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my packs: (wizeprep) (bio 2581) > Chapter 5: 5.4 Laws of Inheritance [Mendel's Laws] > Flashcards

Chapter 5: 5.4 Laws of Inheritance [Mendel's Laws] Flashcards

1
Q

What is Mendel’s First Law?

A

Law of Segregation

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2
Q

State:

The Law of Segregation

A

States that gametes receive only one allele of each gene

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3
Q

Mendel’s most important discovery was the – ——- from parental strains with different traits were not…

A
  1. F1 progeny
  2. True-breeders
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4
Q

What is a true-breeding organism?

A

Organisms that always pass down their phenotypic traits to its offspring

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5
Q

In Mendel’s Law of Segregation:

Where does the F2 Generation come from?

A

Comes from the F1 generation self-fertilizing

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6
Q

In Mendel’s Law of Segregation:

What did Mendel discover in the F2 Generation?

A

The recessive trait reappeared
* Reappeared consistently at a dominant : recessive ratio close to 3 : 1

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7
Q

True or False:

In true breeding parental strains, the two alleles are identical

A

True

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8
Q

Two identical alleles means the plants are…

A

Homozygous

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9
Q

True or False:

Each gamete contains two of alleles of one gene

A

False, each gamete contains just one allele of each gene

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10
Q

What is a reproductive cell known as?

A

A gamete

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11
Q

Each gamete contains — allele of each gene

A

One

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12
Q

State:

The Principle of Segregation

A

When gametes are formed, the two alleles of a gene segregate
* Half of the gametes get one allele, while the other half get the other allele

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13
Q

True or False:

In heterozygous plants, all the gametes will have the same allele

A

False, in homozygous plants all the gametes will have the same allele

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14
Q

Describe:

  1. When a zygote is formed
  2. How it is formed
A
  1. Formed after fertilization
  2. Comprised of the union of two gametes - one from each parent
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15
Q

When the two gametes that formed the zygote carried different alleles for a gene, the resulting zygote…

A

Is heterozygous
* A hybrid containing two different alleles

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16
Q

How can the resulting progeny of the F2 generation be determined?

A

Using a Punnett square

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17
Q

True or False:

The dominant phenotype has to be the same genotype

A

False, since it is dominant the phenotype is the same but the genotype can be different

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18
Q

State:

The Law of Segregation

A

Alleles must segregate equally into gametes such that the progeny (F2) have an equal likelihood of obtaining one of the two alleles

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19
Q

What can be used to test segregation?

A

Testcross

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20
Q

How is a testcross done? What will the results show

A

Cross the F1 progeny with the true-breeding recessive strain instead of allowing them to self-fertilize
* The recessive trait will only be observed if the F1 strain is heterozygous

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21
Q

True or False:

All traits follow the Mendelian rules of dominance

A

False

22
Q

List two ways that traits don’t follow the Mendelian rules of dominance

A
  1. Incomplete dominance: The phenotype of the heterozygote is somewhere in-between the homozygote phenotypes
  2. Codominance: When both traits are expressed
23
Q

What is Mendel’s Second Law?

A

Law of Independent Assortment

24
Q

State:

Mendel’s Second Law (Law of Independent Assortment)

A

Alleles of different genes assort independently of one another during gamete formation

25
Q

There are — possibilities at meiosis when an individual is…

A
  1. Two
  2. Heterozygous at two loci
26
Q

How did Mendel find support for the Second Law?

A

By performing dihybrid crosses

27
Q

What does the law of independent assortment allow for in trait combinations?

A

All trait combinations are possible
* Four equally likely gametes in the F2 generation

28
Q

What would happen if the Law of Independent Assortment was not true?

A

The progeny would all be heterozygous for both genes

29
Q

Punnett Square Rules:

How large should the grid be?

A

Should fit all the alleles from the parents on either side

30
Q

Punnett Square Rules:

Do the parents have to be placed in specific places on a Punnett Square?

A

No, it is arbitrary

31
Q

Punnett Square Rules:

How should alleles be written in a Punnett Square?

A
  1. Dominant alleles written first
  2. In alphabetical order
32
Q

Define:

Locus

A

The physical location of a gene on a chromosome

(Plural: Loci)

33
Q

Define:

Alleles

A

The different versions of a single gene or locus

34
Q

In diploid organisms, how many alleles will the individual inherit for each gene?

A

2 alleles of every gene
* One from mother
* One from father

35
Q

What are some common short-hands for alleles?

A
  1. B and b
  2. B and B’
  3. B1 and B2
36
Q

Define:

Trait

A

Each variant for a character

37
Q

Alleles for a given gene affect the same character but…

A

Can specify different traits

38
Q

Define:

Genotype

A

The specific alleles in an individual (the genetic makeup)

39
Q

Define:

Phenotype

A

The physical appearance of an individual

40
Q

True or False:

Phenotype helps determine genotype

A

Not exactly, genotype helps determine phenotype

41
Q

What does transmission of alleles depend on?

A

Depends on events in meiosis and fertilization

42
Q

Mendel’s Law of Segregation:

— alleles for a heritable character segregate during ——- formation and end up in different gametes

A
  1. Two
  2. Gamete
43
Q

When do members of an allelic pair segregate during meiosis I come together?

A

Fertilization

44
Q

In Mendelian Inheritance:

How many characters are controlled by each gene?

A

One

45
Q

In Mendelian Inheritance:

How many alleles do each genes have?

A

Two
* Each accounts for variations in inherited characters

46
Q

In Mendelian Inheritance:

What do dominant alleles do?

A

Determines an organisms appearance

47
Q

In Mendelian Inheritance:

What do recessive alleles do?

A

Have no noticeable effect if the two alleles at a locus differ

48
Q

In Mendelian Inheritance:

When does the segregation of the two alleles for a heritable character occur?

A

During gamete formation

49
Q

In Mendelian Inheritance:

The alleles or two different genes are…

A

Inherited independently (independent assortment)

50
Q

True or False:

Alleles remain unchanged

A

Mostly. They can be rarely be mutated

51
Q

Can a character be affected by the environment?

A

Yes

52
Q

In the real-world population, pairs of ——— mate with frequencies that depend on their proportions in the ———-

A
  1. Genotypes
  2. Populations

my packs: (wizeprep) (bio 2581) (30 decks)

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