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DNA Replication & Protein Synthesis 1DNADeoxyribonucleic Acid (DNA) is found in what part of the cell?

Nucleus

What is DNA made of?Monomers called Nucleotides (Biochemical group Nucleic Acid: 3 parts: Sugar (deoxyribose)Phosphate groupNitrogen baseNUCLEOTIDESNamed for the base it containsLooks like:Sugar-----------Adenine |phosphateTHIS IS AN ADENINE NUCLEOTIDE4 different Nitrogen BasesNitrogen-containing base Adenine, Guanine=Purine Cytosine, Thymine= Pyrimidine

A nucleotide

DNA Structure 2 Nucleotide monomers are linked by a bond between the SUGAR of one nucleotide & the PHOSPHATE of the next nucleotide. (Dehydration Synthesis using an enzyme)More monomers are added on the end to form a long polymer

Monomers are linked on the end to form a Single Long StrandThis backbone formed by linking sugar to phosphate forms the sides of the DNA ladder: the STRONG, backbone of the DNA strand (polymer) But DNA is double stranded- How are the 2 DNA strands held together?Pairing of nitrogenous bases(by hydrogen bonds)! The steps of the ladder are the same distance across- ALWAYS a purine (2 ring) with a pyrimidine (1 ring) Adenine (pur) pairs with thymine(pyr); Guanine (pur) pairs with cytosine (pyr)Bases Bond to Join 2 DNA Strands (polymers)Joined pairs of nucleotides are called base pairs (PO4) | Sugar----A---T----Sugar | (PO4)MORE ABOUT THE BASESAdenine always bonds to thymine

Cytosine always bonds to guanineAdenine Thymine (A-T)

Cytosine-Guanine (C-G)

DNA is a Double Stranded MoleculeThe four bases (ATGC) form complementary pairs in the double helix.This means that: A always pairs with T. G always pairs with C.

Double stranded DNA..If one strand is ACGCAATTGCATTThe other is TGCGTTAACGTAA This also makes it possible for DNA copy its selfBUT THERES MOREThe DNA molecule isnt flat, its 3-D!!!

The whole thing coils to look like a spiral staircase

What are Chromosomes?Structures the DNA forms (with proteins) to allow ALL of it to fit in the nucleusAll the DNA from 1 of our cells is 6-1/2 FEET long!!!Our cells have 23 different pairs of chromosomes- 46 total.These store ALL the genetic information to make YOU!!!! What has to happen before a cell divides? All the DNA has to be copied, so there will be 2 sets of chromosomes in the cellThis way, BOTH daughter cells (after division) will contain the SAME genetic information as the parent cell. How does Replication happen?DNA strands separate at the origin & the DNA unzipsEnzymes (protein machines) match free nucleotides to each parent strand & bonds them to the backbone of the newly synthesized strand.Initiation of Replication

Semi-conservative ReplicationReplication is like making a second identical copy of each DNA strand. The 2 strands separate, and each is copied separately. This makes 2 double stranded molecules that have one parent strand and one new strand. This is called Semi-Conservative Replication. Each new Daughter DNA has 1 copy of parent DNA (dk blue) and one new strand of DNA (light blue).

Summary:DNA replication results in 2 identical copies from 1 original.Each daughter DNA contains 1 parent strand and 1 new strandBecause base pairing is always complimentary (A-T; G-C), replication enzymes can use the parent strand as a template. Fill in the Newly synthesized Strand.A T C G T G G C T A ATTGGCC. T CCGG.What is the role of DNA?Store ALL the information The material genes are made ofGene - segment of DNA that carries the information necessary to make a protein.How is the information stored? - The order of the DNA bases!!Genes, contA gene is usually thousands of bases long!Because a gene is a series of DNA bases that codes for a protein, the information for the protein is encoded in the sequence (order) of the four DNA bases, ATGC.The DNA in a single human cell = 3,000,000,000 bases (3 billion)

However, scientists were surprised that there are only about 30,000 genes!!

How is the information used by the cell? It needs to change languages to a form the cell uses to do work- PROTEINSBut first, the gene needs to be COPIED! Transcription Genetic information in DNA is copied to mRNA.Where does it happen?What is mRNA? Why is it necessary? 32Answers:Nucleusmessenger RNANeeded to transport coding info from the nucleus to the ribosomes.

How is RNA different from DNA?RNA= ribonucleic acid; Ribose sugar; phosphate; nitrogen baseAdenine, Guanine, Cytosine, and URACIL (base pairs= C-G; A-U)Single Stranded

Transcription has three main phases:InitiationElongationTermination

Initiation RNA polymerase binds to DNA at the START sequence (Promoter) & DNA uncoilsElongation Complimentary nucleotides are added along the sense strand363. Termination When it reaches the stop sequence in the DNA, the RNA polymerase is released from DNA

38Transcription Animationhttp://www.johnkyrk.com/DNAtranscription.html

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf

mRNA Splicing Non-coding sequences (introns) are removed and coding (exons) are spliced together to make mature mRNA

40Overview of Protein Synthesis

Transcribe! Write the DNA sequence of a gene (at least 36 nucleotides long.) Transcribe the sequence of the gene into mRNA

What happens next- TRANSLATIONWhat do you do when you go from one language to another? You TRANSLATE!Languages? nucleic acid is translated to amino acid (protein)43Translation, cont.Key Players: mRNAtRNA (transfer RNA)RibsosomesAmino acidsWhere does it happen?The CYTOPLASMmRNA is the instructions for building the proteinHow is the info stored? In the order of the bases!!! (A,C,U,G)Translation takes place on the ribosomes (machine that makes the protein)tRNA (transfer RNA) reads the nucleic acid and supplies the CORRECT, corresponding amino acidCODONThese serve as the words in the genetic codeA codon is made up of three nucleotide bases (A, U, G, C).Each codon specifies an amino acid (MONOMER) in the protein being made (POLYMER)The codon is read by the tRNA anticodon and the correct amino acid is linked to the growing polypeptide chain46

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Quick QuizThe process where genetic information is copied from DNA to mRNA is called ___________.List 3 differences between DNA and RNAList the 3 phases of transcription.Write the complimentary RNA sequence for the following DNA sequence:AAGGCCTTAGACTGT

Quick Quiz, contThe process of synthesizing a protein FROM the mRNA is called ________________.How many nucleotides in a codon?The anticodon is part of the _________.The codon is part of the ___________.What machine is necessary for translation to take place? What is the monomer of a protein?