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Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Who is considered the father of genetics?

A

Mendel.

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2
Q

What did Mendel use for his genetics experiments?

A

Pea plants.

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3
Q

What were the advantages of using pea plants?

A

They reproduce quickly, ethics aren’t an issue, they have a variety of attributes to study, humans can control their reproduction (unlike animals), and many pea plants can grow in a small space.

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4
Q

What is self-pollination?

A

When the scientist takes pollen from a plant and uses it to fertilize the same plant on the female side (the carpel).

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5
Q

What is cross-pollination?

A

When the scientist takes the pollen from one plant and uses it to fertilize a different plant (of the same species).

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6
Q

What is an example of cross-pollination?

A

Fertilizing a white pea plant with the pollen from a purple pea plant.

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7
Q

What is the P generation?

A

The parent generation.

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8
Q

What is the first generation bred from the P generation called?

A

The F1 generation. These are hybrids of the two parents.

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9
Q

What is the second generation (bred from the F1 generation) called?

A

The F2 generation.

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10
Q

What does “true-breeding parents” mean?

A

It means that the parents’ genes are extremely similar because they were bred from parents that also had similar genes. It is an organism that always passes down certain phenotypic traits to its offspring of many generations, and is homozygous for that trait.

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11
Q

What are the possible combinations from crossing a purple pea plant (FF) with a white pea plant (ff)?

A

100% Ff. Heterozygous, and the plants would be purple because purple is the dominant gene.

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12
Q

Define allele.

A

Alternate versions of a gene.

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13
Q

Define genotype and give the three kinds of genotype.

A

Genotype refers to your genetic makeup, or your combination of chromosomes. The three kinds are homozygous recessive (rr), homozygous dominant (RR), and heterozygous (Rr).

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14
Q

If one parent’s eye color is represented by FF and the other parent is Ff, what could the child inherit from each parent?

A

The child will get one from each parent, so from the 1st one they only have one option: F. From the second, they could inherit F or f, but either way, the dominant gene will show up.

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15
Q

Define phenotype.

A

The genetic traits/genes that are actually physically expressed by the offspring.

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16
Q

What is a Punnett square?

A

A square diagram made of four smaller squares that can be used to find the possible genotypes for an organism.

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17
Q

What is a phenotypic ratio?

A

How many organisms out of four offspring (or the likelihood) will show each trait.

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18
Q

What is a genotypic ratio?

A

How many organisms out of four offspring will be heterozygous, homozygous recessive, or homozygous dominant.

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19
Q

How do you write phenotypic and genotypic ratios?

A

As percentages, or as regular ratios (ex: 3 heterozygous: 1 homozygous dominant.)

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20
Q

What are the possible outcomes, along with the genotypic and phenotypic ratios, of crossing Gg with gg? (The dominant gene represents brown eyes, and the nondominant gene represents blue eyes.)

A

Gg, Gg, gg, gg. 0% homozygous dominant, 50% heterozygous, 50% homozygous recessive (or 0:2:2) for genotype; 50% brown eyes, 50% blue eyes (or 2:2).

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21
Q

How do you know if an organism has the heterozygous or homozygous form of a gene?

A

Look at the parents by performing a testcross.

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22
Q

What is a testcross?

A

Crossing the dominant phenotype with the recessive and observing the offspring.

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23
Q

What is complete dominance?

A

One allele prevents the expression of another.

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24
Q

What does “expression” mean in genetics?

A

The gene that shows up.

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25
Q

If you cross a red snapdragon (CrCr) with a white snapdragon (CwCw), what do you get? (Genotype and phenotype)

A

100% heterozygous, 100% pink.

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26
Q

What is intermediate expression?

A

The phenotype when you get a mixture of the two genes and neither is dominant.

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27
Q

What is incomplete dominance?

A

It is the genotype that results when neither allele is dominant.

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28
Q

What is codominance?

A

When both alleles are expressed in the phenotype, such as type AB blood.

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29
Q

What is a monohybrid cross?

A

Crossing two versions of the same gene, one from each parent, such as crossing Rr and rr for tongue rolling.

