lec 5 patterns of inheritance

Question 1

what are genes?

Answer 1

segment of DNA within a chromosome serving as codes for protein(s)

Question 2

what is important to note about genes with respect to inheritance?

Answer 2

genes are the basic unit of inheritance

Question 3

how many chromosomes in a single cell? how many pairs?

Answer 3

46 chromosomes

23 pairs

Question 4

what are chromomsomes?

Answer 4

long strands of DNA

Question 5

what is a homologus pair?

Answer 5

pair of chromosomes, 1 from each mother +father

Question 6

t/f most of our cells contain exactly the same set of genes

Answer 6

true

Question 7

how many chromosomes do both sperm and egg cells have?

Answer 7

half of a normal cell

23

Question 8

what are alleles?

Answer 8

alternative versions of a type of gene

Question 9

explain alleles using the example of a fur color gene in a mouse

Answer 9

-on mouse chromosome is gene for fur color (lets say gene a)
-mice have 2 forms of gene a (1 from mother, 1 from father)
-therefore mouse has two versions of gene a (alleles)
-ex mouse could have 1 black and 1 brown fur allele

Question 10

individual who carries two copies of same allele is called?

Answer 10

homozygote

Question 11

heterozygote

Answer 11

individual that carries different alleles

Question 12

where do alleles originate from?

Answer 12

mutations

Question 13

what is a mutation?

Answer 13

change in DNA that makes up a gene

Question 14

t/f all mutations are harmful

Answer 14

false, mutations can be harmful, beneficial or neutral

Question 15

genotype

Answer 15

genetic makeup of an organism

Question 16

observeable, physical characteristics of an organism

Answer 16

phenotype

Question 17

when reading genotypes, what type of letter represents the dominant allele? the ressecive allele?

Answer 17

dominant: capital letters

resscesive: lowercase

Question 18

what do dominant alleles determine?

Answer 18

phenotype of an organism

Question 19

what would a genotype look like for a white flower, if the dominant allele is (P) purple and ressecive is (p) white

Answer 19

pp homozygote

-both alleles need to be ressecive for ressecive trait to be phenotype

Question 20

what is dna’s structure?

Answer 20

double helix

Question 21

what is the blending theory? note that this theory does not hold up.

Answer 21

offspring should have phenotype that is intermediate between both parents

Question 22

what is an example of observations not fitting the blending theory ?

Answer 22

eye colour skipping generations in humans

Question 23

who disproved the blending theory? what was his infamous experiment?

Answer 23

Gregor Mendel

-crossing true-breeding varieties of pea plants
-he found that flower colours were most of the time purple, and occasionally white

Question 24

what is true breeding?

Answer 24

-parents are self polinated
-offspring are identical to parents

-have the same alleles

Question 25

what are the 5 points of Mendel’s particulate theory of inheritance

Answer 25

1. alleles cause variation in character
2. offspring inherit 1 copy of a gene (allele) from each parent
3. alleles seperate into different gametes
4. gametes can fuse regardless of the allele they carry
5. alleles can be dominant or recessive

Question 26

what is Mendel’s first law of equal seggregation?

Answer 26

states that two copies of each gene (alleles) seperate

Question 27

what diagram can be used to illustrate Mendel’s first law? why?

Answer 27

punnentt square

-considers all possible combos of gametes
-predicts outcome of cross

Question 28

what is Mendel’s second law of independant assortment?

Answer 28

-gametes=alleles for one trait combine randomly with alleles for other traits

-gametes form, the two alleles of one gene (ex color) segregate during meiosis independantly of any two alleles of other genes (ex texture)

-which allele a gamete receives for gene A has no bearing on allele it receives for gene B

illustrated when tracking more than 1 characteristic

Question 29

explain independant assortment using texture and color of pea plants? what would the genotype for a yellow round pea be? wrinkled green?

R=round r=wrinkled
Y= yellow y=green

Answer 29

if pea was yellow and round= RRYY
green and wrinkled= rryy

Question 30

dihybrid crossing: if a truebreeding yellow, round pea (RRYY) was crossed with a truebreeding green, wrinkled pea, what would be the GAMETES? what would be the F1 gen (result)

Answer 30

RY, Ry, rY, ry

F1= RrYy (round, yellow)

Question 31

how would we illustrate the crossing of F1 generations?

Answer 31

punnentt square, instead of being 2x2, they will be 4x4 because there are more gametes

Question 32

what is incomplete dominance?

Answer 32

-one allele unable to express full phenotype in
heterozygous individual

heterozygote phenotype that intermediates b/w those of the two homozygotes

Question 33

what theory does incomplete dominance resemble? what is an example if incomplete dominance?

Answer 33

blending theory but it is NOT bleding theory

crossing snapdragons
red+ white may sometimes result in pink

Question 34

t/f most characteristics are controlled by multiple genes

Answer 34

true

Question 35

what is an example that proves most characteristics are controlled by multiple genes?

Answer 35

skin color, humans have diff amounts of melanin in skin

skin color controlled by three genes (A, B, C) that have equal effects