can seriously affect a protein, the proteins shape could be altered
3) for example if the shape of an enzymes active site is changed, its substrate may no longer bind to is
4) structural proteins could lose their strength if their shape is changed, making them useless at providing structure
what happens if there’s a mutation on a non-coding DNA
it can alter how genes are expressed
what are the different ways a mutation can change the DNA base sequence
3 points
1) insertions
2) deletions
3) substitutions
what is an insertion
3 points
1) where a new base is inserted into the DNA base sequence where it shouldn’t be
2) this changes the way the groups of three bases are ‘read’ which can change the amino acid they code for
3) they can change more than one amino acid as they have a knock-on effect on bases further on in the sequence
what is a deletion
2 points
1) when a random base is deleted from the DNA base sequence
2) like insertions the change the way a base sequence is ‘read’ and has a knock on effect further down the sequence
what is a substitution
when a random base is the DNA base sequence is changed to a different base
