Chapter 4: Heredity Section1- Genetics Life Science Lesson Plan

Inheriting Traits  Create a short list of characteristics about yourself…  What is another name for these characteristics?  TRAITS

Heredity  Heredity is the passing of traits from parents to offspring.  Inherited Traits- Traits that are passed from parents to their offspring (through fertilization)

Genes are passed… but what are genes?  Genes are sections of DNA on a chromosome.  These genes on chromosomes control the traits that show up in an organism. –There are thousands of genes on a chromosome

 Alleles are different forms of a trait that a gene may contain. –There are 2 alleles for each gene –1 from mom and 1 from dad  Example: Height –1 allele is tall –1 allele is small

Alleles alleles a gene

B. Genetics- is the study of inherited traits. 1. Gregor Mendel- The Father of Genetics “The Man”

Mendel’s Experiment  Mendel studied the traits of Pea Plants –Look Page 105  Crossed 2 Plants with different expressions of the trait –Example- Tall (T)& Short (t) –Round R & Wrinkled r

Mendel’s Experiment  When the plants were crossed he discovered that the new plant formed looked like one of the two parents.  Take a look… Mendel’s Tall vs. Short Plants

VOCABULARY  3. Purebreds- offspring receives the two same alleles for a trait (TT or tt)

VOCABULARY  4. Hybrids- offspring receives two different alleles for a trait (Tt)

2 Types of Alleles a.Dominant allele- covers up or dominates the other trait Represented by a Capital Letter b. Recessive allele- the trait seems to disappear Represented by a lower-case letter

 “Homo”zygous – an organism with 2 alleles for one trait that are the same (written TT)  “Hetero”zygous – an organism with 2 alleles for one trait that are different (written Tt)

 Genotype- the genetic- makeup of an organism (types of letters used)

 Phenotype- the way an organism physically looks/behaves as a result of its genotype.  Types of Words used: Tall, Short, Blonde, Brown, etc.

The Use of Punnett Squares  A Punnett Square can help you predict what an offspring will look like. “What’s the Probability of the baby’s gender?”

 A Punnett Square can help you predict what an offspring will look like 1. Monohybrid: Offspring of parents that differ in only one genetic characteristic

Monohybrid Cross: GG x gg

DYHIBRID CROSSES 2. Dyhybrid: Offspring of parents that differ in TWO genetic characteristic ***USE FOIL to separate the combinations F – FIRST O – OUTSIDE I – INSIDE L – LAST

DIHYBRID EXAMPLE Tall & Green TtGg x TtGg

DIHYBRID EXAMPLE #2 Brown hair vs Blonde hair AaBb x aaBb

Chapter 4 Part 2- Genetics Since Mendel Life Science

Question…  If you crossed Purebred Red four- o’clock flower with Purebred White four-o’clock flower, what would the offspring look like?

 Actually… they were PINK!?!?!

 Incomplete Dominance- when two homozygous parents combine, the offspring results in a blended phenotype  Combining Purebred Red & White and produced Pink

 Neither allele for a trait is Dominant.  The phenotype produced is mixed between the two homozygous parents. –The combining of Purebred Red & Purebred White produced PINK plants.

What would happen if you crossed a Red horse and a White horse?

PINK!?!?!

Just kidding… ROAN

 Although Mendel studied peas that were controlled by two alleles, many traits can be controlled by more than two alleles…

Multiple Alleles  A trait that is controlled by Having more than two alleles is controlled by Multiple Alleles.  Traits controlled by Multiple Alleles produce more than three phenotypes of that trait.

Example (Flip to Page)  Example of Multiple Alleles…  Blood Types: A, B, AB, and O. –The O allele is recessive to both A and B

Other Worksheet…  Phenotype A - AA or AO Genotype  Phenotype B – BB or BO Genotype  Phenotype AB – AB Genotype  Phenotype O – OO Genotype

Polygenic Inheritance  Polygenic Inheritance- when a group of gene pairs acts together to produce one trait. –Which creates more variety in phenotypes

What would be an example?  Many traits such as…Skin Color, Eye Color, Hair Color, and Handspan are traits produced by a combination of genes.

Human Genes & Mutations  Mutations : a permanent change in the DNA sequence  A mutation can be helpful, harmful, or cause no effect.

Mutations  Chromosome disorders- caused by more or fewer chromosomes than normal  Downs Syndrome- caused by an extra copy of chromosome 21

Recessive Genetic Disorders  There are human genetic disorders that are caused by Recessive Genes.  How could this occur?  Both parents contain the recessive allele

 Because parents are Heterozygous, they do not show any symptoms –(Called “carriers” for the trait.)  Cystic Fibrosis is a homozygous recessive disorder.

Sex-Linked Disorders  An allele inherited on a sex chromosomes ( X or Y ) is called a sex-linked gene.  Inherited conditions are linked with the X and Y chromosomes.

 Example- Color Blindness is a sex- linked disorder caused by recessive allele on the X chromosome.

Where did you get your genes from?

Pedigrees  Pedigree- used to follow or trace traits through generations of a family.

No… not the dog food…

Section 3 III. Advances in Genetics A. Genetic Engineering- experimentations that changes the arrangement of DNA that makes up a gene.

Types: 1. Recombinant DNA  Inserting a useful section of DNA into a bacteria  Example- Creating Insulin (Page 143)

2. Gene Therapy-  When a “normal allele” is placed into a virus, the virus then delivers the normal allele when it infects a specific cell. (Figure 13 Page 144)  May be used to control Cystic Fibrosis and other disorders.

3. Genetically Engineering Plants-  Plants are created by genetically inserting the desired genes of one plant into another plant you want to show those genes.  Also genetically engineered: ANIMALS  “Cloning”

Works Cited   04/mendel.htm 04/mendel.htm    