DNA-The code of life Why don’t we all look alike?

CODON 3 LETTER GROUPING OF NITROGEN BASE PAIRS AGC ATT

WARM-UP #7

Why do we Study DNA? 1.Disease 2.Better vegetable, fruit, and animals. 3.Crime 4.History of life

DNA Facts One chromosome has million base pairs. DNA is found in the mitochondria. mDNA is only found in the egg. Sperm has no mitochondria so mDNA is passed to offspring from the mother. One sequence of DNA is a genome or gene. Unwind all our DNA, it will stretch from the moon and back 6000X.

Gene: segment of DNA on your chromosomes that determines your traits. Trait: characteristics about you. It can be a part or a behavior. You inherited your traits from your parents. What is the human genome?

Genetic material of cells… GENES – units of genetic material that CODES FOR A SPECIFIC TRAITGENES – units of genetic material that CODES FOR A SPECIFIC TRAIT Called NUCLEIC ACIDSCalled NUCLEIC ACIDS DNA is made up of repeating monomers called NUCLEOTIDESDNA is made up of repeating monomers called NUCLEOTIDES

DNA (Deoxyribonucleic Acid)

A HISTORY OF DNA DNA double helixDiscovery of the DNA double helix A. Frederick Griffith – Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928) B.Rosalind Franklin - X-ray photo of DNA. (1952) C.Watson and Crick - described the DNA molecule from Franklin’s X-ray. (1953)

Discovery of DNA Rosalind Franklin - Invented X-ray diffraction photography. Photo used to determine the shape of DNA is spiral.

DISCOVERY OF DNA James Watson and Francis Crick used the information from Franklin and other scientists to build a 3-D model of DNA. Won the Nobel Piece Prize in Chemistry in 1961.

Watson & Crick proposed… DNA had specific pairing between the nitrogen bases:DNA had specific pairing between the nitrogen bases: ADENINE – THYMINE CYTOSINE - GUANINE DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule”DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule”

DNA DNA stands for – Functions of DNA: 1. Carries the codes to make proteins. Deoxyribonucleic acid 2.Pass on genes/traits from parent to child

STRUCTURE OF DNA These three parts form the basic unit of DNA called the NUCLEOTIDE. phosphate Sugar (deoxyribose) Nitrogen base Can be A, T, C or G

STRUCTURE OF DNA Side Pieces(The Rope Part) Are alternating units of a 5 carbon sugar and a phosphate group. These go down both sides of the molecule phosphate Sugar (called deoxyribose)

STRUCTURE OF DNA Nitrogen Bases (Steps of the ladder) - The bases are connected to the sugar only !!!!! 1.Adenine - A 2.Thymine – T 3.Cytocine – C 4.Guanine - G

DNA Nucleotide O O=P-O OPhosphate Group Group N Nitrogenous base (A, G, C, or T) (A, G, C, or T) CH2 O C1C1 C4C4 C3C3 C2C2 5 Sugar Sugar(deoxyribose)

phosphate sugar thymine adenine cytocine guanine

How are the nucleotides held together? Nucleotides are held together by covalent bonds between the sugar of one nucleotide and the phosphate of the next.

DNA

DNA Double Helix Nitrogenous Base (A,T,G or C) “Rungs of ladder” “Legs of ladder” Phosphate & Sugar Backbone

Nitrogenous Bases A + T = 2 bonds; C + G = 3 bondsA + T = 2 bonds; C + G = 3 bonds PURINESPURINES Adenine (A) 1.Adenine (A) Guanine (G) 2.Guanine (G) PYRIMIDINESPYRIMIDINES Thymine (T) URACIL for RNA 3.Thymine (T) URACIL for RNA Cytosine (C) 4.Cytosine (C) T or C A or G

BASE-PAIRINGS 2 Bonds CG H-bonds T A 3 bonds

STRUCTURE OF DNA One complete turn of the double helix is 10 base pairs or 10 steps on the ladder

DNA Double Helix P P P O O O P P P O O O G C TA

Chargaff’s Rule Adenine ThymineAdenine must pair with Thymine GuanineCytosineGuanine must pair with Cytosine about the sameTheir amounts in a given DNA molecule will be about the same. G C TA

Chargaff’s Rule Chargaff discovered that the percentage of A and T were equal. The same for C and G. This observation became Chargaff’s rule. This is always the same no matter what organisms.

Genetic Diversity… Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

The Code of Life… The “code” of the chromosome is the SPECIFIC ORDER that bases occur.The “code” of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G…

DNA is wrapped tightly around histones and coiled tightly to form chromosomes See p. 297

How does DNA copy itself? Purpose: DNA copies itself to ensure that each new cell that is produced in gets the correct number of chromosomes and receives an EXACT copy of the DNA molecule. Replication must occur before cell division.

This is called DNA REPLICATION. The DNA molecule serves as its own pattern or template so as an exact copy can be made.

Watson and Crick The model that Watson and Crick where the nitrogen bases pair suggested a mechanism for DNA to replicate.

