4.1 Meiosis - Sources of Genetic Variation (by Jennifer)

How is variation produced in a population?

Jennifer Oh (SL)

1Tuesday, 22 November 11

What is genetic variation?



Variation in alleles of genes




Occurs within and among populations




Occurs within and among populations

The “raw material” of natural selection


Sources of Genetic Variation


Sources of Genetic VariationMutations



Gene mutations



Gene mutations

Chromosome mutations



Gene mutations


Sexual Reproduction



Gene mutations


Sexual Reproduction

Recombination



Gene mutations


Sexual Reproduction

Recombination

Mate selection


Assessment StatementsThese are the assessment statements that deal with this topic:


Assessment StatementsThese are the assessment statements that deal with this topic:

4.1.2 Define gene, allele, and genome

4.1.3 Define gene mutation

4.2.1 State that meiosis is a reduction division of a diploid nucleus to form haploid nuclei

4.2.3Outline the process of meiosis, including pairing of

homologous chromosomes and crossing over, followed by two divisions, which results in four haploid cells

4.3.1Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus, homozygous, heterozygous, carrier

and test cross


Basic Vocabulary


Basic Vocabulary

Before diving into the details of genetic variation, here are some basic terms that you need to know for this topic.


Basic Vocabulary


From assessment statement 4.1.2


Basic Vocabulary


From assessment statement 4.1.2Gene, Allele, Genome


Basic Vocabulary



From assessment statement 4.3.1


Basic Vocabulary



From assessment statement 4.3.1Genotype, phenotype


4.1.2 Vocab


4.1.2 Vocab

Gene - a heritable factor that controls a specific characteristic


4.1.2 Vocab



4.1.2 Vocab



4.1.2 Vocab

Gene - a heritable factor that controls a specific characteristicAllele - one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of the gene


4.1.2 Vocab



4.1.2 Vocab



4.1.2 Vocab

Gene - a heritable factor that controls a specific characteristicAllele - one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of the geneGenome - the whole genetic information of an organism


4.3.1 Vocab


4.3.1 Vocab

Genotype - the alleles of an organism; determines the genetic potential


4.3.1 Vocab

Genotype - the alleles of an organism; determines the genetic potentialPhenotype - the characteristics of an organism


Mutation


Mutation

Mutations are the source of all new genetic information


Mutation

Mutations are the source of all new genetic informationNot always harmful, some are neutral or beneficial


Mutation

Mutations are the source of all new genetic informationNot always harmful, some are neutral or beneficialCan be accumulated over many generations


Mutation

Mutations are the source of all new genetic informationNot always harmful, some are neutral or beneficialCan be accumulated over many generationsGene mutation (4.1.3)


Mutation


Change in the base sequence of an allele


Mutation


Change in the base sequence of an alleleChromosome mutation


Mutation


Change in the base sequence of an alleleChromosome mutation

Pieces of chromosomes may be rearranged during meiosis


Mutation


Sexual Reproduction


Sexual ReproductionProvides rearrangement and shuffling of the genetic material into new combinations


Sexual ReproductionProvides rearrangement and shuffling of the genetic material into new combinationsCrossing over - Recombination



Pieces of chromosome are often exchanged with a chromosome’s homologue



Pieces of chromosome are often exchanged with a chromosome’s homologueIncreases shuffling of allele combinations




Mate Selection




Mate SelectionDifferent combinations of genes will come together in the offspring depending on which two parents mate together


Meiosis


Meiosis

Meiosis is a reduction division of a diploid nucleus to form haploid nuclei (4.2.1)


Meiosis

Meiosis is a reduction division of a diploid nucleus to form haploid nuclei (4.2.1)For this topic, the important part is: crossing over


Meiosis

Meiosis is a reduction division of a diploid nucleus to form haploid nuclei (4.2.1)For this topic, the important part is: crossing overAt Prophase I, the homologous chromosomes pair up (synapsis), and segments of the chromosome can be exchanged


Meiosis

Meiosis is a reduction division of a diploid nucleus to form haploid nuclei (4.2.1)For this topic, the important part is: crossing overAt Prophase I, the homologous chromosomes pair up (synapsis), and segments of the chromosome can be exchangedImportant source of variation for the gene pool of a population


Watch this video!

GREAT video lesson about genetic variation:http://www.khanacademy.org/video/variation-in-a-species?playlist=Biology


http://www.khanacademy.org/video/variation-in-a-species?playlist=Biology




i-Biology Link

4.1 Presentationhttp://i-biology.net/?s=4.1




http://i-biology.net/?s=4.1






More exercises

For more exercises on this topic, look at these pages from the Biozone workbook.

Mutations: p. 197 - 8Meiosis: p. 185 - 8Genetic Variation: p. 181 - 2


The End!15Tuesday, 22 November 11

4.1 Meiosis - Sources of Genetic Variation (by Jennifer)

Technology

gene locus

gene mutationstate

genetic potentialphenotype

genetic potentialtuesday

basic terms

new genetic informationnot

new genetic informationtuesday

heritable factor