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30
Q

What is a dihybrid cross?

A

Crossing two different traits from each parent, such as crossing CCRr and Ccrr for hair color and tongue rolling.

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31
Q

How many boxes are needed for a dihybrid cross in a Punnett square?

A

16.

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32
Q

What is polygenic inheritance?

A

Two or more genes coding for a trait, like in eye color, hair color, IQ, and skin color.

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33
Q

What type of pattern does polygenic inheritance tend to follow?

A

A bell curve.

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34
Q

What is a pedigree?

A

A chart that traces the inheritance of a genetic trait within a family.

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35
Q

What do the squares on a pedigree represent? What about the circles?

A

Squares=males, circles=females

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36
Q

Homozygous recessive

A

Two nondominant genes. Ex. rr

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37
Q

Heterozygous

A

A dominant gene and a nondominant/recessive gene. Ex. Rr.

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38
Q

Homozygous dominant

A

Two dominant genes. Ex: RR.

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39
Q

If there are no fruit flies that are female and have white eyes, but there are male fruit flies with white eyes, white eyes are a…

A

Sex-linked trait.

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40
Q

Define sex-linked trait.

A

The gene for the trait is located on the sex chromosome.

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41
Q

Which sex chromosome usually contains the sex-linked trait’s gene?

A

The X chromosome.

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42
Q

Are males or females more likely to be affected by sex-linked traits? Why?

A

Males are usually affected because the Y chromosome is smaller and cannot counteract mutations. Females have XX, so they are not affected as often.

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43
Q

What does it mean to be a carrier (of a gene)?

A

It means that the organism contains the gene and can pass it on, but it is not affected by the gene.

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44
Q

What is hemophilia?

A

It is a sex-linked trait that is a recessive blood clotting disorder.

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45
Q

Cross a female hemophilia carrier (XX^H) with a regular male. Give the phenotype.

A

25% female, no hemophilia, 25% female as a hemo carrier, 25% male, no hemo, and 25% male, hemophiliac.

46
Q

Why would a male with this genotype (X^H Y) have hemophilia if it’s recessive?

A

The Y chromosome cannot overpower and counteract the hemophilia gene.

47
Q

What increases the chance of passing down sex-linked traits like hemophilia?

A

Inbreeding.

48
Q

What can halves on a pedigree represent?

A

It can mean that the individual is a carrier or that they have the trait with incomplete dominance. (Ex: wavy hair).

49
Q

What are the four blood types?

A

A, AB, B, and O.

50
Q

Which blood type has no antigens?

A

O.

51
Q

What happens if you use a blood type in a transfusion, but the antigens are foreign to the body?

A

The body will produce antibodies, attacking the new blood cells, and producing dangerous blood clots.

52
Q

What are the three allele options that code for blood type?

A

I^A, I^B, and i

53
Q

Why is it significant that type O blood has no antigens?

A

It means that almost anyone can receive it in a transfusion without issues.

54
Q

Type O blood: Percentage of population, antigen type (RBC antigen), plasma antibodies (antibodies it makes to respond to foreign antigens), who can it donate to, who can it receive from, genotype.

A

46%; no antigens, makes Anti-A and Anti-B, donates to all, receives from type O only, ii genotype.

55
Q

Type A blood: Percentage of population, antigen type (RBC antigen), plasma antibodies (antibodies it makes to respond to foreign antigens), who can it donate to, who can it receive from, genotype.

A

40%, A antigens, makes Anti-B, donates to A and AB, receives from O and A, I^A I^A or I^A i genotype.

56
Q

Type B blood: Percentage of population, antigen type (RBC antigen), plasma antibodies (antibodies it makes to respond to foreign antigens), who can it donate to, who can it receive from, genotype.

A

10%, B antigens, makes Anti-A, donates to B and AB, receives from B and O, I^B I^B or I^B i genotype.

57
Q

Type AB blood: Percentage of population, antigen type (RBC antigen), plasma antibodies (antibodies it makes to respond to foreign antigens), who can it donate to, who can it receive from, genotype.

A

4%, A and B antigens, makes no antibodies, donates to AB, receives from all, I^A I^B genotype.

