principles genetics Flashcards
what is a missense mutation
change of amino acid sequence
what is a nonsense mutation
new termination code
what is a silent mutation
no change of the amino acid sequence
what is a frameshift mutation
addition or deletion of a base
what kind of mutation is sickle cell anaemia
missense
what type of inheritance is sickle cell anaemia
co-dominant
what is klienfelters syndrome
3 sex chromosomes (47 XXY)
what is haemophilia A a genetic deficiency of
clotting factor VIII
what kind of inheritance is haemophilia A
X linked recessive but can be spontaneous mutation
are histones positively or negatively charged
positive
what is the DNA cycle
G1 - S - G2 - M - G1
what does mitosis produce
2 identical diploid daughter cells
what does meiosis produce
4 nonidentical haploid daughter cells
where does variation in meiosis come from
crossing over
independent assortment of homologous chromosomes
what occurs in G1
cell growth
when can mutation occur in the cell cycle
between G2 + M and GI + S
what / when is G0
between G1 and S
when cell functions normally and doesn’t replicate - most of life
when does DNA synthesis and replication occur
S phase
S for synthesis
what occurs during G2
DNA replication checked
2nd growth phase - involving proteins etc
what occurs during M
mitosis
m for mitosis
what can you see with Karyotyping
deletions of >5 million base pairings
looks at chromosomes as a whole
what is transcription
DNA to RNA
what is translation
RNA to protein
what are SNPs
single nucleotide polymorphisms
sequence changes in DNA between genes
what is a polymorphism
any variation in a human genome which has a population frequency of >1%
doesn’t cause disease in its own right but may predispose to a common disease
what is a mutation
DNA variant that causes or predisposes to a specific disease
any inheritable change in the human genome
what is a multifactorial disease
multiple polymorphisms cause a risk of disease - combine with environmental factors to cause disease
genes involved will have low penetrance
what is balanced chromosome rearrangement
translocation - usually normal
same amount of genetic information swapped - all chromosomal material is present
what is unbalanced chromosome rearrangement
translocation
extra or missing chromosomal material
usually 1 or 3 copies of some of the genome
what happens to the child if a parent has balanced chromosome arrangement
child inherits normal 2 copies + balanced = 3 copies
what is an acrocentric chromosome
centromere located very near the end of the chromosome
what is a telocentric chromosome
centromere located at terminal end of chromosome
what is epigenic variation
functional modifications to the genome that don’t involve a change in nucleotide sequence
what is aneuploidy
whole extra or missing chromosome
what is translocation
rearrangement of chromosomes
what is reciprocal translocation
segments from 2 different chromosomes have been exchanged
what is monosomy
missing chromosome from a pair
what is trisomy
extra chromosome in a pair
what is down syndrome
trisomy 21
47 XY
3 copies of 21
what can trisomy 14 cause
miscarriage