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ZZZ - General Zoology > Mendel and the Gene Idea > Flashcards

Mendel and the Gene Idea Flashcards

1
Q

What genetic principles account for the transmission of traits from parents to offspring?

A
  1. “Blending” Hypothesis
  2. “Particulate” Hypothesis of inheritance: the gene idea
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2
Q

the idea that genetic material contributed by two parents mixes in a manner analogous to the way blue and yellow paints blend to make green

A

Blending hypothesis

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3
Q

Hypothesis which states that parents pass on discrete heritable units, genes

A

Particulate Hypothesis of Inheritance: The Gene Idea

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4
Q

documented a particulate mechanism of inheritance through his experiments with garden peas

A

Gregor Mendel

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5
Q

What approach did Mendel use to identify the two laws of inheritance?

A

scientific approach

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6
Q

How did Mendel discover the basic principles of heredity?

A

By breeding garden peas in carefully planned experiments

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7
Q

Why did Mendel choose to work with peas?

A
  1. Available in many varieties
  2. Could strictly control which plants mated which
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8
Q

By crossing (mating) two true-breeding varieties of an organism, scientists can study __ __ __

A

patterns of inheritance

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9
Q

Results: When pollen from white flower fertilizes eggs of purple flower, the first generation hybrids all have ___ flowers

A

Purple

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10
Q

a heritable feature

A

character

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11
Q

example of a character

A

flower color

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12
Q

a variant of a character

A

trait

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13
Q

example of a trait

A

purple or white flowers

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14
Q

What characters did Mendel chose to only track?

A

characters that varied in an “either-or” manner

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15
Q

What did Mendel make sure when starting the experiments?

A

His varieties were true-breeding

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16
Q

What do you call the process where Mendel mated two contrasting, true-breeding varieties?

A

Hybridization

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17
Q

The true-breeding parents are called?

A

P generation

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18
Q

The hybrid offspring of the P generation are called?

A

F1 generation

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19
Q

What do you call the offspring when F1 individuals self-pollinate?

A

F2 generation

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20
Q

Law states that hybrid offspring will only inherit the dominant characteristics in the phenotype. The alleles that suppress a trait are recessive traits, whereas the alleles that define a trait are known as dominant traits.

A

Law of Dominance

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21
Q

The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

A

Law of Segregation

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22
Q

What is the first law of inheritance?

A

Law of Dominance

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23
Q

What is the second law of inheritance?

A

Law of Segregation

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24
Q

When Mendel crossed the F1 plants, he discovered a ratio of about __ to __, __ to __ flowers, in the F2 generation

A

3:1, purple:white

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25
Q

Mendel reasoned that in F1 plants, purple flower color was __, and white flower color was __

A

purple = dominant
white = recessive

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26
Q

Four (4) concepts that make up the Mendel’s model

A
  1. Alternative versions of genes
  2. An organism inherits two alleles, one from each parent, and a genetic locus is represented twice
  3. If the two alleles at a locus differ, the dominant allele determines the organism’s appearance
  4. Law of segregation
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27
Q

An organism that is homozygous for a particular gene has a pair of ___ alleles for that gene and exhibits ____

A

Identical alleles
Exhibits True-breeding

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28
Q

An organism that is heterozygous for a particular gene has a pair of alleles that are ___ for that gene

A

Different

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29
Q

its physical appearance

A

phenotype

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30
Q

its genetic makeup

A

genotype

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31
Q

allows us to determine the genotype of an organism with the dominant phenotype

A

testcross

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32
Q

How do you testcross?

A

cross an individual with the dominant phenotype with an individual that is homozygous recessive for a trait

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33
Q

The F1 offspring produced in the testcross were __, __ for one character

A

monohybrid, heterozygous

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34
Q

How did Mendel derive the law of segregation?

A

by following a single trait

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35
Q

How did Mendel derive his second law of inheritance?

A

by following two characters at the same time

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36
Q

Crossing two, true-breeding parents differing in two characters produces __ in the __ generation, __ for both characters

A

dihybrids; F1; heterozygous

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36
Q

illustrates the inheritance of two characters

A

dihybrid cross

37
Q

dihybrid cross produces __ phenotypes in the F2 generation

38
Q

How did Mendel develop the law of independent assortment?

A

using the information from a dihybrid cross

39
Q

each pair of alleles segregates independently during gamete formation

A

Law of Independent Assortment

40
Q

The physical site or location of a specific gene on a chromosome.

41
Q

The laws of __ govern Mendelian inheritance

A

probability

42
Q

states that the probability that two or more independent events will occur together is the product of their individual probabilities

A

Multiplication Rule

43
Q

The probability in a monohybrid cross can be determined using what rule?

