Exam 1: Genetics

Question 1

Another name for base pair substitution:

Answer 1

Single nucleotide polymorphism

Question 2

Most catastrophic form of genetic mutation:

Answer 2

Frameshift mutation

Question 3

Three types of single gene disorders:

Answer 3

Dominant
Recessive
X-linked

Question 4

X-linked recessive disorders predominantly affect which gender? Why?

Answer 4

Men, because with only one X gene, any inheritance will be expressed; for women, takes two

Question 5

X-linked dominant disorders are:

Answer 5

Rare and few in number

Question 6

Define aneuploidy. Which type is better?

Answer 6

Monosomy or trisomy of a chromosome

Trisomies are less devastating than monosomies

Question 7

Which is the only monosomy which people typically survive?

Answer 7

Turner syndrome (female with only one X)

Question 8

Give the aneuploidy for each disease:
Down syndrome
Edward syndrome
Patau syndrome
Turner syndrome
Klinefelter syndrome

Answer 8

Down: trisomy 21
Edward: trisomy 18
Patau: trisomy 13
Turner: 45:X
Klinefelter: 47:XXY

Question 9

XXX females and XYY males:

Answer 9

Typically pretty normal

Question 10

Define polyploidy:

Answer 10

69 instead of 48 chromosomes

Question 11

Define penetrance:

Answer 11

The chance that phenotype follows genotype

Question 12

Define haplotype:

Answer 12

Alleles on a single chromosome

Question 13

What is nondisjunction?

Answer 13

When chromosomes don’t separate during meiosis

Question 14

Which cells are more likely to experience nondisjunction? Why?

Answer 14

Oocytes; proteins are older at time of replication and less reliable

Question 15

At what maternal age does the incidence of Down syndrome begin to rise?

Answer 15

35ish

Question 16

Relationship between X and Y chromosome:

Answer 16

Part of Y is homologous with X; this part is needed for fertility

Question 17

S/s of Turner syndrome:

Answer 17

Menopause before menarche
Webbed neck
“Less female” features
Short stature

Question 18

S/s of Klinefelter syndrome:

Answer 18

Nonfunctional spermatagonia
Infertile
Mostly normal development
Small testes, long limbs

Question 19

Is extra genetic material better or worse tolerated than missing genetic material?

Answer 19

Better tolerated

Question 20

Types of errors with crossover:

Answer 20

Deletion when a chromosome segment is lost

Unequal crossing over leads to duplication on one side and deletion on the other

Question 21

What is chromosome translocation?

Answer 21

Crossover between non-homologous chromosomes

Question 22

Result of chromosome translocation:

Answer 22

Unbalanced gametes result in zygotes that are partially trisomic and partially monosomic

High rate of spontaneous abortion and cancer in survivers

Question 23

Name six dominant single gene disorders:

Answer 23

Familial hypercholesteremia
Huntington disease
Achondroplasia
Marfan's syndrome
Retinoblastoma
La-Fraumeni

Question 24

Name five recessive single gene disorders:

Answer 24

Sickle cell anemia
Cystic fibrosis
Lysosomal storage diseases (Tay-Sachs, Gaucher, Niemann-Pick)
Phenylketonuria
Glycogen storage diseases

Question 25

Name two X-linked recessive diseases:

Answer 25

Duchenne muscular dystrophy

Hemophilia A, B

Question 26

Hemophilia A and B - which factor is missing?

Answer 26

A: VIII
B: IX