DNA and inheritance

Cards (86)

  • DNA
    Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.
  • Organism
    Living entity, eg animals, plants or micro-organisms.
  • Nucleus
    The nucleus controls what happens inside the cell. Chromosomes are structures found in the nucleus of most cells.
  • Chromosome
    The structure made of DNA that codes for all the characteristics of an organism.
  • Gene
    The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production.
  • Allele
    Different versions of the same gene.
  • Genotype
    The alleles that an organism has for a particular characteristic, usually written as letters.
  • Phenotype
    The visible characteristics of an organism which occur as a result of its genes.
  • Dominant allele
    An allele that always expresses itself whether it is partnered by a recessive allele or by another like itself.
  • Recessive allele
    Describes the variant of a gene for a particular characteristic which is masked or suppressed in the presence of the dominant variant.
  • Homozygous
    This describes a genotype in which the two alleles for the characteristic are identical.
  • Heterozygous
    This describes a genotype in which the two alleles for a particular characteristic are different.
  • DNA
    Large and complex molecule that carries the genetic code that determines the characteristics of a living organism
  • Gene
    Section of DNA that codes for a specific protein, the unit of heredity
  • Chromosome
    Long threads of DNA, each made up of many genes, found in the nucleus of most cells
  • James Watson and Francis Crick worked out the structure of DNA in 1953
  • Double helix
    The shape of the DNA molecule, with two strands twisted together in a spiral
  • Base pairs
    Paired chemicals between the two strands of DNA, including thymine, adenine, guanine, and cytosine
  • Complementary base pairing
    Thymine pairs with adenine, guanine pairs with cytosine
  • Allele
    Different forms of a gene, e.g. for eye colour
  • Triplet code
    Sequence of three bases that determines a specific amino acid in a protein
  • DNA
    Hereditary molecule responsible for its function
  • Genetic cross

    Examination and showing of possible offspring combinations using a Punnett square
  • Carrying out a genetic cross
    1. Determine probability of offspring combinations
    2. Calculate probability of offspring combinations
  • Monohybrid cross
    Genetic cross of single gene combinations
  • Punnett square
    Shows possible offspring combinations and allows calculation of probability of these combinations
  • Allele
    Alternative form of a gene
  • Dominant allele

    Allele that is expressed when present
  • Recessive allele

    Allele that is only expressed when two copies are present
  • Genotype
    Genetic makeup of an organism
  • Phenotype
    Physical characteristics of an organism
  • Homozygous
    Having two identical alleles for a particular trait
  • Heterozygous
    Having two different alleles for a particular trait
  • Selfing

    Pollen from one flower landing on the stigma of the same flower
  • Backcross
    Cross between an F1 individual and one of its parents
  • Most phenotypes are controlled by multiple genes
  • Probability
    Extent to which something is likely to be the case
  • Allele combinations created during fertilisation are a random process
  • How to construct Punnett squares
    1. Determine the parental genotypes
    2. Split the alleles for each parental type and add them into your Punnett square around the edges
    3. Work out the new possible genetic combinations inside the Punnett square
    4. Use this to answer the question
  • Punnett square
    A diagram used to predict the possible genotypes of offspring