Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles

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Transcript of Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Beyond Dominant and Recessive Alleles

Exceptions to Mendel’s Principles

Mendel’s Principles

1. The inheritance of traits is determined by individual units known as genes. In organisms that reproduce sexually, genes are passed from parents to their offspring (children).

2. In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.

Mendel’s Principles

3. In most sexually reproducing organisms, each adult has two alleles for each gene – one from each parent.

These alleles are segregated from each other when gametes are formed. One allele goes into each gamete cell.

Page 4: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

But…

Genetics is more complicated than this!!

There are exceptions to Mendel’s principles…

Some alleles are neither dominant nor recessive, and many traits are controlled by

multiple alleles or multiple genes.

Page 5: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Incomplete DominanceIn the case of incomplete dominance one allele

is not completely dominant over the other. Both show in the offspring but they are

blended.

Page 6: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Incomplete Dominance

Curly Hair (CC)

Wavy Hair (Cc)

Straight Hair (cc)

Page 7: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Codominance

Codominance occurs when both alleles contribute to the phenotype of the organism.

Both alleles can be seen in the offspring.

Red Bull White Cow

Roan Cow

Page 8: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Polygenic Traits

Many traits are produced by the interaction of several genes. These are called polygenic

traits, which means having many genes.

Height Skin Color Weight

This allows for a lot of variation in a population.

Page 9: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Gene-Chromosome Theory

States that genes are located in specific spots on specific chromosomes.

If genes are on the same chromosome they are said to be “linked” and passed onto the next generation together.

Page 10: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Crossing Over Crossing over can create even more genetic

variation by creating new combinations of alleles.

Page 11: Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

Environmental Influence on Heredity Article on Fingerprints of Twins See worksheet

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Selection and Genetic Variation 1) selection against recessive alleles If alleles are recessive lethal, then selection can only act on them when they are.

Lethal Recessive Alleles

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Complex Traits of Heredity Chpt. 12. Recall Simple Types of Heredity Recessive Recall, must have both recessive alleles (aa) to have a recessive trait.

Mendel’s Legacy - Centre for Distance Learning and ... cross.pdf · Mendel’s Legacy Genetics is ... Do this monohybrid cross ... – Sometimes pairs of alleles show deviations

After Mendel Ch. 8 – 3 (con’t) Beyond Dominant And Recessive Alleles Dominant/recessive inheritance is the simplest type of gene interaction What causes.

Variations on Mendel’s principles Incomplete dominance Co-dominance Multiple alleles Sex-linked alleles.

Not all traits are simply inherited by dominant and recessive alleles (Mendelian Genetics). In some traits, neither allele is dominant or many alleles.

Genetics - University of Vermontbiology/Classes/296D/19_Genetics.pdf · • Population genetics: – Mendel’s laws – How Mendel’s laws affect the alleles present in a set population.

ESSON Dominant and Recessive Alleles - dvdcheng.weebly.com · Dominant and Recessive Alleles Many human traits follow a pattern of simple dominance. For instance, a gene known as

Important Vocabulary Genotype Phenotype Two alleles make up one genotype Alleles are either dominant or recessive There are exceptions to these rules.

Complex Inheritance. Simple Recessive Heredity Most genetic disorders are caused by recessive alleles; the person must be homozygous recessive in order.

Beyond Dominant & Recessive Alleles Incomplete Dominance & Codominance.

mareclebiologyforensics.weebly.commareclebiologyforensics.weebly.com/uploads/8/6/5/3/86534952/12.3_other... · Beyond Dominant and Recessive Alleles Multiple Alleles: Polygenic Traits:

Chapter 5 (Sections 1 & 2) Heredity Review Game. An organism with two dominant alleles or two recessive alleles is called ______________. (Write both.

11-3 Exploring Mendelian Genetics › cms › lib8 › OR01001812 › Centricity › D… · Exceptions to Mendelian Genetics! Beyond Dominant and Recessive Alleles Some alleles are

Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.

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Transcript of Beyond Dominant and Recessive Alleles Exceptions to Mendel’s Principles.