Chapter 12: Reproduction

• What is sexual reproduction?

  joining (fusion) of male and female gametes
• What type of cell division is involved in sexual reproduction?

  meiosis
• How many parents are involved in sexual reproduction?

  2
• How many parents are involved in asexual reproduction?

  1
• What type of cell division is involved in asexual reproduction?

  mitosis
• What is meiosis?

  cell division that produces four daughter cells (gametes), each with a single set of chromosomes
• What are the male and female sex chromosomes in humans?

  • XX – female

  • XY – male
• What are the male and female gametes in flowering plants?

  • pollen – male gamete

  • ovule/egg – female gamete
• What is the genetic material in cells called?

  DNA
• What is the structure of DNA?

  two complementary strands forming a double helix
• What is a gene?

  small section of DNA that codes for a particular amino acid sequence, to make a specific protein
• What are alleles?

  different forms of the same gene
• What is a recessive allele?

  allele that needs to be present twice to be expressed
• What is a dominant allele?

  allele that is always expressed, even if only one copy is present
• What is a genome?

  the entire genetic material of an organism
• Define the term homozygous.

  two of the same alleles present in an organism
• Define the term heterozygous.

  two different alleles present in an organism
• What type of allele causes polydactyly?

  dominant allele
• What type of allele causes cystic fibrosis?

  recessive allele
• How many chromosomes do normal human body cells have?

  23 pairs (46)
• Why is studying the human genome important? (3)

  • search for genes linked to certain diseases

  • understanding and treatment of inherited disorders

  • tracing past human migration
• Does asexual reproduction have a fusion of gametes?

  no
• What type of offspring does sexual reproduction produce?

  non-identical off spring that are genetically different to parents
• What type of offspring does asexual reproduction produce?

  off spring that are genetically identical to parent (clones)
• What does sexual reproduction result in?

  wide variation within off spring and species
• What does asexual reproduction result in?

  no mixing of genetic information
• How do Meiosis & Fertilisation make new organisms? 


  Meiosis halves the number of chromosomes in gametes, and fertilisation (joining of two gametes) restores the full number of chromosomes.

  The fertilised cell divides by mitosis, producing more cells. As the embryo develops, the cells differentiate.
• Familiarise Yourself with Meiosis:

  
• What is DNA contained in?

  Structures called chromosomes
• What is cytokinesis?

  The dividing of the cell in the last stage of mitosis
• What is Polydactyl?

  extra fingers or toes
• What is Cystic Fibrosis?

  a disorder of cell membranes
• What is a phenotype?

  physical expression of the genotype – the characteristic shown
• What is a genetic cross?

  when you consider the off spring that might result from two known parents.
• What are Punnett squares used for?

  used to predict the outcome of a genetic cross, for both the genotypes the off spring might have and their phenotypes.
• What is the offspring genotype & phenotype of:

  genotype: 100% Bb

  phenotype: all black fur (B is dominant)

  
• What is the probability of being male or female in humans?

  always 50%
• What are the sex chromosomes?

  carry the genetic information that determines the sex of an individual
• What are carriers?

  individuals who are heterozygous for a recessive allele linked to a genetic disorder. They are not affected themselves but they can pass on the affected allele to their offspring.
• What is genetic engineering?

  the process by which scientists can manipulate and change the genotype of an organism.