DNA

A Snapshot of DNA

DNA from a few Angles Cell: Every cell contains a nucleus which is filled with the directions for cell function, DNA. Chromosome: When DNA is tightly coiled and wound it becomes visible in the form of chromosomes. Chromosomes contain our genes which determine our traits. Each chromosome contains over 100 million base pairs (DNA nitrogen bases) Histone: A type of protein which creates a strong bond to DNA allowing it to coil up tightly into chromatin which makes up chromosomes. DNA Double Helix: Composed of a twisted ladder of chromatin. DNA with Nitrogen Bases: There are four nitrogen base pairs that make up the steps or rungs of the DNA ladder: Cytosine pairs with Guanine and Thymine pairs with Adenine. The sides of the ladder are made of phosphate and deoxyribose sugar molecules.

Which is which? CELL DNA DOUBLE HELIX HISTONE DNA W/ NITROGEN BASES CHROMOSOME

A REAL snapshot of DNA

Rosalind Franklin As a physical chemist at King’s College, Franklin studied DNA’s structure using x-ray photography / crystallography alongside Maurice Wilkins. Wilkins was not fond of Franklin but her research was intriguing to him. She proved that the phosphate groups were found on the outside of DNA and she noted the possibility of a helix shape. It was at this time that Wilkins took Franklin’s photographs to Watson and Crick. After publishing many papers and even continuing her research throughout her illness, Rosalind died in 1958 of ovarian cancer.

Watson and Crick DNA Model

Watson, Crick and Wilkins Near Franklin’s college, Watson and Crick worked together at Cambridge trying to determine the structure of DNA. When Wilkins approached Watson and Crick with Franklin’s photographs it became their proof of the double helix structure with two chains of nucleotides going in opposite directions and nitrogen bases in the middle, making the rungs of the ladder. They published their findings in 1953 and in 1962, Watson, Crick, and Wilkins won the Nobel Prize for their discovery. By this time, Franklin had died and she could not receive the prize posthumously.

DNA – deoxyribonucleic acid Resides in the nucleus Shaped like a twisted ladder (Double Helix) Sides of the ladder are made up of sugars and phosphates The steps of the ladder are made of PAIRS of molecules called nitrogen bases. Nitrogen Base + Sugar + Phosphate = NUCLEIC ACID

Nitrogen Bases The are 4 bases AdenineThymine GuanineCytosine PurinesPyrimidines

Purines and Pyrimidines purine pyrimidine

He found the same amount of Adenine and Thymine AND the same amount of Cytosine and Guanine exist in our cells. This provided evidence that certain bases pair with certain bases! He found the same amount of Adenine and Thymine AND the same amount of Cytosine and Guanine exist in our cells. This provided evidence that certain bases pair with certain bases!

Basic Structure

Nucleotide

Proteins Proteins are one of the most important parts of all living things Large, complex molecules that do most of the work in a cell, AND Provide for the structure, function and maintenance of the body’s tissues and organs Made up of amino acids (20 types that combine to make different proteins)

Protein Synthesis Protein synthesis or creation is important for cellular function. Proteins are made of amino acids and our DNA provides the instructions for assembling amino acids in the proper order, thus creating proteins that can do their jobs correctly. The nucleus holds the key for protein synthesis, a process that takes place within every cell of every living thing.

DNA and RNA DNA and RNA work together to make sure the protein synthesis occurs in our cells Both are Nucleic Acids Both have Adenine, Cytosine and Guanine DNA has Thymine but RNA has Uracil

RNA Messenger RNA – carries a message based off of the DNA Transfer RNA – transfer the message Ribosomal RNA – work in the ribosomes to make proteins

REPLICATION When cells of the body divide, the DNA double helix duplicates itself within the nucleus. An enzyme called Helicase unwinds the two strands and the enzyme DNA polymerase reads a the strands and lays down complimentary nitrogen bases. Finally Helicase zips the DNA back up creating TWO daughter strands from one parent strand.

TRANSCRIPTION The synthesis of messenger RNA (mRNA) using DNA as a template. Helicase unzips DNA and RNA polymerase copies the DNA message into a single strand of mRNA where uracil is substituted for thymine as a pair to adenine. mRNA is small enough to leave the nucleus so the DNA message can reach the ribosomes in the cytoplasm.

TRANSLATION The synthesis of protein using mRNA as a template. mRNA travels to a ribosome (rRNA) where it is read in triplets (a codon). Each triplet codes for a specific amino acid which transfer RNA (tRNA) provides. The amino acids link up at the ribosome until an amino acid (polypeptide) chain is created which builds up to make a protein.

Mutations

MUTATIONS What is a mutation? It is a permanent alteration in a sequence of DNA that makes up a gene. Mutations can be so small that they affect a single base pair or so large that it involves multiple genes. Mutations can affect individuals differently depending on where they occur and the type of proteins that are created as a result.

Deletion changes the number of DNA bases by removing a piece of DNA.

Inversion an entire section of DNA is reversed

Translocation a whole chromosome or chromosome segment attaches to another chromosome or segment creating a hybrid.

Insertion increases the number of DNA bases in a gene by adding a piece of DNA

Duplication a piece of DNA that is copied one or more times