Cards (58)

    • What is meiosis?
      Form of cell division in the formation of gametes
      Chromosome number is halved
      Involves two divisions
    • What happens during the first stage of meiosis?
      Chromosome pairs line up along cell equator
      The pair of chromosomes are separated and move to opposite poles of the cell
      Chromosome number is halved
    • What happens during the second stage of meiosis?
      Chromosome line up along the cell equator
      The chromatids are separated and move to opposite poles of the cell
      Four unique haploid gametes are produced
    • What is the advantage of sexual reproduction?
      it creates genetic variation in offspring increasing the probability of a species surviving environmental changes
    • Describe the disadvantages of sexual reproduction?
      Two parents required
      More time and energy required
    • Describe the advantages of asexual reproduction
      Only one parent
      Lots of offspring produced in a short time
      Requires less energy
      No mate needed
    • What is the disadvantage of asexual reproduction
      No genetic variation
    • What is a chromosome?
      Molecule of DNA that carries genetic information in the formation of genes
    • Define gene
      A small section of DNA that codes for something
    • What are alleles?
      Different versions of the same gene
    • What is the genotype?
      The genes present for a trait
    • What is the phenotype?
      The visible characteristics
    • What is sexual reproduction?
      Involves the production of gametes by meiosis.
      A gamete from each parent fuses to form a zygote.
      Genetic information from each gamete is mixed so the resulting zygote is unique.
    • What are gametes?
      Sex cells
      Haploid
    • What must occur prior to meiosis?
      Interphase - copies of genetic information are made during this process
    • Describe fertilization and its resulting outcome
      Gametes join together to restore the normal number of chromosomes and the new cell divides by mitosis.
      As the embryo develops , cells differentiate
    • What is asexual reproduction?
      Involves mitosis
      Produces genetically identical offspring known as daughter cells
    • Describe the circumstances in which malarial parasites reproduce sexually and asexually
      Sexual reproduction in the mosquito
      Asexual reproduction in the human host
    • Describe the circumstances in which fungi reproduce sexually and asexually
      Asexual reproduction by spores
      Sexual reproduction to give variation
    • Describe the circumstances in which plants reproduce sexually and asexually
      Sexual reproduction to produce seeds.
      Asexual reproduction by runners
    • What is DNA?
      A double stranded polymer of nucleotides , wound to form a double helix.
      The genetic material of the cells found in its nucleus
    • Define genome
      The entire genetic material of an organism
    • Why is understanding the human genome important?
      Searching for genes linked to different types of disease.
      Understanding and treating inherited disorders.
      Tracing human migration patterns from the past.
    • How many chromosomes do human body cells have?
      46
    • How many chromosomes do human gametes have?
      23
    • What are the monomers of DNA?
      Nucleotides
    • What are DNA nucleotides made up of?
      Common sugar
      Phosphate group
      One of the four bases
    • State the full names of the four bases
      Adenine
      Thymine
      Cytosine
      Guanine
    • Describe how nucleotides interact to form a molecule of DNA
      Sugar and phosphate molecules join to form a sugar-phosphate backbone in each DNA strand.
      Base connected to each sugar.
      Complementary base pairs joined by weak hydrogen bonds.
    • Explain how a gene codes for a protein
      A sequence of three bases in a gene forms a triplet.
      Each triplet codes for an amino acid.
      The order of amino acids determines the structure and function of the protein
    • Why is the folding of amino acids important in proteins such as enzymes?
      The folding of amino acids determines the shape of the active site which must be highly specific to the shape of its substrate
    • What is protein synthesis?
      The formation of a protein from a gene.
    • What are the two stages of protein synthesis?
      Transcription
      Translation
    • What does transcription involve?
      The formation of mRNA from a DNA template
    • Outline transcription
      DNA double helix unwinds.
      RNA polymerase binds to a specific base sequence of non coding DNA in front of a gene and moves along the DNA strand.
      RNA polymerase joins free RNA nucleotides to complementary bases on the coding DNA strand.
      mRNA formation complete. mRNA detaches and leaves the nucleus
    • What does translation involve?
      A ribosome joins amino acids in a specific order dictated by mRNA to form a protein
    • Outline translation
      mRNA attaches to a ribosome.
      Ribosome reads the mRNA bases in triplets. Each triplet codes for one amino acid which is brought to the ribosome by a tRNA molecule l.
      A polypeptide chain is formed from the sequence of amino acids which join together.
    • What is a mutation?
      A random change in the base sequence of DNA which results mostly in no change to the protein coded for or genetic variants of the protein. Mutations occur continuously.
    • Describe the effect of a gene mutation in coding DNA
      If a mutation changes the amino acid sequence , protein structure and function may change.
      If a mutation does not change amino acid sequence , there is no effect on protein structure or function.
    • What is non coding DNA?
      DNA which does not code for a protein but instead controls gene expression