Genetic Variation and its Control

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  • Created by: Hope
  • Created on: 02-06-13 18:20

Why Organisms are different

Offspring resmeble their parents because they conain genetic information passed onto them by their parents.

Chromosomes and genes

  • Chromosomes, found in the cell necleus contain many genes. 
  • A gene is a section of DNA, which carries coding for a particular protien. 
  • Different genes control the development of different characterisitcs of an organism. 
  • Many genes are needed to carry all the genetic information for a whole organism.

Number of genes and chromosomes varies from species to species. Humans have 46 choromoes that carry around 30,000 genes in each cell. 

Genetic Factors

Although individuals of a species look similar, they are not usually idenitical these differences are calling variation. 

Inherited Variation

Variation due to genetic causes is inherited variation...

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Why Organisms are different 2

...For example, children usually look a little like their father, and a little like their mother. But will not look identical to either of their parents. As they get half of their inherited factors from each parent. 

  • Eye colour 
  • Hair colour
  • Skin colour
  • Lobe/Lobeless ear

Enviromental Factors

Characteristics of animal and plant species can be affected by such factors...

  • Climate 
  • Diet
  • Accidents
  • Culture 
  • Lifestyle

E.g- Eat lots you will become heavier/Eat less skinnier, A plant in the shade will grow taller to get light

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Why Organisms are different 3

  • Your language 
  • Your religion
  • Flower colour in hydrangeas (as these plants produce blue flowers in acidic soil and pink flowers in alkaline soil)

Combined genetic and enviromental factors

Some features vary due to a combination of the two factors.

E.g Identical twins inherit exactly the same genetic information from their parents. But if you take a pair of twins and twin A has eaten more than twin B, twin A is likely to end up heavier.

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