Inheritance

Cards (24)

  • Sexual reproduction
    • Involving 2 parents and fusion of gametes and mixing of chromosomes.
    • The offspring contains a mixture of genes and is genetically different to either parents.
    • Occurs by meiosis
  • Fertilisation
    • The fusion of the nucleus of a male gamete with the nucleus of a female gamete.
    • When the gametes combine, they merge the two sets to form 46 chromosomes. Referred as a diploid.
    • Gametes are made by meiosis
  • Asexual reproduction
    • Involves one parent and there is no fusion of gametes. Because there is no mixing of genetic information.
    • The offspring is genetically identical to the parent.
    • Occurs by mitosis
  • The genome
    • Is the entire set of genetic material of an organism.
  • Genes
    • A small section of DNA on a chromosome that codes for a particular sequence of DNA.
  • Chromosomes
    • Two long strands of DNA coiled up to form a chromosome.
    • Human body cells contain 23 pairs of chromosomes.
  • DNA
    • A double helix polymer, made up of two strands forming a twisted ladder shape.
  • Gene identification
    • Identifying genes linked to different disorders.
  • Mutations
    • A mutation is a permanent change in the nucleotide of DNA.
  • Alleles
    • Different forms of a particular gene.
    • Peoples characteristics are determined by the alleles.
    • They are either dominant or recessive.
  • Dominant Allele
    • Is always expressed, regardless of the other allele.
    • It only needs one copy to be present.
  • Recessive allele
    • Only expressed if the other allele is also recessive.
    • Represented by a lower case letter e.g bb
    • Needs two copies for it to be present
  • Polydactyly
    • Is a disorder involving extra fingers or toes.
    • Caused by a dominant allele.
  • Recessive allele
    • Is caused by a recessive allele.
    • Is a disorder of the cell membrane, it causes mucus to build up in the lungs and digestive system.
  • Heterozygous
    If the two alleles of a particular gene are different.
  • Homozygous
    • If the two alleles of a particular gene are identical.
  • Embryonic screening
    • Is a form of genome screening.
    • Looking for genes that may make that person susceptible to genetic disorders.
  • Advantages of screening
    • Screening ensures the implanted embryos are healthy.
    • Prevent suffering
    • Financial saving, reduction in disorders that need to be treated.
  • Disadvantages of screening
    • Expensive
    • Ethics, the embryos that are of no use are destroyed which is considered as unethical and against religious views.
    • Parents become selective
  • A gamete
    • Reproductive cells e.g sperm cell
    • Haploid (23 chromosomes)
  • Meiosis
    • 2 Cell divisions
    • Before the cell divides, the genetic information is duplicated, forming two armed chromosomes.
    • After replication, the chromosomes arrange into pairs.
    • First division involved chromosomes lining up the centre of the cell.
    • The pairs are pulled apart so each new cell only have 1 copy of each chromosome.
    • Second division involves when the chromosomes line up again and cell divides.
    • Forming 4 gametes which are genetically different as the chromosomes get shuffled up.
  • Genotype
    • The combination of alleles that a person as for a particular trait.
  • Phenotype
    • The observable characteristics of an organism.
    • For example, eye colour
  • Sex determination
    • The human body cells has 23 pairs of chromosomes
    • 22 pairs of chromosomes control characteristics only, but one of the pairs carry the genes that determines the sex.