Sources of Variation
Learning intention: To develop an understanding of genetic variation
Success criteria: Discuss how meiosis & mutation causes variation in gene pools
Embedded Files
Hei Mahi: What do you already know?
Hei Mahi: What do you already know?
ACTIVITY: Use the instructions below to build a model of a DNA molecule.
ACTIVITY: Use the instructions below to build a model of a DNA molecule.
What causes variation?
What causes variation?
Different adaptations to the particular environment through:
Mutation
Meiosis
Inheritance
Mutation
Mutation
A mutation is a permanent change to the base sequence of DNA.
Mutations are random.
Mutations are the only source of new alleles.
These new alleles create new phenotypes that evolution can act on.
Mutations can be helpful, harmful or neutral.
Causes of Mutations:
Spontaneous - are natural errors where the main cause is errors during DNA replication
Induced - are caused by environmental factors called mutagens which damage the genetic material in the nucleus
Somatic and Gametic Mutations:
Somatic mutations occur in body cells and are not passed on to the next generation (do not enter the gene pool)
Gametic mutations occur in sex cells or gametes and can be passed on to the next generation (and enter the gene pool)
If the mutations is beneficial it is likely to increase in allele frequency in the gene pool
If the mutation is harmful it is likely to be removed from the gene pool
If the mutation is neutral it is likely that it will stay hidden in the gene pool unless conditions change
Types of Mutations:
ACTIVITY: Watch the video and complete the worksheet.
ACTIVITY: Watch the video and complete the worksheet.
Biozone Activities
Biozone Activities
E62 - The Role of Mutations in Populations, pg. 88
E63 - Mutations Can Produce New Alleles, pg. 89
E64 - Somatic and Gametic Mutations, pg. 90
Meiosis
Meiosis
Meiosis is cell division that produces new gametes (sex cells).
In animals, these are the sperm and egg or ova.
In plants, these are the pollen and egg or ova.
Meisosis occurs in the reproductive organs of plants or animals.
Three things occur during meiosis to cause variation:
Independent assortment
Crossing over
Segregation
You need to be able to describe each of these and relate them to the amount of variation that is caused.
ACTIVITY: Explain each of the three processes occurring during meiosis that lead to variation
ACTIVITY: Explain each of the three processes occurring during meiosis that lead to variation
Draw and explain, or model and annotate, each of the following:
Complete summary of meiosis.
You can use the resources linked above or find your own information through research.
Biozone Activities
Biozone Activities
E65 - Meiosis, pg. 91
E66 - Meiosis and Variation, pp. 92 -93
E67 - Modelling Meiosis, pp. 94 - 95
Exit Card
Exit Card
Complete the worksheet below on paper and hand it to your teacher at the end of the lesson.
Additional Opportunities for Learning/ Optional
Additional Opportunities for Learning/ Optional
Gene Expression
Gene Expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product, ie. phenotype.
The expression outcome of mutation may change as the environment changes.
A mutation that was beneficial could become harmful etc.
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