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Biology Test 4 - Ch 12-15 > Chapter 14 - Mendelian Genetics > Flashcards

Chapter 14 - Mendelian Genetics Flashcards

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1
Q

Co

A

= together

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2
Q

Di

A

= two

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3
Q

Geno

A

= offspring

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4
Q

Hetero

A

= different

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5
Q

Homo

A

= same

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6
Q

Mono

A

= one

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7
Q

Pedi

A

= a child

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8
Q

Pheno

A

= appear

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9
Q

Pleio

A

= more

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10
Q

Poly

A

= many

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11
Q

Gene

A

= produce

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12
Q

Alleles

A

Alternative versions of a gene that produce distinguishable phenotypic effects.

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13
Q

Carrier

A

An individual who is heterozygous at a given genetic locus, with one normal allele and one potentially harmful recessive allele.

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14
Q

Codominance

A

The situation in which the phenotypes of both alleles are exhibited in the heterozygote.

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15
Q

Complete Dominance

A

The situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.

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16
Q

Dihybrid

A

An organism that is heterozygous with respect to two genes of interest.

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17
Q

Dominant Allele

A

An allele that is fully expressed in the phenotype of a heterozygote.

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18
Q

Epistasis

A

A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited.

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19
Q

F1 Generation

A

The first filial, or hybrid, offspring in a series of genetic crosses.

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20
Q

F2 Generation

A

Offspring resulting from interbreeding of the hybrid F1 generation.

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21
Q

Genotype

A

The genetic makeup, or set of alleles, of an organism.

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22
Q

Heterozygous

A

Having two different alleles for a given gene.

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23
Q

Homozygous

A

having two identical alleles for a given gene.

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24
Q

Hybridization

A

The mating, or crossing, of two true-breeding varieties.

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25
Q

Incomplete Dominance

A

The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.

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26
Q

Law of Independent Assortment

A

Mendel’s second law

Stating that each pair of elleles segregates independently during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes.

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27
Q

Law of Segregation

A

Mendels first law.

Stating that each allele in a pair separates into a different gamete during gamete formation.

28
Q

Monohybrid

A

An organism that is heterozygous with respect to a single gene of interest.

29
Q

P Generation

A

The parent individuals from which offspring are derived in studies of inheritance.

P stands for parental.

30
Q

Phenotype

A

The physical and physiological traits of an organism that are determined by its genetic makeup.

31
Q

Pleiotropy

A

The ability of a single gene to have multiple effects.

32
Q

Polygenic Inheritance

A

An additive effect of two or more gene loci on a single phenotypic character.

33
Q

Punnett Square

A

A diagram used in the study of inheritance to show the results of random fertilization in genetic crosses.

34
Q

Recessive Allele

A

An allele whose phenotypic effect is not observed in a heterozygote.

35
Q

Testcross

A

Breeding of an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype.

36
Q

Trait

A

Any detectable variation in a genetic character.

37
Q

True-breeding

A

Referring to organism that produce offspring of the same variety when they mated with the same varieties; are homozygous for characters being considered.

38
Q

Modern Genetic Theory

A

Based on particular inheritance in which heredity is passed from parent to offspring by discrete units called genes.

39
Q

Gregor Mendel

A

Austrian monk who is considered the father of modern genetics and discovered many of the basic facts of inheritance.

40
Q

Inherited features(called characters) come in variety or traits

A
  • A given gene codes for a character but can come in a variety of forms called alleles
    • Somatic cells have 2 copies of every gene or allele
      • Alleles may be identical so the individual is homozygous or
      • Alleles may differ so the individual is heterozygous
      • The identity of the alleles an individual possesses is called the genotype while the phenotype is the appearance those alleles give to the individual
      • Individuals receive one allele from each parent
      • Alleles are divided into separate gametes during meiosis based on the Law of Segregation so that gametes only possess one copy of each alleles
41
Q

Monohybrid Breeding Experiment

A

Only one character is examined at a time.

