Genetic Variation

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Goal

To learn the basic genetic mechanisms that determines the traits expressed by individuals in a population

Natural Selection Theory

Variation in a population of organismsResults of Mutations

Results of Immigration

Result of survival features of individual organisms

Natural Selection Theory

Environments are dynamicChanging resources

Climate (long term weather)

Natural disasters

Natural Selection Theory

Selective PressureEnvironmental changes can cause pressure

Organisms unable to adapt quickly enough will die

Organisms that adapt are able to pass on their successful traits to future generations

Natural Selection Theory

IsolationIf one portion of a population is separated from another portion then a new species may evolve

Natural Selection Theory

Mechanisms for population changeKey to change is variation among the individuals in the population

Individuals are unique due to their genes

Genetics

GeneticsNucleic Acids

Huge molecules that hold information

DNA (deoxyribonucleic acid) is the nucleic acid that holds all the genetic information for organisms

ghr.nlm.nih.gov

DNA

Genetic code of all living things

Complete set of blueprints and operating instructions for assembling and managing one particular kind of organism

Has four basic building blocksAdenine (A)

Thymine (T)

Guanine (G)

Cytosine (C)

DNA

A and T can only bond with each otherG and C can only bond with each otherWhen four bases bond together in a long chain they form a double helix (ladder)Typical DNA molecule may be about 5 cm long

DNA

DNA found in the nucleus of the cell

DNA is coiled into a compact structure called a chromosome

Every cell in every plant and animal has a completed set of chromosomes that define the organism

Every time the cell divides to produce two daughter cells the complete set of chromosomes is produced

Chromosome, Gene, DNA

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Genes determine traitsGenes: are the units of heredity that is a sequence of bases (A,T,G,C) that give instructions on how to assemble a certain protein

Genes are the sugars, phosphates, and bases along the DNA strand in the chromosome

The proteins go to the cells to make things such as fats, bone, muscle, nerves, and everything else in a living organism

Alleles

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AllelesEach gene has two copies which are called the alleles.

(2 alleles= 1 gene)

Dominant allele the allele that controls what will happen or which trait will be exhibited (Capital Letter)

Recessive allele the allele that is “overruled” and this trait or function will not be seen because of the dominant allele (Lower case letter).

Punnett Squares

A technique for predicting the characteristics of offspring

Example of Punnett Square

Punnett Square

Always put the dominant allele (G) before the recessive allele (g) so you would write Gg

Results:One homozygous dominant (GG)

Two heterozygous (Gg)

One homozygous recessive (gg)

Discovery of Heredity

Gregor MendelScientist pioneer to work with pea plants to show how a species can exhibit certain characteristics from one generation to the next.

He was the scientist to support the idea of dominant (capital letter) and recessive (lower case letter) traits.

history.nih.gov

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kentsimmons.uwinnipeg.ca

Genotype Genotype

Genotype is the genetic makeup of the organism (genes/letters)

Example:

(letters represent trait…color in this case)

Pea flower color B=dominant allele (purple), b=recessive allele (white)

A purple offspring would have either a BB or Bb genotype

A white offspring would only have a bb genotype

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Phenotype

Phenotype: how the organisms looks (trait/picture)

Example: purple flower, white flower, tall plant, short plant

Inheritance

Inheritance is passing genetic information from one generation to the next

You inherited alleles from your parents