Reproduction

• How many parents is sexual reproduction?

  2
• What is produced by meiosis in sexual reproduction?

  Gametes (Sperm and egg or pollen and egg)
• What is produced by meiosis in asexual reproduction?

  Cells divide by mitosis
• What does genes do from each parent in Sexual reproduction?

  Offspring inherit genes from each parent
• What does genes do from each parent in Asexual reproduction?

  produced genetically identical offspring
• What does Sexual reproduction produce?

  Genetic variation
• What does genetic variation do in sexual reproduction?

  Increased species long term survival chances
• What does Asexual reproduction not produce?

  Genetic variation - for growth and repair of tissues
• Where does Meiosis occur?

  In the reproductive organs of an organism
• What does Meiosis produce?

  Genetically different gametes (sperm and egg in animals) - each produced is haploid (2 cell divisions in meiosis, resulting in 4 gametes)
• When does fertilisation occur?

  when 2 gametes meet and join - The cell produced now has a full set of chromosomes (diploid)
• Why does fertilisation occur when 2 gametes meet and join?

  2 parents has contributed DNA to the offspring, this results in genetic variation
• What happens with fertilised cells?

  Divide by mitosis. This produces 2 genetically identical daughter cells
• What is mitosis?

  The division of one cell into two. Chromosomes are duplicated to ensure that each new cell is genetically identical - mitosis is used for growth and repair of tissues
• What does genome of an organism contain?

  The entire Genetic material.
• How many base pairs does the human genome contain?

  Over 3 million
• What does sequencing the human gene allow?

  to try understand how genetic linked diseases (such as cystic fibrosis, sickle cell disease and some cancers) are caused and how we can treat/prevent them and human evolution
• What is meiosis?

  2 stage cell division, resulting in haploid daughter cell (gametes)
• What’s a diploid?

  A cell containing 2 complete sets of chromosomes, 1 from each parent
• What’s a haploid?

  A cell containing a single set of unpaired chromosomes (half the amount)
• What is a gene?

  a short section of DNA which codes for a particular protein
• What is a chromosome?

  A cross shaped structure found in the nucleus- made of DNA - 46 in human body cells (diploid) and 23 in gametes (haploid). 1 pair determines sex - XX female - XY male different forms of each gene
• What is an allele?

  Different forms of the same gene
• What is DNA made up of?

  2 strands locked together by bases. The shape is a double helix
• What are most characteristics controlled by?

  several genes interacting but some are controlled by 1 gene alone
• What is a Homozygous?

  2 of the same allele for a characteristics (Eg - HH or hh)
• What is a Heterozygous?

  2 different alleles for a characteristics (Eg, hh)
• What is a genotype?

  The combination of alleles an individual has for a particular characteristic (Eg, HH or Hh or hh)
• What is a Phenotype?

  The characteristic expressed in an individual due to their genotype (Eg, Hh produces red flowers, hh produces blue flowers)
• What are Dominant alleles?

  Alleles that are always expressed when present even on 1 of the chromosomes - They are represented by capital letters
• What are Recessive alleles?

  Are only expressed if there are 2 of the same - They are represented by lower case letter
• What are the examples of genetic disorders?

  • Polydactyly (Dominant disorder)
  • Cystic Fibrosis (Recessive disorder)
• What is variation?

  The name given to differentices between inviduals of the same species
• What is variation due to?

  Genetic or environmental causes - often extensive variation within species
• Who was the Evolution by Natural Selection exposed by?

  Charles Darwin
• What do organisms within a species show? - Evolution by Natural Selection

  A wide ranger of variation due to their genes and their environment
• What can New variants/ features with a species arise?

  Through mutation (changes in DNA code) - often can be harmful but sometimes can beneficial.
• What happens If new variants within a species can arise through mutations are beneficial?

  They provide a survival advantage to an individual, which means they will have a good chance at being passed on to the next generation
• What does natural selection occur through?

  • Individuals within a species show genetic variation.
  • The individuals with the characteristics that means they are better adapted to their environment will survive
  • The allele that have enabled the organism to survive are useful and will then be passed onto the next generation. This process occurs over a large number of generations