Topic 4 – Wearing your Genes Biological Diversity

To Ponder…. Questions: Why do some people have blue eyes and others have brown eyes? What makes some people red heads and others brunettes? Are some people born great musicians or do their talents develop with practice? Why is one sibling a great athlete when the other is not?

Genetics Heredity is the passing on of characteristics from parents to their offspring A characteristic is also called a trait The study of heredity is called genetics

Two kinds of inherited Variation 1. Continuous Variation Any trait that has a range of possibilities Anything that deals with measurement or weight and color EXAMPLES: Hair Color, Skin Color, Height, Weight

2. Discrete Variation Any trait that has a limited number or possibilities Either _________ or __________. Example: Tongue roller, earlobe (attached or detached), left or right handed

QUESTIONS  Would hair color be a discrete or continuous variation? hair color would be continuous because there are many different options

List all the blood types possible List all the blood types possible. Would blood type be a discrete or continuous variation? Blood Types would be discrete because it is a limited number of options. You are either A or B or AB or O (+/-)

GREGOR MENDEL First known geneticist and “father of genetics” Was an Austrian monk and was born in 1822 Did most of his genetic studies on pea plants http://www.youtube.com/watch?v=aDpLDBaEBjk

Gregor Mendel: Mendels Laws of Heredity 1. Each trait is controlled by two factors-genes (one from each parent) 2. Each gene has two forms (alleles) – dominant or recessive 3. For each trait an organism could inherit either: Two dominant alleles Two recessive alleles One dominant and one recessive allele 4. The distribution of dominant and recessive genes from the parents to the offspring was determined by chance

Mom Dad Dominant and Dominant Recessive and Dominant Dominant and Recessive Recessive and Recessive http://www.youtube.com/watch?v=54wxJ6E_2K8&feature=related

Dominant Traits A dominant trait is a trait that takes charge over any other allele. It will mask the recessive trait It will show up in the offspring if they get that trait EXAMPLE: ‘E’ is the symbol representing the dominant trait for detached earlobes. ‘EE’ or ‘Ee” will have the dominant trait showing up.

Recessive Traits A recessive trait is a trait that will only show up in the offspring if you have two of the recessive alleles. It allows the dominant trait to control it EXAMPLE: ‘e’ is the symbol representing the recessive trait for attached ear lobes ‘ee’ is needed for the recessive trait to show up. http://www.youtube.com/watch?v=dPk_V1KkMuU&feature=related

Eye Color (Dominant to Recessive) Eyecolor—Brown color is dominant and blue is recessive. A person can have a brown allele and a blue allele but still have brown eyes because the brown allele is dominant and “hides” the blue allele. Dark brown, Light brown, Light Gray, Blue, Green.

Facts: We are all made of cells Cells have a nucleus which contains 46 chromosomes for humans These chromosomes are made up of genes Genes have 2 forms called alleles (dominant and recessive) Phenotype is the outward appearance of alleles It is what you see (earlobes for example)

Genotype is the genetic combination of alleles (the genetic make-up) EE or Ee or ee Homozygous is when the genotype has both the same alleles Two dominant alleles would show the dominant trait Two recessive alleles would show the recessive trait Heterozygous is when the genotype has one of each type of allele

Punnett Square The punnett Square can be used to see the genotype possibilities of offspring traits Used to help predict Mendelian genetics

Example: R= dominant r = recessive Generally, dominant alleles are represented with a capital letter, and recessive alleles are represented with a lower case letter. Example: R= dominant r = recessive

“Purebred” species have two alleles of the same trait Represented by two of the same letters. This is called homozygous. For instance: BB or bb. Species with two different alleles or two different forms of the gene would be “hybrid” Represented by two different “letters” and by called “heterozygous”. For instance: Bb

Steps for using the Punnett square: http://www.youtube.com/watch?v=d4izVAkhMPQ&feature=related Steps for using the Punnett square: One parent’s alleles (genotype) go along the top The other parent’s alleles go down the side. You fill in the squares like doing the communicative property of multiplication. B b B BB Bb b Bb bb

Steps for using the Punnett square: Let’s say the parents are Bb and Bb (the same genotype). What would be their phenotype? Brown Eyes B b So you would predict: ¼ offspring to be BB, or Brown Eyes 2/4 or 1/2 to be Bb, or Brown Eyes and ¼ to be bb or Blue eyes B BB Bb b Bb bb

M/F R M/F r M/F R r M/F R r HOMOZYGOUS DOMINANT PARENTS HOMOZYGOUS RECESSIVE PARENTS M/F R M/F r ___recessive trait ___dominant trait ___recessive trait ___dominant trait HOMOZYGOUS DOMINANT AND HETEROZYGOUS PARENTS TWO HETEROZYGOUS PARENTS M/F R r M/F R r ___recessive trait ___dominant trait ___recessive trait ___dominant trait

Sex Linked Traits Sex linked traits are connected to the X or Y chromosome (X-chromosome is larger) EXAMPLES: color blindness (red-green--mostly males) voice (masculine, etc.)

-http://www.youtube.com/watch?v=IJqFk-28G08

Traits Incomplete Dominance is when traits blend to make a third trait Example: White and red flowers reproduce to make pink flowers Quantitative Inheritance is when not all traits are controlled by one pair of genes Example: hair color – this is VERY hard to study

Nature (genetics) vs. Nurture (environment) Are all characteristics inherited? A persons weight can be altered by genetics, diet and activity level Some people think that genetics are the cause of everything about a person EXAMPLE: Likes and dislikes Some people think that the environment can mould and shape a person Example: Identical Twins http://www.youtube.com/watch?v=3AIHC4PNCak

Nature is a persons genetics What you are born with Nurture is the environmental affects on a person Abilities, skills, scars, cosmetic surgery, injuries

Changing our Genetic Material Changes to DNA are called Mutations Mutations cause changes in the structure of organisms Mutagens are things that cause mutations X rays, ultraviolet rays, cosmic rays, some chemicals http://www.youtube.com/watch?v=efstlgoynlk

In some cases, mutations in individual cells cause cancer Cancerous cells go through rapid cell divisions and do not develop in the same way healthy cells do Mutations in DNA can be passed on in the genetic material to offspring