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6.3 Mendel and Heredity

•  Inherited characteristics •  Passed generation to

generation •  Eye color, leaf shape, tail

length

Traits

Genetics – The study of biological inheritance patterns & variations in organisms

6.3 Mendel and Heredity

"  Mendel laid the groundwork for genetics.

•  “Father of Genetics” •  Australian Monk •  Bred pea plants to predict the

outcome of meiosis •  Gregor Mendel showed that traits

are inherited as discrete units called genes.

•  He crossbred plants with different traits and counted the number of offspring that exhibited the same characteristics as one of the parents.

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6.3 Mendel and Heredity

"  DNA Introduction

•  Huge information database

•  Contains instructions/code to make proteins for cell

•  4 Bases (A-T, C-G) adenine, guanine, cytocine, thymine

•  Order of the bases will determine how proteins are made

•  DNA in the chromosome that gives the instructions is called a gene

6.3 Mendel and Heredity

"  2 Steps to Make Proteins

1.  Transcription 2.  Translations

DNA RNA Protein

transcription translation

Proteins – control life

Enzymes – speed up chemical reactions by lowering activation energy

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6.3 Mendel and Heredity

"  Review Enzymes Pgs 52-56

6.3 Mendel and Heredity

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6.3 Mendel and Heredity

"  How enzymes work video

•  http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

6.3 Mendel and Heredity

•  Segments of DNA on a chromosome that contain the code for the production of a specific protein (trait)

•  Patterns of A, T, G, and C code for the instructions that make things your body needs to function (like the enzymes to digest food or the pigment that gives your eyes their color).

•  As cells duplicate, they pass this genetic information to the new cells.

Genes

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6.3 Mendel and Heredity

"  Where are genes found?

•  Locus – specific location on a chromosome

Gene = 1 protein

6.3 Mendel and Heredity

"  3 Laws of inheritance

1.  Law of Dominance

2.  Law of Segregation

3.  Law of Independent Assortment

Law of Segragation

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6.3 Mendel and Heredity

"  Mendel’s data revealed patterns of inheritance.

•  Mendel made three key decisions in his experiments. –  use of purebred plants –  control over breeding –  observation of seven

“either-or” traits

Purebred – offspring inherits all parents characteristics Cross – mate 2 organisms

6.3 Mendel and Heredity

•  Mendel used pollen to fertilize selected pea plants.

Mendel controlled the fertilization of his pea plants by removing the male parts, or stamens.

He then fertilized the female part, or pistil, with pollen from a different pea plant.

–  P generation crossed to produce F1 generation –  interrupted the self-pollination process by removing male

flower parts

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6.3 Mendel and Heredity

•  Mendel allowed the resulting plants to self-pollinate.

–  P is the Purebred parent –  Among the F1 generation (offspring), all plants had purple

flowers –  F1 plants are all heterozygous –  Among the F2 generation, some plants had purple flowers

and some had white

6.3 Mendel and Heredity

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

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6.3 Mendel and Heredity

"  Ratio – comparison that tell how things relate.

Ratio Fraction Percentage 3:1 3/1 3%

6.3 Mendel and Heredity

•  Mendel drew three important conclusions.

–  Traits are inherited as discrete units. –  Organisms inherit two copies of each gene, one from each

parent. –  Donate only 1 copy of each gene –  The two copies segregate

during gamete formation. –  The last two conclusions are

called the law of segregation (alleles seperate during meiosis) .

purple white