Genetics & Diseases

Question 1

chromosome types

Answer 1

somatic cells: contain 46 chromones, diploid cells

gametes: contain 23 chromones, haploid cells, one of each chromosome pair
meiosis: formation of haploid cells from diploid cells
mitosis: formation of somatic cells
autosomes: first 22 chromones, both are identical being homologous

sex chromosomes: remaining pair of chromones

• females: homologous pair (xx)
• males: nonhomologous pair (xy)

Question 2

euploid cells

Answer 2

have multiple of the normal number of chromosomes (divisible by 23)

Question 3

polypoid cells

Answer 3

when euploid cell has more than the diploid number (more than 46 total)

• triploid: a zygote having three copies of each chromosome (69 total)
• tetraploid: four copies of each (92 total)

Question 4

aneuploid cells

Answer 4

somatic cell that does not contain a multiple of 23

• trisomy: cell containing 3 copies of one chromosome
• monosomy: presence of only one copy of any chromosome

Question 5

disjunction & nondisjunction

Answer 5

disjunction: normal separation of chromosomes during cell division
nondisjunction: usually the cause of aneuploidy

Question 6

autosomal trisomy & example

Answer 6

occurs in all cells

• partial trisomy: extra part of chromosome in each cell
• chromosomal mosaics: trisomy’s occurring in some cells
• ex: down syndrome: trisomy 21

Question 7

sex chromosome aneuploid & examples

Answer 7

sex cell having more than two x chromosomes

• ex: trisomy x: female having three x chromosomes
• ex: turner syndrome: females with only one x chromosome
• ex: klinefelter syndrome: people with two x chromosome and one y chromosome

Question 8

locus, allele, homozygous, & heterozygous

Answer 8

locus: position of a gene along a chromosome
allele: a different form of a particular gene at a given locus
homozygous: loci on a pair of chromosomes have identical genes
heterozygous: loci on pair of chromosomes have different genes

Question 9

dominate, recessive, co-, carrier

Answer 9

dominant allele: observable, shown with capital letter

recessive allele: effects are hidden, shown with lowercase letter

co-dominant/co-recessive: two dominates or two recessives

carrier: one who has disease gene but is phenotypically normal

Question 10

genotype & phenotype

Answer 10

genotype: what they have, make up
phenotype: what is expressed and observable

Question 11

autosomal dominate disorder

Answer 11

abnormal allele is dominate

• ex: huntingtons disease

d

d

D

Dd hetero affected

Dd hetero affected

d

dd homo normal

dd homo

normal

Question 12

autosomal recessive disorder

Answer 12

abnormal allele is recessive, must have two for disorder to show

• ex: cystic fibrosis

D

d

D

DD homo normal

Dd hetero carrier

d

Dd hetero carrier

dd homo

affected

Question 13

sex linked disorders

Answer 13

usually expressed in males since females have another x to mask the abnormal x

x-linked recessive: affected males cannot pass it down to sons but can to daughters

• ex: duchenne muscular dystrophy

Question 14

multifacotoral inheritance

Answer 14

environmental factors effect expression of trait

polygenic: variation of traits caused by the effect of multiple genes, the perfect storm