Genetics test Flashcards
How many chromosomes are in a normal gamete
23
What are autosomes
22 pairs of identical chromosomes
What are histones
structural proteins used to form chromosomes
What does the centromere do
divides the chromosome into short arm (p) and long arm (q)
What is metacentric
when the chromosomes have equal arm lenth
What is submetacentric
when the chromosomes have one arm longer than the other
What is acrocentric
When the p arm (short) contains such small amounts of genetic material that it is almost negligible
What is advanced maternal age
pregnant women who will be 35 or older on their expected date of confinement
How many sets of chromosmes do triploidy fetuses have? Total? How does this normally happen?
3 sets of chromosomes, totally 69. They are rarely born alive and come from 2 sperm fertilization
How many sets of chromosomes do tetraploidy fetuses have? Total? When do they miscarry?
4 sets of chromosomes, totally 96. They miscarry in the first trimester
What is an aneuploid? Examples?
any genotype in which the total chromosome number is not a multiple of 23. Example: monosomy and trisomy
What is meiotic nondisjunction
a pair of chromosomes fail to separate during either of the meiotic divisions
What are the two categories of structural abnormalities
balanced and unbalanced
What is a balanced structural abnormality
has normal amount of chromosomal material and has functional centromere with 2 functioning telomeres
What is an unbalanced structural abnormality
chromosome has missing or extra genetic info
What is Robertsonian translocation
where 2 chromosomes lose short arem and fuse near centromeric region, this leads to balanced karyotypes with 45 chromosomes (leads to trisome 21 offspring)
What are alleles
variants of a gene
What are wild-type alleles
one prevailing allele for a gene
What is de novo
neither parent possessed the mutation
If both parents are carriers of an autosomal recessive condition, what percentage of their offspring with have the disease
25%
What are consanguineous unions
mating between individuals who are second cousins or closer ( there is an increased risk of autosomal recessive disorders)
Who are x-linked recessive mutations expressed in? Examples?
Expressed in all males and homozygous females, passed on by females
From which side is mitochondrial DNA inherited from
maternal, sperm mitochondria are eliminated from the forming embryo
Mitochondrial diseases typically manifest as dysfunction in what organs
high-consuming organs: brain, muscle, heart, and kidneys
