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Ch 14 Flashcards

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1
Q

Steps in cross-pollination of pea plants

A
  1. Remove stamens from purple flower. 2. Transfer pollen from stamens of white flower to carpel of purple flower. 3. Pollinated carpel matures into pod. 4. Plant seeds from pod. 5. Examine offspring: all purple flowers.
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2
Q

What isMendel’s 3rd Principle?

A

Some alleles are dominant and others are recessive. Dominant alleles need only one copy to be expressed, while recessive alleles need two copies.

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3
Q

Result of the F₂ generation in Mendel’s experiment

A

The diagram shows the genetic cross of heterozygous plants, resulting in a 3:1 ratio of tall to short plants.

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4
Q

Trait

A

Some aspect of an organism that can be described or measured. Example: eye color, flower color.

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5
Q

What is Mendel’s 4th principle?

A

The two alleles must separate when gametes (sex cells) are formed. Gametes only contain one allele for each trait (haploid). At fertilization, the single alleles are joined to make a pair in the offspring (back to diploid). (The Law of Segregation)

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6
Q

Resulting phenotypic ratio from a dihybrid cross.

A

9 : 3 : 3 : 1

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7
Q

plants involved in breeding and crossing

A

Plants can be crossed with other closely related plants to create off spring with new/ desirable traits, such as:
- crossing peas that are mildew resistant with peas that are high yielding to get plants that are both
- creation of ornamental plants such as orchids
-crossing two different spicy peppers to get ghost peppers which are even spicier

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8
Q

Diagram showing a testcross with possible genotypes and phenotypes.

A

In a testcross, if all offspring are purple, the parent must be homozygous dominant (PP). If half are white and half are purple, the parent is heterozygous (Pp).

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9
Q

Traits are inherited independent of each other (in peas?).

A

In pea plants, the allele for tallness may be inherited with the allele for yellow seed color or the allele for green seed color. This is because these two genes are on non-homologous chromosomes. This leads to the random separation of chromosomes during meiosis, producing many combinations.

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10
Q

Describe the parental generation and first generation in Mendel’s 2 gene cross experiments

A

The diagram illustrates the cross-pollination from different plants, showing the parental generation (RRYY x rryy) and the resulting first generation (RrYy).

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11
Q

FOIL Method in Genetics

A

FOIL stands for First, Outside, Inside, Last, used to determine possible gametes.

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12
Q

Mendel’s choice of plant for genetic study.

A

He chose the garden pea plant to investigate how traits were passed from generation to generation.

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13
Q

Phenotype

A

Physical or physiological characteristics of an organism determined by the genotype. Examples include normal Hb or sickle cell Hb, blue eyes, brown feathers, and 5 fingers on a hand.

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14
Q

A couple has 7 children; all girls. They are pregnant with their 8th child. What is the probability it will be a boy?

A

Even if a couple has 7 girls, the chance that their current pregnancy will be a boy is ½ (½ chance each time).

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15
Q

What is Mendel’s 2nd principle?

A

Each organism inherits 2 alleles, one from each parent. Organisms receive one allele from each parent, making a total of two alleles.

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16
Q

Recessive allele

A

an allele that is not observed in the phenotype of a heterozygote. Need to inherit 2 recessive alleles to see that phenotype. Example: will only see white coloration when inherit bb

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17
Q

What is Mendel’s 5th principle?

A

Each set of homologous chromosomes lines up and separates randomly during meiosis I, producing different combinations of gametes.
(Law of Independent Assortment)

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18
Q

Types of plants in Mendel’s initial experiments

A

Pure-breeding or true-breeding plants. Called P generation (parental generation); top generation in in image

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19
Q

Gametes from Genotype TTYy

A

The gametes produced are TY, Ty, TY, Ty.

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20
Q

Genotype

A

An organism’s actual genetic makeup; their set of alleles. Examples include BB, Bb, bb

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21
Q

Self-pollinated F1 (YyRr x YyRr) –> What gametes will be produced from these parents?

A

Determine all possible gametes from meiosis using the distributive property: YR, Yr, yR, yr.

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22
Q

Homozygous: an individual that inherits 2 identical alleles for a gene

A

Example: BB or bb. Also called true-breeding or pure-bred

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23
Q

Dominant allele

A

an allele that is fully expressed in the phenotype of a heterozygote. Example: B=Black and b=white; BB or Bb results in black coloration. Dominant does NOT mean the allele occurs more frequently or is better!

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24
Q

Mendel studied 7 different traits.

