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OCR Biology F215 > Genetics > Flashcards

Flashcards in Genetics Deck (16)
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0
Q

Define the term genotype

A

The alleles present within cells of an individual for a particular trait/characteristic

1
Q

Define the term phenotype

A

The characteristics expressed by the organism (caused by the genotype)

2
Q

Define the term dominant allele

A

Expressed in the phenotype even if a different allele for the same gene is present

3
Q

Define the term recessive allele

A

Only expressed in the phenotype if no dominant allele is present

4
Q

Define the term co dominant

A

Alleles are co dominant if they both contribute to the phenotype

5
Q

Define the term heterozygous

A

Two different alleles

6
Q

Define the term homozygous

A

Two copies of the same allele

7
Q

Define the term linkage

A
  • Genes for different characteristics that are present at different loci on the same chromosome
  • The combination of alleles are usually inherited together because they segregate together in meiosis
8
Q

How should a genetic diagram be laid out?

A
  1. Parental phenotype
  2. Parental genotype
  3. Gametes
  4. Punnet square
  5. F1 phenotype (ratio)
  6. F1 genotype
  7. Gametes
  8. Punnet square
  9. F2 genotype ratio
  10. F2 phenotypic ratio
9
Q

What is sex linkage?

A

If the gene for the characteristic is on the sex chromosome

10
Q

Define the term homogametic

A

Women XX

11
Q

Define the term heterogametic

A

Men XY

12
Q

What causes haemophilia?

A

Could be a recessive allele of a gene, that codes for a faulty version of the protein factor.

X^H - normal X^h - haemophilia

13
Q

What is a monohybrid cross?

A
  • parents - homozygous dominant x homozygous recessive (NN X nn)
  • f1 generation - all heterozygous offspring (Nn)
  • f2 generation phenotypic ratio 3 : 1 (dominant : recessive)
14
Q

What is a dihybrid cross?

A
  • parents - homozygous dominant x homozygous recessive (NNGG x nngg)
  • f1 generation - all heterozygous offspring (NnGg)
  • f2 generation - 9 : 3 : 3 : 1 (dominant both : dominant 1st recessive 2nd : recessive 1st dominant 2nd : recessive both)
15
Q

What is a co dominant cross?

A
  • parents - homozygous for one allele x homozygous for other allele (H^n H^n x H^s H^s)
  • f1 generation - all heterozygous offspring (H^n H^s)
  • f2 generation - 1 : 2 : 1 (homozygous for one allele : heterozygous : homozygous for the other allele)