Lab 5: Karyotype and Genetics Flashcards
human karyotype
display individuals xsomes arranged in homologous pairs
How is a human karyotype prepared
- Photograph a cell during mitosis (metaphase)
- Put picture into a computer for analysis
- Electronically arrange the xsomes into pairs (according to size and centromere position)
Do you know why it might be necessary to prepare a karyotype?
allows detection of many chromosomal abnormalities (missing or extra)
Metacentric
centromere is in middle of chromosome
Subterminal
between middle and end
Acrocentric
located close to one end
nondisjunction
Extra chromosome (21st pair b/c xsome fail to separate
- Occurs in Anaphase I where both members go to one pole
- Meiosis II where sister chromatids fail to separate in anaphase II and both chromatids go to one pole
how does non disjunction result to genetic problems
results in the production of gametes containing a greater or lesser chromosomal amount than normal ones
Down Syndrome
extra chromosome one 21st pair
Patau syndrome
extra chromosome on 13th pair
Edwards syndrome
extra chromosome on 18th pair
Turner syndrome
female w/ only one X
- Female sex organs do not mature, menstruate, sterile
Klinefelter’s syndrome
male having XXY
- Phenotypically male but possess female body features
Cri-du chat
Deletion of tip of one of 5th chrosomosomes
- cries like a cat
steps of solving genetic problems
- Define alleles
- determine genotypes of parents and types of gametes produced
- use punnett square
- express result
Genetics
Studies relationships b/w genes and chromosomes
Locus
position of a gene on chromosome
Alleles
alternate forms of same gene (A and a) found at same locus on homologous chromosomes (codes different phenotype)
First Filial (F1) Generation
offspring resulting from crossing of individuals of parental generation
Second Filial (F2) Generation
offspring resulting from crossing F1 members
monohybrid cross
examines inheritance of a single trait
dihybrid cross
examines inheritance of 2 diff trains on 2 diff pairs of homologous chromosomes
Incomplete Dominance
Neither allele is dominant
When result is hetero it shows a third phenotype
Multiple Allele inheritance
Some genes show more than 2 alternate forms such as ABO blood types (IA, IB, i)
Polygenic inheritance
Multiple alleles act together to get a characteristic (skin, height, eye)
Sex linked inheritance
Sex-linked diseases are inherited through one of the sex chromosomes, which are the X and Y chromosomes.
pedigree
Diagram of family history using symbols to
show relationships (genetic variants, traits, diseases)
