Genetics

A: describe how Mendel developed his theories of genetics;

☻ Gregor Mendel (1822-1884)☻Austrian Monk☻First person who developed a workable model of

genetics.☻Educated man who studied sciences and math.

http://www.youtube.com/watch?v=DYK2zB3sItI&NR=1&safety_mode=true&persist_safety_mode=1&safe=active

☻1.) Pea plant is ideal: Long and short stems, round and wrinkled seeds.

☻Complete flower (male and female parts on one flower)

☻Flower enclosed by petals prevents crossbreeding

☻2.) First developed purebred strains

☻Characteristics would carry through to the next generation.

☻Tall plant would always produce a tall plant.

☻3.) Next cross purebred lines of plants by removing the male flower parts and cross pollinating.

☻They are called the F1 generation

☻The new plants had all red flowers leading to the law of dominance.

☻4.) Then crossed F1 generation; these seeds are now the F2 generation.

☻This generation, white flowers again showed up.

☻Altogether found same results with seven traits of pea plants.

YouTube Video:

http://www.youtube.com/watch?v=xrDjN_4HKf0&safety_mode=true&persist_safety_mode=1&safe=active

☻Law of Dominance: certain traits are dominant and make recessive traits appear to disappear.

☻Later scientists called these dominant or recessive traits allels.

B: Explain the Mendelian laws of genetics;

C: Define vocabulary terms of heredity;

☻Chromosomes- rod shaped bodies that occur in pairs in the nuclei of the cell and that carry the genetic makeup.

☻Genetics- study of how traits are passed from one generation to another.

☻Genes- heredity units located on a chromosomes.

☻DNA- ( Deoxyribonucleic acid) a nucleic acid that makes up chromosomes and controls inherited traits.

☻Allele- place on a gene that results in a dominant or recessive trait.

☻Homozygous- pertaining to the condition in which both genes at a particular location are the same allele or are identical (either dominant or recessive)

☻Heterozygous- pertaining to the conditions in which two alleles at a given location are different.

☻Dominant- expressive gene, these are indicated by capital letters.

☻Recessive- the genes do not express themselves; these are represented by lowercase letters.

☻Probability- the likelihood that some events or outcome will occur.

☻Meiosis- cell division that produces

gametes, which contain the haploid

number of the chromosome.

☻Phenotype- how an allele expresses itself.

☻Genotype- the genetic composition of an individual.

☻Law of Independent Assortment: factors (genes) for certain characteristics are passed from parents to the next generation separate from the other factors or genes that transmit other traits.

☻Gene for a tall pea plant does not effect color at all.

D: compare and contrast phenotype and genotypes;

☻Phenotype- how an allele expresses itself.☻What it looks like -can see it☻Controlled by genotype - dominant gene is seen

☻Genotype- the genetic composition of an individual.

☻Cannot see it (Rr) -Expressed in phenotype☻Traits - dominant seen

☻50% from each parent - only 5% different from all

other humans

E: Analyze Punnett squares;

☻R.C. Punnett mathematician developed a diagram to illustrate possible combinations for a trait.

☻Letters are used to illustrate traits. Capital letter indicates dominant trait.

☻Lower case letter indicates a recessive trait.

☻Alleles are paired for traits. They may be paired in a homozygous or heterozygous matter.

You Tube Video:

• http://www.youtube.com/watch?v=d4izVAkhMPQ

• AaBb

a BAB A b

a b

AB

a B

A b

a b

F: Discuss the make up of chromosomes in a cell;

All of the material responsible for the transfer of traits is grouped together in structures called chromosomes.

Rod shaped, X during Mitosis

Chromosomes are long strands of protein and nucleic acid molecules. (DNA)

Can be arranged in an infinite number of ways.

Within these molecules is the genetic code that determines all the characteristics of an organism.

Different segments of the chromosomes control different traits that are expressed in the organism.

Each chromosome segment that controls a trait is called a gene.

Each cell of an organism contains all of the DNA needed to control all traits of the organism.

This makes cloning using a single cell possible.

Genes• Each gene on the chromosome has two

alleles

• One contributed by each parent.

• Off spring receives exactly half of their genetic material from each parent.

At fertilization, the two cells, each containing half the genetic code from each parent, unite.

They form a new genetic code for the fertilized egg.

There are huge numbers of ways that

genes can be paired.

Meiosis

• Meiosis is the process by which reproductive cells are made.

• The chromosomes divide in half to form the gametes (sex cells).

• They recombine when fertilization takes place to insure that the new organism has the correct number of chromosomes.

Who controls gender in off spring?

Male- x y Female- x x

Parent cells

Gametes

Fertilization Occurs

Possible outcomes

G: Determine the structure and function of DNA;

DNA

• Made of 2 strands that wrap around each other. (Double Helix)

• The building blocks: nitrogen bases:

Adenine (A)

Purines Guanine (G)

Thymine (T)

Pyrimidines

Cytosine (C)

A-T always pair

G-C always pair

DNA is the genetic makeup/code or blueprint for life.

H: Discuss the process of DNA replication and transfer;

Prior to cell division the DNA copies itself in a process called replication. (Interphase)

The strands of DNA separate,

Each half duplicates the missing side.

Now there are two strands exactly alike

Replication uses the following steps:

— Separation of Standards

— Base Pairing

— Bonding of Base

RNA

The DNA’s message is transferred to the rest of the cell by means of a messenger known as RNA.

As the organism grows, the cells know how to differentiate to form different parts.

K: Explain how hybrid plant varieties are developed.

Hybrid plants take on superior characteristics to the parent plant known as hybrid vigor.

Parent plants must be purebred (have the ability to breed true.)

Farmers can get larger yields, tapered to their soil type, earlier in the season.Drought tolerance.

Heat resistance

Insect resistance

Disease resistance

Plants are able to cross-pollinate, so scientists must ensure that only the desired cross can occur.

It takes several generations before the cross is complete and ready to be grown in production.

First, purebred lines must be developed, then they can be crossed.

The parent line must be grown for several generations to prove that it will grow true.

They use the genetics characteristics in a parent plant to develop new cultivars that will out perform their parents.

Plant breeders learned that crossing two purebred lines resulted in a more vigorous plant known as a hybrid.

Different species of plants are known as cultivars.

Plant breeders use genetic characteristics of plants to breed new cultivars that will grow in a specific condition.

Plant breeders always have a definite goal in what they are breeding for.

J: Specify how genetic principals are used in plant breeding;

Plant breeding is the process of matching genetic factors from parent plants to produce offspring superior to the parent plants.

Plant breeding has occurred for hundreds of years. All plants now grown were once wild.

Essay example answer:

DNA replicates during Interphase in the cell cycle.

First, the DNA splits by breaking apart at the hydrogen bonds.

Next, the bases re-pair. A only pairs with T, and C only pairs with G. this makes the pairing possible.

Finally, the bases re-bond. That process of replication produces 2 identical sets of DNA.

Now the cell is ready to divide in Mitosis.