Variation Flashcards
What is polygenic inheritance? 5
- Phenotypes affected by multiple genes
- At more than one locus
- These genes interact with each other
- To control the single characteristic
- Phenotype is also affected by environment
What type of variation does polygenic inheritance show?
Continuous
Describe continuous variation
Individuals in a population vary within a range with no distinct categories
Give 3 examples of continuous variation
- Height
- Mass
- Skin colour
What is discontinuous variation?
Two or more distinct categories
Give an example of discontinuous variation
Blood type
What does variation in genotype result in?
Variation in phenotype
Define monogenic inheritance
Characteristic controlled by one gene
What type of variation does monogenic inheritance show?
Discontinuous
What causes genetic variation?
- Mutations
- Random mating
- Independant assortment and crossing over of chromatids in meiosis
What factors cause cancerous cells? 3
- UV light
- Carcinogens in cigarettes
- X Rays
How does cancer affect the cell cycle? 4
- Shorter interphase
- Faster cell cycle
- Cell divides uncontrollably
- Cells don’t specialise
Define intraspecific variation
Individuals of same species have the same genes but different alleles causing variation in phenotype
