TO DO: Notebook, pencil/pen

WARM UP: What is DNA? Why is it so important? HOMEWORK:

Weebly and vocabulary

October 13, 2015

Biology OutcomesAble to interpret the importance of genetic inheritance for the live of a person or a living creature in general, related to the development of biotechnology.

Able to conclude among the systems in the human body is related to each other and how they maintain homeostasis.

KEY CONCEPT Traits (characteristics) are inherited as discrete (separate) units

Before we begin…Sit quietly for 30 seconds as you THINK!!!!

Think about this…

What are some traits you have that make you look like your mom or dad? If you don’t know what your mom or dad looks like, what are some qualities that make you look unique from the rest of your family? Or do you look more like one parent than another?

Why do you think this is???

Traits are distinguishing characteristics that are inherited (like hair color or blood type)

Genetics is the study of biological inheritance patterns and variation

Heredity: The passing of traits from parents to offspring

Key Vocabulary Terms

In the 1800s, Gregor Mendel (an Austrian monk) made the first studies in predicting how traits would transfer from one generation to another

Many in Mendel’s day thought traits were blended …. A red flower and a white flower would make a pink flower

Background Information

A. Mendel studied pea plants for 3 main reasons:

1. All the traits came in 2 easy to recognize forms

2. Both male and female gametes (sex cells) are produced on the same plant

3. The reproductive parts are tightly enclosed in petals preventing pollen from other plants entering

B. Fertilization

The uniting of male and female gametes (sex cells)

Plants “pollinate”1.A hybrid plant would have

one of each form of a trait

Think for a minute…- then pair/share

Have you ever heard of the term hybrid before????Def: the offspring of two animals or plants of different breeds, varieties, species, or genera, esp. as produced through human manipulation for specific genetic characteristics Can you think of any examples of hybrids?Livestock examples-

Yorkshire Pig x Hampshire Pig= Blue ButtBlack Angus x Hereford= Black BaldyThoroughbred x Arabian= Anglo Arabian

Mendel controlled thefertilization of his pea plantsby removing the male parts,or stamens.

He then fertilized the femalepart, or pistil, with pollen froma different pea plant.

B. Mendel’s 1st Experiments1.Mendel’s 1st Experiments were

called Monohybrid crosses (the plants were different by just one trait)Example: all pea plants had purple flowers and green seeds, but some are tall and some short

B. Mendel’s 1st Generation1. He crossed a pea plant that was pure

purple flowers (it had only purple genes) with a plant that was pure for white (only white genes)

2. The offspring were all purple, no white pea flowers grew

3.The white trait seemed to disappear

C. Mendel’s 2nd Generation1.Mendel crossed two of the

offspring from the 1st generation

2.His results were 3 of every 4 plants were purple and 1 in 4 was white

3.The white trait reappeared

3. Abbreviations1. P1 = parent in the 1st generation

2. The offspring of P1 were called the F1

generation

“F” stands for filialFilial stands for son or daughter

3. The offspring of the cross between 2 F1

plants were called the F2 generation

What disappeared in the 1st generation?The trait for whiteWhat reappeared in the 2nd generation?The trait for white

• Mendel observed patterns in the first and second generations of his crosses

D. Mendel’s Conclusions1. Mendel concluded that each organism has 2

factors that control each of its traits

2. The factors controlling traits are called genes

3. One comes from each parent

4. They are found on the chromosomes

5. Genes exist in alternative forms

E. Law of Segregation:1.During fertilization, the 2 different

genes randomly pair to produce 4 different combinations of alleles

2.They separate independently

xParents

Offspring

Tt Tt

T T Tt Tt tt

Law of Segregation

The Rule of Dominance• Mendel called the observed

trait dominant and the trait that disappeared recessive.

• Mendel concluded that the allele for tall plants is dominant to the allele for short plants.

T T

T

T

t t

t

t

Tall plant Short plant

All tall plants

F1

The Rule of Dominance• When recording the results of

crosses, it is customary to use the same letter for different alleles of the same gene.

• An uppercase letter is used for the dominant allele and a lowercase letter for the recessive allele.

• The dominant allele is always written first.

T T

T

T

t t

t

t

Tall plant Short plant

All tall plants

F1

Phenotypes and Genotypes

• The way an organism looks and behaves is called its phenotype.

• The allele combination an organism contains is known as its genotype.

• An organism is homozygous for a trait if its two alleles for the trait are the same.

• An organism is heterozygous for a trait if its two alleles for the trait are different from each other.

The Law of Independent Assortment

Genes for different traits are inherited independently of each other.

Example: seed shape and seed color

Punnett Squares

homozygous vs heterozygous

an organism that is homozygous for a trait has two alleles for the trait that are the same.an organism that is heterozygous for a trait has two different alleles (dominant and recessive).

punnett square

punnett sqaures are used to predict what possible offspring may be.

dihybrid cross