Mendelian Genetics

Vocabulary

• Trait- characteristic of an organism (ex. coat color)• Gene- segment of DNA that codes for a protein• Allele- alternate form of a gene (C or c)• Phenotype- observable traits of an organism (brown fur)• Genotype- genetic makeup, or set of genes an organism has

(CC or Cc or cc)• Dominant- the expressed allele or trait (C)• Recessive- the non expressed allele or trait (c)• Autosomal- describes genes found on the 22 non-sex

chromosomes• Sex-linked- describes genes found on the sex chromosomes

Mendels’ Law of Heredity• Gregor Mendel studied many traits that he saw in pea plants.

By keeping meticulous notes of plant bleedings and offspring counts he was able to deduce that traits are inherited in predictable fashion. This lead him to develop the law of heredity that describe how traits and genes are inherited from parent to offspring.

1. Dominance• The law of dominance states that more than one form of

genes exist, these alternate forms are called alleles. Genes that are expressed always are dominant, genes that are expressed only if both parents have the gene are recessive. (there are many exceptions to this rule, co-dominance, incomplete dominance, etc)

• http://www.interactive-biology.com/3879/mendels-law-of-dominance/

2. Segregation • The law of segregation states that alleles separate during

gamete formation and therefore are inherited separately. This means that for each trait there is one allele inherited from each parent. Any particular trait, the pair of alleles of each parent separate and only one allele from each parent passes to an offspring.

• http://www.phschool.com/science/biology_place/biocoach/inheritance/analysis.html

3. Independent Assortment• The law of independent assortment states that alleles of

different genes assort independently from one another during gamete formation and are therefore inherited independently. This means that when looking at more than one trait, each trait still gets one gene from each parent.

• http://www.phschool.com/science/biology_place/biocoach/inheritance/pracuia1.html

Genetic Diseases

• Genetic diseases are caused by mutations. Most genetic diseases are caused by traditional mutations like substitutions, insertions, and deletions of one or more nucleotide in chromosome. Non-disjunction, an error in meiosis, where chromosomes fail to separate accounts for the other types of genetic diseases.

• Genetic diseases can either be inherited from parents or newly acquired “de novo”.

• Inherited mutations can be tracked throughout families and are classified as either dominant or recessive and autosomal or sex-linked.

Lizzie Velásquez’s Story- http://www.aboutlizzie.com/#!lizzies-story/ccm8

• Pedigrees are used to trace how a genetic disease is inherited and allows us to determine the mode of inheritance. • Dominant or Recessive?• Autosomal or Sex-linked?

Pedigrees

http://www.bogari.net/Bogari/Medical_Genetics_files/3-1%20Patterens%20of%20Inheritance.pdf

Links• http://www.hobart.k12.in.us/jkousen/Biology/mendel.htm• http://www.youtube.com/watch?v=CBezq1fFUEA• http://www.youtube.com/watch?v=GTiOETaZg4w• http://www.youtube.com/watch?v=lppF8Mv4sbo• http://www.youtube.com/watch?v=NWqgZUnJdAY• http://www.youtube.com/watch?v=Y1PCwxUDTl8• http://www.youtube.com/watch?v=qRxyIc4vMgA• http://www.youtube.com/watch?v=GFv1HtK-Q9Q• http://www.youtube.com/watch?v=2930XAuGXCI• http://www.youtube.com/watch?v=qolJlhVg6mw• http://www.youtube.com/watch?v=0jg9GmkuPEA