DNA the stuff of life genetic blueprint essence of being human what makes you, you

Humans cells make tens of thousands of different proteins. All of them are linear chains of amino acids (usually hundreds of amino acids linked together, single file).

FACT- all proteins are single chains of amino acids. The order of the amino acids is different in different proteins. The essence of a protein is the order of the amino acids.

For all living things- there are 20 different amino acids.

Proteins don’t function as linear single file ‘snakes’: Computer graphic of protein 3D structure

Proteins can form so many functions because of the great diversity of structures that can form: How many different chains of just 6 amino acids can be formed? 20 6 = 64,000,000 FYI: largest known protein: 30,000 amino acids

Why do 2 chains of amino acids fold differently:

Of the 20 different amino acids. Some are: Large Small Positively charged Negatively charged Water soluble Water insoluble

In any protein, some of the amino acids are critical.

The DNA molecule is a double helix.

Crick and Watson and others knew that DNA was made of 4 building blocks (4 bases): In all living things: A, C, G, and T

Crick and Watson discovered ‘base pairing’: In all living things: A=TG=C

Base Pairing??

DNA is two chains, held together by base pairs.

DNA The order of the bases is the genetic code!

Coincidence? The order of the bases is the essence of DNA. The order of the amino acids is the essence of a protein.

What is a gene? A gene is a tiny segment of DNA that contains the information to make a product.

What is a gene? A gene is a tiny segment of DNA that contains the information to make a protein.

Central Dogma Arrows represent the transmission of genetic information. m

Nucleic Acids DNA = deoxyribonucleic acid RNA = ribonucleic acid Both molecules are found in all living things.

What is RNA?

Base pairing: G=C A=U

DNA- permanent (All of your DNA is present in all of your cells, all of the time) RNA- RNA molecules are small, transient, carriers of genetic information.

The DNA unwinds and the genetic information is copied into RNA form.

The mRNA and the DNA are base-pairing. The order of bases in the genetic code is maintained.

Translation = production How to make a protein

Absolute- The genetic code is a triplet code.

It was suggested in the 1960s that a ‘bilingual molecule’ must exist. Why? DNA/RNA > protein It does exist- It is the tRNA.

Transfer RNA

They are everywhere!

Where proteins are produced- the Ribosome

Formation of the protein- joining of the first two amino acids:

The shift= translocation

The genetic code is universal (plant, animal, microorganism). The genetic code list mRNA codons and the amino acid each codon specifies.

____AUG nt.... UAG ___ How many amino acids are found in the protein encoded by this mRNA?

DNA animations See

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Mutation! A change in the genetic code of a DNA molecule is a mutation. Its physical!!

Mutation: 1 change in the DNA ==> 1 change in the mRNA ==> Can produce a change in a particular protein. One amino acid change “may” be fatal.

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Mutations that add nucleotides or lose nucleotides from a gene are called frameshift mutations

Human genetic diseases are often caused by a change of one amino acid in a particular protein: Sickle-cell anemia The sixth amino acid in the normal protein is glutamic acid, while sickle beta chain has valine in its place. This is the sole difference between the two.

Types of Mutation Spontaneous mutation- occurs as a result of natural processes in cells Induced mutation- caused by mutagens, substances that cause a much higher rate of mutation

Mutagen A mutagen is a natural or human-made agent which can alter the structure or sequence of DNA.

Types of mutagens Chemical mutagens There are over 70,000 man made chemicals available commercially, including fertilizers, preservatives, pesticides herbicides, drugs, etc. that we may ingest. Many natural compounds that may occur in our air, food and water are also potential mutagens.

Types of Mutagens Radiation (X-rays and others) Natural sources: cosmic rays from the sun and outer space, radioactive elements in soil and terrestrial products (wood, stone) and in the atmosphere (radon) Artificial sources of radiation which contribute to our radiation exposure. Among these are medical testing, nuclear testing and power plants, and various other products (TV's, smoke detectors, airport X-rays).

DNA repair systems Because DNA damage occurs spontaneously and as a result to ubiquitous environmental agents, most organisms possess some capacity to repair their DNA.