42
Q

Individuals are considered true breeding if they always produce offspring with a given trait(therefore are homozygous)

A
  • In a classic monohybrid cross, in the P generation, 2 true breeding individuals of different traits are bred and produce all hybrid F1 offspring
  • If F1 offspring interbreed, they produce F2 offspring
  • If only one of the 2 alleles contributes to the phenotype of a hybrid, it is termed the dominant allele and the other is the recessive allele
    • Hybrids are therefore heterozygous
  • For complete dominance, in the F2 generation, 3 of 4 offspring will show the dominant trait while 1 of 4 will show the recessive trait seen in one of the original P generation parents
    • Genotypic ratio in the F2 generation of a monohybrid cross is always 1:2:1 (AA-homozygous dominant:Aa-heterozygote:aa-homozygous recessive)
    • Phenotypic ratio in the F2 generation of a monohybrid cross is always 3:1 of dominant phenotype to recessive phenotype
43
Q

(True Breeding)An individual who has the dominant phenotype could be homozygous dominant or a heterozygote

A
  • The only way to tell which genotype is present is to conduct a test cross by breeding the dominant phenotype individual with one that shows the recessive phenotype (which is always homozygous recessive)
    • If all offspring show the dominant phenotype, the original dominant parent was homozygous dominant
    • If ½ of the offspring are dominant phenotypes and ½ are recessive phenotypes, the original dominant parent was a heterozygote
44
Q

(True Breeding)A dihybrid cross follows 2 characters at once

A
  • Assume for now the genes for the 2 characters are on separate chromosomes
  • Due to independent assortment during meiosis I, pairs of chromosomes will segregate into different gametes so that all maternal or all paternal alleles are not inherited together
  • This means an individual heterozygous for 2 genes, A and B (AaBb), could produce 4 different combinations of alleles in the gametes
    • AB, Ab, aB or ab
    • If this individual was crossed with another AaBb, the resulting 16 square Punnett would show a predictable 9:3:3:1 phenotypic ratio
      • 9 of the 16 offspring will be dominant for both A and B genes
      • 3 of the 16 offspring will be dominant for gene A and recessive for gene b
      • 3 of the 16 offspring will be recessive for gene a and dominant for gene B
      • 1 of the 16 offspring will be recessive for both gene a and gene b
45
Q

Variations from Mendel and range of dominance(complete dominance)

A

Classic Mendelian Genetics

  • One allele is completely dominant over the recessive allele
  • Heterozygotes will have the exact same phenotype as a homozygous dominant
  • F2 genotypic ratio 1:2:1; phenotypic ratio 3:1
46
Q

Variations from Mendel and range of dominance(Incomplete Dominance)

A
  • Neither allele is dominant over the other
  • Heterozygotes have a single, novel phenotype that is intermediate between the homozygotes’ phenotype
  • F2 genotypic and phenotypic ratio is 1:2:1
47
Q

Variations from Mendel and range of dominance(Co-dominance Dominance)

A
  • Neither allele is dominant over the other

- Heterozygotes express both allele’s gene products independently from each other

48
Q

Variations from Mendel and range of dominance(Multiple Alleles)

A
  • 3 or more variations of a gene can occur at a given gene loci
  • Individuals still only have 2 alleles at their loci
49
Q

Variations from Mendel and range of dominance(Pleiotropy)

A
  • Single gene influences multiple phenotypes
50
Q

Variations from Mendel and range of dominance(Polygenic Inheritance)

A
  • Multiple genes influence single phenotype
51
Q

Variations from Mendel and range of dominance(Epistasis)

A
  • 2 or more genes interact with some genes masking phenotypes of other genes
52
Q

Human Genetics

A

Recessive disease

 - Individuals need to be homozygous recessive to have the disease
 - Carriers are heterozygotes but do not have the disease

Dominant disease
- Individuals can be heterozygotes or homozygous dominant

53
Q

dominant and recessive; heterozygous and homozygous; genotype and phenotype.