A

Mendel studied the following traits: seed shape, seed color, pod color, plant height, flower color, pod shape, and flower position.

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25
Heterozygous: an individual that inherits 2 different alleles for a gene
Example: Bb; Also called "hybrid"
26
The Testcross
A testcross allows us to determine the genotype of an individual that has the dominant trait, the test cross is all recessive.
27
Reason for choosing pea plants in Mendel's experiments.
Pea plants can self-fertilize and traits appear in two distinct forms (alleles), such as short or tall.
28
Diagram of Mendel's cross of homozygous plants
The diagram illustrates Mendel's cross of homozygous plants, showing the "P" generation and the resulting F1 generation, which are all heterozygous tall (Tt).
29
Probability of a pea plant seed being short from a Tt x Tt cross
Each pea plant seed (offspring) from a Tt x Tt cross has a ¼ chance of being short.
30
Gregor Mendel
Gregor Mendel (1800s); an Austrian monk, applied mathematics to his study of genetics.
31
Comparison of Homozygous dominant and heterozygous individuals
They are indistinguishable phenotypically; both show the dominant trait.
32
What is Mendel's 1st principle
A gene controls each trait, and there are different versions of a gene called alleles. Each trait is controlled by a gene.
33
Gene
Discrete unit of hereditary information or a specific sequence of DNA that codes for a protein.
34
F₁ generation
Name given to the hybrid offspring in genetic crosses of P generation; will all show the dominate trait; middle generation on image
35
Allele
Alternative versions of a gene. Example: red vs. white flowers; A, B, or O blood group instructions.
36
Process used to reproduce the F₂ generation
He allowed the F₁ plants to self-pollinate and reproduce (Tt x Tt).
37
Type A blood characteristics
Type A blood has A antigens on the cell surface and makes Anti-B antibodies.
38
Meaning of 'O' in blood type
Has an unmodified marker on the surface of the red blood cell (this image has been simplified to show no marker, indicating the absence of the A and B antigens)
39
Harmless Bacteria and Antigen exposure at birth
There are harmless bacteria in the atmosphere with molecules on their surface that have a very similar shape to our 'A' and 'B' antigens, and we are exposed to them as soon as we are born. This causes your immune system to produce antibodies against antigens you did not inherit; and your immune cells will build a memory to this. This would make future immune responses much quicker.
40
Different genotypes possible for Type A Blood
Homozygous A (AA) or Heterozygous A (AO)
41
Who can Blood Type O receive blood from during a blood transfusion? Who can type O blood donate to?
Type O blood makes both anti-A and anti-B antibodies, so It can only have O blood. Type O blood has neither Antigen A nor B on its surface so it is the universal donor!
42
There are 2 different alleles for the Rh factor.
Rh+ and Rh-
43
Human blood groups exhibit multiple alleles and codominance.
Multiple alleles: There are 3 alleles that exist in a population, A, B, and O. Codominance: Both the A and B allele are dominant when paired together or separate. O is recessive to both A and B alleles.
44
Example of immune response with wrong blood type.
For someone with Type A blood, if they were transfused with type B blood, the “B” would be a foreign antigen and would trigger a response
45
Example of codominance in chickens
BB x WW = BW (speckled) - both black and white feathers
46
Genotype for Type AB Blood
AB
47
Example of codominance in blood alleles
A and B blood alleles (AB)
48
Is it possible for a Type A and Type B parent to have offspring with Type O blood? Explain.
Yes, if both parents were heterozygous (AO x BO)
49
The “O” type marker is a basic marker present on everyone's red blood cells.
Everyone has the “O” type of marker (H marker) extending from their red blood cells.
50
Different genotypes possible for Type B Blood
Homozygous B (BB) or Heterozygous B (BO)
51
Antibodies in the blood
Antibodies float in the blood along with red blood cells (RBCs).
52
Antibodies and Their Shape
Since antibodies are proteins, they have a specific shape and will attach onto the antigen for which they were made (these are the antigens that you did not inherit).
53
Meaning of Rh-.
You DON'T have the protein/marker on the surface of your RBC (Red Blood Cell). This leads to the fact that you DO have the anti-Rh+ antibody.
54
Meaning of 'A' & 'B' in blood type AB
Represents two types of markers (A and B Antigens) on the surface of a red blood cell
55
Genotype for Type O Blood
OO
56
Who can Blood Type A receive blood from in a blood transfusion?
Type A blood makes anti-B antibodies so cannot have B or AB blood but can have A or O blood.
57
Who can Blood Type B blood receive blood from during a transfusion?
Type B blood makes Anti-A Antibodies so It cannot have A or AB blood but can have B or O blood.
