Flashcards in IMMS DNA AND GENETICS Deck (94)
where is DNA found?
in the nucleus and mitochondria
what is the structure of DNA?
arranged in double alpha helix with complimentary base pairings
DNA coils around histones and form nucleosomes -> supercoils -> chromosomes
how many chromosomes are there?
22 pairs and 2 sex chromosomes
what are autosomes?
chromosomes that don't determine sex
what is the karyotype?
the number and appearance of chromosomes in a cell
the spreads are arranged in size order
what is DNA like in prokaryotes?
no nuclear membrane
DNA in single chromosomes
DNA can be circular
what is DNA like in eukaryotes?
DNA is in a nucleus
DNA is bound to proteins
what is the structure of a chromosome?
made of 2 identical strands of chromatids joined in the centre by a centromere
what are the functions of DNA?
- storing and transferring genetic information
- template and regulator for transcription and protein synthesis
- DNA is the genetic material and the structural basis of hereditary and genetic diseases
what are nucleotides?
they are the building blocks of DNA
what are nucleotides made of?
which nitrogenous bases are found in DNA?
A = T
C = G
which nitrogenous bases are found in RNA?
A = U
C = G
what are duplication mutations?
sections repeat themselves
incorrect protein is generated
what are the different types of deletion mutations?
out of frame
what are out of frame deletion mutations?
the sequence shifts meaning the reading frame of the sequence is changed
what are in frame deletion mutations?
one codon is removed thus only one amino acid is lost
reading frame is not changed
what are mutations of regulatory sequence?
the coding sequence is still intact, but the gene itself is switched on or off
what can cause DNA damage?
what are DNA repair issues?
base or nucleotide excision
mismatch repair or transcription-couples repair
what are non-sense mutations?
a mutation that produces a stop codon
this results in an incomplete, usually non-functional protein
eg duchenne muscular dystrophy
give an example of a condition caused by a non-sense mutation
duchenne muscular dystrophy
what is a mis-sense mutation?
a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid (substitution)
can have varied effect and can be silent non-functional protein
give an example of a condition caused by a mis-sense mutation
sickle cell disease
CAG is replaced with CTG
what is a splice site mutation?
it affects the accurate removal of an intron
what is the expansion of a tri-nucleotide repeat mutation?
a triple repeat is repeated several times in the first part of the coding sequence
give an example of a condition caused by a tri-nucleotide repeat?
if CAG is repeated >36 times the patient will develop huntingtons
what is anticipation?
in diseases such as Huntington's, repeats get bigger when they are transmitted to the next generation
this results in earlier symptoms of greater severity
what is the effect of an insertion mutation?
causes a frame shift