Inheritance and Variation

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Created by
Gerald Kamau

Cards (43)

  • What are chromosomes?

    Long molecules of DNA inside a nucleus.
    23 pairs inside the nucleus of body cells.
  • What is DNA?

    It is a chemical that all genetic material in a cell is made from.
  • What is the structure of DNA?
    DNA strands are polymers made up of repeating molecules in a double helix shape.
  • What is a gene?
    Small section of DNA found on a chromosome
    Genes encode for the sequence of amino acids to make a specific protein.
  • What do genes code for?
    A particular sequence of AMINO ACIDS put together to make SPECIFIC PROTEINS
  • What is a genome ?
    The entire set of genetic material in an organism
  • Why is it important to understand the human genome? (3)
    1)Allows scientists to IDENTIFY GENES that link to different types of disease i.e Down Syndrome
    2)Development of effective treatments
    3)Can be used to trace migration of certain populations by tiny differences in GENOMES.
  • How many chromosomes are in a normal body cell?
    46 (or 23 pairs)
  • How many chromosomes in a gamete (sex cell)?
    23
  • what are the gametes in plants
    -Plant gametes-ovule & pollen
  • what is the type of cell division in Asexual reproduction
    mitosis
  • Examples of organisms that reproduce asexually

    Bacteria, yeast and some plants
  • What type of cell division are gametes (sex cells) produced by?

    Meiosis
  • 2 details about the four gametes produced in meiosis
    1-Each contain 1 set of chromosomes
    2-Each gamete genetically different
  • after fertilisation what type of cell division will you observe in the embryo?
    MITOSIS
  • How many pairs of chromosomes are in a human body cell?
    23 Pairs
  • What do each of the chromosomes control?
    22 pairs of chromosomes are matched/homologous pairs-control CHARACTERISTICS
    23rd pair-XY or XX -Sex defining chromosomes
  • What are the male and female combinations of sex chromosomes?
    Males: XY-
    Females:XX-
  • Explain the chances of a child being male/female using a punnet diagram.
    50% chance of male and 50% chance of female.
  • How do you use genetic diagrams to find the probability of getting a boy or a girl?
    1-Put possible gametes from one parent down side, and from other parent along the top
    2-In middle boxes, fill in letters from top & side (like multiplication)
    3-There are 2 XX result & 2 XY results -50% chance of boy/girl
  • What do the pairs of letters in the middle of a Punnett square show?
    The possible gamete combinations
  • What do inherited genes control?

    The characteristics you develop. Genes code for proteins.
    Some characteristics controlled by single gene
    Most characteristics controlled by several INTERACTING GENES
  • What are alleles?

    different VERSIONS of genes. You have 2 copies of every gene in your body-one on each chromosome in a pair
  • What does it mean if an organism is Homozygous?
    If its 2 alleles for a particular gene are the same.

    E.g BB is Homozygous, Bb is heterozygous
  • What does it mean if an organism is Heterozygous?
    If its 2 alleles for a particular gene are different.

    e.g Bb is heterozygous , BB is homozygous dominant, bb homozygous recessive
  • If two alleles are different (heterozygous), which characteristics will be expressed?
    In heterozygous individuals the dominant characteristic will always be expressed/show up in the phenotype/characteristic.See an expert-written answer!We have an expert-written solution to this problem!
  • What is a genotype?
    The combination of alleles you have e.g- BB Bb etc
  • What is a phenotype?

    Visible characteristics of an organism, due to its genotypes' interaction with the environment

    eg- eye colour/hair length/features
  • A person who is heterozygous for brown eyes (Bb) has children with a person who has blue eyes (bb). What percentage chance will each child have to get blue eyes?
    50%
  • How do you interpret a family tree diagram/pedigree diagram?
    square-male
    circle-female
    coloured square/circle-affected
    blank square/circle-unaffected
    half coloured square/circle-carriers
  • What is cystic fibrosis?
    It is a genetic disorder of the cell membranes. Causes thick, sticky mucus to build up in air passages and pancreas.
  • Cause of cystic fibrosis?
    Caused by a Recessive Allele -'f'
    Alleles-'Ff'-unaffected but is a carrier
    Alleles- 'ff'- has cystic fibrosis
  • What is Polydactyly + cause

    A genetic disorder where a baby is born with extra fingers or toes.
    Cause:Dominant Allele- 'D'

    'Dd' has Polydactyly
    'dd' unaffected
  • Why can't you have carriers of Polydactyly?
    It is caused by a dominant allele. If you get one copy of the allele the phenotype will be expressed.
  • What is the chance of someone not being born with Polydactyly if both parent are heterozygous (Dd) for the disease.
    25%
  • How can genetic disorders be detected?
    EMBRYONIC SCREENING
    IVF -before implantation-cell can be removed from embryo to analyse genes.
    Embryos with defective alleles/genes destroyed.
  • Embryonic screening pros

    1-helps to stop suffering
    2-There are laws to stop it going too far-parents can't select sex of baby.
    3-Treatment for genetic disorders costs NHS/tax payers money
  • What is Variation ?
    inherited differences in Organisms caused by genetics or environmental factors
  • How can genes and environmental factors affect variation ?
    Genes-differences in the genotype
    Environment-e.g.plant-growth controlled by food/light/water etc
  • What are mutations ?

    Changes to the sequence of bases in DNA. Mutations include substitutions, deletions and additions.