Chapter 11 Mendel And The Gene Idea

Question 1

The blending hypothesis

Answer 1

Is the idea that genetic material from two parents blends together

Question 2

The particulate hypothesis

Answer 2

Is the idea that parents pass on discrete heritable units called genes

Question 3

Mendel discovered the basic principles of heredity by breeding

Answer 3

Garden peas

Question 4

Mendel chose peas because

Answer 4

There are many varieties with distinct features or characters

Character variants are called traits

He could control mating

Question 5

Mendel chose to track only characters that occurred in

Answer 5

Two distinct alternative forms

Question 6

True breeding

Answer 6

Plants that produce offspring of the same variety when they self pollinate

Question 7

Hybridization

Answer 7

Mating two contrasting true breed varieties

Question 8

The true breeding plants are called the_______ and the hybrid offspring of the P Generation are called _________

Answer 8

P Generation, F1 Generation

Question 9

When F1 individuals self pollinate or cross pollinate with each other the _________generation is produced

Answer 9

F2

Question 10

Mendel reasoned that in the _______plants, the heritable factor for white flowers was masked in the presence of the purple flower factor

Answer 10

F1

Question 11

Mendel model to explain the 3:1 pattern

Answer 11

Alternative versions of genes account for variations in inherited characters l. These are called alleles

For each character an organism inherits two alleles, one from each parent

If two alleles differ then the dominant allele determines appearance

Law of segregation-the two alleles for a heritable character separate during gamete formation

Question 12

An organism with two identical alleles for a character is said to be

Answer 12

Homozygous

Question 13

An organism that has two different alleles for a gene is said to be

Answer 13

Heterozygous

Question 14

Phenotype va genotype

Answer 14

Phenotype is physical appearance

Genotype is genetic makeup

Question 15

How can we tell the genotype of an individual with a dominant phenotype?

Answer 15

Test cross by breeding the mystery individual with a homozygous recessive individual and if any offspring display the recessive phenotype the mystery parent must be heterozygous

Question 16

Mono hybrids

Answer 16

Individuals that are heterozygous for one character

Question 17

A cross between monohybrids is called

Answer 17

Monohybrid cross

Question 18

Crossing two true breeding parents differing in two characters produces

Answer 18

Dihybrids

A dihybrid cross between F1 dihybrids can determine whether two characters are transmitted to offspring as a package or independently

Question 19

Law of independent Assortment

Answer 19

Each pair of alleles segregates independently of any other pair during gamete formation

Question 20

Inheritance may deviate from simple Mendelian patterns in the following situations

Answer 20

Alleles are not completely dominant or recessive

When a gene has more than two alleles

When a single gene produces multiple phenotypes

Question 21

Three degrees of dominance

Answer 21

Complete dominance-when phenotypes of the heterozygote and dominant homozygote are identical

Incomplete Dominance- the phenotype F1 hybrids is somewhere in between the phenotypes of the two parental varieties

Codominance-two dominant alleles affect the phenotypes in separate distinguishable ways

Question 22

Alleles are simply variations in

Answer 22

A genes nucleotide sequence

Question 23

Tay-Sachs

Answer 23

A dysfunctional enzyme causes an accumulation of lipids in the brain

Question 24

Dominant alleles are not necessarily more common than

Answer 24

Recessive alleles

Question 25

Pleiotropy

Answer 25

Genes have multiple phenotypic effects

Question 26

Epistasis

Answer 26

A gene at one locus alters the phenotypic expression of a gene at a second locus

Example is a Labrador coat color depends on two genes

Question 27

Quantitative Characters

Answer 27

Are those that vary in the population along a continuum

Question 28

Polygenic Inheritance

Answer 28

An additive effect of two or more genes on a single phenotype

Example is skin color in humans

Question 29

Multifactorial

Answer 29

Genetic and environmental factors collectively influence phenotype

Question 30

Pedigree

Answer 30

A family tree that describes the interrelationships of parents and children across generations

Question 31

Carriers

Answer 31

Are heterozygous individuals who carry the recessive allele but are phenotypically normal

Question 32

Cystic fibrosis

Answer 32

The most common lethal genetic disease in the United States

Allele results in defective chloride transport channels in plasma membranes leading to a buildup of chloride ions outside the cell

Question 33

Huntington’s Disease

Answer 33

A degenerative disease of the nervous system