6.2 Monogenic Inheritance Flashcards

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1
Q

variation is the phenotypic differences between who?

A

organisms of the same species

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2
Q

what 4 things can variation be the result of?

A
  1. independent assortment of homologous chromosomes
  2. crossing over in meiosis
  3. random fertilisation of gametes
  4. mutation
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3
Q

monogenic inheritance explains what?

A

how genes are passed one generation to the next

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4
Q

monogenic inheritance - the basic laws by which characteristics were inherited were established by who?

A

Mendel

scientist and monk in the 19th century

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5
Q

(monohybrid inheritance) inheritance of a single characteristic is controlled by what?

A

a single gene

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6
Q

(monohybrid inheritance) a single gene can have how many alleles?

A

multiple

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7
Q

(monohybrid inheritance) what 3 things can alleles be?

A

dominant
recessive
co-dominant

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8
Q

(monohybrid inheritance) what is a gene?

A

specific length of DNA occupying a position on a chromosome known as a locus

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9
Q

(monohybrid inheritance) what is a chromosome?

A

linear sequence coding for many genes

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10
Q

(monohybrid inheritance) what does it mean if genes are homozygous?

A

same alleles

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11
Q

(monohybrid inheritance) what does it mean if genes are heterozygous?

A

different alleles

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12
Q

(monohybrid inheritance) what do chromosomes exist in?

A

pairs
one chromosome originally from the mother
one chromosome originally from the father

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13
Q
  1. when performing a genetic cross you first need to state what?
A

phenotypes of both the parents

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14
Q
  1. when performing a genetic cross you need to then state what of the parents?
A

genotype

assign letters to represent alleles

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15
Q

3.when performing a genetic cross, after you have stated the genotype what do you have to state of the parents?

A

gametes

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16
Q
  1. when performing a genetic cross you use what type of square? and what does it show?
A

punnet square

show random fusion of gametes

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17
Q
  1. when performing a genetic cross, after you have done the punnet square you state what?
A

proportion of each genotype produced amongst the offspring

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18
Q
  1. when performing a genetic cross, you then state the corresponding what?
A

phenotype for each genotype

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19
Q

what did mendel carry out many of his experiments on?

A

pea plants

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20
Q

when a homozygous green pea plant is crossed with a homozygous yellow pea plant which allele is dominant?

A

allele for green pea plant

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21
Q

what are true breeding/pure breeding organisms?

A

organisms containing homologous alleles for a particular gene

22
Q

co-dominance occurs when 2 alleles occur for a gene, both of which are what?

A

dominant

23
Q

(co-dominance) what happens to the alleles in the phenotype?

A

both are expressed

24
Q

(co-dominance) give an example of an organism in which co-dominance is found:

A

colour of snapdragon flowers

25
Q

(co-dominance - snapdragons) the allele which codes for red flowers codes for production of what?

A

an enzyme catalysing production of the red pigment

26
Q

(co-dominance - snapdragons) the allele coding for white flowers codes for what?

A

altered version of the enzyme which doesn’t catalyse production of the pigment so flowers are white

27
Q

(co-dominance - snapdragons) when do red flowers occur?

A

when the plant is homozygous for the allele coding for the red pigment

28
Q

(co-dominance - snapdragons) when do white flowers occur?

A

when the plant is homozygous for the allele coding for the white pigment

29
Q

(co-dominance - snapdragons) when do pink flowers occur?

A

when the plant is heterozygous - allele for red pigment produces enough for flowers to be pink

30
Q

(co-dominance - snapdragons) how are co-dominant alleles represented?

A

uppercase letter with a smaller lowercase letter to indicate colour

31
Q

(sex linkage) some characteristics are carried on which chromosomes?

A

sex chromosomes

32
Q

(sex linkage) why do are there a number of genes on the X chromosome men have only one copy of?

A

Y chromosome is smaller than the X

33
Q

(sex linkage) why may characteristics caused by recessive alleles on the X chromosome appear more frequently in men?

A

because it is missing on the Y in males - females may have dominant allele present on another X chromosome

34
Q

(Sex linkage) what is a sex linked genetic disorder?

A

Haemophilia

35
Q

(Sex linkage) what happens in haemophilia?

A

Blood clots slowly due to lack of protein blood clotting factor
Small cuts could be fatal

36
Q

(Sex linkage) if a male inherits the recessive allele for haemophilia on their X chromosome will they inherit it?

A

Yes

Don’t have the corresponding dominant allele on their Y chromosome

37
Q

(Sex linkage) do females who are heterozygous for haemophilia suffer?

A

No they are carriers

38
Q

(Multiple alleles) how many alleles does a gene have to be classed as a multiple allele?

A

3+

39
Q

(Multiple alleles) how many alleles can be present in an individual?

A

2

40
Q

(Multiple alleles) what is determined by a gene with multiple alleles?

A

Blood group

41
Q

(Multiple alleles) blood group - what does immunoglobulin gene code for?

A

Production of different antigens on surface of RBCs

42
Q

(Multiple alleles) blood group what does Ia result in?

A

Production of antigen A

43
Q

(Multiple alleles) blood group - what does Ib code for?

A

Production of antigen B

44
Q

(Multiple alleles) blood group - what does Io code for?

A

Neither antigen

45
Q

(Multiple alleles) blood group - which alleles are co dominant?

A

Ia and Ib

46
Q

(Multiple alleles) blood groups - which allele is recessive?

A

Io

47
Q

(Determining sex) which chromosome determines sex?

A

23rd

48
Q

(Determining sex) which chromosome carries the gene causing the embryo to develop as male?

A

The Y chromosome

49
Q

(Determining sex) how is the sex of the offspring determined?

A

By the sperm fertilising the egg containing an X or Y

50
Q

(Dihybrid inheritance) what is dihybrid inheritance used to show?

A

Inheritance of 2 characteristics caused by two genes

51
Q

(Dihybrid inheritance) give an example of dihybrid inheritance?

A

Phenotype of pea plants
Yellow or green
Round or wrinkled