Chromosomes and monogene inheritance Flashcards
monogenic
Mutation in one gene
Balanced abnormality
structural rearrangements of genetic material with no overall gain or loss detected with conventional karyotyping
Q-Banding
Chromosomes are staindes with flourescent dye, which binds to AT-rich DNA
G-banding
Chromosomes are subject to controlled digestion with trypsin and stained with giemsa stain (creates dark and “white” bands.
R-Banding
The chromosomes are heat-denatured in saline before being stained giemsa (reverse coloring from G-banding)
C-Banding
The chromosomes are denatured with a saturated solution of barium hydroxide before giemsa staining
Karyotype
an individual’s complete set of chromosomes.
Comparative genomic hybridization
a molecular cytogenetic method for analysing copy number variations (CNVs) relative to ploidy level in the DNA and refrence DNA.
autozygosity
term used to denote alleles or chromosomal segments of DNA that are identical (homozygous by descent)
Polyploid
Euploidy
Aneuploidy
nondisjunction
Paired chromosomes fail to seperate during anaphase of meiosis I
Monosomic
one pair of chromosomes
Trisomic
aneuploids, carrying an extra chromosome to the normal somatic complement
Robertsonian translocation
Loss of P-arm the chromosomes 13, 14, 15, 21 and 22 are robertsonian chromosomes (short P-arm)
- Segregation of robertsonian translocation can lead to trisomy, monosomy, carrier and normal.
Chromothripsis
is a mutational phenomenon characterized by massive, clustered genomic rearrangements that occurs in cancer and other cases non-cancer cells
Unbalanced abnormality
structural rearrangements of genetic material with overall gain or loss detected with conventional karyotyping
TADs
Gene conversion
Oocyte
is chromosome 23 and x
Spermatocyte
Chromosome is 23, x or y
How is the chromosome structure?
P-arm, Q-Arm, telomere (TTAGGG) in ends and centromere in center
Chromosome roles
- Transmits genetic information through meiosis/mitosis
- Control expression of genetic information
How is expression chromosomal controlled?
Chromosomal territories are specific, active genes are placed near the center and non-active in the periphery (this placement is fluid)
Chromatin loops
occurs when stretches of genomic sequence that lie on the same chromosome (configured in cis) are in closer physical proximity to each other than to intervening sequences
Structural abnormalities
Happens during chromosomes pairing includes:
- Translocation
- Inversions
- Duplication
- Deletion
- Ring
- Marker
Numerical abnormalities
Happens during division errors includes:
- Polyploidies
- Aneuplodies
Recombination event between pseudoautosomal regions near SRY on Y-chromosome
If the SRY moves from the Y- chromosomes leads to XX-males and XY-women
Reciprocal translocation
recombination between two non-homologue chromosomes –> if no deletion at breakpoint person is normal (the breakpoint disturbs dominant gene and increases infertility
P-arm
Has genes for ribosomal DNA
Locus
Unique location of a gene on a chromosome
Allele
Alternative version of a gene
Hemizygote
Only have one allele
Multifactoral
Mutations in several genes plus milieu
- Higher severity equeals greater recurrance
Locus heterogeneity
Mutation in different genes leads to same disease
Allele heterogeneity
Mutation in same gene leads to same disease (can also be different mutation that leads to different disease)
Compound heterozygote
Has two different allele mutations and no healthy allele, leads to an in between phenotype
X-inactivation
is a process by which one of the copies of the X chromosome is inactivated in therian female mammals.
Allelic homogeneity
Haploinsufficiency
Non-allelic homologous
balanced abnormality
difference between mandelian and complex herritage conditions
