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Genetics > Lecture 5 > Flashcards

Lecture 5 Flashcards

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Biology 101 flashcards
1
Q

What is a barr body?

A

present inside nucleus of female somatic cells

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2
Q

Where are centrioles?

A

In the centrosomes present outside the nucleus of cells

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3
Q

How can you identify a red blood cell?

A

doesn’t have a nucleus

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4
Q

define x-inactivation

A

one x chromosome does not uncoil into a chromatin– referred to as a barr body – genes are not active on barr body because it does not uncoil

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5
Q

do males have barr bodies?

A

NO- only one per somatic cell in females

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6
Q

define barr body

A

condensed, inacive c-chromosome found in the nuclei of somatic cells of females

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7
Q

Who discovered barr body?

A

Murray Barr

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8
Q

How do X and Y chromosomes differ?

A

differ in size and the information they carry

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9
Q

defective genes found on the sex chromosomes are referred to as…?

A

sex-linked genetic disorders/diseases

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10
Q

Which type of sex linked disease is most common?

A

x-linked recessive

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11
Q

types of x-linked recessive disorders?

A

Hemophilia A, Red-green color blindness, duchene muscular dystrophy, male pattern baldness

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12
Q

Who will have x linked recessive diseases

A

males because women have two x’s so other will protect them- men only have one x so if they have it, they will show it- women only carriers

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13
Q

Define Hemophilia

A

A person with hemophilia is lacking certain proteins that are necessary for normal blood clotting

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14
Q

Typical example of x linked recessive?

A

hemophilia

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15
Q

How common is x-linked dominance?

A

very rare

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16
Q

What is the percent chance of a woman with an x-linked dominant disorder passing it to their fetus?

A

50%

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17
Q

Examples of x-linked dominant disorders

A

vitamin D resistant Rickets, incontinentia pigmenti

18
Q

Are male or female viable offspring due to incontinentia pigmenti?

A

female offspring- male offspring are mostly not viable

19
Q

Who transmits y linked disorders?

A

transmitted from father to son- NOT TO DAUGHTERS

20
Q

Why are there few Y linked disorders?

A

Because the y chromosomes is relatively small and contains few genes

21
Q

Examples of y linked disorders

A

male infertility, hypertrichosis pinnae (hair in ears)

22
Q

How is mitochondrial inheritance passed?

A

through genes present in mitochondria - mother to all offspring

23
Q

Example of a disease transmitted through the mitochondria

A

Leber’s hereditary optic neuropathy- loss of central vision before the age of 30

24
Q

polygenic inheritance

A

There is more than one gene responsible for a trait- multiple genes responsible

25
Q

What does polygenic inheritance result in?

A

continuous variation

26
Q

Example of a polygenic inheritance gene

A

height- result of the involvement of more than one gene

skin color is another example

27
Q

Linked genes

A

located on the same chromosome and cannot segregate independently because physically connected (close to each other)

28
Q

When is crossing over more likely?

A

the farther the genes are away from each other on the chromosomeE

29
Q

Example of linked genes in flies

A

the genes for eye color and wing length are on the same chromosome so they are inherited together

30
Q

Example of linked genes in humans

A

dark hair and brown eyes, black hair and curly hair, blonde hair and fair skin, dark skin and dark hair

31
Q

Mosaicism

A

denotes the presence of two populations of cells with different genotypes in one individual who has developed from a single fertilized egg

32
Q

How are cells expressed in mosaicism

A

cells within the same person having different genetic makeup

33
Q

What causes mosaicism

A

caused by error in cell division very early in the development of embryo

34
Q

Example of mosaicism

A

Neurofibromatosis type 1

35
Q

Which cells does somatic mosaicism occur in

A

somatic - NOT SEX CELLS

36
Q

Chimera

A

animals that has two or more different populations of genetically distinct cells that originated in different zygotes

37
Q

What is chimera formed from?

A

four parent cells- two fertilized eggs or early embryos fused together

38
Q

define epistasis

A

interaction of non allelic genes- one gene affects the phenotypic expression of a second gene

39
Q

Example of epistasis in mice

A

in mice there is a gene that codes for the presence or absence of pigmentation in fur- the second gene codes for color of fur

40
Q

define pleiotrophy

A

occurs when a gene has more than one phenotypic expression

41
Q

example of pleiotrophy

A

sickle cell anemia- gene that codes for hemoglobin is defective- can’t produce normal hemoglobin and shape of hemoglobin affected

42
Q

multifactorial and polygenic disorders

A

cancers, diabetes, heart disease, hypertension, mental retardation, obesity, Alzheimer’s, schizophrenia

Genetics (12 decks)

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