Inheritance

  1. What is a chromosome?
    A long length of DNA along which genes are spaced
  2. What is a gene?
    A length of DNA that codes for a protein
  3. What is a chromatid?
    Two chromosome replicants held together by a centromere
  4. What is a homologous pair?
    • A pair of chromosomes in a diploid cell containing the same genes but possibly different alleles
    • Form bivalents during meiosis
  5. What is an allele?
    An alternate form of a gene created by mutation
  6. What is the locus?
    The position a gene occupies on a chromosome
  7. What is the genotype?
    The alleles present in a cell
  8. What is the phenotype
    The observable characteristics due to the expression of the alleles present in a cell
  9. What is meant by the term: Heterozygous
    Different alleles on the chromosome pair (Bb)
  10. What is meant by the term: Homozygous
    The same alleles on the chromosome pair (BB)
  11. What is meant by the term: Dominant
    • An allele that is expressed even if heterozygous 
    • Produces a functional protein
  12. What is meant by the term: Recessive?
    • An allele that is expressed only if dominant 
    • Caused by a mutation resulting in the allele producing a non-functional protein
  13. What is meant by the term: Co-dominant?
    • Both alleles are expressed in the phenotype if they are both present.
    • They both produce functional, but different, proteins
  14. What does a monohybrid cross involve?
    A single gene with more than one allele
  15. What does a sex linked cross involve?
    • A gene situated on a sex chromosome
    • This means that males will express the phenotype differently to females because males have only one X chromosome and therefore only need one recessive allele for it to be expressed
Author
camturnbull
ID
255789
Card Set
Inheritance
Description
AQA BIOL4 Inheritance
Updated