Messelson and Stahl They proved that DNA is semiconservative by attaching radioactive material to DNA. As the cell divided, they observed the new DNA in each cell and saw that it contained half of the old. Semiconservative: contains half of the old strand when DNA is replicated.

STEPS OF DNA REPLICATION 1. Helicase begin to unzip the double helix at many different places. The hydrogen bonds between the bases are broken. Occurs in two different directions. 2. Free floating in the cytoplasm nucleotides pair with the bases on the template. DNA polyermase bonds together the nucleotides. Small segments are bonded together.

3.Two identical strands of DNA result. The DNA will twist back together. DNA is called SEMICONSERVATIVE because it uses an old strand to make a new one. This results in 2 new identical DNA molecules.

DNA Replication Video h?v=zdDkiRw1PdU&feature= player_embedded

DNA Replication Fork Point where DNA is split apart to replicate. Forms a Y!

Role of Enzymes 1. Helicase unzips the two DNA strands. 2. DNA polymerase is the enzyme that joins individual nucleotides to produce a new strand of DNA. Proofreads DNA when finished!

DNA Replication in Prokaryotic Cells 1. Proteins binds to starting point. 2. Starts at a single point and proceeds in both directions.

Eukaryotic Replication Since eukaryotic cells are so much bigger, the replication will start at dozens to hundreds of different places on the DNA.

DNA REPLICATION What if there is a mistake? There is always a chance that the wrong nucleotide bonds to another. HOWEVER, DNA polymerase is responsible for “reading” the bases and recognizing and replacing damaged or wrong nucleotides. This PROOFREADING allows for only one (1) error in ONE BILLION nucleotides.

DNA Fingerprinting When DNA is found at a crime, the DNA is replicated many times to make enough to test. Once they have fingerprinted it, they can compare to find suspect. Video +crime+scene&view=detail&mid= C024AD0C C024AD0C7 97&first=21&FORM=LKVR22&adlt=strict

DNA Fingerprinting

Speed of DNA Replication In the human cell, 50 nucleotides can be added every second. It would that several days for replication to occur if the DNA did not start at several spots on the DNA so that it is occurring in many places on the DNA strand.

Transciption – Making of RNA Transcription – process of copying DNA to produce a complimentary strand of RNA. Transcription is making RNA from DNA Purpose = to make RNA that is complimentary to the DNA

Types of RNA There are three (3) types RNA: 1. Messenger RNA – (mRNA) carries messages from the DNA in the nucleus to the cytoplasm. 2. Transfer RNA – (tRNA) 20 different kinds which are only able to bond with one (1) specific type of amino acid.

Types of RNA 3. Ribosomal RNA – (rRNA) major component (part) of the ribosomes

RNA TRANSCIPTION Transcription – the process by which DNA makes RNA. Steps in RNA Transcription: 1.A special enzyme tells DNA its time to make RNA. 2.The enzyme tells the nucleotides to only bond with RNA nucleotides. -The code letters for RNA are: A, C, G and U.

RNA TRANSCIPTION 3. Process occurs just like DNA replication --When complete, only a single strand of RNA is formed UNLIKE DNA’s double strand. --All three types of RNA are formed this way. --All leave the nucleus and travel out into the cytoplasm.

Transcription Video scription&view=detail&mid=EE2661D8806 7BDEFF3E7EE2661D88067BDEFF3E7&fi rst=0&FORM=LKVR8&adlt=strict

RNA TRANSLATION Definition=Protein Synthesis: the formation of a protein using information coded on DNA and carried out by RNA in the assembly of amino acids. Proteins are: a.Amino acids in chains – 20 kinds b.Made of 10’s or 100’s or 1000’s of amino acids c.Must be arranged in a specific sequence for each type of protein d.Function & type of protein is determined by amino acid sequence e.DNA makes RNA f.RNA orders the amino acids

RNA TRANSLATION Translation Process : 1.mRNA goes to the ribosomes, tRNA goes to the cytoplasm. 2. tRNA picks up amino acids& brings them to the ribosome. 3. mRNA tells tRNA in which sequence to assemble the proteins. (mRNA is the template!) 4. An amino acid chain is a protein.

RNA TRANSLATION So WHAT?? : RNA makes amino acid chains Proteins make cells DNA makes RNA Amino acid chains make proteins

Go to gslc.genetics.utah.edu/units Translate & Transcribe a Protein and What is a Protein?

Translation Groups of 3 nucleotides on the mRNA code for each amino acid to build a protein. These groups of 3 are called: CODONS The tRNA brings the correct amino acid to the chain. You will build your own proteins tomorrow with the mRNA that you made yesterday!

We have been told that DNA is the blueprint for life, BUT what does that mean? DNA holds the instructions that tell a cell how to construct amino acid chains. That is important because amino acid chains build proteins. AND Proteins build cells

Steps to Protein Synthesis 1. DNA replication – make new DNA 2. Transcription – DNA message given to RNA 3. Translation – RNA is translated in amino acid chains(protein).

