Genetics and DNA

Traits

All of the features that an organism inherits

color of your eyeshair colortype of ears

DNA

Deoxyribonucleic AcidDouble Helix- twisted ladder shape

Found in every living cellContains all the information required to produce a living organism

Gene

Part of the DNA code on a chromosome

Humans have tens of thousands of genes on every chromosome

Contains the genetic make up

Genotype

The code or genetic make up TT, tt, Tt

Phenotype

Physical Characteristics Hair color, type You can tell just by looking at someone

Environment influences/effects how the genetic makeup is shown

Environmental Effects vary from

organism to organism Competition from

other organisms has a great deal of effect on a population

An organism’s appearance can change based on the environment.

Genetics

Study of heredity Passing of one trait from one generation

to the next

A rapidly growing field with more and more information about humans and other organisms

Gregor Mendel An Austrian,

Roman Catholic priest and scientist who is known as the father of genetics

He studied the inheritance of traits in pea plants.

Image From: history.nih.gov

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Allele

Different forms of a gene

T- tall t- short

Dominant vs. Recessive

Dominant alleles show in an organisms phenotype whenever present in its genotype.

Recessive alleles show their effect in an organisms phenotype only when two are present in the genotype

Principle of Segregation

Each parent passes only one allele for a trait to its offspring

Principle of Independent Assortment

The alleles for a trait do not influence the alleles for another

Predicting Genetic Outcomes Mendel used probability to make

predictions

Reginald C. Punnett developed the Punnett Square 50 years after Mendel’s work was published

When the parent’s genotypes are known, a Punnett square is used to predict the possible offspring

Impact over Time

Over long time periods, the environment impacts a species’ ability to survive

Non Living Influences

Include: temperature, rainfall, fire, elevation, volcanic eruptions, periodic flooding and pollution

Reasons for Adapting Availability for

food, predators, and the number of species living in an area affect a species’ survival

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Darwin and Wallace

Over time environmental factors can change the genetics of a species

Natural Selection

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Selective Breeding Humans choose the desired traits in the

offspring

Breeders of animals and plants in today's world are looking to produce organisms that will possess desirable characteristics, such as high crop yields, resistance to disease, high growth rate and many other phenotypical characteristics that will benefit the organism and species in the long term.

Erwin Chargaff showed that in natural

DNA the number of guanine units equals the number of cytosine units and the number of adenine units equals the number of thymine units.

Chargaff's research would later help Watson and Crick to deduce the double helix structure of DNA.

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Rosalind Franklin Worked with x-ray

radiation to take the first pictures of DNA

Died of cancer most likely related to her work with X-rays

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Structure of DNA James Watson and

Francis Crick In 1962 James Watson

(1928– ), Francis Crick (1916–2004), and Maurice Wilkins (1916–2004) jointly received the Nobel Prize in medicine or physiology for their determination in 1953 of the structure of deoxyribonucleic acid (DNA).

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www.abpischools.org.uk

Image From: www.abpischools.org.uk

DNA by the numbersDNA by the numbers Each cell has about 2

m of DNA. The average human

has 75 trillion cells. The average human

has enough DNA to go from the earth to the sun more than 400 times.

DNA has a diameter of only 0.000000002 m.

The earth is 150 billion mor 93 million miles from the sun.

DNA is made of a long sequence of smaller units strung together. There are four basic types of unit: A, T, G, and C. These letters represents the type of base each unit carries: adenine, thymine, guanine, and cytosine. The sequence of these bases encodes instructions.

Some parts of your DNA are control centers for turning genes on and off, some parts have no function, and some parts have a function that we don't understand yet.

Other parts of your DNA are genes that carry the instructions for making proteins — which are long chains of amino acids. These proteins help build an organism.

Mutations

Process in which DNA changes to form new alleles Cross eyed, downs syndrome, extra

digits, Opposable Thumb Some are advantageous

Types of Mutations Substitution

A substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G). Such a substitution could:

For example, sickle cell anemia Sickle cell anemia is a genetic disease with

severe symptoms, including pain and anemia. The disease is caused by a mutated version of the gene that helps make hemoglobin — a protein that carries oxygen in red blood cells.

Insertion:

Insertions are mutations in which extra base pairs are inserted into a new place in the DNA.

Original: The fat cat ate the wee rat.

Insertion: The fat cat xlw ate the wee rat

                       

         

Deletion

Deletions are mutations in which a section of DNA is lost, or deleted.

Muscular Dystrophy:

How mutations occur DNA fails to copy accurately

Most of the mutations that we think matter to evolution are "naturally-occurring." For example, when a cell divides, it makes a copy of its DNA — and sometimes the copy is not quite perfect. That small difference from the original DNA sequence is a mutation.

External influences can create mutations Mutations can also be caused by

exposure to specific chemicals or radiation. These agents cause the DNA to break down. This is not necessarily unnatural — even in the most isolated and pristine environments, DNA breaks down. Nevertheless, when the cell repairs the DNA, it might not do a perfect job of the repair. So the cell would end up with DNA slightly different than the original DNA and hence, a mutation