Inheritance🧬

    Cards (33)

    • A gene is a unit of inheritance. It is a small segment of DNA that controls the production of one polypeptide that determines a characteristic
    • Alleles are different form of the same gene
    • Homozygous (RR/rr)
      heterozygous (Rr)
    • Female XX, male XY
    • Mutation is a sudden, random change in the structure of a gene or in the number of chromosomes in the nucleus.
    • Gene mutation
      • albinism : people with albino allele (recessive) cannot produce a pigment for skin,hair and eye colour. They are sensitive to sunlight and easily sunburnt.
      • sickle cell anemia : gene controlling haemoglobin is affected. The mutated gene is recessive causing red blood cell to be sickle shaped which can interfere with the oxygen carrying property of red blood cells
    • Chromosome mutations
      • Down syndrome : humans normally have 46 chromosomes. Down syndrome people have 47 (extra chromosome 21)
    • Factors increasing rate of mutation
      • chemicals (eg: tar)
      • radiation ( eg: ultraviolet light, X-rays)
    • What is a gene?
      A gene is a unit of inheritance that controls the production of one polypeptide determining a characteristic.
    • Where is the gene for human eye colour located?
      On chromosome 15.
    • What are alleles?
      Alleles are different forms of the same gene.
    • What does the allele 'B' represent in the context of eye colour?
      The allele for black eye colour.
    • What does the term 'phenotype' refer to?
      Phenotype refers to the expressed trait or observable characteristic of an organism.
    • What is the genotype for Taylor Swift's eye colour?
      bb
    • How is a genotype defined?
      A genotype is the genetic make-up of an organism represented by a pair of alleles.
    • What does it mean if an organism is homozygous?
      It means the two alleles controlling the trait are identical.
    • What does it mean if an organism is heterozygous?
      It means the two alleles controlling the trait are different.
    • What is the difference between dominant and recessive alleles?
      A dominant allele expresses itself in both homozygous and heterozygous conditions, while a recessive allele expresses itself only in homozygous condition.
    • What is the dominant allele for eye colour?
      Black allele (B)
    • What is a Punnett Square used for?
      A Punnett Square is used to determine the genotype of the offspring.
    • How many pairs of chromosomes do humans have?
      23 pairs
    • What are the sex chromosomes in humans?
      Females have XX chromosomes, while males have XY chromosomes.
    • Why might the observed ratio of boys to girls in a family differ from the expected ratio?
      Because the ratio figures are based on chance/probability and are often inaccurate with small sample sizes.
    • What are variations in traits between individuals of the same species dependent on?
      Interactions between genes and the environment.
    • What are the two categories of variation?
      • Continuous variation
      • Discontinuous variation
    • What are the differences between discontinuous and continuous variation?
      Discontinuous variation:
      • Few clear-cut phenotypes
      • Controlled by one or a few genes
      • Not affected by environmental conditions
      • Examples: eye colour, blood group

      Continuous variation:
      • Range of phenotypes
      • Controlled by many genes
      • Affected by environmental conditions
      • Examples: height, skin colour
    • What is mutation?
      Mutation is a sudden, random change in the structure of a gene or in the number of chromosomes.
    • How can mutations produce variation between individuals?
      Mutations result in new alleles.
    • What are examples of gene mutations?
      • Albinism: Recessive allele causing lack of pigment.
      • Sickle-cell anemia: Recessive mutation affecting haemoglobin.
    • What is an example of a chromosome mutation?
      • Down's syndrome: Extra chromosome 21, resulting in 47 chromosomes.
    • What is the typical rate of mutation?
      The rate of mutation is usually very low.
    • What can increase the rate of mutation?
      The presence of mutagens such as chemicals and radiation.
    • What are some factors that can increase the rate of mutation?
      • Chemicals (e.g., tar)
      • Radiation (e.g., ultraviolet light, X-rays)
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