Inheritance Flashcards

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1
Q

Define a gene

A

A gene is a unit of inheritance with a specific sequence of nucleotides as part of a DNA molecule containing information to synthesise a polypeptide

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2
Q

Define an allele

A

An allele is an alternative form of a gene

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2
Q

What is a dominant allele

A

An allele that can always be expressed in the phenotype

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3
Q

What is homozygous dominant

A

Having 2 identical dominant alleles

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3
Q

What is heterozygous

A

Having 2 different alleles

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3
Q

What is a recessive allele

A

An allele that can be expressed in the phenotype when it is homozygous

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4
Q

What is homozygous recessive

A

Having 2 identical recessive alleles

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5
Q

Define genotype

A

Genotype is the genetic makeup of an organism

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6
Q

Define phenotype

A

Phenotype is an observable trait of an organism

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7
Q

Define codominance

A

Codominance is when both alleles have equal effect on the offspring, so both alleles are expressed in the phenotype

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7
Q

Define monohybrid inheritance

A

Monohybrid inheritance is the inheritance of a single characteristic

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7
Q

How is genotype linked to phenotype

A

Phenotype is the expression of the genotype in a tangible form

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8
Q

What is Mendel’s Law of Segregation

A

Mendel’s Law of Segregation states that genes occur in pairs and that each gamete only receives 1 allele of each pair, so the 2 alleles of the organism are separated into different gametes to ensure variation

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9
Q

What are male sex chromosomes

A

XY

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10
Q

What are female sex chromosomes

A

XX

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11
Q

Define sex linkage

A

Sex linkage is the carrying of genes on sex chromosomes

12
Q

In a pedigree, what are males and females represented by

A

Male - square
Female - circle

13
Q

What are autosomes

A

Homologous chromosomes except sex chromosomes

14
Q

Define variation

A

Variation is the differences in traits between individuals of the same species

15
Q

What types are variation are there

A
  • Continuous variation
  • Discontinuous variation
16
Q

What are some causes of variation

A

Genetic factors
- Chromosome and gene mutation
- Random fertilisation of gametes

Environmental factors

17
Q

Describe continuous variation

A
  • Range of phenotypes
  • Greatly affected by environmental conditions
  • Controlled by many genes
18
Q

Describe discontinuous variation

A
  • A few clear-cut phenotypes
  • Relatively unaffected by environmental conditions
  • Controlled by just 1 or a few genes
18
Q

Define evolution

A

Evolution is the change in heritable characteristics of biological populations over successive generations

18
Q

What is Darmin’s theory of evolution

A

Darwin’s theory of evolution states that all organisms arise and develop through natural selection

19
Q

What are the principles of natural selection

A
  • Variation
  • Heredity
  • Overproduction
  • Limited resources
  • Fitness
  • Genetic composition
20
Q

Describe how natural selection works

A
  • Variation within population caused by spontaneous mutation
  • Only fittest will survive
  • Those with genetic variation best adapted to environment more likely to survive till maturity
  • Higher chance of reproducing and passing down desirable genes to offspring
21
Q

What are some environmental factors that act as forces of natural selection

A
  • Amount of water and food
  • Living space