58
What is the blood type of this RBC?
Type AB Positive
59
Three different alleles for human blood type
A allele: Iᴬ (dominant), B allele: Iᴮ (dominant), O allele: i (recessive)
60
Meaning of Rh+.
You have the protein/marker on the surface of your RBC (Red Blood Cell). This leads to the fact that you DON'T have the anti-Rh+ antibody.
61
If a Type B person receives Type A red blood cells in transfusion, what will happen?
Agglutination occurs when anti-A antibodies attach to Type A antigens, leading to the destruction of red blood cells.
62
Meaning of 'A' in blood type
Indicates the presence of one type of cell surface marker ("A" antigen) on a red blood cell (and the anti-B antibodies).
63
Rh factor
Red Blood Cells can have a different cell surface marker in addition to the alleles for ABO Blood Type called Rh factor. You are either positive for this antigen (you have it) or you are negative (you do not have it). The blood cell in the diagram has it so they are Rh positive.
64
The Rh Issue: Mom = Rh-, Baby = Rh+
If a mother is Rh- and the baby is Rh+, problems can develop if their blood mixes during birth. The mother is exposed to Rh antigens and may produce anti-Rh antibodies. In subsequent pregnancies, these antibodies can cross the placenta and endanger the fetus. An injection can prevent the formation of anti-Rh antibodies.
65
Type B blood characteristics
Type B blood has B antigens on the cell surface and makes Anti-A antibodies.
66
Who can Blood Type AB receive blood from during a transfusion?
Type AB blood does not make antibodies against other blood types so It can have any type of blood and is the universal recipient.
67
Multiple alleles
Multiple alleles occur when there are more than two alternative forms of a gene. Examples include rabbit fur color (4 total alleles exist, see photo) and human ABO blood groups (3 total alleles exist: A, B, or O alleles).
68
If you are given the wrong type of blood, this will trigger an immune response.
Receiving the wrong blood type causes an immune response due to foreign cell surface markers.
69
Codominance
Inheritance characterized by the full expression of both alleles in the heterozygote.
70
Relationship between the "H" marker and Type AB Blood.
If you have type AB blood, you make two enzymes that modifies the "H" marker into the "A" marker and "B" marker by adding different types of sugars to to them.
71
Characteristics of Type AB Blood and Type O Blood
Type AB Blood has both the A & B antigens on their surface, but do not make either types of antibodies. Type O Blood has neither A no B antigens on their surface but makes both anti-A and anti-B Antibodies.
72
Type of inheritance for Rh factor alleles.
Normal dominant/recessive inheritance. Positive (+) allele is dominant to negative (-) allele.
73
Relationship between the "H" marker and Type A Blood.
If you have type A blood, you make an enzyme that modifies the "H" marker into the "A" marker by adding certain types of sugars to to it.
74
Example of codominance in cattle
RR (red) x WW (white) = RW (roan)
75
Is it possible for two Rh positive parents to have offspring with Rh negative blood? Explain.
Yes, as long as both parents are heterozygous (+- x +-)
76
The Rh factor genetic information is inherited independently of the ABO blood type alleles.
The inheritance of the Rh factor is separate from that of the ABO blood type; this means they are located on two different (non-homologous) chromosomes.
77
Relationship between the "H" marker and Type B Blood
If you have type B blood, you make an enzyme that modifies the "H" marker into the "B" marker by adding certain types of sugars to to it.
78
Immune Response to foreign Antigen
A 'foreign' antigen will trigger your immune system to create/produce antibodies that will attempt to fight off the "foreign cells".
79
Relationship between the "H" marker and Type O Blood.
If you have type O blood, you do NOT make enzymes that modify the "H" marker, so your "H" marker remains unmodified. This makes you type O.
80
Other types of inheritance patterns beyond Dominant & Recessive
Inheritance patterns can include incomplete dominance, codominance, multiple alleles, and polygenic traits.
81
Numbering individuals in a pedigree
Individuals are numbered according to age, with the oldest on the left.
82
Blood donation and reception for Bombay Blood Type
Can donate blood to anyone but can only receive blood from other Bombay individuals.
83
Eye color as an example of a polygenic trait
Eye color is influenced by two main genes, but at least 14 other genes also contribute to the final eye color. The pigment melanin helps color the iris, and small color differences arise from different combinations of alleles.
84
Epistasis
Interaction between the alleles of two different genes in which one modifies the phenotypic expression of the other. (One gene is in charge of gene expression of a 2nd gene) In this example, the mice must have at least one dominant C allele to show any color. If they are cc, the are albino. Gene C controls expression of gene A.