Prokaryotic - Protein synthesis Location – cytoplasm At the same time. Eukaryotic – Protein synthesis

SO, HOW DOES AN AMINO ACID CHAIN GET BUILT? RNA stands for ribonucleic acid It differs from DNA in three ways: 1. RNA is single stranded. 2. The sugar in RNA is called ribose. 3.Uracil is one of the bases in RNA. There is NO thymine in RNA. This means A goes with U and G still goes with C. Well, first we have to make something called RNA

DNA Replication Replication: coping of DNAReplication: coping of DNA The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing:The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing: A-T, G-C Each strand of the original DNA serves as a template for the new strandEach strand of the original DNA serves as a template for the new strand

Semiconservative Model Replication is called semiconservation because one strand of DNA is used to as a template to make the new DNA.

Steps of DNA Replication 1.DNA unzips and the hydrogen bonds between the nitrogen bases pulled apart. The base pairs are separated and are left exposed. This occurs in two different directions. This occurs along hundreds of different places at a time.. Parental DNA DNA Template New DNA

Steps of Replication 2. Free-floating nucleotides are paired up to the free nucleotides. DNA polymerase bond the nucleotides together. 3.Two identical strands result. DNA polymerase checks for mistakes when complete.

DNA Replication DNA has 80 million base pairs in a chromosomes. DNA is copied at about 50 base pairs per second. This would take a month if replication did not occur at hundreds of different places at once.

1. Why is replication necessary? 2. Describe how replication works. 3. Use the complementary rule to create the complementary strand: A--- ? G--- ? C--- ? T--- ? A--- ? G--- ? A--- ? G--- ? C--- ? A--- ? G--- ? T--- ? Replication Quiz

1. Why is replication necessary? So both new cells will have the correct DNA 2. When does replication occur? During interphase (S phase). 3. Describe how replication works. Enzymes unzip DNA and complementary nucleotides join each original strand. 4. Use the complementary rule to create the complementary strand: A--- T G--- C C--- G T--- A A--- T G--- C A--- T G--- C C--- G A--- T G--- C T--- A Replication Quiz

(1961) Watson & Crick proposed… …DNA controlled cell function by serving as a template for PROTEIN structure.…DNA controlled cell function by serving as a template for PROTEIN structure. 3 Nucleotides = a triplet or CODON3 Nucleotides = a triplet or CODON (which code for a specific AMINO ACID) See p.303 AMINO ACIDS are the building blocks of proteins.AMINO ACIDS are the building blocks of proteins.

DNA Transcription DNA can “unzip” itself and RNA nucleotides match up to the DNA strand.DNA can “unzip” itself and RNA nucleotides match up to the DNA strand. Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids. See p.301

DNA Translation The cell uses information from “messenger” RNA to produce proteinsThe cell uses information from “messenger” RNA to produce proteins See p We will discuss details of this on a later date

Types of Nitrogen Base Pairs DNA 1.Adenine w/ thymine 2.Cytosine w/ guanine RNA 1.Uracil w/adenine 2.Cytosine w/guanine

CAUGCA

Transcription/Translation Quiz 1.identify the amino acids coded for by these codons: UGGCAGUGC ACCGUCACG

1. Why is transcription necessary? Transcription SIGNALS messenger RNA (mRNA) to carry the code for proteins out of the nucleus, to the ribosomes in the cytoplasm. 2. Describe transcription. RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA. 3. Why is translation necessary? Translation assures that the right amino acids are joined together by peptides to form the correct protein.

4. Describe translation. The cell uses information from MRNA to produce proteins. 5. What are the main differences between DNA and RNA. DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil. 6.Using the chart on page 303, identify the amino acids coded for by these codons: UGGCAGUGC tryptophan-glutamine-cysteine

7. WHAT ORGANELLES ARE INVOLVED IN TRANSCRIPTION?

AMAZING DNA FACTS… DNA from a single human cell extends in a single thread for almost 2 meters long!!!DNA from a single human cell extends in a single thread for almost 2 meters long!!! It contains information equal to some 600,000 printed pages of 500 words each!!!It contains information equal to some 600,000 printed pages of 500 words each!!! (a library of about 1,000 books)

LET’S REVIEW DNA… LM p.44 1.List the conclusions Griffith & Avery, Hershey & Chase drew from their experiments. 2.Summarize the relationship between genes & DNA. 3.Describe the overall structure of the DNA molecule. 4.What are the 4 kinds of bases?

Reading Questions: 1.Are RNA Polymerase the same as DNA polymerase? 2.What role do “Promoters” have in transcription? 3.

SNORK ACTIVITY DIRECTIONS TURN TO THE “DNA, RNA & SNORKS” PAGE IN PACKET: READ THE 2 PARAGRAPHS ABOVE THE TABLE, AND THE 3 RD PARAGRAPH BELOW THE TABLE.

AUA, UCG, GGC, UAU