GB1: Chapter 14

Question 1

character

Answer 1

heritable feature that varies among individual (ex: flower color)

Question 2

trait

Answer 2

each variant for character (ex: purple)

Question 3

true-breeding

Answer 3

produce same offspring of same variety over generations

Question 4

hybridization

Answer 4

crossing of 2 true-breeding varieties

Question 5

P-generation

Answer 5

parental gen. (true-breeding)

Question 6

F1-generation

Answer 6

first filial gen. (P-gen. hybrid offspring)

Question 7

F2-generation

Answer 7

2nd filial gen.

Question 8

gene

Answer 8

sequences of nucleotides at specific place along chromosome

Question 9

locus

Answer 9

specific physical location of gene on chromosome

Question 10

allele

Answer 10

alternative versions of genes; variation in gene’s nucleotide sequence

Question 11

phenotype

Answer 11

appearance/physiological trait

Question 12

genotype

Answer 12

genetic makeup

Question 13

testcross

Answer 13

breeding an organism of unknown genotype with recessive heterozygote

Question 14

monohybrid cross

Answer 14

cross between 2 heterozygotes for character

Question 15

dihybrids

Answer 15

heterozygotes for 2 characters

Question 16

Law of independent assortment

Answer 16

2 or more genes assort independently (each pair of alleles segregates independently of any other pair of alleles) during gamete formation

Question 17

multiplication rule

Answer 17

probability that 2 or more independent events will occur in sequence

Question 18

addition rule

Answer 18

probability of occurrence of 1 event or other of 2 mutually exclusive events summed together

Question 19

complete dominance

Answer 19

phenotypes of heterozygotes and homozygotes are the same

Question 20

incomplete dominance

Answer 20

phenotype of F1 hybrids are a mix between parental phenotypes

Question 21

codominance

Answer 21

2 dominant alleles affect phenotype in separate ways

Question 22

Tay-sachs disease

Answer 22

• inherited disorder
• child’s brain cells cannot metabolize specific lipids due to disfunctionality of crucial enzyme
• lipids accumulate, child experiences seizures, blindness, degredation of motor/mental performance
• Need 2 alleles to have disease, so recessive disease

Question 23

polydactyly

Answer 23

• dominant allele causes disease
• baby born with extra fingers/toes
• recessive allele is more common due to low frequency of this condition

Question 24

pleiotropy

Answer 24

genes that have multiple phenotypic effects

Question 25

epistasis

Answer 25

expression of a gene at one locus alters the phenotypic expression of a gene at a second locus

Question 26

Quantitative characters

Answer 26

they vary in the population along a continuum, indicates polygenic inheritance

Question 27

polygenic

Answer 27

additive effect of two or more genes on a single phenotype

Question 28

multifactorial

Answer 28

Traits that depend on multiple genes combined with
environmental influences

Question 29

pedigree

Answer 29

family tree describing
interrelationships of parents and children across
generations

Question 30

carriers

Answer 30

heterozygous, carries
recessive allele but phenotypically normal

Question 31

Albinism

Answer 31

• recessive condition
• lack of pigmentation in skin & hair

Question 32

cystic fibrosis

Answer 32

• cystic fibrosis allele results in defective or absent chloride transport channels in plasma membranes, leads to buildup of chloride ions outside the cell
• symptoms: mucus buildup in internal organs, abnormal absorption of nutrients in the
  small intestine

Question 33

sickle-cell disease

Answer 33

• substitution of a single amino acid in the hemoglobin protein in red blood cells
• homozygous: all hemoglobin is abnormal (sickle-cell)
• heterozygous: usually healthy but suffer some symptoms; BUT are less susceptible to malaria parasite
• symptoms: physical weakness, pain, organ damage, paralysis

Question 34

Achondroplasia

Answer 34

• dominant allele
• rare form of dwarfism

Question 35

Huntington’s disease

Answer 35

• degenerative disease of
  the nervous system
• phenotypic effects show at 35-40 years old
• condition is irreversible & fatal