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Bio 190 > Ch 16 > Flashcards

Ch 16 Flashcards

1
Q

What are the three general rules for genes that follow a Mendelian pattern of inheritance?

A
  • For crosses involving two or more genes, the genes obey Mendel’s law of independent assortment
  • Genes are generally passed unaltered from cell to cell, and from generation to generation
  • The genes obey Mendel’s law of segregation
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2
Q

True or false: An epigenetic effect causes a change in gene expression without altering the sequence of DNA.

A

true

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3
Q

Epigenetic inheritance refers to epigenetic changes that occur

A

during gamete formation.

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4
Q

Genomic imprinting refers to the

A

marking of DNA so that the phenotype of offspring depends on the parental origin of the gene.

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5
Q

The inheritance pattern of the Igf2 gene in mice, in which only the paternal gene is expressed, is known as:

A

genomic imprinting

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6
Q

Mendelian inheritance is characterized by three general rules: 1. Except in the case of rare ____enes are passed unaltered from generation to generation; 2. Each gene obeys Mendel’s law of ____ and 3. During crosses, two or more genes obey Mendel’s law of independent ___

A

mutations; segregation; assortment

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7
Q

True or false: As a result of genomic imprinting, individuals with the same genotype may have different phenotypes.

A

true

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8
Q

Which of the following characterize an epigenetic effect?

A
  • Causes a change in gene expression

* The change must be passed from cell to cell

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9
Q

In what type of inheritance pattern are phenotypes dependent on the parental origin of the alleles?

A

Genomic imprinting

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10
Q

Modification of a gene or chromosome during gamete formation that alters a gene’s expression but does not change the DNA sequence is known as ______ ______

A

epigenetic

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11
Q

In genomic imprinting, the transcription of the imprinted gene is inhibited because

A

imprinting, the transcription of the imprinted gene is inhibited because.

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12
Q

The phenomenon where offspring express a paternal or maternal allele depending on how a particular gene is marked is known a ___

A

genomic / gentic imprinting

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13
Q

Which of the following is an example of an imprinted gene?

A

the gene Igf2 in mammals

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14
Q

Methylation patterns are established during the formation of ______

A

gametes

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15
Q

Individuals may have the same genotype but very different phenotypes as a result of

A

genomic imprinting

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16
Q

True or false: Only genes inherited from the mother are imprinted.

A

False

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17
Q

In the phenomenon of genomic _____ , the gene from only one parent is expressed.

A

imprinting

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18
Q

In the somatic cells of female mammals, the genes on one of the two copies of the X chromosome are not expressed. This phenomenon is known as X-chromosome ____

A

inactivation

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19
Q

The marking process that occurs during genomic imprinting is the addition of _____ groups to DNA.

A

methyl

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20
Q

A highly condensed X chromosome is known as a(n) ___

A

barr body

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21
Q

The calico pattern in cats is due to random X-chromosome inactivation in a

A

female that is heterozygous for an X-linked gene with black (XB) and orange (XO) alleles.

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22
Q

When are methylation patterns established?

A

During formation of gametes

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23
Q

The cells of humans and other mammals have the ability to ____ their X chromosomes, and are therefore able to inactivate all but one of them

A

count

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24
Q

In genomic imprinting, which genes are silenced?

A

Genes inherited from either the mother or the father depending on the gene.

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25
Q

In triple X syndrome, how many X chromosomes are converted into Barr bodies and why?

A

two, because one active X chromosome is needed

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26
Q

X-chromosome inactivation refers to the process that occurs in

A

female mammals, when the genes of one of the two X chromosomes are not expressed.

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27
Q

The region on the X chromosome that is known to play a role in Barr body formation is known as the

A

X inactivation center

28
Q

A Barr body is a(n)

A

highly condensed X chromosome.

29
Q

The Xist gene, which is involved in X inactivation, encodes a(n) ___ molecule.

A

RNA

30
Q

In cats, the calico pattern is caused by the random X-chromosome ______ in females that are heterozygous for an X-linked gene with black and _______ alleles.

A

Inactivation, Orange

31
Q

How is the Xist gene involved in X inactivation?

A

It synthesizes RNA, which coats one of the X chromosomes. Proteins then associate with the RNA, promoting compaction into a Barr body.

32
Q

In humans and other mammals, X chromosomes are counted. This process ensures that any normal somatic cell contains ____

A

one

33
Q

In mice, the Agouti gene regulates

A

the deposition of yellow pigment in hair.

34
Q

Some people are born with abnormalities in the number of their sex chromosomes. For example, people born with triple X syndrome have three X chromosomes, and those born with Klinefelter syndrome have two X chromosomes and one Y. How does X inactivation proceed in these cases?

A

All of the X chromosomes are inactivated except for one.