85
Heterozygotes (Carriers) can be phenotypically normal if one copy of the normal allele is present.
This is because one normal allele is enough to produce sufficient quantities of the "good" protein. Examples include cystic fibrosis (CF), PKU, and Tay-Sachs.
86
How to tell if pattern of inheritance is autosomal recessive on pedigree
Autosomal Recessive inheritance pattern indicates that if both parents are unaffected and an offspring is affected, the trait must be recessive. Parents are heterozygous carriers.
87
Diagram showing the relationship between H substance, precursor substance, and ABH antigens in Bombay phenotype.
The diagram illustrates how H substance (HH or Hh) leads to ABH antigens, while Bombay Oh (hh) results in no ABH antigens.
88
Examples of Autosomal Dominant conditions
Achondroplasia (a type of dwarfism), Huntington’s Disease (nervous system disorder onset in 30s-40s). Dominant conditions are typically more severe and sometimes lethal in the homozygous dominant form.
89
Examples of Polygenic Traits
Height, skin color, eye color
90
_____________ is a type of inheritance where one allele is not completely dominant over the other.
Incomplete dominance The result is a heterozygote with an intermediate phenotype.
91
How to tell if pattern of inheritance is autosomal dominant on pedigree
Autosomal Dominant inheritance pattern indicates that if both parents are affected and an offspring is unaffected, the trait must be dominant.
92
Effect of being homozygous dominant for achondroplasia
Lethal homozygous dominant condition in Achondroplasia; Results in spontaneous abortion of the fetus.
93
PKU
A genetic disorder that is autosomal recessive and affects the conversion of the amino acid phenylalanine to tyrosine. Can be controlled by diet.
94
Example of incomplete dominance in Andalusian chickens.
BB (black feathers) x WW (white feathers) = BW "blue" feathers in offspring.
95
Huntington's disease
Huntington's disease is caused by a dominant allele, requiring only one mutated copy (it is an autosomal dominant condition). It is typically onset around age 40. It is a progressive disease that breaks down the nerve cells in the brain.
96
Diagram showing epistatic interactions on coat color in Labradors.
Epistatic interactions in Labradors determine coat color based on genetic combinations. Yellow Labs have no dark pigment (ee), Chocolate Labs have brown pigment (E_bb), and Black Labs have black pigment (E_B_).
97
Tay-Sachs disease
Tay-Sachs disease is an example of a condition caused by autosomal recessive alleles. Affected individuals do not make an enzyme that breaks down fats in the brain. They usually die by age 5.
98
polygenic beak depth variation
Diagram showing polygenic beak depth variation Illustrates the variation in beak depth as a polygenic trait, showing frequency distribution.
99
Polygenic Inheritance
A mode of inheritance where the additive effect of two or more genes determines a single phenotypic character.
100
Pedigree definition
A pedigree is a chart of the genetic history of a family over several generations.
101
Cystic Fibrosis
Cystic Fibrosis (CF) is an example of a disorder caused by autosomal recessive alleles, where sticky mucous builds up in the lungs. It must be inherited from both parents.
102
Epistasis in mice
Gene for pigment deposition is epistatic to the gene for melanin production in mice. The albino mouse can make melanin, but the allele for depositing the color into the hair shaft controls whether you see that produced melanin.
103
Meaning of unshaded symbols in a pedigree
Unshaded symbols mean an individual is unaffected.
104
Example of incomplete dominance in 4 o’clock flowers.
RR = red flowers, WW = white flowers, RW = pink flowers.
105
Reason AA and Aa produce the same phenotype
Having one copy of the unmutated allele allows some functional protein to be made, often resulting in no change to the phenotype.
106
Meaning of half-shaded symbols in a pedigree
Half-shaded symbols mean they are carriers, but this is not always given.
107
Symbol for males in a pedigree Symbol for females in a pedigree
Males are represented as squares. Females are represented as circles.
108
Autosomal Recessive pattern of inheritence
Recessive alleles that cause human disorders are usually mutated versions of normal alleles. Defective alleles code for either a malfunctioning protein or no protein at all.
109
Meaning of shaded symbols in a pedigree
Shaded symbols mean an individual is affected by a condition.
110
A horizontal line between a man and woman represents mating, and resulting children are shown as offshoots to this line.
A horizontal line between a man and woman represents mating, and resulting children are shown as offshoots to this line.

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