Genetics Flashcards
how are chromosomes arranged?
22 pairs of autosomal pairs
1 pair of sex chromosomes
what is meiotic non disjunction
when two homologous chromosomes move into the same daughter cell resulting in monosomic or trisomic offspring
trisomy 21 is…
downs syndrome
trisomy 18 is…
Edwards syndrome
trisomy 13 is…
patau’s syndrome
turner’s syndrome is…
An X chromosome monsomy
only one X chromosome from mother
Paternal X chromosome missing due to non disjunction
Klinefeltor’s syndrome is…
47, XXY
what is reciprocal translocation of genes
interchange of genetic material between non homologous chromosomes
what is robertsonian translocation
Acrocentric chromosomes lose short arms and the long arms fuse together to form a single long chromosome.
what is insertion
one chromosome passes on its genetic material to another without reciprocation.
what is an inversion
segment of a chromosome undergoes 2 breaks and reinserted in a reversed order
What are de novo mutations
Mutations that occur despite having no family history
Acquisition of mutation maybe…
De novo germline
Inherited germline
De novo somatic
What is a mutation
DNA sequence changes which result in genetic diseases
Rare (population frequency <1%)
What are alleles
single genes differing between individuals in DNA sequence
(common such as eye colour)
What is gene loci
Area of chromosome where gene is located
What is a polymorphism
More common sequence changes not resulting in disease
~5% of population
Distinction between polymorphisms and mutations increasingly blurred as more genetic links are found for disease
Homozygous dominant vs homozygous recessive vs heterozygous
Single nucleotide polymorphisms SNPs are…
Most common type of polymorphism
Most are harmless
Some can cause disease
Increasingly detected by sequencing
What is acetylation in dna
It spreads out dna so it cab be transcribed
What is methylation in DNA
It coils DNA strands more tightly so less likely to be transcribed
What happens if promoter region is deleted
The gene will be silenced
