Genetics

Question 1

What is a nucleotide made up of?

Answer 1

Sugar: Deoxyribose (ribose)
Base (A,G,T,C)
Phosphate

Question 2

What are the complimentary base pairs? How many hydrogen bonds in each?

Answer 2

A-T (2)

G-C (3)

Question 3

When and where does RNA processing occur? What are some examples?

Answer 3

After translation, in the nucleus.

5’ capping, poly-A tail, splicing

Question 4

Why is the poly-A tail important?

Answer 4

RNA degrading enzymes only work 3’ to 5’. When the RNA enters the cytosol, the poly-A tail acts as a protective feature against these enzymes.

Question 5

What are the 3 stop codons? The start codon?

Answer 5

STOP: UAA, UAG, UGA

START: AUG

Question 6

A mutation that does not alter protein function.

Answer 6

Silent mutation

Question 7

A mutation that results in reduced or abolished protein function (usually recessive)

Answer 7

Loss of Function mutation

Question 8

A loss of function mutation in which a mutated version of a protein of enzyme disrupts the function of the normal protein

Answer 8

Dominant Negative mutation

Question 9

A mutation that confers a new or enhanced activity on a protein (most dominant)

Answer 9

Gain of Function mutation

Question 10

A mutation that can be transmitted to offspring.

Answer 10

Germline mutation

Question 11

A mutation that cannot be transmitted to offspring.

Answer 11

Somatic mutation

Question 12

What are the 3 different types of point mutations?

Answer 12

Silent
Missense
Non-sense

Question 13

A mutation in which a new codon encodes the same amino acid, so there is no change in the coding protein

Answer 13

Silent mutation

Question 14

A mutation in which there is an alteration of a codon to one that encodes a different amino acid. Give an example.

Answer 14

Missense mutation

Sickle Cell Anemia

Question 15

A mutation in which an alteration produces a stop codon, resulting in premature termination of a protein. Give an example.

Answer 15

Non-sense mutation
McArdle disease (glycogen storage disease Type V)

Question 16

A mutation that shifts the way DNA is read.

Answer 16

Frameshift mutation

Question 17

Name the two types of frame shift mutations and give examples.

Answer 17

Insertion (Ex. Tay-Sachs Disease)

Deletion (Ex. Breast cancer, BRCA gene)

Question 18

A mutation in which there is an abnormal expansion of simple repetitive sequences which are scattered throughout the genome. Give an example.

Answer 18

Repeat expansion mutation

Ex. Huntington’s Disease

Question 19

A DNA sequence for which two or more variants are present at high frequency in the general population (>1%)

Answer 19

Polymorphism

Question 20

Why is polymorphism useful?

Answer 20

• Responsible for diversity among population

- Used as genetic markers to predict predisposition to disease

Question 21

An organized profile of a person’s chromosomes

Answer 21

karyotype

Question 22

What are the 4 types of chromosome mutations?

Answer 22

Deletion
Duplication
Inversion
Translocation

Question 23

A mutation that results in the deletion of a small portion of a chromosome. Give an example.

Answer 23

Deletion

Ex. Cri du Chat Syndrome (chromosome 5)

Question 24

A mutation that results in an extra copy of part of a chromosome. Give an example.

Answer 24

Duplication

Charcot-Marie-Tooth (chromosome 17)

Question 25

A mutation that results in the reverse direction of part of a chromosome.

Answer 25

Inversion

Question 26

A mutation that results in part of one chromosome attached to another chromosome. Give an example.

Answer 26

Translocation

Ex. Burkitt lymphoma (chromosomes 8 and 14) OR Down syndrome (chromosomes 21 and 14)

Question 27

What are the two types of genome mutations?

Answer 27

Polyploidy

Aneuploidy

Question 28

The presence of three or more chromosomes in more than two sets of chromosomes. Give an example.

Answer 28

Polyploidy

Ex. Triploid Syndrome

Question 29

The presence of additional or missing individual chromosomes. Give 3 examples of autosomal chromosome mutations and 2 examples of sex chromosome mutations.

Answer 29

Aneuploidy

Autosomal:
Down syndrome (Trisomy 21)
Edward Syndrome (Trisomy 18)
Patau Syndrome (Trisomy 13)

Sex:
Klinefelter Syndrome (XXY)
Turner Syndrome (X)

Question 30

A condition in which cells within the same person have a different genetic makeup

Answer 30

Mosaicism

Question 31

What factors should you consider in referring out to a geneticist?

Answer 31

Family GENES

Family History
Groups of congenital anomalies
Extreme or exceptional presentation
Neurodevelopmental delay or degeneration
Extreme or exceptional pathology
Surprising lab results

Question 32

What are some characteristics of Turner Syndrome?

Answer 32

• either 45X or mosaic 46XX/45X
• lethal in first trimester of pregnancy
• malformed but functioning kidney
• aortic coarctation
• short stature
• lymphedema of extremities
• infertility in adult women

Question 33

What are some characteristics of Marfan Syndrome?

Answer 33

• often familial but high rate of de novo
• mutation in FBN1 gene
• autosomal dominant
• aortic dilation
• arachnodactyly
• connective tissue disorder

Question 34

What are some characteristics of neurofibromatosis, type 1 (NF1)?

Answer 34

• autosomal dominant but high rate of de novo
• clinical criteria: cafe au lait macules, neurofibromas, axillary/inhumanly freckling, Lisch nodules in eyes
• mutation in NF1 gene

Question 35

What are some characteristics of Alzheimer’s disease?

Answer 35

-progressive, irreversible brain disease
-targets memory an thinking skills
-Mutations that cause early-onset Alzheimer’s: APP (amyloid precursor protein), PS1 (presnilin-1), and PS2 (presnilin-2)
Susceptibility polymorphism that leads to higher RISK of AD: apolipoprotein E (APOE)

Question 36

What are some characteristics of Williams Syndrome?

Answer 36

• contiguous gene deletion at 7q11.2
• CV disease
• short stature
• intellectual disability
• connective tissue abnormalities
• “cocktail personality”