58
Q

Positive (RH+) blood: Percentage of population, antigen type (RBC antigen), plasma antibodies (antibodies it makes to respond to foreign antigens), who can it donate to, who can it receive from, genotype.

A

85%, RH antigens, no antibodies, donates to positive RH, receives from all, RR or Rr genotypes.

59
Q

Negative (RH-) blood: Percentage of population, antigen type (RBC antigen), plasma antibodies (antibodies it makes to respond to foreign antigens), who can it donate to, who can it receive from, genotype.

A

15%, no antigens, makes Anti-Rh antigens, donates to all, receives from RH-, rr genotype.

60
Q

What blood type is considered the universal donor?

A

O-.

61
Q

What blood type is considered the universal recipient?

A

AB+.

62
Q

What does “multiple alleles” mean?

A

Three or more alleles per gene.

63
Q

Which two blood type alleles are codominant?

A

I^A, and I^B.

64
Q

Which blood type allele is recessive?

A

i (Type O).

65
Q

Cross Type O with Type AB.

A

50% I^A i, 50% I^B i. (50% type A, 50% type B).

66
Q

Which is dominant: No Rh antigens (rr, negative) or Rh antigens present (RR or Rr, positive)?

A

Rh antigens present.

67
Q

Cross type O+ (homozygous +) with type A-. (heterozygous A). Also, how do you go about this?

A

First, cross type A and type O. I^A i * ii= 50% I^A i, 50% ii.
Then, cross the positive and negative: RR*rr= 100% Rr, 100% positive. Overall, 50% A+, 50% O+.

68
Q

What is Rh disease?

A

When an Rh+ male and an Rh- female have a baby, the child may have positive blood. While in the womb, the placenta surrounds the baby and keeps from mixing baby’s and mom’s blood. After birth, mom is exposed to the baby’s blood and will make antibodies. After the first kid, her antibodies will attack the next child, making it a miscarriage. She cannot have more that one baby.

69
Q

How can you treat Rh disease?

A

With Rhogam, which is a medicine that, when injected, will prevent the antibodies from attaching to the antigens.

70
Q

What are three ways to study human genetics?

A

Pedigrees, population sampling (often with blood type), and twin studies (comparing identical twins).

71
Q

What is the difference between fraternal and identical twins in terms of development in the womb?

A

Fraternal twins are dizygotic, meaning they came from two different eggs and two different sperm to make two different zygotes in the womb at the same time. Identical twins are monozygotic, meaning that they came from one zygote that separated.

72
Q

Name 6 types of human inheritance.

A

Single genes, single genes with multiple alleles, polygenic, sex-linked, sex-influenced, and chromosomal disorders.

73
Q

Define single gene.

A

One gene with two versions (because there are two chromosomes.)

74
Q

Define sex-influenced gene/trait.

A

It is a gene on an autosome, and its expression is influenced by sex hormones.

75
Q

What is an example of a sex-influenced trait?

A

Early male-pattern baldness, which is activated by testosterone.

76
Q

What percent of the population has the baldness gene?

A

25%.

77
Q

When are women more likely to have the baldness gene activated and why?

A

After menopause, when testosterone levels spike.

78
Q

What are some examples of chromosomal disorders?

A

Mutations, deletions, addition, translocations, and nondisjunction.

79
Q

Define mutation as in a chromosomal disorder.

A

An irregular, changed gene.

80
Q

Define addition as in a chromosomal disorder.

A

Extra DNA is added.

81
Q

Define translocation as in a chromosomal disorder.

A

The movement of DNA from one chromosome to another, often when non-homologous chromosomes pair up for crossing over.

82
Q

Define nondisjunction.

A

Failure of chromosomes to separate properly during meiosis, leaving some cells with irregular numbers of chromosomes. (Ex: monosomy and trisomy.)

83
Q

Define deletion as in a chromosomal disorder.

A

The loss of DNA.

84
Q

What is an example of a disorder caused by deletion?

A

Cri du Chat, in which the offspring is missing part of a chromosome. This causes the infants to have high-pitched cries. You can identify it with a chromosome map or gene linkage.

