Introduction to Genetics Review (Exam Review #45-58 & #73-94) Flashcards

1
Q

What is probability?

A

The likelihood of an event

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2
Q

What is the probability of rolling 2 fours on a die in a row?

A

1/36

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3
Q

What diagrams are used to show the possible gene combinations that could result from a genetic cross?

A

Punnett Squares

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4
Q

What are organisms that have 2 identical alleles for the same trait called?

A

Homozygous

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5
Q

What are organisms that have 2 different alleles for the same trait called?

A

Heterozygous

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6
Q

What word is used to describe the physical characteristics of a genetic cross?

A

Phenotype

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7
Q

What word is used to describe the genetic makeup of a genetic cross?

A

Genotype

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8
Q

Draw a Punnett Square to show a cross between a heterozygous round seed and a wrinkled seed. (Round allele: R, Wrinkled allele: r) Give the possible genotypes and phenotypes and their percentages.

A

Genotypes:

Rr-50%

rr-50%

Phenotypes:

Round-50%

Wrinkled-50%

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9
Q

Draw a Punnett Square to show a cross between a homozygous purple, heterozygous long-feathered Foo-Foo bird and a pink, short-feathered Foo-Foo bird. (P: purple, p: pink, L: long-feathered, l: short-feathered) Give the possible genotypes and phenotypes and their percentages.

A

PL Pl PL Pl

pl PpLl Ppll PpLl Ppll

pl PpLl Ppll PpLl Ppll

pl PpLl Ppll PpLl Ppll

pl PpLl Ppll PpLl Ppll

Genotypes:

PpLl-50%

Ppll-50%

Phenotypes:

Purple with long feathers-50%

Purple with short feathers-50%

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10
Q

What is the law of independant assortment?

A

Alleles assort independently from one another.

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11
Q

What happens in incomplete dominance?

A

The traits combine.

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12
Q

Give an example of incomplete dominance.

A

A red flower and a blue flower have purple offspring

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13
Q

What happens in codominance?

A

Both traits show through.

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14
Q

Give an example of codominance.

A

A dog with a brown parent and a white parent has spots of both colors.

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15
Q

What are traits that are controlled by two or more genes called?

A

Polygenic

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16
Q

Genes that have more than two alleles are said to have what?

A

Multiple alleles

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17
Q

The two chromosomes in a human that determine an individual’s sex are called what?

A

Sex chromosomes

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18
Q

What is a pedigree?

A

A chart showing the appearance of a trait in a family

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19
Q

Which pattern(s) of inheritance are consistent with this pedigree?

i. Sex-linked
ii. Complete dominance
iii. Cocominance

A

Complete dominance

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20
Q

According to this pedigree, what is the best guess of the genotypes of the student’s parents?

A

Heterozygous

21
Q

According to the pedigree, what is(are) the most likely genotype(s) of the student’s sister?

A

WW or Ww

22
Q

Aside from genetics, what factor plays an important role in a person’s traits?

A

Environment

23
Q

What is the allele for Blood-type A?

A

IA

24
Q

What is the allele for Blood-type B?

A

IB

25
Q

What is the allele for Blood-type AB?

A

IAIB

26
Q

What is the allele for Blood-type O?

A

i

27
Q

List all the possible genotypes for Type-A blood.

A

IAIA and IAi

28
Q

List all the possible genotypes for Type-B blood.

A

IBIB and IBi

29
Q

List all the possible genotypes for Type-AB blood.

A

IAIB

30
Q

List all the possible genotypes for Type-O blood.

A

ii

31
Q

What is the dominant allele of the AB blood groups?

A

IA and IB

32
Q

What is the recessive allele of the AB blood groups?

A

i

33
Q

What is the dominant allele for the Rh blood group?

A

Rh+

34
Q

What is the recessive allele for the Rh blood group?

A

Rh-

35
Q

A man heterozygous for type-A blood marries a woman heterozygous for type-B blood. What is the probability as a percentage that their child will have type-O blood?

Hint: Use a Punnett Square

A

25%

36
Q

Name a disorder caused by a recessive allele.

A

Color-Blindness

37
Q

Name a disorder caused by a dominant allele.

A

Huntington’s

38
Q

Name a trait controlled by codominant alleles.

A

Blood type

39
Q

In diseases like cystic fibrosis and sickl cell anemia, what causes the disorder?

A

A change in the DNA

40
Q

What are sex-linked genes?

A

Genes on the X or Y chromosome

41
Q

Give 2 examples of sex-linked disorders in humans.

A

Color-blindness and hemophilia

42
Q

In fruit flies, eye color is a sex-linked trait on the X-chromosome. If a female fruit fly heterozygous for red eyes (red eyes are dominant) is crossed with a white-eyed male (white eyes are recessive), what percentage of their offspring will have white eyes?

Hint: use a Punnett Square

A

50%

(remember that red eyes are XR and white eyes are Xr)

43
Q

Why do males tend to have a higher probability of getting a sex-linked disorder than females?

A

They only have one X chromosome, and therefore only have one allele for each X-linked gene. That allele, being the only one, must show through.

44
Q

What is nondisjunction?

A

It occurs when homologous chromosomes fail to separate.

45
Q

Describe 2 chromosomal disorders.

A

Turner’s: Only 1 X-chromosome

Klinefelter’s: 1 Y and too many X’s

46
Q

What is DNA fingerprinting used for?

A

It is used to identify people.

47
Q

What is the purpose of the human genome project?

A

To map the human genome

48
Q

What is gene therapy?

A

Injecting a “good” gene to replace a “bad” one

49
Q

What are some ethical issues that can be raised with human genetics?

A

Answers may vary