chapter 13 - patterns of inheritance

Question 1

chromosomes def

Answer 1

long molecules of DNA wrapped around nucleosomes…

Question 2

what percentage of DNA codes for function protein in eukaryotes… what about prokaryotes?

Answer 2

Around 1% for eukaryotes, 90% for prokaryotes

Question 3

how many chromosomes do humans have?

Answer 3

46, 23 pairs

Question 4

how are human chromosomes arranged?

Answer 4

in the order of size, though the last one - #23 is the sex chromosome

Question 5

human male chromosome

Answer 5

XY

Question 6

human female chromosome

Answer 6

XX

Question 7

homozygous def

Answer 7

same alleles

Question 8

heterozygous def

Answer 8

different alleles

Question 9

genotype def

Answer 9

the actual alleles inherited

ex: genes coding for flower color AA, Aa, or aa

Question 10

phenotype def

Answer 10

the physical characteristics or traits of an organism

ex: purple flowers

Question 11

who and when were the principles of genetics created [by]?

Answer 11

mendel in 1860s

Question 12

how did mendel create these principles?

Answer 12

used pea-plants which self-pollinate, grow easily + quickly, and have 7 contrasting traits

Question 13

principle of dominance

Answer 13

1 trait is ALWAYS expressed

Question 14

principle of segregation

Answer 14

during meiosis homologous chromosomes separate into each cell

Question 15

what is a cross?

Answer 15

making of 2 organisms

Question 16

P = ?

Answer 16

parental generation

Question 17

F1 = ?

Answer 17

first generation

Question 18

F2 = ?

Answer 18

second generation

Question 19

how can we predict results?

Answer 19

punnett squares determine probability or chances of a specific outcome

Question 20

principle of independent assortment

Answer 20

chromosomes segregate independently of one another during meiosis - only get 1 pair of each cell

Question 21

what other factors can affect offspring separate from predictions?

Answer 21

carrying capacity or amount of resources it can sustain:

I. food
II. water
III. habitat

Question 22

product rule

Answer 22

chance of 2 or more independent events occurring simultaneously = probability of each multiplied

Question 23

dihybrid cross def

Answer 23

2 traits, hybrid for both

Question 24

what kind of a trait is height? what is it influenced by?

Answer 24

Height is a multifactorial trait-

multifactorial inheritance is influence by more than 1 gene and the environment

Question 25

can some alleles be neither dominant nor recessive?

Answer 25

yes

Question 26

are traits only controlled by a single allele/gene?

Answer 26

no; many traits are controlling by multiple alleles or multiple genes

Question 27

what are 4 exceptions to mendel’s law?

Answer 27

I. Incomplete dominance
II. Multiple alleles
III. Codominance
IV. polygenic traits

Question 28

incomplete dominance def

Answer 28

the heterozygous phenotype is somewhere BETWEEN the two homozygous phenotypes AND NEITHER allele is COMPLETELY dominant OR COMPLETELY recessive

ex: red + white flowers make pink

Question 29

codominance def

Answer 29

both traits are fully and SEPARATELY expressed

ex 1: red + white flowers make red and white speckled

ex 2: blood type AB - fully A and fully B

Question 30

what is blood type is an example of?

Answer 30

codominance AND multiple alleles

multiple alleles - genes with more than 2 allele forms : A, B, and i

codominance - blood type fully A and fully B

Question 31

polygenic inheritance def

Answer 31

a trait produced by two or more genes, and usually shows a RINGE in phenotype

ex: skin color, eye color, height, personality

Question 32

what can occasionally in polygenic inheritance?

Answer 32

epistasis: one gene overshadows all of the others
ex: labrador retriever fur colors, eye colors, and albinism

[ bad gene(s) make bad traits, all bad people make bad society ]

Question 33

pleitropy def

Answer 33

genetic effect of 1 gene on multiple phenotype traits- alleles at 1 locus may have effects on 2 or more traits

ex: sickle cell

[ 1 bad gene makes mANY bad traits, bad powerful person make bad… everything]

Question 34

epistasis def

Answer 34

the interaction between genes at two or more loci…. the phenotype differs from what would be expected if the loci were expressed separately

ex: polygenic

Question 35

what mendel principle are linked genes an exception to?

Answer 35

principle of independent assortment

Question 36

linked genes def

Answer 36

genes physically located on the same chromosome will be inherited together

ex: blonde hair + blue eyes, red hair + freckles

Question 37

how are linked genes separated?

Answer 37

only can be separated by crossing over

the farther the distance between the genes, the greater chance of being unlinked

Question 38

sex-linked traits def

Answer 38

Y chromosome carry few genes

X chromosome contains MANY genes that affect many traits

ex: colorblindness

Question 39

sex linked genes def

Answer 39

genes on sex chromosomes

Question 40

x-linked genes def

Answer 40

genes on the X chromosomes are linked

• females inherit the trait as normal and principle of dominance applies
• males inherit the gene on the X but not the Y

Question 41

how are x-linked genes passed through parents to children?

Answer 41

moms to sons; dads to daughters

males only have one X, they express it whether it is dominant or recessive