A

Multiplication Rule

44
Q

states that the probability that any one of two or more exclusive events will occur is calculated by adding together their individual probabilities

A

Rule of Addition

45
Q

The rules of probability can be applied to predict the outcome of crosses involving __ __

A

multiple characters

46
Q

equivalent to two or more independent monohybrid crosses occurring simultaneously

A

dihybrid or other multicharacter cross

47
Q

each character first is considered separately and then the individual probabilities are multiplied together

A

Calculating chances for various genotypes from such crosses

48
Q

Inheritance patters are often more complex than predicted by simple Mendelian genetics

A

relationship between genotype and phenotype is rarely simple

49
Q

Inheritance of characters by a single gene may deviate from ____ ____ ____

A

simple Mendelian patterns

50
Q

occurs when the phenotypes of the heterozygote and dominant homozygote are identical

A

Complete Dominance

51
Q

two dominant alleles affect the phenotype in separate, distinguishable ways

A

Codominance

52
Q

Example of codominance

A

human blood group MN

53
Q

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties

A

Incomplete Dominance

54
Q

Dominant and recessive alleles do not really __; lead to ____

A
  • do not really “interact”
  • lead to synthesis of different proteins that produce a phenotype
55
Q

Frequency of Dominant Alleles

A

Dominant alleles are not necessarily more common in populations than recessive alleles

56
Q

most genes exist in populations in more than two allelic forms

A

Multiple alleles

57
Q

The __ __ __ in humans is determined by multiple alleles

A

ABO blood group

58
Q
  • a gene has multiple phenotypic effects
  • the phenomenon of a single gene affecting multiple traits
A

pleiotropy

59
Q

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

60
Q

Example of epistasis

61
Q

occurs when one characteristic is controlled by two or more genes

A

polygenic inheritance

62
Q

Example of polygenic inheritance

A

height, skin color, eye color, weight

63
Q

usually indicates polygenic inheritance

A

quantitative variation

64
Q

when the phenotype of a character depends on environment as well as on genotype

A

Nature and Nurture: The Environmental Impact on Phenotype

65
Q

is the phenotypic range of a particular genotype that is influenced by the environment

A

The norm of reaction

66
Q

are those that are influenced by both genetic and environmental factors

A

Multifactorial characters

67
Q

An organism’s phenotype

A
  • physical appearance
  • internal anatomy
  • physiology
  • behavior
  • reflects overall genotype and unique environmental history
68
Q
  • family tree that describes the interrelationships of parents and children across generations
  • can also be used to make predictions about future offspring
69
Q

can be traced and described using pedigrees

A

inheritance patterns of particular traits

70
Q

Many genetic disorders are inherited in a __ manner

71
Q

Recessively inherited disorders show up only in individuals __ for the allele

A

homozygous

72
Q

Carriers are __ individuals who carry the recessive allele but are phenotypically normal

A

heterozygous

73
Q

caused by a defective gene that makes the body produce abnormally thick and sticky fluid, called mucus

A

cystic fibrosis

74
Q

Examples of inherited disorders due to recessive genes

A
  1. Cystic fibrosis
  2. Sickle-cell Disease
75
Q

a group of conditions in which red blood cells are not shaped as they should be

A

Sickle-cell Disease

76
Q

How many African-Americans are affected with sickle-cell disease?

A

one out of 400

77
Q

Symptoms of cystic fibrosis

A
  • mucus buildup in some of the internal organs
  • abnormal absorption of nutrients in the small intestine
78
Q

Symptoms of sickle-cell disease

A
  • physical weakness
  • pain
  • organ damage
  • paralysis
79
Q
  • can increase the probability of the appearance of a genetic disease
A

matings between relatives

80
Q

matings between relatives are called __ __

A

consanguineous matings

81
Q

Some human disorders are due to __ alleles

82
Q

Example of inherited disorders due to dominant genes

A
  1. Achondroplasia
  2. Huntington’s disease
83
Q

form of dwarfism that is lethal when homozygous for the dominant allele

A

Achondroplasia

84
Q

degenerative disease of the nervous system

A

Huntington’s disease

85
Q

Huntington’s disease has no obvious phenotypic effects until about ____ of age

A

35-40 years

86
Q

human diseases have both genetic and environment components

A

multifactorial disorders

87
Q

Examples of multifactorial disorders

A
  1. heart disease
  2. cancer
88
Q

can provide information to prospective parents concerned about a family history for a specific disease

A

genetic counselors

89
Q

can identify whether your baby is more or less likely to have certain birth defects, many of which are genetic disorders.

A

fetal testing

90
Q

the liquid that bathes the fetus is removed and tested

A

amniocentesis

91
Q

sample of the placenta is removed and tested

A

chorionic villus sampling (CVS)

ZZZ - General Zoology (23 decks)

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