Genes & variation

• What is the genetic material of an organism?

  The chromosome
• Where is genetic material stored in a cell?

  In the nucleus
• What is a chromosome made of?

  A long molecule of DNA
• What is a gene?

  A short section of a chromosome
• What does each gene code for?

  A specific characteristic
• How does the order of bases in a gene affect proteins?

  It decides what protein is made
• What do different proteins control?

  The development of different characteristics
• What are different versions of a gene called?

  Alleles or variants
• What is variation within a species?

  Differences among organisms of the same species
• How can you illustrate variation among dog breeds?

  Different breeds look different from each other
• What is genetic variation caused by?

  Differences in genotype
• How does genotype affect phenotype?

  It affects the characteristics shown
• How are genes inherited?

  Passed down from parents
• What causes environmental variation?

  The conditions in which organisms live
• How does sunlight affect plant growth?

  It can lead to healthy, green growth
• What happens to a plant grown in darkness?

  It grows tall and spindly with yellow leaves
• What is the relationship between genes and environment in variation?

  Most variation is caused by both factors
• What determines the maximum height of an organism?

  Its genes
• What influences whether an organism reaches its maximum height?

  The environment, like food availability
• What is discontinuous variation?

  Variation with separate groups, no in-betweens
• What is continuous variation?

  Variation with a range of values
• How does continuous variation differ from discontinuous variation?

  Continuous variation has a range, discontinuous does not
• What are the types of variation?

  • Genetic Variation
  • Environmental Variation
  • Discontinuous Variation
  • Continuous Variation
• What are the characteristics of discontinuous and continuous variation?

  Discontinuous Variation:

  • Separate groups
  • No in-betweens

  
  

  Continuous Variation:

  • Range of values
  • Many possible heights
• What is variation in organisms primarily due to?

  Differences in their DNA
• What are the two types of variation mentioned?

  Discontinuous and Continuous variation
• What is discontinuous variation?

  • Two or more separate groups
  • Each individual belongs to one group
  • Example: Blood groups (A, B, AB, O)
• What are the characteristics of discontinuous variation?

  Caused by one gene, not environment
• What is continuous variation?

  • Individuals vary within a range
  • No separate groups
  • Examples: Height and mass of organisms
• What are the characteristics of continuous variation?

  Caused by multiple genes or genes and environment
• What do mutations create when they happen within a gene?

  A genetic variant
• What is the effect of most mutations on an organism's phenotype?

  They don’t have any effect
• How can some mutations affect an individual's phenotype?

  They can change traits like fur color
• What are mutations?

  Changes to the order of bases in DNA
• How often do single mutations have a big effect on phenotype?

  Very rarely
• What should you understand about continuous and discontinuous variation?

  • Continuous variation has no separate groups
  • Discontinuous variation has distinct groups
  • Mutations can alter phenotype
  • Most mutations do not affect phenotype
• What is the question posed at the end of the study material?

  What is meant by a mutation?