chapter 13 observing patterns in inherited traits

Question 1

blending theory

Answer 1

people thought that traits were equally powerful in determining the offspring’s genetics
- flaws: one would expect variation to disappear, which it doesn’t

Question 2

gregor mendel

Answer 2

studied genetics of pea plants, strong background in plant breeding and mathematics

Question 3

genes

Answer 3

units of information about specific traits that are passed from parents to offspring. each has a specific locus on a chromosome

Question 4

alleles

Answer 4

different molecular forms of a gene that arise by mutation. dominant alleles mask a recessive allele when paired with it

Question 5

homozygous

Answer 5

having two identical alleles at a locus
AA or aa

Question 6

heterozygous

Answer 6

having two different alleles at a locus
Aa

Question 7

genotype

Answer 7

refers to particular alleles an individual carries
* one can’t always determine the genotype based on the organism’s observable traits

Question 8

phenotype

Answer 8

refers to an individual’s observable traits

Question 9

monohybrid cross

Answer 9

breeding a homozygous dominant organism with a homozygous recessive
result: 100% heterozygous

Question 10

second step of a monohybrid cross

Answer 10

breeding two heterozygous offspring
result: 75% dominant, 25% recessive

Question 11

mendel’s law of segregation

Answer 11

an individual inherits a unit of information (allele) about a trait from each parent

Question 12

probability

Answer 12

the chance that each outcome of a given event will occur is proportional to the number of ways that event can be reached

Question 13

test cross

Answer 13

a test used to determine if an individual is homozygous dominant, recessive, or heterozygous

Question 14

monohybrid cross

Answer 14

AABB x aabb

Question 15

dihybrid cross

Answer 15

AaBb

Question 16

mendel’s law of independent assortment

Answer 16

genes assort independently, gene A and gene B are not contingent
- mendel concluded that the two “units” for the first trait were to be assorted into gametes independently of the two “units” of the other trait
- members of each pair of homologous chromosomes are sorted into gametes at random during meiosis

Question 17

F2 ratio of a dihybrid cross

Answer 17

9:3:3:1

Question 18

linkage groups

Answer 18

genes on one type of chromosome
- fruit flies
- 4 homologous chromosomes
- 4 linkage groups
- not all genes on chromosomes are tightly linked

Question 19

full linkage

Question 20

incomplete linkage

Question 21

crossover frequency

Answer 21

the probability that crossing over would disrupt two genes is more likely when the disrupt two genes is more likely when the distance between them is larger

Question 22

tremendous variation

Answer 22

the number of genotypes possible in offspring as a result of independent assortment and hybrid crossing is 3n
- n being the number of gene loci at which the parents differ
- 3^20 = 3.5 billion (and that is just 20 differences)

Question 23

“simple”/complete dominance

Answer 23

the dominant allele usurps the recessive allele fully

Question 24

codominance

Answer 24

if two alleles are present, both are expressed
ex: human blood type
- AB are codominant when paired
- O is recessive
I for dominant, i for recessive

Question 25

blood type ___ is the universal donor

Answer 25

o; it has neither “type a” or type b glycolipids on the membranes of its red blood cells