DNA

DNA Vocabulary 0 DNA: Deoxyribonucleic acid 0 Trait: Inherited characteristic that DNA codes for 0 Heredity: The passing of traits from one generation to the next. DNA controls heredity

Discovery of DNA 0 Frederick Griffith: When he combined harmless bacteria with heat-killed deadly bacteria the harmless bacteria killed the mice. 0 This is known as transformation

Discovery of DNA 0 Oswald Avery: Used the scientific method to alter Griffith’s experiment to test the bacteria. He was able to determine that … 0 DNA IS THE TRANSFORMING MATERIAL!

Discovery of DNA 0 Alfred Hershey and Martha Chase: They saw that viruses had to inject their genetic material into bacteria in order to replicate. The genetic material was DNA.

Discovery of DNA 0 Rosalind Franklin: Took pictures of DNA which gave a clue to the structure of DNA.

Discovery of DNA 0 Frances Crick and James Watson: Saw Franklin’s image of DNA and recognized the helical shape. They were able to build models of the DNA structure and match it to Franklin’s images. Franklin got no credit at the time.

The Structure of DNA 0 DNA is made up of monomers of nucleotides. 0 A polymer of nucleotides make up a DNA molecule 0 A nucleotide is made up of 0 A phosphate group 0 A deoxyribose (sugar) 0 A nitrogenous base (Adenine, Thymine, Guanine, Cytosine)

The Structure of DNA 0 There are two strands of DNA in each DNA molecule 0 The sides of the strand are connected by the sugar and phosphate which alternate 0 This makes up the “sugar phosphate backbone” 0 In the center of the double backbone are the nitrogenous bases

The Structure of DNA 0 The backbones run in opposite directions 0 It is called Anti-Parallel 0 The phosphate side is known as 5’ (5 prime) 0 The other side is known as 3’ (3 prime) 0 One side of the backbone runs from 5’ to 3’ 0 The other side runs from 3’ to 5’

Base Pairing 0 There are two types of nitrogenous bases 0 Purines 0 Adenine and Guanine 0 Pyrimidines 0 Thymine and Cytosine

Base Pairing 0 A purine bonds to a pyrimidine 0 So… 0 Adenine bonds with Thymine 0 Guanine bonds with Cytosine

The Structure of DNA 0 The anti-parallel strands cause the DNA to become a double helix 0 This was discovered by Watson and Crick

Genes and Chromosomes 0 Gene: A sequence of nitrogenous bases which code for a trait 0 Chromosome: Strand of DNA 0 Each DNA molecule contains many genes 0 Each DNA molecules makes up a chromosome 0 Each cell in our body contains 23 pairs of chromosomes 0 Each chromosome contains many genes!

DNA Replication

Replication 0 DNA can make a copy of itself 0 When its done, each daughter DNA molecule will have one new strand and one original strand 0 Don’t forget, DNA strands run Anti-Parallel

Replication 0 Origin of Replication: Where DNA replication occurs 0 Replication goes in both directions 0 Replication fork: the “Y” shaped region where new DNA strands are created 0 Helicase: Enzyme that unwinds the double helix 0 Polymerase: Enzyme replicates the DNA by adding nucleotides 0 Ligase: Joins the Okazaki fragments of DNA to create a single DNA strand

Protein Synthesis

Lets Recap… 0 DNA contains genes 0 Genes are made up from the sequence of nitrogenous bases 0 There are many genes on one chromosome 0 Genes direct the synthesis of proteins!

Proteins 0 A monomer of a protein is… 0 An amino acid 0 DNA codes for 20 amino acids!

RNA 0 Stands for Ribonucleic acid 0 Still has a 5’ and 3’ side 0 Single stranded 0 Three types of RNA 0 mRNA (messenger RNA) 0 tRNA (transfer RNA) 0 rRNA (ribosomal RNA) 0 Instead of thymine, it has Uracil

Protein Synthesis 0 DNA is TRANSCRIBEDinto mRNA and then TRANSLATED into a protein. 0 Transcription: This is when the base sequence of DNA is copied onto a strand of mRNA 0 Remember… DNA can’t leave the nucleus… so it needs the mRNA to take the information to the ribosomes

Transcription 0 Template Strand: DNA strand that is used to create the mRNA 0 RNA polymerase begins transcribing the DNA at a PROMOTER SITE. 0 Goes from 5’ to 3’ 0 Transcription goes on until the RNA Polymerase comes to a terminator sequence (Stops) 0 Remember… Uracil replaces Thymine in RNA

Practice 0 DNA 3’ A T G A G C C C G T T G 5’ 0 RNA 5’ U A C U C G G G C A A C 3’ 0 DNA 3’ C G C C G A T A C G A T C 5’ 0 RNA 5’ G C G G C U A U G C U A G 3’ 0 DNA 3’ A T G C G T C A G C C G C A 5’ 0 RNA 5’ U A C G C A G U C G G C G U 3’

The Genetic Code 0 Codon: A combination of 3 nucleotides 0 Each codon is specific to an amino acid 0 They’re read from 5’ to 3’ 0 Different codons can code for the same amino acid 0 But… each codon specifies only ONE amino acid 0 Helps to protect our genes from mutations

Translation 0 Translation: interpreting the mRNA and building a protein (translating the information) 0 tRNA: Transfers(brings in) amino acids to a ribosome to form a polypeptide 0 One side attaches to the amino acid 0 The other side is the anti-codon 0 rRNA: Brings the tRNA together with the mRNA 0 Read from 5’ to 3’

Interpreting the Genetic Code 0 Translation beings at the START codon, and ends at a STOP codon.

Mutations 0 A change in the DNA 0 Mutations can lead to cancer 0 Chemicals, radiation, mistakes during DNA replication 0 The sequence of codons is important in order to create the correct protein 0 Example: “The car was won” but if you start at the wrong point “Hec arw ont”

Mutations 0 Point mutation: A single nucleotide base change 0 Base pair insertion: Addition of nucleotide pairs 0 Base pair deletion: Loss of nucleotide pairs 0 Frameshift Mutation: alters the reading frame