L16 GENETICS II Flashcards

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1
Q

What is incomplete dominance?

A

Incomplete dominance is the heterozygous form of an individual where it is the intermediate of the 2 given forms.

Both alleles are expressed in incomplete dominance.

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2
Q

In incomplete dominance, the WHAT always reflects the WHAT?

A

PHENOTYPE always reflects GENOTYPE.

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3
Q

What is codominance?

A

Codominance is the phenomenon where two allelez are expressed in separate, distinguishable ways.

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4
Q

What is a non-mendelian trait?

A

A trait that does not strictly follow the recessive/dominance rules.

An example is human height, it is varied between each person and each person has their own potential height range.

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5
Q

TRUE OR FALSE: one pair of alleles always corresponds to one genotype.

A

FALSE: many alleles can code for one single gene.

these are polygenic traits!

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6
Q

What is epistasis?

A

Epistasis is the phemonemnon where individuals can posess a gene that masks other genes on a different locus.

Think of albinism. They carry the dominant epistatic gene and express no pigment.

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7
Q

What is Pleiotropy?

A

The expression of 2+ traits by a single gene.
.

Marfan syndrome is the mutation of the FBN1 gene and results in varied symptoms: elongated limbs, scoliosis, enlarged aorta, vision issues, connective tissue malfunctions.

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8
Q

What is polygenic inheritance?

A

Polygenic inheritance is the phenomenon where multiple genes interact to express one unique trait. An example is skin colour and all its variations.

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9
Q

Fill in the blanks.

A
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10
Q

What is meant by sex-linked inheritance?

A

Sex-linked inheritance refers to the traits/characteristics influenced by genes found on the X sex chromosome.

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11
Q

All children will inherit which chromosome?

A

All children inherit the X sex-chromosome from maternal. Their sex will depend on inheriting another X (female) or Y (male) chromosome from paternal.

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12
Q

What is hemizygous?

A

Individual that has a gene without an allelic counterpart.

IE. Men will not have second allele for genes found on their X chromosome, they are considered hemizygous.

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13
Q

What is polyploidy?

A

The precense of 2+ sets of chromosomes.

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14
Q

What is aneuploidy?

A

Anomaly in chromosome numbers.

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15
Q

Name the two types of aneuploidies.

A

Trisomy: Tri=3
Meaning 1 extra chromosome.
Monosomy: Mono=1
Meaning 1 missing chromosome.

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16
Q

What is Disomy?

A

Disomy is having normal amount of chromosomes (Di=2)

17
Q

What causes aneuploidies?

A

Nondisjunction during meiosis.

18
Q

What is nondisjunction?

A

Nondisjunction is an abnormal division in meiosis where chromosome(s) fail to separate.

19
Q

Give an example of an aneuploidy.

A

Trisomy-21 is Down Syndrome. It means there is a third chromosome on pair #21.
The result is intellectual disability, sexual sterility, characteristic facial features.

20
Q

What is the only survivable monosomy in humans?

A

Turner syndrome: individual with only 1 X chromosome.

21
Q

TRUE OR FALSE: A gamete can survive with 1 Y chromosome, no X chromosome.

A

FALSE: all gametes need 1 X chromosome to survive.

22
Q

What is a barr body?

A

A metabolically inactive X chromosome.
It is a less severe aneuploidy.

23
Q

What is the purpose of a Barr body?

A

The purpose of a Barr Body is to ensure the amount of X-chromosome gene material remains the same between males&females.

24
Q

How many barr bodies in each?
XX
XXX
XXY
XY

A
  1. XX= 1 barr body
  2. XXX= 2 barr bodies
  3. XXY= 1 barr body
  4. XY= no barr bodies.

remember, women will always have 1 barr body by default.