inheritance, variation and evolution

    Cards (84)

    • DNA
      The chemical that all of the genetic material in a cell is made up from
    • DNA
      • It contains coded information - the instructions to put an organism together and make it work
      • It's found in the nucleus of animal and plant cells, in really long structures called chromosomes
    • Chromosome
      Long molecules of DNA
    • Gene
      A small section of DNA found on a chromosome that codes for a particular sequence of amino acids which are put together to make a specific protein
    • Genome
      The entire set of genetic material in an organism
    • Genome
      • Scientists have worked out the complete human genome
      • Understanding the human genome is an important tool for science and medicine - it allows identification of genes linked to diseases, and tracing the migration of human populations
    • Nucleotide
      The repeating units that DNA strands are made up of, consisting of a phosphate group, a sugar, and one of four bases (A, T, C, G)
    • DNA structure
      • The bases always pair up in a complementary way (A with T, C with G)
      • The order of bases determines the order of amino acids in proteins
    • Protein synthesis
      1. DNA in the nucleus is transcribed into mRNA
      2. mRNA carries the code to ribosomes in the cytoplasm
      3. Ribosomes assemble the amino acids into proteins according to the mRNA code
    • Protein
      Chains of amino acids that fold into unique shapes to perform specific functions
    • Protein functions
      • Enzymes - biological catalysts
      • Hormones - carry messages around the body
      • Structural proteins - provide physical strength
    • Mutation
      A random change in an organism's DNA sequence
    • Mutations
      • They can sometimes be inherited
      • They can change the sequence of amino acids in a protein, affecting its shape and function
    • Types of mutation
      • Insertions - adding a new base
      • Deletions - removing a base
      • Substitutions - changing one base for another
    • Sexual reproduction
      Genetic information from two parents is combined to produce genetically different offspring
    • Sexual reproduction
      • Gametes (sperm and egg) are produced by meiosis, which halves the chromosome number
      • Fusion of gametes restores the full chromosome number in the offspring
    • Asexual reproduction
      Reproduction from a single parent to produce genetically identical offspring
    • Asexual reproduction
      • Occurs by mitosis, where the parent cell divides to form two genetically identical daughter cells
      • Produces clones of the parent
    • Advantages of sexual reproduction
      • Offspring have a mixture of genes from both parents, increasing variation and chance of survival
      • Natural selection can act on the variation to improve adaptations
    • Advantages of asexual reproduction
      • Only needs one parent
      • Uses less energy than sexual reproduction
      • Faster than sexual reproduction
      • Can produce many identical offspring
    • Organisms that can reproduce both sexually and asexually
      • Malaria parasite
      • Fungi
      • Many plant species
    • Organisms of the same species have differences
    • Variation
      Differences between organisms of the same species
    • Genes
      • They are the codes inside your cells that control how you develop
      • They are passed on in sex cells (the ones that fuse during reproduction)
      • Most animals and quite a lot of plants get their genes from two parents, so the combining of genes causes variation (except for identical twins)
    • Characteristics defined by single genes
      • Eye colour
      • Blood group
      • Baldness
    • Environment
      Includes the surrounding conditions that influence the development of organisms
    • Characteristics are influenced by both genes and the environment
    • Environmental variation
      • Plant growth in plenty of sunlight vs plant growth in darkness
      • Suntan
    • Most characteristics are due to a combination of genes and the environment
    • Genetic variation
      Characteristics that are inherited and passed on in genes
    • Genetic variation

      1. Genes are the codes inside cells that control how an organism develops
      2. Genes are passed on in sexual reproduction
      3. Most animals and many plants reproduce sexually to combine genes from two parents
      4. Offspring are genetically identical except for identical twins
    • Characteristics
      • Some are defined by genes (e.g. eye colour, blood group, fingerprints)
      • Others are influenced by the environment
    • Environmental variation
      Differences between members of the same species due to environmental factors
    • Environmental variation
      • A plant grown in plenty of sunlight would be tall and green, but the same plant grown in darkness would grow tall and spindly and have pale leaves
    • Environmental variation covers many differences - from being attacked by pests, to getting suntan, to having no hair (never happened to me yet though)
    • Most characteristics
      • Determined by a mixture of genetic and environmental factors (e.g. body weight, height, skin colour, academic or athletic prowess)
    • Mutations
      Changes to the sequence of bases in DNA that can lead to changes in the protein that a gene codes for
    • Most mutations have no effect on the structure of the gene, so most mutations have no effect on the organism's phenotype
    • If a new phenotype makes an individual more suited to the environment

      It can become common throughout the species relatively quickly by natural selection
    • You can't blame all of your faults on your parents - the environment usually plays a role too
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