Mutations & Repair + Mendelian Genetics

Question 1

Mutations affect the only copy of the genetic information available.
(Prokaryotes/Eukaryotes)

Answer 1

Prokaryotes

Question 2

Mutations in _____ cells of Eukaryotes can be inherited.

Answer 2

Germ cells

Question 3

Mutations in ______ cells are not inherited and affect tissues only.

Answer 3

Somatic cells

Question 4

Cancer in a ____ mutation. (germ cell/somatic cell)

Answer 4

Somatic cell

Question 5

Mutations in germ cells that predispose to cancer can be inherited. (T/F)

Answer 5

True

Question 6

Germline mutations give rise to ______ mutation in offspring.

Answer 6

Constitutional

Question 7

what does constitutional mutation mean?

Answer 7

• Every cell of that offspring will carry the mutation.

- If happens very early in cleavage stages, results in mosaic mutation.

Question 8

Somatic mutation will only be harmful if:

Answer 8

they result in a substantial clone of mutant cells.

Question 9

Name the major types of mutation/

Answer 9

1. Substitution
2. Deletion
3. Insertion
4. Rearrangement

Question 10

Name the types of substitution mutation.

Answer 10

• Transition: py for py
• Transversion: py for pur OR pur for py
• Nonsense: make a stop codon

Question 11

What are the 4 causes of mutation?

Answer 11

1. Errors during DNA replication.
2. Chemical modification.
3. Intercalation.
4. Double-strand breakage.

Question 12

Errors during DNA replication result in:

Answer 12

Tautomer formation.

Question 13

Intercalation can result in:

Answer 13

Insertion or deletion

Question 14

Double-strand breakage can result in:

Answer 14

Deletions

Question 15

Name three intercalators.

Answer 15

• Ethidium
• Bromide
• Acridine orange

Question 16

Name 2 chemical modifiers.

Answer 16

• Nitrous acid

- alkylating agents

Question 17

Chemical modification can cause what mutations?

Answer 17

• Transitions
• Transversions
• Frameshifts
• DNA repair

Question 18

Radiation exposure (UV/X-rays) cause what type of mutation?

Answer 18

• DS breakage

- Thymine dimers

Question 19

Generally, mutation repair system have these steps:

Answer 19

1. Detect
2. Remove
3. Repair

Question 20

Mismatch repair “detect” enzyme:

Answer 20

-Dam methylase

Question 21

Mismatch repair “remove” enzyme:

Answer 21

-Exonuclease I

Question 22

Mismatch repair “repair” enzymes:

Answer 22

• DNA polymerase III

- DNA ligase

Question 23

Base-excision repair “detect” enzyme:

Answer 23

DNA glycosylases

Question 24

Base-excision repair “remove” enzyme:

Answer 24

AP endonucleases

Question 25

Base-excision repair "repair: enzymes:

Answer 25

- DNA polymerase I | - DNA ligase

Question 26

How is the correct strand chosen during mismatch repair?

Answer 26

Strand with error is unmethylated

Question 27

Defects in human mismatch repair system lead to a strong predisposition to:

Answer 27

Hereditary nonpolyposis colorectal cancer

Question 28

Nucleotide Excision Repair is used for:

Answer 28

bulky distortions of DNA helix. | e.g., thymine dimers

Question 29

Thymine dimers are caused by:

Answer 29

UV radiation exposure

Question 30

What enzyme cleaves the defected DNA in E. coli during nucleotide excision repair?

Answer 30

ABC exinuclease

Question 31

Defects of the human thymine dimer system leads to:

Answer 31

Xeroderma pigmentosum

Question 32

Symptoms of XP:

Answer 32

- UV sensitivity - keratoses - scaring of the eyelids - cornea ulceration - multiple skin tumors - many pts die before 30

Question 33

Define genotype.

Answer 33

The genetic constitution of an individual

Question 34

Define phenotype.

Answer 34

The observable expression of a genotype as a morphological, biochemical, or molecular trait.

Question 35

In autosomal dominant disorders, _______ are phenotypically affected.

Answer 35

Heterozygotes

Question 36

Inheritance pattern for hypercholesterolemia is:

Answer 36

Autosomal dominant.

Question 37

Name the two variations of hypercholesterolemia.

Answer 37

- Xanthelasmus | - Corneal arcus

Question 38

Xanthelasmus is AD heterozygous/homozygous.

Answer 38

Heterozygous

Question 39

Homozygous variation of hypercholesterolemia is called:

Answer 39

Corneal arcus

Question 40

What are the symptoms of xanthelasmus?

Answer 40

Achilles tendon xanthomas

Question 41

Metacarpophalangeal tendon xanthomas is associated with this Dz.

Answer 41

Corneal arcus

Question 42

Corneal arcus is the homozygous/heterozygous variation of hypercholesterolemia.

Answer 42

Homozygous

Question 43

In Autosomal Dominant pedigree, ____ % of the offsprings have the Dz.

Answer 43

50

Question 44

Huntington's chorea inheritance pattern is:

Answer 44

Autosomal Dominant

Question 45

What are the exceptions to the Autosomal Dominant inheritance pattern?

Answer 45

1. New mutation in gamete of phenotypically normal parent. 2. Variable penetrance. 3. Variable expressivity.

Question 46

How do the exceptions to the autosomal dominant inheritance affect the pattern?

Answer 46

They mask the presence of the mutant genotype in the parental phenotype.

Question 47

In Autosomal Recessive inheritance, only _______ are phenotypically affected.

Answer 47

homozygotes

Question 48

Male and females are equally affected in autosomal recessive inheritance. (T/F)

Answer 48

True

Question 49

What is the % chance recurrence risk for each sibling in autosomal recessive inheritance?

Answer 49

25%

Question 50

Examples of Autosomal Recessive Dz:

Answer 50

- Cystic fibrosis - Sickle cell anemia - Tay-Sachs Dz - PKU

Question 51

Cystic fibrosis is an AD/AR Dz.

Answer 51

AR

Question 52

"Mother to son" transmission is this inheritance pattern.

Answer 52

X-linked Recessive

Question 53

Male and female phynotypes are equally affected in X-linked Recessive inheritance. (T/F)

Answer 53

False; Incidence of phenotype is much higher in males than females.

Question 54

In X-linked recessive Dz, mutant gene is transmitted from father to:

Answer 54

ALL daughters | NO sons

Question 55

What is a manifesting heterozygote?

Answer 55

Heterozygous females are usually unaffected by X-linked recessive inheritance but may show some variable expression of the trait.

Question 56

Define The Lyon Hypothesis.

Answer 56

- All females are mosaics with respect to X. | - Inactivated X chromosomes are called Barr bodies.

Question 57

Inactivated X chromosomes are called:

Answer 57

Barr bodies.

Question 58

Hemophilia A inheritance pattern:

Answer 58

X-linked Recessive

Question 59

Mitochondrial disorders are purely _____ inheritance.

Answer 59

maternal | mother to everybody!

Question 60

Sons and daughters are equally affected in mitochondrial disorders. (T/F)

Answer 60

True