Chap 10 Patterns of Inheritance

Question 1

What does DNA do with our genes?

Answer 1

carries our genes

Question 2

What is a gene?

Answer 2

a portion of DNA whose sequence of nucleotides (A,C,G,T) encodes a protein

Question 3

What determine many of an organisms’s characteristics?

Answer 3

the proteins expressed in cells - e.g. eye, hair, skin color

Question 4

What are chromosomes?

Answer 4

packets of genetic information

Question 5

Describe the structure of a chromosome.

Answer 5

long strands of DNA wrapped around histone proteins

Question 6

How many genes are in a chromosome?

Answer 6

lots

Question 7

When are chromosomes passed on?

Answer 7

during cell division

Question 8

How many chromosomes do humans have?

Answer 8

46 (23 from each parent when male and female gamete fuses at fertilization)

Question 9

How are chromosomes paired (type of cell)?

Answer 9

in diploid cells

Question 10

The zygote is what after fertilization?

Answer 10

diploid

Question 11

What does it mean when a cell is diploid?

Answer 11

it has two sets of chromosomes

Question 12

Each chromosome is a member of what?

Answer 12

a homologous pair

Question 13

Meiosis does what to homologous pairs?

Answer 13

separates them

Question 14

Diploid cells have what for each gene?

Answer 14

two alleles

Question 15

Alleles might be…?

Answer 15

identical or different

Question 16

Who discovered the basic law of inheritance?

Answer 16

Gregor Medel

Question 17

What did Gregor Mendel use to study heredity?

Answer 17

pea plants

Question 18

Why did Gregor Mendel use pea plants to study heredity?

Answer 18

it is easy to control which plant mates with which, and he was able to set up systematic breeding experiments

Question 19

What gave Mendel clues about the genes of parents?

Answer 19

offspring

Question 20

True-breeding plants produce what?

Answer 20

produce offspring identical to themselves

Question 21

Hybrid plant produce what?

Answer 21

(outwardly resemble true-breeders) but produce mixed offspring

Question 22

Are some alleles dominant?

Answer 22

yes

Question 23

Dominant alleles do what?

Answer 23

exert their effects whenever they are present (yellow seed)

Question 24

Are some alleles recessive?

Answer 24

yes

Question 25

Recessive alleles do what?

Answer 25

its effect is masked if a dominant allele is also present (green seed)

Question 26

Recessive alleles often do what?

Answer 26

encode nonfunctional proteins

Question 27

Why do some plants produce both yellow and green seeds?

Answer 27

because each plant has two alleles for each gene (because of their homologous pairs of chromosomes)

Question 28

May homologous chromosomes have different alleles?

Answer 28

yes

Question 29

What does a genotype represent?

Answer 29

an individual's two alleles for one gene

Question 30

What does it mean when a genotype is Homozygous dominant?

Answer 30

individuals have two dominant alleles for a gene

Question 31

What does it mean when a genotype is heterozygous?

Answer 31

individuals have one dominant and one recessive allele

Question 32

What does it mean when a genotype is homozygous recessive?

Answer 32

individuals have two recessive alleles

Question 33

What is the genotype responsible for?

Answer 33

the phenotype

Question 34

What is a phenotype?

Answer 34

the physical appearance - e.g. observable characteristic like seed color

Question 35

How is the phenotype determined?

Answer 35

by how the alleles interact with each other

Question 36

How do you determine the genotype of a parent?

Answer 36

by looking at the offspring

Question 37

Can individuals with the dame phenotype have different genotypes?

Answer 37

yes

Question 38

How do genotypes lead to phenotypes (seeds)?

Answer 38

the seed color gene encodes a pigment-metabolizing enzyme allele Y encodes an active enzyme, producing yellow pigment due to a mutation, allele y encodes and inactive enzyme that does not produce yellow pigment

Question 39

What represents gamete formation and fertilization?

Answer 39

Punnett squares

Question 40

What does a Punnett square do?

Answer 40

uses the genotypes of the parents to reveal which alleles the offspring may inherit

Question 41

Explain Homozygous dominant with seeds.

