chapter 15: chromosomal basis of inheritance

phenotype of the parents

the offspring having a different phenotype than either of the parents

abnormal number of a particular chromosome

zygote only has one copy of an chromosome

zygote has an extra copy of a chromosome

organism has more than 2 sets of chromosomes

nucleotide base removed from DNA strand

nucleotide base duplicated in a DNA strand

set of nucleotides are inverted

set of nucleotides from different DNA strand is inserted into a new strand

a gene is located on a sex chromosome

the x chromosome is larger than the Y chromosome, therefore can carry more genes

• x inactivation occurs in every somatic cell in a human woman. it’s when one of the x chromsomes is inactivated/condensed because there it already a copy of it

• barr body is the name of a condensed chromosome

it means you are heterozygous for a recessive disorder

(# recombinant) / (# total offspring)

determined by the frequency of the genes occurring together

…then the genes are most likely on the same chromosome

crossing over

• sister chromatids or homologous chromosomes not separating in meiosis

• genetic disorders from having additional chromosome or lacking a chromosome

• meiosis 1: occurs when homologous chromosomes don’t separate properly. causes all gametes in the 4 daughter cells to be affected

• meiosis 2: occurs when sister chromatids do not separate properly. causes the 2 daughter cells to be affected

insertion, deletion, translocation, duplication

occurs when someone has 3 copies of chromosome 21

a male has 2 x chromosomes (XXY)

a female is missing an x chromosome (X0)

the maternal allele and paternal allele are distinguished and only one is used, silencing the other.

because the organelles are donated by the mother, not the father