lab 5 Flashcards
what is a kayotype?
arranging adult or fetal chromosomes into pairs based on the sizes and position of centromeres. it allows for the detection of any abnormalities in chromosomes.
how do you prepare a karyotype?
prepared during metaphase of mitosis because this is when chromosomes are most distinct. arranged in descending sizes (1 is longest, 22 shortest). 1- photograph of chromosomes, 2- cut out individual chromsomes, 3- arrange them in order from descending size and centromere placement (m, s, a).
what is metacentric?
centromere at middle of chromosome
what is subterminal?
centromere located between middle and end
what is acrocentric?
centromere located very close to one end of chromosome
why is it necessary to prepare a karyotype?
karyotypes allow detection of any abnormalities in the chromosomes.
what is nondisjunction?
when chromosomes fail to separate properly during meiosis. gametes could have too few or too many copies of chromosomes or homologous chromosomes may have failed to separate in anaphase 1 and both members of the pair go to one pole. having extra chromosomes or missing some
what is trisomy 21?
down syndrome, there is 3 copies of chromosome 21 rather than 2 due to the chromosomes failing to separate properly. this is autosomal.
what is Patau Syndrome?
trisomy 13, a genetic disorder in which a person has 3 copies of genetic material from chromosome 13, instead of the usual 2 copies
what is Edward’s syndrome?
Trisomy 18 is a disorder in which babies are born with 3 copies of chromosome 18 instead of 2
what is Turner’s syndrome?
a condition that affects only females, results when one of the X chromosomes is missing or partially missing, resulting in short height, failure of the ovaries to develop and heart defects.
what is Klinefelter’s syndrome?
affects males that have an extra X chromosome (XXY). this results in more female characteristics, small breasts, wider hips, smaller penis
what is Cri-du-chat syndrome?
the loss of a half of the short arm of chromosome 5.
what is the locus?
the position of a gene on a chromosome
what is a genotype?
the genes present on the chromosomes of an individual (AA, Aa, aa)
what is a phenotype?
the physical expression of a gene
what are alleles?
alternate forms of the same gene at the same locus on homologous chromosomes that affect the same characteristic
what is a dominant allele?
an allele that needs to be present on only one of the two homologous chromosomes to be expressed and masks expression of other alleles. (A)
what is a recessive allele?
an allele that must be present on both homologous chromosomes in order to be expressed (aa)
homozygous
the presents of identical allels on homologous chromosomes (AA, aa)
heterozygous
the presents of unlike alleles on homologous chromosomes (Aa)
what is F1 generation (first filial)?
offspring resulting from crossing of individuals in parental gen
what is F2?
offspring resulting from crossing members of F1 gen among themselves
what is a monohybrid cross?
examines the inheritance of a single trait (Aa, AA, aa)
what is a dihybrid cross?
examines the inheritance of two diff traits located on two diff pairs of homologous chromosomes (AABb, aabb, ect)
