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MCBG > Genotype, Phenotype + Inheritance > Flashcards

Genotype, Phenotype + Inheritance Flashcards

1
Q

What is the meaning of hemizygous?

A

Only one allele of a gene is present

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2
Q

What is the meaning of homozygous?

A

Two alleles of gene are the same

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3
Q

What is the meaning of heterozygous?

A

Two alleles of a gene are different

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4
Q

What are the different modes of inheritance?

A

dominant - determines the phenotype in a heterozygous
recessive - the non-dominant allele in a heterozygote > both alleles need to be recessive for trait to appear

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5
Q

What is a codominant allele?
Example

A

There is an equal influence of two alleles on the phenotype
e.g. blood type

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6
Q

What is polygenic inheritance?
Example

A

Where phenotypes are affected by multiple genes
Continuous trait
e.g. skin colour

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7
Q

What is a pedigree chart?

A

A diagram which shows genetic information from a family using standardised symbols

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8
Q

2 purposes of a pedigree chart

A
  • Determines the pattern of inheritance for a given trait
  • Discovers whether the gene is location on a X or Y chromosome
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9
Q

What is genotype?

A

Genetic description f a person

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10
Q

What is phenotype?
Examples

A

Observable characterised of a person
e.g. hair,eye colour, expression of enzyme
As a result of genotype interaction with environment

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11
Q

What is an allele?

A

Different version of the same gene on the same position of a chromosome

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12
Q

What symbols are used for males, females + unknown sex in a pedigree chart?
Affected vs unaffected

A

Males - square
Females - circle
Unkown - diamond

Unaffected - white
Affected - black/filled in

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13
Q

What is the symbol for carrier/heterozygous recessive allele in pedigree charts?

A

Half filled
Black dot

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14
Q

How are twins represented on a pedigree tree?

A

Connected by two diagonal lines
Identical twins have one horizontal line between them too

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15
Q

Example of autosomal dominant disease

A

Achondroplasia
Ehlers-Danlos syndrome
Marfan’s syndrome
Huntington’s disease

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16
Q

Example of autosomal recessive disease

A

Cystic fibrosis
Albinism
PKU
Sickle cell anaemia
Xeroderma pigmentosum

Must be homozygous

17
Q

Example of X-linked recessive disease

A

Haemophilia A and B
Fragile X syndrome
Duchene muscular dystrophy

18
Q

How do X-linked recessive diseases affect genders + offspring?

A

Affected males:
- have heterozygous daughter as can only pass on X chromosome o daughter
- cannot pass on to sons
- heterozygous carrier mother (at least)

Affected female:
- have affected father
- carrier mother

19
Q

Parents of affected female of X linked recessive disease

A

Affected father
Carrier (or affected) mother

20
Q

Parents of affected male of X linked recessive disease

A

Heterozygous carrier mother (or affected)

21
Q

Who is affected by Y-linked dominant pedigree

A

Only men

22
Q

What does monogenic inheritance mean?
Example

A

When phenotype is influenced by one gene
Discontinuous trait
e.g. widow’s peak

23
Q

What is linkage?

A

Genes don’t show independent assortment during meiosis in metaphase

24
Q

What does the location of genes on chromosome have to do with their inheritance?

A

Genres that are closer together are more likely to be inherited together - tightly linked

25
Q

What is penetrance?

A

Describe whether there is clinical expression of a phenotype in a person
% of people with a genotype that show a symptom

26
Q

What is expressivity?

A

Describe the different in clinical prevention between two people with the same genotype
The severity of disease in different people

27
Q

What are the 5 patterns of Mendelian inheritance?

A

Autosomal recessive
Autosomal dominant
X linked dominant
X linked recessive
Y- linked

28
Q

What is a pattern of non-Mendelian inheritance?

A

Mitochondrial inheritance
Controlled by single genes coed for by mitochondrial genes

29
Q

What are autosomes?

A

Non-sex chromosomes

30
Q

What are the features of a X linked dominant trait on a pedigree chart?

A

No generations are skipped
Affected sons have affected mothers
Affected fathers have affected daughters

31
Q

What are the features of a X linked recessive trait on a pedigree chart?

A

Affected daughters have affected fathers
Affected mothers have affected sons

32
Q

What is the chance of offspring being affected by autosomal recessive disease?

A

25%

33
Q

How are mitochondrial diseases passed down?

A

Maternal line

34
Q

What is Klinefelter syndrome?

A

Where boys are born with an extra X chromosome
47 XXY

35
Q

What is the karyotype of Klinefelter syndrome?

A

47, XXY

MCBG (9 decks)

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