Answer 41

if a cross between a yellow-seed pea plant an d a green-seed pea plant yields all yellow seeds... then the yellow-seed parent must be homozygous dominant (YY)

Question 42

Explain Heterozygous with seeds?

Answer 42

if a cross between a yellow-seed pea plant and a green-seed pea plant yields some green seeds... then the yellow-seed parent must be heterozygous (Yy)

Question 43

Punnett squares is prediction showing what?

Answer 43

the relative proportion of the offspring's phenotypes and genotypes

Question 44

Mendel deduced what?

Answer 44

the law of segregation

Question 45

What is the law of segregation?

Answer 45

two alleles of each gene "segregate" (move apart from each other), during gamete formation

Question 46

Punnet squares can be used to track what?

Answer 46

the inheritance of genetic disorders - e.g. cystic fibrosis

Question 47

What tracks the inheritance of two genes at once?

Answer 47

dihybrid crosses

Question 48

What do dihybrid crosses do?

Answer 48

track the inheritance of two genes at once

Question 49

What can be shown on one large Punnett square?

Answer 49

two genes on different chromosomes (the alleles for each gene are shown in the parent, gametes, and offspring)

Question 50

Meiosis explains what?

Answer 50

the law of independent assortment

Question 51

What is the law of independent assortment?

Answer 51

chromosomes (carrying alleles) are packaged into gametes independently of each other as the spindle pulls them into place

Question 52

How are genes on different chromosomes are inherited?

Answer 52

inherited separately

Question 53

Why can we predict the genotype and phenotype ratios of the offspring?

Answer 53

because chromosomes are assorted independently

Question 54

How are genes on the same chromosome inherited?

Answer 54

inherited together

Question 55

What is different when chromosomes are inherited together?

Answer 55

different ratios will be seen in offspring

Question 56

Genes that are physically near each other on the same chromosome are what?

Answer 56

linked/inherited together

Question 57

When can genes become "unlinked"?

Answer 57

during cross over

Question 58

What does crossing over do to linked genes?

Answer 58

physically separates the two genes onto two different chromosomes

Question 59

Do all genes follow Mendelian inheritance patterns?

Answer 59

no

Question 60

What creates a new phenotype?

Answer 60

incomplete dominance

Question 61

The way alleles interact changes what?

Answer 61

the nature of the phenotypes but not the genotypes

Question 62

Give an example of incomplete dominance?

Answer 62

Red and White alleles can make pink

Question 63

Can one gene influence many phenotypes?

Answer 63

yes

Question 64

What is pleiotropy?

Answer 64

one gene has multiple effects on the phenotype - e.g. a gene might affect more than one biochemical pathway, e.g. marfan syndrome

Question 65

What type of genes have unique inheritance patterns?

Answer 65

sex-linked

Question 66

What is a sex-linked gene?

Answer 66

phenotypes that affect one sex more than the other (that is, the alleles controlling them are on the X or Y chromosome)

Question 67

How many alleles for X-linked genes do males have?

Answer 67

one

Question 68

How many alleles for X-linked genes do females have?

Answer 68

two

Question 69

Does the Y chromosome have alleles for X-linked genes?

Answer 69

No

Question 70

Which allele is expressed for the X on males?

Answer 70

whichever allele males have on their single X chromosome is the one that is expressed as a phenotype

Question 71

What prevents double dosing of gene products?

Answer 71

X-inactivation

Question 72

Each cell does what to prevent double dosing of gene products?

Answer 72

each cell in an XX individual randomly inactivates one X chromosome (the genes on the inactivated chromosomes won't be used to produce proteins)

Question 73

What can alter a phenotype?

Answer 73

the environment (e.g. siamese cats have a mutation in a gene for an enzyme responsible for pigment production in their fur. the mutates enzymes is active only in cool body parts, while in warm body parts the mutated enzyme is inactive and no color is produced. Thus the cats have black paws, face, ears, and tail while the rest of the body is colorless)