intro genetics

Question 1

histones

Answer 1

• proteins that chromosomes wind around
• regulates activities of genes

Question 2

what are genes responsible for?

Answer 2

traits like eye color, heigh, enzyme function, ect.

Question 3

genotype

Answer 3

distinct combination of genes passed down from the parents determines an offspring’s entire genetic make

Question 4

true or false: the DNA sequences comprising a gene can be slightly different

Answer 4

true

Question 5

alleles

Answer 5

variants of the same gene , responsible for variations in which a given trait can be expressed

Question 6

why is there variation in gene expression?

Answer 6

due to the fact that alleles come in pairs, with one allele of each gene being inherited from each parent

Question 7

true or false: all genes end up being translated into visible traits

Answer 7

false

Question 8

phenotype

Answer 8

• observable traits like eye and hair color
• result of expressed genes

Question 9

homozygous

Answer 9

two identical alleles are inherited

Question 10

heterozygous

Answer 10

two different alleles are inherited

Question 11

Dominant traits

Answer 11

only require one allele for the given trait to be expressed

Question 12

recessive traits

Answer 12

can only be expressed when the genotype is homozygous

Question 13

homozygous dominant

Answer 13

has both dominant alleles

Question 14

homozygous recessive

Answer 14

both recessive alleles

Question 15

heterozygous

Answer 15

one dominant and one recessive allele

Question 16

incomplete dominance

Answer 16

occurs when one allele for a specific trait is not completely expressed over the other allele
- heterozygous alleles can display an intermediate of the dominant and recessive

Question 17

NAT2*12A

Answer 17

present in fast acetylators but not in slow acetylators

Question 18

NAT2*14B

Answer 18

present in slow acetylators but not in fast acetylators

Question 19

intermediate acetylator phenotype’s genotype

Answer 19

NAT212A / NAT214B

Question 20

among ethnically diverse populations; which acetylator-phenotype was identified the most frequently?

Answer 20

slow

Question 21

what is the process of which through genetic testing determined that a particular combination of N-acetyltransfersase 2 alleles has become more frequent in Western/Central Eurasians

Answer 21

positive selection

Question 22

why may there be positive selective advantage?

Answer 22

alleles for some phenotypes are more likely be passed on to subsequent generations than others
- individuals with these genotypes have a higher survival rate
- these individuals might reproduce more successfully than others in a particular environment.

Question 23

selective pressure

Answer 23

a reason why organisms with a specific phenotype are more likely to survive
- important for natural selection, which determines which genes will be passed to subsequent generations and which will not

Question 24

what was the underlying reason for the higher frequency of the slow acetylator allele?

Answer 24

positive selection advantage occurred when people transitioned from having a hunter-gatherer lifestyle to more of an agricultural lifestyle
- the slow acetylator phenotype was identified twice as often in populations that farmed or herded than in those that hunted and gathered. This transition caused a drastic change in people’s diets as they had to determine which plants could and couldn’t be eaten and how to use fire

Question 25

lactose

Answer 25

Lactose, which is a disaccharide composed of galactose and glucose, is broken into its component parts by the enzyme lactase. This enzymatic reaction occurs in the small intestine of young mammals. As mammals approach adulthood, however, the gene responsible for lactase synthesis turns off. As a result, they no longer make lactase and their diets change appropriately. Presumably this is one of the main reasons why calves transition to eating grass, and dogs and cats begin to consume meat. As our human ancestors moved out of Africa and into the northern European region, they began to domesticate cows and started to consume cow’s milk and other dairy products.

Question 26

1) Did lactase persist in these people? 2) Was it associated with mutations in the gene responsible for the synthesis of lactase? and 3) Does a lack of these mutations explain the condition known as ‘lactose intolerance’?

Answer 26

yes

Question 27

what races are more lactase deficient/intolerant?

Answer 27

Asian, South American, and African

Question 28

symptoms of lactose intolerance

Answer 28

abdominal pain, bloating, diarrhea and vomiting

Question 29

diagnosis of lactose intolerance

Answer 29

genetic test to assess the makeup of the lactase gene, an intestinal biopsy to measure intestinal lactase enzyme activity, monitoring changes in blood glucose after drinking a solution containing lactose, or excluding dairy products from the diet to see if the symptoms disappear