Ch 14

Question 0

explain how a mutation can be good, bad, or have no effect at all

Answer 0

beneficial-if it allows an organism to survive in a changing environment
bad-if it harms the organism or causes death
no effect-if a 2nd mutation can cancel out the first mutation

Question 1

what is a mutation

Answer 1

changes in the genetic sequence

Question 2

what is a point mutation

Answer 2

it results from a single substitution, deletion, or insertion

Question 3

what effects does a substitution mutation have on the codons?

Answer 3

they usually only affect a single amino acid

Question 4

what effect does a frame shift mutation have on the codons

Answer 4

(deletions & insertions) affect every amino acid past the point mutation

Question 5

distinguish between the 4 different types of chromosomal mutations

Answer 5

deletion- a piece of chromosome is lost
duplication- results in copies of genes
insertion- piece of chromosome breaks off and reattaches backwards
translocation- piece of chromosome breaks off and attaches to ANOTHER chromosome

Question 6

what is nondisjunction

Answer 6

occurs during meiosis when homologous chromosomes fail to separate

Question 7

what is polyploidy

Answer 7

condition when organisms have extra sets of chromosomes

Question 8

what type do organisms are often polyploidy

Answer 8

plants

Question 9

how many alleles must be inherited in the case of a dominant gene or disorder

Answer 9

1 copy

Question 10

list 3 dominant genetic disorders and describe each

Answer 10

achondroplasia- on C4 form of dwarfism affecting growth of long bones, most cases appear spontaneously
hunting tons disease- on C4 causes DNA, CAG repeat, to repeat more times, progressive loss of muscle control & brain. ( longer sequence earlier it appears)
hypercholesterolemia- cholesterol 19, alot of cholesterol and heart disease

Question 11

how many alleles must be inherited in the case of a recessive gene or disorder?

Answer 11

2 copies

Question 12

list 5 examples of recessive genetic disorders

Answer 12

phenylketonuria(PKU)
Tay-sachs
albinism
galactosemia
cystic fibrosis

Question 13

describe what happens in someone who is PKU+ and what treatments are available

Answer 13

the enzyme can’t break down phenylalanine in milk. it accumulates in brain & can lead to mental retardation. they can have a special diet as infants, mothers must be on a special diet

Question 14

describe what happens in someone with Tay-Sachs

Answer 14

they can’t produce hexosaminidase A to break down lipids(gangliosides). builds up & breaks down nervous system. blindness, deafness, and seizures, usually death occurs

Question 15

what causes albinism

Answer 15

a mutation in a gene that provides instructions for making a protein in melanin

Question 16

describe what happens in someone with galactosemia

Answer 16

the body is unable to use galactose. it can build up & damage liver, brain, kidneys, eyes

Question 17

describe what happens in someone with cystic fibrosis

Answer 17

the protein that allows chloride ions to pass through membranes isn’t formed properly. too much mucus is produced which interferes w/ breathing and digestive processes of the pancreas

Question 18

what mutation results in sickle cell anemia

Answer 18

a single point substitution which results in glutamic acid instead of valine for protein hemoglobin. hemoglobin sticks in long strands, RBC become sick shaped

Question 19

what are the results of inheriting sickle cell anemia?

Answer 19

blood flow is blocked-severs pain, weakness, damages brain, heart, spleen. results in resistance to malaria

Question 20

why has the gene for sickle cells not been removed from the gene pool

Answer 20

the cells destroy the parasite causing malaria in Africa

Question 21

what is an example of a multiple allele trait

Answer 21

blood type

Question 22

who discovered Sex chromosomes

Answer 22

thomas hunt Morgan

Question 23

describe his experiment that led to the discovery of sex-linked traits

Answer 23

he bred fruit flies. he crossed red eyes f w/ white eyes m (P1). all F1 offspring had red eyes. he crossed m&f from F1. F2 gen F had red eyes, M had red or white. there were no white eyes f. gene for eye color is on X chromosome

Question 24

describe 3 sex linked traits found on the X chromosome

Answer 24

color blindness- inability to distinguish certain colors
hemophilia- failure to produce protein required for normal blood clotting
duchenne muscular dystrophy- gene coding for muscle protein, progressive weakening of skeletal muscle

Question 25

what is a pedigree

Answer 25

a chart that shows relationships in a family can be used to trace the inheritance of various traits

Question 26

distinguish between trisomy and monosomy

Answer 26

trisomy results when individuals have an extra chromosome

monopsony results when individuals are missing a chromosome

Question 27

describe Down’s syndrome

Answer 27

results from trisomy 21. 1 in 800 babies. mild to severe mental retardation, increases frequency if birth defects, higher susceptibility of many diseases

Question 28

describe 2 sex chromosome disorders

Answer 28

turners syndrome- XO, monosomic, females don’t mature sexually and are often times sterile
klinefelters syndrome-XXY, males often sterile, abnormal body proportions

Question 29

what is a karyotype

Answer 29

microphotograph of the chromosomes during cell division, homologous pairs arranged from largest to smallest

Question 30

describe morgans experiment that led to the discovery of linkage groups

Answer 30

flies w/ gray bodies had long wings, black bodies had short wings. he crossed P1 & got gray long wings. Two F1 produced F2, short black and gray long. some “weirdoes” w/ both characteristics. 2 genes next to each other on chromosome, but to make “weirdo” the genes were swapped in crossing over

Question 31

explain how X chromosome inactivation leads to calico female cats

Answer 31

cats have an orange fur gene and black fur gene on chromosomes. the random silencing of on X in each cell generates the pattern of their coats