Genetics

Question 1

Genetics

Answer 1

The study of heredity

Question 2

Genetic disease

Answer 2

a disease caused by a mutation in the genetic material

Question 3

Congenital disease

Answer 3

A disease present at birth

Question 4

Epigenetics

Answer 4

the study of changes in gene function that occur without a change in the DNA of this gene

Question 5

Examples of Codominance

Answer 5

MHCs and ABO blood group

Question 6

Meiosis I

Answer 6

Replication and separation of chromosomes to make 2 cells that are diploid

Question 7

Meiosis II

Answer 7

Separation of sister chromatids and cell division leading to haploid gametes

Question 8

Homologous recombination

Answer 8

Sister chromasomes lined up on the metaphase plate have a crossing over of chromatids which resolves switching some genetic material from one to the other

Question 9

Metacentric Chromosome

Answer 9

P and Q arm are same length

Question 10

Submetacentric

Answer 10

P arm is shorter than Q arm

Question 11

Acrocentric

Answer 11

P arm is almost completely nonexistent

Question 12

Diploid human genome

Answer 12

46, XX or 46 XY
Chromosomes 1-22 Autosomes
Arranged in Karyotype Largest to smallest

Question 13

Karyotype Nomenclature

Answer 13

Total number of Chromosomes
Sex Chromosomes
Any Chromosomal Abnormalities

Question 14

Chromosomal Disorders

Answer 14

Aneuploidy: loss or gain of a chromosome
Polyploidy: the presence of one or more additional sets of chromosomes

Question 15

How does aneuploidy occur

Answer 15

Non-disjunction
Mostly occurs during oogenesis in females
More likely at later age

Question 16

Trisomy 21

Answer 16

Down Syndrome
Growth retardation
Mental retardation
Early onset alzheimers
40% risk congenital heart disease
15-20 fold risk of Leukemia

Question 17

Trisomy 13

Answer 17

Patau Syndrome
Severe facial dismorphism
Cardiac malformations
50% die within first week of life
Rest die by 6 months

Question 18

Trisomy 18

Answer 18

Edwards Syndrome
Characteristic finger folding
Heart abnormalities
Survival beyond 1 year very unusual

Question 19

45, X

Answer 19

Turner Syndrome
Intrauterine Edema
Neck Webbing
Short Stature (SHOX)
Infertility

Question 20

47, XXY

Answer 20

Klinefelter Syndrome
Tall Stature
Gynaecomastia
Infertility
Mild learning deficits

Question 21

47, XXX

Answer 21

Triple X
No physical abnormalities
Normal fertility
Mild learning difficulties

Question 22

47, XYY

Answer 22

XYY
Tall Stature
Normal fertility
Mild learning difficulties
Some behavioral issues

Question 23

Balanced vs. Unbalanced Chromosome Rearrangement

Answer 23

Balanced: No loss or gain of essential chromosome material
Unbalanced: Loss or gain of essential chromosome material

Question 24

Translocations

Answer 24

Reciprocal: balanced unless breaking point is through a gene
Robertsonian: Accentric chromosomes, balanced because P arm has little gene info

Question 25

Inversions

Answer 25

Pericentric: include the centromere Paracentric: Dont include centromere

Question 26

Isochromosomes

Answer 26

Centromere splits so P arms join together and Q arms join together

Question 27

Williams Syndrome

Answer 27

``` Caused by microdeletions Distinct facial appearance Cardiovascular abnormalities Mental retardation Distinct cognitive profile ```

Question 28

What are the consequences of chromosomal structural abnormalities

Answer 28

Very little effect on individual | Can lead to mitotic spindles abnormalities leading to increase in partial trisomy or monosomy

Question 29

Haploinsufficiency

Answer 29

Mutation in a gene leads to absence of half a signal that requires the full stimulation to work (Familial Hypercholesteremia)

Question 30

Dominant Negative Effect

Answer 30

``` Mutant Protein interferes with function of a normal protein Osteogenesis imperfecta Types 1 (1/2 normal amount) Type II (mutation in protein leads to 1/4 normal amount ```

Question 31

Gain of function

Answer 31

New property of a protein Achondroplasia: Mutation of FGFR3 results in overactive receptor Huntington Disease: Mutant protein is cytotoxic

Question 32

Allelic Heterogeneity

Answer 32

Different alleles can effect the same function. Presence of different nonfunctional alleles can cause problems that look like a double mutation RET Gene

Question 33

Locus Heterogeneity

Answer 33

Mutations on different genes can have the same effect

Question 34

New Mutations

Answer 34

Spontaneous mutation rate (Extremely rare)

Question 35

Incomplete Penetrance

Answer 35

Some conditions do not manifest even in people who are dominant for the mutation

Question 36

Delayed onset

Answer 36

Diseases that manifest later in life may be passed on to offspring. Someone can die before manifesting the disease

Question 37

Gonadal Mosaicism

Answer 37

People can have some gametes with a mutation and some that don't carry it

Question 38

Pleiotropy

Answer 38

Single gene with diverse effects | All the conditions caused by Marfan Syndrome related to fibrillin gene mutation and weak connective tissue

Question 39

Variable Expressivity

Answer 39

Some people express more or less severe symptoms of the same disease

Question 40

Why are there differences in penetrance and expressivity

Answer 40

Modifier Genes Environmental Factors Complex genetic interactions

Question 41

What can happen to histones

Answer 41

Acetylation: More gene expression HAT acetylates N termini, HDAC removes it Methylation: Less expression, Lysine residues of carboxyl termini Phosphorylation

Question 42

Rett Syndrome

Answer 42

Neurological disorder in girls | Mutations of MECP2 protein lead to altered expression of brain function genes

Question 43

X inactivation

Answer 43

Equalizes the contribution of X chromosome in males and females Random X is inactivated

Question 44

Mechanism of X inactivation

Answer 44

XIST RNA codes for DNA methylation, alteration of chromosome structure, and barr body formation XIC is Xq13.2

Question 45

Anticipation

Answer 45

Increased severity of disease in successive generations caused the continued expansion of repeats Mechanism of expansion thought to be slipped mispairing

Question 46

CAG repeats

Answer 46

Huntington's disease | Gain of function mutation leads to toxic protein

Question 47

CTG repeats

Answer 47

Myotonic Dystrophy | Repeats cause DNA to hairpin resulting in changes to RNA splicing

Question 48

GAA repeats

Answer 48

Friedrich Ataxia

Question 49

CGG repeats on FMR1 genes

Answer 49

``` Fragile X syndrome Mental retardation Distinct facial morphology X linked recessive Break at Xq27.3 ```

Question 50

Genomic Imprinting

Answer 50

``` Prader Willi (Paternal imprinting on chromosome 15, hypotonia, hypogonadism, obesity) Angelman Syndrome (Maternal imprinting, Seizures, severe mental retardation, unprovoked smiling, lack of speech) ```