85
Q

What is gene linkage?

A

When two genes are so close together on a chromosome that they stay together instead of separating during crossing over.`

86
Q

What is an example of a disorder caused by addition?

A

Fragile X, in which there is a little extra DNA on the end of the X chromosome. It is a more common genetic disorder, and males are more likely to be affected. It leads to mild intellectual disability.

87
Q

What are two examples of a disorder caused by chromosomal translocation?

A

Certain types of leukemia and Down syndrome.

88
Q

What are examples of nondisjunction?

A

Trisomy 21/Down syndrome, trisomy 13, Klinefelter’s syndrome, XXX, XYY Jacob’s syndrome, Turner’s syndrome.

89
Q

Define trisomy 21

A

AKA Down syndrome, there are 3 copies of chromosome 21 instead of 2, leading to developmental and intellectual delays.

90
Q

Define trisomy 13.

A

Patau syndrome, extra copy of chromosome 13. This leads to cleft palate and/or lip in mild cases.

91
Q

What is Klinefelter’s syndrome XXY?

A

When nondisjunction happens in the sex chromosomes, males can develop breasts and be infertile, although they are biologically male.

92
Q

What is a karyotype?

A

A picture of all an individual’s chromosomes.

93
Q

What are two other sex chromosome trisomies?

A

XXX, and Jacob’s syndrome

94
Q

What is an example of a monosomy?

A

Turner’s syndrome- the genes are X_. There is a missing X chromosome. The victim is often sterile.

95
Q

How likely is it for a woman who’s 20 to have a child with Down syndrome? 30? 40 years old?

A

20: 1/2000; 30: 1/900, 40: 1/32

96
Q

Nondisjunction is more likely in…parents. (older/younger)

A

Older

97
Q

With advanced maternal or paternal age, comes increases in… and a decrease in…

A

Increases: nondisjunction for females, mutation rate for males. Decreases: ability to miscarry a defective fetus for females.

98
Q

What are five tests used to predetermine the presence of genetic defects in a fetus?

A

Alpha fetoprotein (AFP) testing, ultrasound, Amniocentesis, endoscopy, and Chorionic Villi.

99
Q

What is AFP testing?

A

At 16 weeks pregnant, the mother can get blood test checks for AFP from the fetal liver found in the mother’s blood. Low levels of AFP could be Down syndrome; high levels could be twins or neural tube defects.

100
Q

What are two examples of neural tube defects?

A

Spina bifida and anacephaly.

101
Q

What is anacephaly?

A

It is a neural tube defect in which the brain does not fully form.

102
Q

What is spinal bifida?

A

Your spinal cord and brain need to be covered with a tube of cells, but in spina bifida, certain areas of the spine are not covered by the tube. The spine comes up in certain places where it shouldn’t.

103
Q

How can the mother prevent these neural tube defects?

A

By taking folic acid.

104
Q

What is a very safe way to check for any pregnancy irregularities?

A

You can use ultrasound for prenatal detection of genetic diseases.

105
Q

What are conjoined twins and how do they form?

A

They are twins whose cells reconnected during pregnancy, so they come out connected in certain areas. Some may survive this condition, but not all.

106
Q

What is amniocentesis?

A

Injecting 2-3 mL of amniotic fluid into the placenta. This allows for karyotyping the baby’s chromosomes by culturing the baby’s skin cells and 100 biochemical tests to determine any defects. Can be done 15-17 weeks gestation. Can be dangerous.

107
Q

What is chorionic villi testing?

A

At 8-10 weeks pregnant, the doctor can use sonar and a flexible needle to remove fetal chorion cells. This can be dangerous, but it allows for karyotyping.

108
Q

What is endoscopy?

A

AKA fetoscopy, it involves using a camera and an endoscope that is inserted directly into the organ. It can help detect hydrocephalus.

109
Q

What is hydrocephalus?

A

It is a condition in which the baby produces too much cerebral spinal fluid than is necessary, preventing the brain from growing and developing properly.

110
Q

How can hydrocephalus be treated?

A

Put in a shunt to release fluid into the stomach.

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