Why is he considered the father of genetics?

Born in Heinzendorf Austria in 1822 Grew up on a family farm and learned about cultivating

flowers and fruit trees. He went to college. He was brilliant. He struggled with

scientific reading. After college he entered a monastery 1843. He used plants to study the way traits are passed from

parents to offspring. He grew almost 30,000 pea plants. In 1865 he presented his work.

2 lectures and only 40 copies made. 1868 Elected Abbot of Monastery and his duties prevented

him from sharing his work. In 1900 his work was rediscovered. His ideas were used to justify Darwin’s theory of evolution.(pg 106)

He wanted to know why traits sometimes appear in one generation but not the next. He also wanted to know why the missing traits seemed to reappear in future generations.

TimelineTimeline 2

Trait = A distinguishing quality that can be passed from one generation to the other (i.e. cleft or smooth chin).

Dominant Trait = The trait observed when at least one dominant allele for a characteristic is inherited (i.e. Cc = cleft chin).

Recessive Trait = The trait that is apparent only when two recessive alleles for the same characteristic are inherited (i.e. cc = smooth chin).

Genes = Segments of DNA that carry hereditary instructions and are passed from parent to offspring.

DNA (click to see video) = Deoxribonucleic Acid

Alleles = Different forms of a single gene (i.e. Cc where C is for cleft chin and c is for smooth chin)

Genotype = The inherited combination of alleles (i.e. CC Cc or cc).

Phenotype = An organisms inherited appearance (i.e. cleft chin or smooth chin)

Ratio: is the comparing how many there are of one kind of something to how many there are of another (i.e 3:1). Ratios can be represented by fractions and reduced by dividing the fraction (2/4 = ½).

Probability: is the mathematical chance that an event will occur (i.e. a coin toss = 50/50).

Generation : is a group of organisms living during roughly the same time period.

Dominant Trait: is the trait observed when there is at least one dominant allele inherited (i.e. Cc = cleft)

Recessive Trait: is the trait observed only when there two recessive allele for the same characteristic are inherited (i.e. cc = smooth)

Self –Pollinating = A plant that contains male and female parts and can fertilize its own eggs (see picture page 107)

Cross – Pollinating = Two different plants reproducing by sending the pollen from one plant to the eggs of another (see picture page 108).

Homozygous (True Breeding) = Is when an organism carries only one form of a gene governing a characteristic. Always produces kids with the same traits as the parents because the parents pass on only one kind of instructions or genes (i.e. CC or cc).

Heterozygous (not true breeding) = Is when an organism carries two different forms of a gene governing a characteristic ( i.e. Cc)

His work was not widely accepted until 16 years after his death.

DNA and Genes really hadn’t been discovered yet.

They grow quickly Usually self - pollinating They have several inherited characteristics

that can be studied (flower color, seed color, seed shape, pod color, pod shape, flower position and plant height).

What are inherited characteristics? They are inherited features, such as flower

color that can vary among individuals.

Self pollinating (male and female reproductive cells are on the same

flower)

Cross pollinating (male and female reproductive cells are on different

plants.

1. Different forms or versions of genes account for variations in inherited characteristics.

2. For each character, an organism inherits two genes, one from each parent.

3. If two alleles differ, then one, the dominant allele, is fully expressed in the organism’s appearance; the other, the recessive allele, has no noticeable effect on the organism’s appearance.

4. During gamete (haploid 1n) production the egg and sperm each receive only one of the genes that are present in two copies in normal body cells (diploid 2n)

SELF POLLINATION

Plant carries male and female structures. Pollen from one flower or plant can fertilize the eggs of the same flower or another flower on the same plant. 1 Parent

CROSS POLLINATION

Pollen is taken from one plant’s anther’s (male) and placed on other plant’s stigma (female).

Two Parents

The two versions of a gene that govern the same characteristic are known alleles. (For example the gene for flower color exists in two different forms ………..

Purple ( Dominant (P) ) and white (recessive (p) ). These different forms of the gene are known as alleles.

Parents could be PP, Pp or ppso let’s imagine PP x pp ……….

P P pp

Dad Mom

Mendel performed crosses to study seven different characteristics of pea plants.

Each cross was between the two traits or forms of the characteristic. For example see page 109 fig.6.

A true breeding cross RR x rr (true breeding round x true breeding wrinkled) produced the 1st generation of all round peas.

Show punnett square to show why.

Mendel chose to call the trait that seemed to show the DOMINANT trait and the one that did not show the RECESSIVE trait.

Mendel repeated this same experiment with at least 6 other crosses and found the same results each time.

Mendel allowed the 1st generation from each of the 7 crosses to self-pollinate.

This time the plant that showed only the dominant trait in the first experiment (i.e roundness) reproduced within itself (self – pollination) and the recessive trait showed up again in the offspring in exactly 3:1 ratio for each of the 7 characteristics he studied.

Look at table on page 110. Try Math Break

A ratio is comparing how many there are of one kind of something to how many there are of another. Ratios can be represented by fractions and reduced by dividing the fraction. What is the ratio of boys to girls in this class?

Probability is the mathematical chance that an event will occur. What is the chance of flipping tails on one

toss of a two-sided coin? ▪ ½ or 50%

What is the chance of flipping tails 3 times in a row?▪ ½ x ½ x ½ = 1/8

DOMINANT

The big letter represents the dominant or stronger form of a gene for a characteristic.

R

RECESSIVE

The small letter represents the recessive or weaker form of a gene or characteristic.

r

Each parent donates one set of instructions, known as genes to the offspring. The Zygote (fertilized egg) would have at two least genes for each characteristic (one from mom and one from dad). The two genes that govern the same characteristic are known as alleles. A punnett square is used to visualize all possible combinations of alleles from parents.

PP = alleles for a true breeding (homozygous) purple pea plant

pp = alleles for a true breeding (homozygous) white pea plant.

PP x pp = all four possibilities of Pp = (non-true breeding heterozygous)

* Note: Only some traits are single gene traits as explained above. Many traits turn out to be controlled by several genes from mom and dad.

HETEROZYGOUS

Would be one big letter (R) representing a gene (allele) and one small letter (r).

Rr

HOMOZYGOUS

Would be two big letters (RR) or two small letters (rr).

RR or rr

Also referred to as True – Breeding or Pure Bred.

GENOTYPE

Inherited alleles or forms of a gene for a characteristic

PHENOTYPE

Organism’s inherited appearance (how it looks)

Mendel published his work and presented his findings in two lectures. He had only 40 copies of his results published.

He was elected abbot of the monastery in 1868. His duties prevented him from visiting scientists and attending conferences where he could have discussed the results.

He died in 1884. His work was rediscovered in 1900.

His results were used to justify Darwin’s Theory of Evolution.

Darwin came up The Theory of Evolution. He had questions that he could not answer. How did organisms pass traits on to their

offspring? Why did some traits seem to be passed

on and others not? How did the traits of the parents work

together in the offspring -- did they compete, or combine?

When scientists today work to decode the human genome, they use high-tech methods to view the microscopic chromosomes and even pluck individual genes out of a cell. But in Darwin's time, it was impossible to see any of that. No one was sure how animals or plants passed down traits. And Darwin knew that the lack of an explanation forheredity left a big gap in his theory of natural selection.

Source: http://www.pbs.org/wgbh/evolution/library/06/1/l_061_01.html

Practice