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General Biology 1 > Chapter 13 > Flashcards

Chapter 13 Flashcards

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1
Q

Sex-linked (X-linked)

A

trait determined by a gene on X chromosome

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2
Q

What species did Thomas Morgan Hunt look into?

A

Drosophilia

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3
Q

Autosomes

A

any eukaryotic chromosomes not a sex chromosomes

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4
Q

What is the default sex in embryonic development?

A

Female

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5
Q

Genes on Y chromosome

A

Make male genitalia
Make secondary sexual structures

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6
Q

Any individual with one Y chromosome is normally

A

Male

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7
Q

Name an example of a human genetic disorder that is sex-linked?

A

Hemophilia

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8
Q

Which statement is true about inheritance of hemophilia between females and males

A

Heterozygous females are asymptomatic carriers

Men who receive a recessive allele on their X c’some have the disease

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9
Q

Barr body

A

Inactivated X chromosome

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10
Q

Dosage compensation

A

A phenomenon by which expression of genes carried on sex chromosomes is kept the same in males and females, despite a different number of sex chromosomes

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11
Q

Genetic mosaics

A

When a woman is heterozygous for a sex linked gene, some cells will express the dominant allele and other may express the recessive

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12
Q

Nondisjunction

A

failure of homologues to separate properly during meiosis

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13
Q

What are the possible aneuploidies when nondisjunction occurs in female meiosis?

A

XX or no X chromosomes (O)

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14
Q

What are the possible aneuploidies when nondisjunction occurs in male meiosis?

A

XY, YY, or no sex chromosomes (O)

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15
Q

Aneuploidy

A

gain or loss of a chromosomes

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16
Q

T or F: nondisjunction only occurs in sex chromosomes

A

F: nondisjunction occurs in both autosomes and sex chromosomes

17
Q

Aneuploidy is a result of _________

A

Nondisjunction

18
Q

Monosomy

A

loss of one copy of an autosome

19
Q

Trisomy

A

gain of an extra autosome

20
Q

Down syndrome

A

an extra copy (trisomy) on chromosome 21

21
Q

T or F: Aneuploidy is more severe in sex chromosomes than in autosomes

A

F: It is LESS severe than in autosomes

22
Q

Triple X (XXX)

A

develop as normal females with 2 Barr bodies

1/1000 females

23
Q

Klinefelter syndrome (XXY)

A

develop as a male with many female characteristics, often mentally delayed

1/1000 male births

24
Q

Turner syndrome (XO)

A

sterile female, stunted sexual development
1/5000 female births

25
Q

Which aneuploidy variation is lethal during embryonic development?

A

YO

26
Q

Generally what is the Chromosomal theory of inheritance? And how did Morgan’s early work find support for it?

A

Chromosomal theory of inheritance - theory stating hereditary traits are carried on chromosomes

Morgan found

27
Q

How is sex determined in humans?

A

Sex chromosomes
Females: XX
Males: XY

28
Q

How many autosomes do humans have? How many sex chromosomes?

A

Autosomes - 22 pairs
Sex chromosomes - 23rd pair

29
Q

Which chromosomes determines ‘maleness’ in humans?

A

Y

30
Q

If females have double the X-genes, do they express twice as many proteins encode on the X c’somes? Why or why not.

A

No, because of dosage compensation, which

31
Q

True or false: Early in embryonic development in females, one X-chromosome gets turned off (Barr body) all cells in the adult female have the same X-chromosome inactivated.

A

True

32
Q

Why do genetic mosaics form?

A
33
Q

Nondisjunction of chromosomes in meiosis leads to ___________. (one word)

A

Aneuploidy

34
Q

Down syndrome is an example of what type of chromosomal disorder?

A

Trisomy

35
Q

Why would Aneuploidy in sex chromosomes is less severe than in autosomes?

A

Autosomes is densely packed with genes
E.g., if you lose chromosome 1, you will lose a lot of important genes

If you are missing a sex chromosome, more flexibility

Sex chromosomes have fewer genes essential for functioning

What you lost from a sex chromosomes is not as impairing as what you lost from an autosome

36
Q

What types of disorders can result from Aneuploidy of sex chromosomes?

A

Triple X (XXX)
Klinefelter syndrome (XXY)
XO
OY
XYY (Jacob syndrome)

General Biology 1 (13 decks)

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