mendelian genetics

Question 1

what are the characteristics of a good model organism?

Answer 1

short life span/reproduction cycle, observable, easy to take care of in lab; common examples include bacteria (e. coli), pea plants, fruit flies

Question 2

theories of inheritance?

Answer 2

blending, influential, and particulate

Question 3

“blending” hypothesis

Answer 3

theory of inheritance where genetic material contributed by two parent mixes like how blue and yellow paints mix to make green; was disproved following the reappearance of traits in F2 generation

Question 4

“influential” hypothesis

Answer 4

theory of inheritance where Aristotle contented that fathers contributed the most offspring; was disproved through reciprocal crosses

Question 5

“particulate” hypothesis

Answer 5

theory of inheritance where parents pass on discrete heritable units (genes), like card shuffled in a deck; was supported through mendels experiments.

Question 6

trait

Answer 6

variant of character/characteristics

Question 7

character(istic)

Answer 7

heritable feature

Question 8

gene

Answer 8

segment of DNA that helps determine characteristic

Question 9

allele

Answer 9

alternate forms of a gene

Question 10

what is a monohybrid cross?

Answer 10

matings between individuals that differ in only one characteristic; homozygous genotypes which result in opposite phenotype for a certain genetic trait; responsible for inheritance of one gene

Question 11

what are the genotypes of the P generation?

monohybrid cross

Answer 11

yellow seed = YY; green seed = yy

Question 12

what are the genotypic and phenotypic proportions of the F1 and F2 generations?

monohybrid cross

Answer 12

F1= 100 % yellow ( genotype: Yy)
F2 3/4 yellow (genotype: 1/4 YY & 1/2 Yy), 1/4 green (genotype: 1/4 yy)

Question 13

what is a reciprocal cross?

Answer 13

breeding expierment designed to test the role of parental sex on a given inheritance pattern; a cross in which the sex of two parents is reversed

Question 14

what are dominant traits?

Answer 14

traits that appear in the F1 generation; both parent and offspring are affected by the trait related to the gene; determined by the allele

Question 15

what are dominant alleles?

Answer 15

the allele the is expressed out of the two version of the allele that were given from parents; determines the trait; written in uppercase letters, first letter of discription

Question 16

what are recessive traits?

Answer 16

traits that disappear in the F1 generation; trait that is expressed only when the genotype is homozygous

Question 17

what are recessive alleles?

Answer 17

a type of allele that when present on its own will not affect the individual; written as lowercase letters

Question 18

what are genotypes?

Answer 18

actual alleles present in individual, denoted by two letter for each gene

Question 19

what are phenotypes?

Answer 19

observable/visible trait

Question 20

homozygous genotypes

Answer 20

have 2 of the same allele for a particular gene

Question 21

homozygous dominant

example

Answer 21

YY

Question 22

homozygous recessive

example

Answer 22

yy

Question 23

heterozygous geneotypes

Answer 23

have 2 different alleles for a particular gene (denoted as Yy)

Question 24

how do dominant and recessive alleles affect the phenotype of heterozygotes?

Answer 24

alleles contribute to the outward appearence of organisms, a dominant allele produces a dominant phenotype in offspring who have one copy of the allele, which can come from just one parent; recessive alleles produce a recessive phenotype and the offspring must have two copies, with one being from each parent in order for the recessive allele to be expressed as the phenotype

Question 25

mendels first postulate | unit factors in pairs

Answer 25

genetic characterisitcs controlled by alternative versions of genes, that exit in pairs in individual organisms: each individual inherits two alleles, one from each parent and in monohybrid crosses there are three combos of unit facors (YY, Yy, yy)

Question 26

mendels second postulate | dominance and resecciveness

Answer 26

if the two alleles at a locus differ: one allele, the dominant allele, determine the organisms phenotype; the other allele, recessive allele, has no noticeable effect on the organisms phenotype

Question 27

mendels third postulate | law of segregation

Answer 27

the two alleles for a heritable character seperate (segregate) suring gamete formation and end up in different gametes; the two alleles segregate to offspring randomly (true for unlinked genes)

Question 28

how do you use a punnett square to determine the genotypic and phenotypic proportions of the offspring of a cross?

Answer 28

you can use a punnett square to determine this by putting the gametes of parent 1 on the top of the square, and gamete of parent 2 on the left side of the square, using this you can see the resulting offspring based off where the alleles intersect; the square as a whole represents 100% of offspring, while a single square within the square represent 25% of offspring

Question 29

if given the genotypic or phenotypic proportions of offspring, how do you use a punnett square to determine the genotypes of the parents that produced that offspring?

Answer 29

...

Question 30

what is a test cross?

Answer 30

cross of individual with dominant phenotype but unknown genotype, with recessive homozygous individual; can determine genotype of individual with dominant phenotype but unknown genotype

Question 31

when would you do a test cross and what information can it give you?

Answer 31

would do a this procedure to identify whether an organism exhibiting a dominant trait is heterozygous or homozygous for a specific allele; this information can determine the genotype of individuals with dominant phenotypes but an unknown genotype

Question 32

what is a dihybrid cross?

Answer 32

two characters that are different produces F1 offspring heterozygous for two characters: YYRR (yellow round) * yyrr (green wrinkled)

Question 33

what are the genotypes of the P generation? | dihybrid cross

Answer 33

genotypes of parents = YYRR (yellow round) & yyrr (green wrinkled)

Question 34

what are the genotypic and phenotypic proportions of the F1 and F2 generations? | dihybrid cross

Answer 34

F1: YyRr (yellow round) F2: 9/16 YyRr (yellow round), 3/16 yyRr (green round), 3/16 Yyrr (yellow wrinkled), & 1/16 yyrr (green wrinkled) ratio = 9:3:3:1

Question 35

mendels fourth postulate | law of independant assortment

Answer 35

using information from a dihybrid cross, mendel deceloped the law of independant assortment: each pair of alleles segregates independantly during gamete foundation; reflects the rules of probability

Question 36

rule of multiplication | product or "and" law

Answer 36

probability that two or more outcomes will occur together = product of their individual probabilities; ie probability of getting rr = 1/2 * 1/2 = 1/4

Question 37

rule of addition | sum law

Answer 37

probability that any two or more exclusive events will occur = sum of thier individual probabilities; ie probability of Rr = 1/4 + 1/4 = 1/2