Unit 5: Genetics - Advanced Biology 2024-25

Down’s syndrome

Trisomy 21 (three 21 chromosomes)

Patau Syndrome

Trisomy 13

Edward's syndrome

Trisomy 18

Turner’s Syndrome

missing X chromosome

Klinefelter’s

in males, extra X chromosome

Double Y

extra Y chromosome (in males only)

Cri-du-chat

piece of chromosome 5 is missing

sex cells

gametes (sperm and eggs)

haploid

Prophase l

crossing over (genetic variation)

Metaphase l

Independent assortment (genetic variation)

Anaphase l

full chromosome pairs pulled apart

Meiosis ll

cell continues dividing

zygote

first cell in a new organism

karyotype

picture of chromosomes

deletion

loss of part of a chromosome

duplication

extra copies of part of a chromosome

inversion

reverse the direction of parts of a chromosome

translocation

part of the a chromosome break off and attach to another chromosome

nondisjunction

the homologous chromosomes failed to separate

homozygous

same

heterozygous

different

allele

a form of a gene that determines traits

phenotype

physical trait

incomplete dominance (medium tailed cats)

neither allele is completely dominant

heterozygous offspring have a mix of the traits

codominance

two genes are expressed at the same time, so neither is dominant or recessive.