Human Genetic Defects

Question 1

point mutation

Answer 1

single nucleotide changes causing substitution, insertion, deletion (latter 2 can cause frameshift)

Question 2

transition mutation

Answer 2

Purine to purine or pyrimidine to pyrimidine. point mutation

Question 3

transversion mutation

Answer 3

purine to pyrimidine or vice versa

Question 4

What two point mutations cause frameshifts?

Answer 4

insertion and deletion

Question 5

Aneuploidy

Answer 5

genome with extra or missingchromosomes

Ex: trisomy 21 or down syndrome

Question 6

aneuploidy is caused by?

Answer 6

nondisjunction

Question 7

turner syndrome

Answer 7

nondisjunction in sex chromosomes

Question 8

Klinefelter

Answer 8

boy is born with extra X chromosomes (XXY)

Question 9

chromosomal abberations

Answer 9

chromosome segments are changed (duplication, inversion, and translocation)

Question 10

duplications

Answer 10

chromosome segment is repeated on same chromosome

Question 11

inversion

Answer 11

chromosome segments are rearranged in reverse orientation

Question 12

translocation? Two types?

Answer 12

segment is moved to another chromosome. Can be reciprocal or Robertsonian

Question 13

reciprocal

Answer 13

Type of translocation. two non-homologous chromosomes swap chunks

Question 14

Robertsonian

Answer 14

Type of translocation. one chromosome from a pair becomes attached to another from a pair
e.g. an extra chromosome 21 attached to 14 can cause Downs as well, tripled 21 chunk

Question 15

Chromosomal Breakage

Answer 15

spontaneous or induced (mutagenic agents, x-rays) deficiency= lost fragment

Question 16

Mutagenic agents include

Answer 16

Cosmic rays, X-rays, UV rays, radioactivity, mustard gas, most carcinogens, chemical compounds include colchicine (inhibits formation of spindle fibers)

Question 17

Cystic fibrosis

Answer 17

fluid buildup in tracts -bronchi, exocrine glands, pancreas, intestines

Question 18

Tay-sachs

Answer 18

lysosome defect;

can’t breakdown lipids for normal brain fxn

Question 19

sickle-cell

Answer 19

defective hemoglobin due to substitution mutation

Question 20

Huntingtons

Answer 20

degeneration of nervous system

Question 21

Cri Du Chat

Answer 21

deletion on chromosome 5

Question 22

extranuclear inheritance

Answer 22

extra-nuclear genes are found in mitochondria and chloroplasts. Defects in mito DNA can reduce cell’s ATP production. Mitochondria passed to zygote all come from mother, so all related diseases are mother inherited. Note that mitochondria have their own ~70S ribosomes