Chromosomal & Multifactorial Dysfunction

Question 1

Mitosis:

Answer 1

Complete replication of DNA (2 new identical cells)

Question 2

Chromosomal structure:

Answer 2

Chromosomal banding: banding occurs based on stains A-T and C-G (banding identifies regions of chromosome)

Centromere also an identifier and is remnant of where 2 sister chromatids were bound

Question 3

Chromosomal Loci:

Answer 3

Related to chromosomal banding Numbers and letters help describe where it is on the chromosome

Question 4

Chromosomal nondisjunction:

Answer 4

occur in meiosis I or II
cells with variation on the # of chromosomes are termed aneuploid

Question 5

Variation in number

Answer 5

polyploidy occurs when an entire extra set of chromosomes is present triploidy= 69/ tetraploidy= 92
trisomy= 21
-Others include 8/13/18

Question 6

Trisomy Clinical manifestations:

Answer 6

mental, behavioral characteristics, increased risk for congenital heart disease, GI structural defects, childhood leukemia, alzheimers
others include 8/13/18

Question 7

Sex Chromosome Aneuploidy: Monosomy X

Answer 7

Turner Syndrome
karyotype:45/ One X
characteristic: short, ovarian dysgenesis, obstructive left sided heart lesions, intelligence typically normal
parental origin of X

Question 8

Sex Chromosome Aneuploidy: Trisomy X

Answer 8

Karyotype: 47, 3 X’s
characteristics: sterility, menstrual irreg., mild mental retardation

Question 9

Sex Chromosome Aneuploidy: Kleinfelter Syndrome

Answer 9

Karyotype: 47, XXY
Characteristics: taller than average, low test levels, small testes,

Question 10

Sex Chromosome Aneuploidy: 47 XYY Syndrome

Answer 10

47, XYY
Characteristics: taller than average, increases incidence of minor behaviora and learning disorders

Question 11

Translocations:

Answer 11

A genetic change in which a piece of one chromosome breaks off and attaches to another chromosome

Question 12

Reciprocal Translocations:

Answer 12

Mutual exchange of material between 2 chromosomes
Consequence: normal, partial trisomy, deletion of genetic material

Question 13

Robertsonian Translocations:

Answer 13

Exchange of chromosomal material in which short arms of 2 chromosome are lost and long arms fuse together
consequence to offspring normal, trisomy, monosomy

Question 14

Chromosomal Deletions:

Answer 14

Terminal deletion: single break at tip of chromosome
Interstitial deletion: two breaks occur
Cri-du-chat chromosome 5 pair

Question 15

Cri du chat:

Answer 15

Deletion on short arm of chromosome 5

Clinical manifestations: mental retard, microcephaly, congenital heart failure

Genetic mechanism: genes in 5p15.2 region associated with cerebral development

Question 16

Concordance and DIscordance:

Answer 16

Concordance: Expression of disease in 2 related family members

Discordance: Expression of disease in one family member but not a second

Question 17

Genetic Disorders in twins:

Answer 17

Monozygotic twins: 100% concordance

Dizygotic twins: Less than 100% and similar to that among other siblings

Question 18

Environmental-related and multi-factorial disorders in twins:

Answer 18

Environmental disorders: equal concordance rates among MZ and DZ twins

Multi-factorial disorders: MZ twins with greater concordance than DZ twins (rates not 100 though)