chapter 2: genes and genetic diseases

Question 1

the single-ringed bases (pyrimidines) are

Answer 1

cytosine and thymine

Question 2

double-ringed bases (purines)

Answer 2

adenine and guanine

Question 3

______ consist of one deoxyribose molecule, one phospate group and one base.

Answer 3

Nucleotide

Question 4

codon

Answer 4

triplet of amino acid; 3codons that signals the end of a gene- termination codon/nonsense codon

Question 5

polypeptide

Answer 5

chain of proteins

Question 6

dna polymerase

Answer 6

assist with base-pairing when replicating DNA.

Question 7

transcription

Answer 7

synthesis of RNA from DNA and uses RNA polymerase

Question 8

translation

Answer 8

the formation of a polypeptide from RNA and does not require DNA polymerase

Question 9

silent mutation

Answer 9

occurs if a base-pair is changed but the DNA still codes for the amino acid.

Question 10

frameshift mutation

Answer 10

insertion or deletion of one or more base-pairs and can change the entire reading frame

Question 11

mutagen

Answer 11

is an agent that increases frequency of mutation

Question 12

spontaneous mutation

Answer 12

when a mutation occurs but there is no exposure to a mutagen.

Question 13

promoter site

Answer 13

signals the beginning of a gene and is the location of the RNA polymerase binding.

Question 14

anticodon

Answer 14

the sequence of 3 nucleotides that undergo complementary base-pairing in translation

Question 15

ribosomes

Answer 15

are RNA complexes that are synthesized in the nucleolus and secreted into the cytoplasm, possibly through pores in the nuclear envelope

Question 16

aneuploid

Answer 16

cell does not contain a multiple of 23 chromosomes.

Question 17

monsomy

Answer 17

presence of only one copy of a given chromosome in a cell.

Question 18

Down syndrome

Answer 18

example of aneuploidy occurring in 1 in 800 live births. persons with D.S have a distinctive facial appearance with a low nasal bridge, epicanthal folds, protruding tongue, flat-low set ears. They have poor muscle tone and short stature. These disease produces mental retardation with an IQ between 25 and 70 (low)

Question 19

Turner syndrome

Answer 19

has a karyotype of 45, X. (missing X). Females who are usually sterile, have minimal body hair, short stature with a webbed neck and coarctation of the aorta.

Question 20

Klinefelter syndrome

Answer 20

males with 47, XXY. Testes are small, long limbs, body hair is sparse, the voice is somewhat high pitched.

Question 21

cri-du-chat

Answer 21

deletion of chromosome 5. low birth weight, mental retardation, microcephaly

Question 22

Fragile X syndrome

Answer 22

develops due to a break or gap on the X chromosome.

Question 23

autosomal dominant gene transmission

Answer 23

the affected parent transmitting the gene to half of his/her children. (50% chance)

Question 24

autosomal recessive trait

Answer 24

males and females are equally affected. Generally parents will not display the trait but each will pass the recessive trait to 25% of their children. The child must be homozygous for the trait to express the recessive trait

Question 25

huntington’s disease

Answer 25

autosomal dominant; progressive brain disorder that causes uncontrolled movement, emotional problems and loss of thinking ability.

Question 26

Marfans syndrome

Answer 26

Autosomal dominant; inherited disease that affects connective tissue of the heart.

Question 27

PKU

Answer 27

recessive trait

Question 28

red/green color blindness

Answer 28

X-linked; can’t distinguish red or green (MALES)

Question 29

hemophilia

Answer 29

x-linked recessive disorder where the blood cannot clot properly due to deficiency of Factor VIII