6.1 Reproduction and Genetics

• What is sexual reproduction?

  Reproduction involving the fusing of gametes (Two parents)
• What is Asexual reproduction?

  Reproduction that does not involve gametes (One parent)
• What are example of asexual reproduction?

  • Budding in yeast (mitosis)
  • Binary fission (bacteria)
• What are the advantages of sexual reproduction?

  • Genetic variation
  • if the environment changes offspring is able to survive alone
  • natural selection can be speeded up by humans to increase food production (selective breeding)
• What are the disadvantages of sexual reproduction?

  • Natural selection
  • Time consuming
  • Harder to mate
• What are advantages of asexual reproduction?

  • Energy and time-efficient
  • only one parent is needed
  • many identical offspring can be produced in difficult situations
• What are the disadvantages of asexual reproduction?

  No genetic variation meaning its harder for offspring to survive in a different environment without parent
• What will the gender of the offspring be if produced asexually?

  Female (only they can reproduce asexually EXCEPT seahorses)
• Why does sexual reproduction result in variation?

  • offspring generates genetic information from both parents when gametes fuse
  • gametes are produced by meiosis
  • selection of genetic info from gametes is random
• Examples of organisms able to reproduce both sexually and asexually

  • Malarial parasites - sexual in human host asexual in mosquito
  • Fungi - asexually by spores sexually to give variation
  • Plants - seeds sexually asexually by runners (strawberry, daffodils)
• How many chromosomes do (most) human cells contain?

  23 pairs, 46 chromosomes
• What are some exceptions in the number of chromosomes in humans?


  • Gametes - 23
  • Down syndrome - 47
  • Mature red blood cells
• How many daughter cells are produced by mitosis?

  2
• How many daughter cells are produced by Meiosis?

  4
• When a cell divides to form gametes:

  • copies of genetic info are made
  • cell divides twice to form 4 gametes
  • all gametes are genetically different
• What are chromosomes? 


  A thin strand of DNA containing sections of genes
• What is a diploid cell?

  two sets of chromosomes (46, 23 pairs)
• What is a haploid cell?

  Half ( 1 set 23 total)
• How does genetic variation happen during the meiosis process?

  DNA crossover
• What happens during fertilisation?

  1. sperm and egg nuclei fuse
  2. 23 chromosomes from each cell- 46 total
  3. Zygote - embryo - feotus
• How does a zygote divide?

  Mitosis
• Why is there genetic variation in gametes?

  each gamete produced is genetically different from each other. Gametes contain random mixtures of the original chromosomes
• What is DNA?


  A polymer that contains the genetic material in the nucleus of a cell
• What is the DNA structure?

  Double helix
• What are the repeating units of DNA called?

  Nucleotide
• What type of polymer is DNA?

  polynucleotide
• What does the nucleotide?

  1. sugar
  2. phosphate
  3. base (ATCG)
• What is a Gene?

  A small section of DNA which determines an inherited characteristic
• What does a Gene code for?

  The particular sequence of amino acids, to make a specific protein
• What is the Genome?

  The entire genetic material of an organism
• What is the importance of understanding the human genome?

  • search for genes linked to different types of disease
  • understanding and treatment of inherited disorders
  • use in tracing human migration patterns from the past
• What was the human genome project?

  • designed to sequence the entire human genome
• What does a group of three bases code for?

  one amino acid
• What does the order of bases in the DNA control?

  The order in which the amino acid lines up to produce a particular protein
• Why does the amino acid sequence of a protein matter?

  • different sequences produce different proteins
  • sequence complimentary to bases
• If DNA can't leave the nucleus, how can genes control protein synthesis at ribosomes found in the cytoplasm?

  Genes in the DNA produce a template for the protein - mRNA

  The mRNA template reflects the sequence of bases in the DNA, but is small enough to leave the nucleus through the pores in the nucleus membrane
• What is the protein synthesis method?

  1. DNA unravels due to an enzyme

  2. Gene produces a template (mRNA)

  3. mRNA template is small enough to leave through the pores in the nuclear membrane

  4. Template latches onto the ribosomes, reads the mRNA (tripletcodon)

  5. Carrier molecules attach to template in order given by DNA (complimentary bases)

  6. More carrier molecules join forming a chain (protein)
• What happens when the protein chain is completed?

  Molecule folds up to become a unique shape

  • enables protein to do job as enzymes, hormones or forming structures in the body such as collagen
• What does it mean if a gene is 'expressed'?

  when a gene codes for a protein that is synthesised in a cell
• What is a non-coding DNA and what are its functions?

  • DNA that does not code for proteins
  • switches genes on and off (effect how a gene is expressed)