35
Q

If the Agouti gene in mice undergoes a gain-of-function mutation, the gene will be

A

over-expressed, resulting in yellow fur.

36
Q

Which of these sequences plays a critical role in Barr body formation?

A

The X inactivation center (Xic)

37
Q

Female mice carrying the Avy allele were divided into a control group (fed a standard diet) and an experimental group (fed a diet supplemented with folic acid and vitamin B12). Both groups were fed their respective diets before and during pregnancy and up to the stage of weaning. Offspring that inherited the Avy allele were then analyzed with regard to their coat color. What do these results show?

A

Offspring of females fed a supplemental diet had darker coats

38
Q

What is encoded by the Xist gene of the X chromosome?

A

An RNA molecule

39
Q

True or false: Smoking of cigarettes induces the formation of lung cancer only by causing genetic mutations in tumor-suppressor genes.

A

False

40
Q

The process of X-chromosome inactivation involves the gene ______, which encodes a very long ______ molecule. This molecule coats one of two X chromosomes, thus starting a process that ultimately leads to compaction of the chromosome into a Barr body.

A

Xist ; RNA

41
Q

Extranuclear inheritance patterns involve genes located in the

A

chloroplasts and mitochondria

42
Q

Adult, wild-type mice with genotype AA for the Agouti gene will have what color coat hairs?

A

Brown with black tips

43
Q

What is the structure of the mitochondria and chloroplasts genomes?

A

Single, circular DNA molecule

44
Q

Mice with a gain-of-function mutation in the Agouti gene will have fur that has a(n) ____ color.

A

yellow

45
Q

In a particular plant, the pigmentation of the offspring depends exclusively on the pigmentation of the female parent. This phenomenon is known as ____________ inheritance.

A

maternal

46
Q

The graph shown here represents the effect of diet supplementation on coat color in mice. More than 25% of the offspring with ______ coats had mothers that were fed a supplemental diet, while less than 10% had mothers that were given a standard diet.

A

heavily mottled

47
Q

This figure shows a cross in four-o’clock plants. What would be the expected phenotype(s) of the offspring?

A

All will have white leaves

48
Q

The role of epigenetics and disease has been most extensively studied with regard to

A

cancer

49
Q

In plants, which gamete typically provides most of the cytoplasm to the zygote?

A

The egg cell

50
Q

Which organelles demonstrate extranuclear inheritance?

A

Chloroplasts

Mitochondria

51
Q

This digram shows an egg cell from a maternal four-o’clock plant with white leaves. The egg cell contains mutant that will produce chloroplasts with very little _________ pigment.

A

proplastids

52
Q

Mitochondrial and chloroplast genomes are composed of a single, molecule.

A

circular DNA

53
Q

Mitochondrial transmission in eukaryotes typically occurs by what type of inheritance?

A

Maternal inheritance

54
Q

What is the phenomenon called in which a trait of the offspring is solely determined by the value of the trait in the female parent because it is passed on via the organelles in the egg cell?

A

Maternal inheritance

55
Q

Which of the following organs are most likely to be affected by a mitochondrial disease?

A

Heart, eyes, and kidney

56
Q

Leaf pigmentation in four-o’clock plants is inherited via the chloroplast genome. A female plant with variegated leaves is crossed with a male plant with white leaves. What is the result of this cross?

A

Some offspring will have green leaves, some will have white leaves, and some will have variegated leaves.

57
Q

When two genes are located close to one another on a chromosome, they tend to be transmitted together. This phenomenon is known as

A

linkage

58
Q

In most plant species, chloroplasts are inherited via the ____ cell, because it contributes most of the cytoplasm to the zygote.

A

egg

59
Q

In a two-factor cross, genes that are close together on a chromosome do not follow Mendel’s law of

A

independent assortment

60
Q
  • All normal prolastids
  • All mutant proplastids
  • A combinations of normal and mutant proplastids
A
  • green leaves
  • white leaves
  • green, white, or variegated leaves
61
Q

Bateson and Punnett, and later Morgan, did experiments on the transmission of genes in various organisms. Their results did not conform to Mendel’s law of independent assortment because they observed

A

many more F2 offspring with the parental combination of traits than predicted

62
Q

While some eukaryotic species exhibit ___ or ______ inheritance, the most common pattern of mitochondrial transmission in eukaryotes is via maternal inheritance.

A

biparental & paternal

63
Q

On this pair of chromosomes, what alleles are linked?

A

b and c

b+ and c+

64
Q

What organs are often affected by mutation in human mitochondrial genes?

A 
Kidney
Heart
Muscle
Brain
Eyes
65
Q

When genes are linked, recombinant offspring can be produced by _____ between two chromosomes

A

crossover

66
Q

Which phenomenon describes the presence of two genes very close to each other on the same chromosome, and which are transmitted together as a unit?

A

linakge

Bio 190 (21 decks)

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