Genetic Diagrams Flashcards

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1
Q

What causes differences in the inherited characteristics of an organism?

A

Alleles

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2
Q

What are alleles?

A

Different versions of a gene

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3
Q

Define the term ‘genotype’.

A

The combination of alleles an organism has

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4
Q

Define the term ‘phenotype’.

A

The visible characteristics an organism has

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5
Q

What is meant by ‘homozygous’?

A

Having two of the same allele for a particular gene

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6
Q

What is meant by ‘heterozygous’?

A

Having two different alleles for a particular gene

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7
Q

How is a dominant characteristic expressed?

A

An organism can have either:

  • Two dominant alleles for a particular gene (e.g. BB)
  • One dominant and one recessive allele for a gene (e.g. Bb)

(Dominant alleles overrule recessive alleles)

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8
Q

How is a recessive characteristic expressed?

A

Both of the organism’s alleles must be recessive (e.g. bb)

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9
Q

Some characteristics are controlled by a single gene.

What are most phenotypic features controlled by?

A

Multiple genes interacting

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10
Q

What is monohybrid inheritance?

A

The inheritance of a single characteristic

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11
Q

(Example)

Demonstrate how you can show monohybrid inheritance in a punnett square.

A
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12
Q

What can you use monohybrid crosses to show?

A

How recessive and dominant traits for a single characteristic are inherited

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13
Q

(Example)

Show how you can use a monohybrid cross to determine the sex of offspring at fertilisation.

A
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14
Q

How many matched pairs of chromosomes are there in every human body cell?

A

23 pairs

(this is because they each have 46 chromosomes altogether)

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15
Q

What type of allele causes cystic fibrosis?

A

A recessive allele

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16
Q

(Exam-style question)

Mark and his wife (who is not shown in the diagram) have a baby with cystic fibrosis.

Use the family pedigree to find the possible genotypes of Mark’s wife.

A

Ff or ff