Genetics Flashcards

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1
Q

Define Gene

A

A gene is a hereditary unit composed of a DNA section. They determine the characteristics of an organism by forming a protein.

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2
Q

Define gene locus

A

a fixed point on a chromosome for a gene

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3
Q

Define allele

A

variation of a gene at a particular gene locus

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4
Q

Define genotype

A

the allele combination of an individual

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5
Q

Define phenotype

A

the physical, behavioral or physiological characteristics of an organism which are a result of the combination of the genotype and the environment.

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6
Q

Define dominant

A

Allele will be expressed in the heterozygous genotype

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7
Q

Define recessive

A

Only expressed in the phenotype when the genotype is homozygous.

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8
Q

Define homozygous

A

Two of the same alleles for a gene at a specific gene locus

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9
Q

Define heterozygous

A

Two different alleles for a gene at a specific gene locus

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10
Q

Define a chromosome

A

A long thread-like structure
Composed of DNA
Carries genes

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11
Q

Define autosomal

A

To do with any chromosome except the sex chromosomes

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12
Q

Write the mode of inheritance statement for a DOMINANT trait

A

The mode of inheritance is dominant because every affected individual () at least one affected parent ()

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13
Q

Write the mode of inheritance statement for a RECESSIVE trait

A

The mode of inheritance is recessive because an affected individual () has two unaffected parents( and _)

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14
Q

How do you determine if a recessive trait is X-linked?

A

X-linked if an affected mother () passes the trait to all of her sons ()
(otherwise autosomal)

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15
Q

How do you determine if a dominant trait is X-linked?

A

X-linked if an affected father () passes the trait to all of his daughters ()

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16
Q

State the mode of inheritance of huntingtons and provide alleles

A

Autosomal dominant
H = huntingtons
h = unaffected / no huntingtons

17
Q

State the mode of inheritance of cystic fibrosis and provide alleles

A

Autosomal recessive
A = unaffected / no cystic fibrosis
a = cystic fibrosis

18
Q

State the mode of inheritance of haemophilia and provide alleles

A

X - linked recessive
X^H = unaffected
X^h = haemophilia

19
Q

State the mode of inheritance of sickle-cell anemia and provide alleles

A

Codominant
Hb^A = normal cells
Hb^S = sickle cells

20
Q

State the F1 genotype ratio when two heterozygous individuals are crossed

A

1:2:1
or 25% : 50% : 25%

21
Q

State the F1 phenotype ratio when two heterozygous individuals are crossed

A

3:1
or 75% : 25%

22
Q

What is the scaffold for Explain questions

A

Because, then, therefore

23
Q

What is the scaffold for Compare questions?

A

Whereas

24
Q

What is the scaffold for Describe questions

A

This means that

25
Q

Define co-dominant

A

Alleles are equally expressed in the phenotype (e.g. in sickle cell trait HBA and HBS are expressed)