GENETICS

Objectives: Objective 10- Identify the differences between DNA & RNA. Objective Identify the mechanisms through which DNA can be mutated.

Objective 10 Vocabulary terms Base pair GuanineNucleotideTranslationReplicationAdenineCytosineThymineTranscription Amino Acid

There were many scientists who contribute to the findings of the DNA structure. Let’s review a few. Erwin Chargaff- was a biochemist that found that the amount of Adenine always equal the amount of thymine. Guanine always equal cytosine. His findings are known as Chargaff rules.

Rosalind Franklin Was a chemist that was able to capture the images of DNA molecules on X-ray. She was a woman in the science field that they (colleagues)didn’t respect her ideas. Her colleagues didn’t think women had ideas worth listening to and they didn’t give her work the credit she was due. In fact if they all worked together they could have founded the structure a lot sooner.

Watson, Crick, and Wilson After seeing images that Ms. Franklin had taken in her lab, they concluded that DNA resembles a twisted ladder shape know as a double helix. They were given the Nobel prize for identifying the structure of DNA. They used this model to predict how DNA is copied.

Double Helix The spiral arrangement of two complementary strands of DNA. Let’s learn what I mean about Complementary.

In a DNA molecule, the shapes of the bases cause the bases to pair in a certain way. Cytosine always pairs with Guanine. Adenine always pairs with Thymine.

There are two types of nucleic acids called DNA and RNA. DNA stands for deoxyribonucleic acid. DNA is the genetic material- the material that determines inherited characteristics. A strand of DNA looks like a twisted ladder( double helix structure) DNA is copied every time a cell divides. DNA has a specific code for making all proteins the cell needs. The proteins are made of amino acids.

Bases of DNA: adenine, thymine, cytosine, guanine. Bases of RNA: adenine, URACIL, cytosine, guanine. (Uracil replaces thymine in RNA)

The difference between DNA and RNA are: DNA is deoxyribonucleic acid, and exact copies of a set of DNA are found in each cell of an organism. RNA is ribonucleic acid, which is similar to DNA but is used to carry copies of DNA code around the cell and to build proteins based on this code.

DNA is double stranded and stays inside the nucleus. RNA is single stranded and moves from the nucleus into the cytoplasm DNA has 5 deoxyribose sugar while RNA has 5 ribose sugar molecule.

RNA- ribonucleic acid, a molecule that is present in all living cells and that plays a role in protein production.

The subunits of nucleic acids are called nucleotides which are made up of the elements carbon, oxygen, hydrogen, nitrogen, and phosphorus. A nucleotide consists of a sugar, a phosphate, and a base. A nucleotide consists of a sugar, a phosphate, and a base.

Nucleotide- in a nucleic-acid chain, a subunit that consists of a sugar, a phosphate, and a nitrogenous base. The four types of nucleotides are: adenine, thymine, guanine, and cytosine adenine, thymine, guanine, and cytosine

The four bases are adenine, thymine, guanine, and cytosine. Each base has a different shape.

Making proteins requires two basic steps: Transcription and translation Transcription-is the synthesis of mRNA from a DNA template. Adv.

It is similar to DNA replication in that a DNA strand is used to make a strand of mRNA. Next, the mRNA is transferred to ribosomes by the tRNA where translation occurs. Adv

Translation -is the process where ribosomes synthesize proteins using the mRNA transcript produced during transcription. Adv

Transfer RNA A small RNA molecule, consisting of a strand of nucleotides folded into a clover leaf shape, that picks up an unattached amino acid within the cell cytoplasm and conveys (carries) it to the ribosome for protein synthesis. Abbreviation: tRNA ADV

Messenger RNA An RNA produced by transcription that carries the code for a particular protein from the nuclear DNA to a ribosome in the cytoplasm an acts as a template for the formation of that protein. Also called mRNA adv

Replication – make copies of the DNA DNA copies are made by splitting the molecule down the middle and then adding new nucleotides to each side. Adv

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Mutations

Mutations occur when there is a change in the order of bases in a organism’s DNA.

Mutation- a change in the nucleotide-base sequence of a gene or DNA molecule.

Example of mutation

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Three types of changes can occur in the order of bases in DNA: substitution, insertion and deletion.

1. deletion (a base is left out) 2. insertion (an extra base is added) 2. insertion (an extra base is added) 3. substitution (most common) (wrong base is used) 3. substitution (most common) (wrong base is used)

Sickle cell anemia is caused by a mutation( substitution) in a single nucleotide of DNA, which then causes the wrong amino acid to be assembled in a protein used in blood cells.

Changes in the order of bases in DNA can occur through errors when the DNA is copied or damaged by physical or chemical agents called mutagen

Remember: Radiations causes mutations. Mutations can be helpful, harmful or have no effect on the organism.

A MUTAGEN is a substance that can cause a mutation in DNA. Examples of mutagens include high-energy radiation from X rays and ultraviolet radiation (sun), asbestos, and the chemicals in cigarette smoke