INHERITANCE

Interest Approach

Pea plants Different colored flowers

What was different about each plant??

History of Genetics

1670’s Scientists believed

that each sperm contained a “little man” that would develop into a human

Then mother only served as an incubator

History of Genetics cont.

1750’s “Blending of Inheritance Theory”

Example:

Black animal mated to a white animal would produce a gray animal

History of Genetics cont.

1850’sGregor Mendel Austrian monk and worked in the

monastery garden mating pea plants Determined that characteristic were

inherited by discrete factors that would eventually become know as genes

Gregor Mendel

Discovered many principles

Principle of segregation Principle of independent assortment

Principle of Segregation

Every individual carries pairs of factors for each trait and that the members of the genes segregate at random during the formation of gametesSince segregation is random, predictable ratios of traits are found in the offspringDuring segregation, chromosomes go from a pair (2n or diploid) to singles (1n or haploid). Good way to remember:

“Hap a diploid is 1n”

Principle of Independent Assortment

Members of each pair of genes are distributed independently when the gametes are formed and are unaffected by other gene pairs on other chromosomes

When pairs of genes on different chromosomes separate, they have an equal chance or probability of going to an individual gameteNo predetermined order for the dividing pairs

EVERY GENE FOR ITSELF

Chromosomes

Located in the nucleus of the cell and contain all of the genetic material in the cell

Arranged in pairs

Made up of a substance called DNA

Two Types of Chromosomes

Haploid Half the diploid or

somatic (non-sex cell or gamete) number of chromosomes (n or 1n)

Diploid Number of

chromosomes found in the somatic or body cells (2n).

Twice the number of chromosomes found in the gametes

Chromosomes in Animals

Cattle

Sheep

Goat

Swine

Horse

Human

2n

60

54

60

80

60

46

1n

30

27

30

40

30

23

DNA

Deoxyribonucleic AcidThree Components Deoxyribose sugar Phosphate Four nitrogenous

bases Adenine (A) Thymine (T) Guanine (G) Cytosine (C)

Nucleotides

Combination of the deoxyribose, phosphate and one of the four bases Nucleotides bond together to form

one strand of the DNA molecule Two of the strands wind around each

other in a double helix to form the DNA molecule

In the two pairs of DNAC is always paired with G

AND

A is always paired with T

The Gene

Genes are points of activity found in each chromosome that govern the way in which traits develop. Genes are specific areas on each chromosome and are made up of DNA

Protein Synthesis

RNA (ribonucleic acid) is a group of molecules in charge of “reading” and “translating” the genetic code for the formation of new proteinsRNA uses the DNA as a template to read the code in order to produce the right protein with the correct order and number of amino acids.

Three Types of RNA

Transfer RNA (t RNA) Plays a key role in protein synthesis (building). Each tRNA molecule can combine with one amino acid and can transport the a. a. to the new protein building site in the cytoplasm of the cell

Three Types of RNA cont.

Ribosomal RNA (rRNA) Also plays a key role in protein

synthesis. It helps control the connecting of the parts of the protein (the amino acids) together.

Three Types of RNA cont.

Messenger RNA (mRNA)Helps complete the building of the proteinPhysically sequencing the amino acids that were carried to the building site by the tRNA and chemically connected by the rRNAThe mRNA directs the sequence based on the order it obtains from the DNA molecule

In RNA Translation. . .

C is paired with G

T is paired with A

A is paired with U

Activity: Building DNA

Materials Needed: Several of each:

Four different colored gumdrops or other material that a toothpick can be inserted into

Toothpicks

Activity cont.

Instructions: Designate each color of gumdrops a different

base (A=red, T=green, for example) Designate the toothpicks as the bonds

between the bases Give the students a list of bases that ranges

from 10 to 15 bases long The students will then lay out the sequence

using the gumdrops and the sticking toothpicks into the sides

Activity Instructions cont.

The students must then decide the complimentary pair for each base and connect it to the given base

(to make a double helix other toothpicks must be used on the outer sides of the bases to connect the pairs of bases together in a rotating matter)

Example

T

A

C

Given Gumdrops

A

T

G

Toothpicks

Complimentary Gumdrops

Toothpicks to hold bonds together in rotating matter