Dna revision Flashcards
what are chromosomes?
they’re long thread like structures that are found in the nucleus, and allow DNA to be accurately copied during these cell divisions.
how many chromosomes do we have?
46, 23 pairs.
what are the two different types of chromosomes?
Autosomes and sex cells.
how many of both do we have?
we have 44 autosomes and 2 sex cells.
what is a gene?
a section on dna thats responsible for our traits, eg. hair, eye colour etc.
what does dna stand for?
deoxyribonucleic acid.
what is dna?
a molecule that contains the genetic code that is unique to every individual
what are the four bases in dna?
Adenine, Thymine, Cytosine and Guanine
dna is universal, true or false?
true.
why might you want to put dna from one organism into another?
to give another organism the genes of the first organism, and since genes are universal, this is possible.
what is dna in the shape of?
a corkscrew. and theres usually two strands of dna bound together called a double helix.
what happens when dna strands are split?
half of the dna is new and half of it is copied.
whats a karyotype
a complete listing/layout of the chromosomes.
what are mutations?
changes in the dna sequence.
whats a mutagen?
a substance or chemical that increases the number of mutations.
what are the two different types of mutations?
point mutations and chromosomal mutations.
what causes a point mutation?
when a single base pair is changed, added or deleted.
what happens when a base is changed?
it may change the function of a protein, or it may result in the identical protein.
what causes a chromosomal mutation?
when larger stretches of dna or complete chromosomes are lost or gained, (which is often fatal).
what does a neutral (silent) mutation mean?
it means theres no change in the amino acid, so the final protein remains the same.
what does a negative mutation mean?
the new protein doesnt function as well.
what does a positive mutation mean?
the new protein functions better, (but this is rare).
