Week 7: Disease Causing Abnormalities in DNA and Chromosomes

Question 1

Degeneracy of Genetic Code

Answer 1

some amino acids have more than one nucleotide codon specifying them during protein synthesis

Question 2

Non Ambiguity

Answer 2

A codon will only encode for one protein

Question 3

Synonymous (silent) substitution

Answer 3

As a result of the redundancy in the genetic code, a mutated codon quite often specifies the same amino acid as the original codon. With no change in the amino acid, no change in the phenotype might be expected

Question 4

Example of Synonymous/silent substitution

Answer 4

transition at 3rd position

Question 5

Non synonymous substitution

Answer 5

Transversion causes one amino acid to be replaced by another

Question 6

Missense mutation

Answer 6

change of a single base pair causes the substitution of a different amino acid in the resulting protein; can result in minimal to severe adverse effects

Question 7

Nonsense mutation

Answer 7

An amino acid specifying codon is replaced by a premature stop codon (UAA, UAG, UGA)

Question 8

Frameshift Mutation

Answer 8

If a sequence of coding nucleotides that is NOT a multiple of three is deleted or inserted, there is a shift in translational reading frame, resulting in an in frame premature termination codon

Question 9

Germ Cell (constitutional) abnormality

Answer 9

present in all nucleated cells, present very early in development

Question 10

Somatic (or acquired) abnormality

Answer 10

present in only certain cells or tissues of a person

Question 11

Structural Abnormalities

Answer 11

Arises through chromosome breakage events that are not repaired

Question 12

Numerical Abnormalities

Answer 12

Changes in chromosome number that often arises through errors in chromosome segregation

Question 13

Deletion

Answer 13

chromosomal material is lost

Question 14

Inversion

Answer 14

chromosomal material is switched around

Question 15

Ring chromosome

Answer 15

Chromosomal material is included in a circular chromosome

Question 16

Dicentric chromosome

Answer 16

a chromosome with 2 centromeres

Question 17

Acentric chromosome

Answer 17

a chromosome lacking a centromere

Question 18

Translocation

Answer 18

If two chromosomes each sustain a single break, incorrect joining of the broken ends can result in the movement of chromosome material between chromosomes

Question 19

Euploid

Answer 19

normal chromosomal makeup of an individual

Question 20

Aneuploid

Answer 20

deviations involving the loss or gain of one or more chromosomes

Question 21

Non Disjunction

Answer 21

paired chromosomes fail to separate

Question 22

Polyploid

Answer 22

many multiples of chromosomes (i.e 3n triploids)

Question 23

Hypomorph

Answer 23

The mutant gene product is incapable of carrying out its normal task or have a significantly reduced ability to work normally

Question 24

Neomorph

Answer 24

The mutant gene product may acquire an altered function or occasionally a new function that is harmful in some way causing cells to die or to behave inappropriately

Question 25

what is involved in the change of protein structure?

Answer 25

loss of function and gain of toxic function

Question 26

How do proteins fold in a hydrophilic environment?

Answer 26

proteins fold with the hydrophobic amino acid located in the interior, and the hydrophilic amino acids on the surface

Question 27

Modifier Genes

Answer 27

genes whose mutations can modify the effect/ consequence of other gene mutations

Question 28

How do environmental factors effect the expression of the disease phenotype?

Answer 28

1. At a distance (external radiation sources) 2. By direct exposure to harmful chemicals that we digest 3. By contact with microbes and toxins