A

Dominant: Phenotype that is apparent in a heterozygote

Recessive: Phenotype that is not apparent in a heterozygote

Heterozygous: Having 2 different alleles for a given character

Homozygous: Having 2 copies of the same allele for a given character

Genotype: The actual genetic makeup, what alleles are present

Phenotype: The appearance the alleles give to the organism for a given character

54
Q

Dominant

A

Phenotype that is apparent in a heterozygote

55
Q

Recessive

A

Phenotype that is not apparent in a heterozygote.

56
Q

Heterozygous

A

having 2 different alleles for a given character.

57
Q

Homozygous

A

Having 2 copies of the same allele for a given character.

58
Q

Genotype

A

The actual makeup, what alleles are present.

59
Q

Phenotype

A

The appearance the alleles give to the organism for a given character.

60
Q

How does a testcross help determine if an individual with the dominant phenotype is homozygous or heterozygous

A

The dominant phenotype can either be homozygous dominant or a heterozygote and you can not tell by looking at them. A test cross is a mating between the ambiguous dominant phenotype and a recessive phenotype that you know must be homozygous recessive. If you get any offspring from this mating that have the recessive phenotype, you know the dominant phenotype individual was a heterozygote. If you get only dominant phenotype offspring, you know the unknown dominant phenotype was homozygous dominant.

61
Q

Mendel’s law of independent assortment and the behavior of chromosomes during meiosis

A

In dihybrid or higher crosses, each pair of alleles segregates independently during gamete formation if they are on different chromosomes. This occurs at
the metaphase I step of meiosis I when the homologues line up at the metaphase plate. It is completely random which side each homologue picks with regards to maternal or paternal origin. This gives many different variations of gametes, with
2n possibilities.

62
Q

Example: Monohybrid cross between Aa (mom) x Aa (dad): What’s the chance of getting an offspring that is Aa?

A

Rule of multiplication:

  • Chance of Aa (mom) giving an “A” = ½
  • Chance of Aa (dad) giving an “a” = ½
  • Multiple: ½ x ½ = ¼

But need Rule of addition also since mom could have given “a” and dad given
- “A”: ½ x ½ = ¼

Need to add first ¼ + second ¼ to give overall ½ chance of getting Aa from this mating.

63
Q

Differences of phenotypic expression of heterozygote(come, incomplete, and co-dominance)

A

Complete dominance: Heterozygote will have the dominant phenotype only

Incomplete dominant: Heterozygote will have a unique phenotype that is neither the dominant nor recessive

Codominance: Neither allele is considered dominant nor recessive. Both alleles manifest themselves

64
Q

Describe the inheritance of the ABO blood system

A

There are 3 alleles (multiple alleles): A (IA), B (IB) and O (i)

The A and B alleles are dominant over the O. A and B are codominant to each other. This gives 6 possible genotype and 4 possible phenotypes.

Genotype = Phenotype
IAIA or IAi = Type A
IBIB or IBi = Type B
IAIB = Type AB
ii = Type O
65
Q

Understanding inheritance of human genetic diseases and how “carriers” function

A

Many human diseases are inherited by simple Mendelian complete dominance and follow the same genotypic and phenotypic ratios predicted by Mendel. Depending on whether or not the disease is a dominant or recessive disease will influence if the person has symptoms of the disease.

If it’s a dominant disease, the heterozygote as well as the homozygous dominant genotype will have the disease. Many dominant genetic diseases are not passed on between parents and offspring but are instead result of spontaneous mutations in the offspring that can then be passed on if the disease is not a fatal one.

If it’s a recessive disease, only the homozygous recessive genotype will have the disease phenotype. Individuals that are heterozygotes for a recessive disease are called carriers since they possess the abnormal allele and can pass it on to offspring but they themselves do not show symptoms of the disease.

Biology Test 4 - Ch 12-15 (5 decks)

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