Honors: Ch. 10 Pg. 180 Academic: Ch. 12 Page 286 DNA & REPLICATION Honors: Ch. 10 Pg. 180 Academic: Ch. 12 Page 286

1. 2. 3. 4.

DNA DNA= DEOXYRIBONUCLEIC ACID Found in the Nucleus of eukaryotic cells. Primary Function= to store and transmit the genetic information that tells cells which proteins to make and when to make them. “Blueprints”

DNA IS…. An ORGANIC compound = NUCLEIC ACID Made up of repeating subunits called NUCLEOTIDES Composed of TWO long chains of nucleotides.

DNA (& RNA) polymers of Nucleotides Three subunits: 1) Sugar molecule -Deoxyribose 2) Phosphate Group (P and O) 3) Nitrogen Base (can be 1 of 4) Guanine Cytosine Adenine Thymine

Circle the Nucleotide… NU C L E O T I D E S Circle the Nucleotide…

NU C L E O T I D E S Nucleotides come together in long chains. The Nucleotides are held together by covalent bonds. The 2 chains of DNA are held together by hydrogen bonds between the nitrogen bases= “BASE PAIR RULE”

C DNA 1) The 3 parts that make up a nucleotide include? A) Sugar, nitrogen base, RNA strand B) Sugar, Phosphate gp, DNA strand C) Sugar, Nitrogen Base, Phosphate gp D) None of the above C

A DNA 2) Nitrogen base pairs are held together by what type of bond? A) Hydrogen Bond B) Covalent Bond C) Ionic Bond A

DNA 3) According to the rules of complimentary base pairing, Adenine (A) can only bond with what other base? A) Cytosine © B) Thymine (T) C) Guanine (G) D) Adenine (A) B

D DNA 4) Where is DNA located in Eukaryotic Cells A) Cytoplasm B) Mitochonria C) Chloroplast D) Nucleus D

C DNA 5) What type of organic compound is DNA? A) Lipids B) Proteins C) Nucleic Acids D) Carbohydrate C

DNA 6) How many letters are in DNA’s alphabet? A) 1 B) 2 C) 3 D) 4 D

B DNA 7) The primary function of DNA is to: A) Make proteins B) Store and transmit genetic information C) control chemical process within the cell D) prevent mutations B

DNA 8) True or false: In a DNA molecule the nucleotides are held together by Hydrogen bonds. A) True B) False B

B A S E S: A T C G The Nitrogenous Bases are known by their coded letters A, G, T, C.

Nitrogenous bases come in two types: 1 . PURINES PURINES have TWO rings. Come in TWO types: 1. Adenine 2. Guanine

1. Cytosine 2. Thymine Nitrogen bases come in two types: 2. PYRIMIDINES PYRIMIDINES have ONE ring. Come in TWO types: 1. Cytosine 2. Thymine

Complementary Base-Pairing: Describes the pairing behavior of the bases. TWO rules: 1. Cytosine bonds with Guanine 2. Adenine bonds with Thymine

Sugar-Phosphate Backbone QUICK QUIZ: G pairs with C T pairs with A ? Bond Hydrogen Bond ? Sugar-Phosphate Backbone ? Bond Covalent Bond

DNA is a double-stranded helix Hydrogen bonds connect the nitrogenous bases holding the two strands of DNA together The A’s on one strand Hydrogen bond to the T’s on the other, likewise for G’s and C’s. (Nitrogen bases= H-bond) Base pairing explains the % A’s = % of T’s

WHY IS IT IMPORTANT?!?! Why is it important that the sides are strong (covalent bonds) & the middle is weak (hydrogen bonds)???

They helped determine that DNA= double stranded Important People!!! They helped determine that DNA= double stranded Erwin Chargaff’s Rules: % of guanine (G) and cytosine (C) are nearly equal in DNA of many species the same for % of thymine (T) and adenine (A). X-Ray Evidence Rosalind Franklin took X-ray images of DNA. Showed that the strands of DNA are twisted. The Double Helix Model Francis Crick and James Watson

The Double Helix In 1953, JAMES WATSON & FRANCIS CRICK suggested a model for the structure of DNA. Two nucleotide strands wrap around each other to form a double spiral. (spiral staircase).

DNA is a double-stranded helix DNA makes up 1% of our body weight. One cell = 3 meters of DNA. Typed out in times 12 pt font your entire DNA sequence would fill enough paper that when stacked would reach the top of the Washington Monument in D.C.

DNA Replication DNA is copied through a process= DNA replication. Each strand of the double helix has all the information needed to reconstruct the other half through “base-pairing” Because each strand can be used to make the other they are referred to as “complementary”

DNA Replication DNA Replication= the process of copying DNA. Video DNA Replication= the process of copying DNA. The semi conservative model: when a double helix replicates, each of the 2 daughter molecules will have 1 old strand (parental or template) and 1 new strand. Parent Daughter

DNA Replication You are left with 2 IDENTICAL molecules of DNA double helix! Original New New Original Original strands of DNA O N N O Semi-conservative Model

WHY IS IT IMPORTANT?!?! Why is it important that the sides are strong (covalent bonds) & the middle is weak (hydrogen bonds)???

1. 2. 3. 4. Transfer of genetic information from DNA to RNA Transfer of genetic information in the RNA to a protein 4.

DNA Replication

Replication Replication takes place in the nucleus of the cell. To get started you need: DNA Free DNA nucleotides Enzymes: 1)Helicase 2) Primase 3) DNA Polymerase 4)Ligase

DNA Replication Helicase – unzipping enzyme Video Step 1: Double helix unzips Replication begins at origins of replication Helicase – unzipping enzyme H-bonds break Replication fork=point at which the 2 strands split Step 2: Each original strand becomes a template strand (white) DNA Primase adds a primer to the end of each DNA strand Complementary bases fill in from the 5’ end to the 3’ end (opposite directions) DNA polymerase – building enzyme – adds new bases one at a time. Step 3: DNA Ligase “glues” together nucleotides on the lagging strand.

DNA Replication 2 distinctive ends: 5' (5-prime) and 3' (3-prime) ends. the 5' end= a phosphate 3' end= a hydroxyl group. **DNA and RNA polymerases add nucleotides to the 3' end of the strand (synthesized in a 5' to 3' direction).

fills in new nucleotide bases DNA Replication Enzyme (Helicase) Unzips T A A G C A T T C G T A A G C New Strands A T T C G T A A G C A T T C G Enzyme (DNA Polymerase) fills in new nucleotide bases

WHY IS IT IMPORTANT?!?! Why is it important that the sides are strong (covalent bonds) & the middle is weak (hydrogen bonds)??? Allows the weak middle to be pulled apart so that the cell can make copies of its DNA.

Replication Despite its speed (50–500 pairs per second), replication is very accurate. It only makes approximately one mistake in every 10 billion nucleotide pairs. Mistakes in the DNA sequences are called mutations. DNA polymerases and DNA ligase proofread the new daughter strands and fix these mistakes.

DNA Replication

1. 2. 3. 4. Transfer of genetic information from DNA to RNA Transfer of genetic information in the RNA to a protein 4.

DNA vs. RNA DNA stores the information for how to make proteins. The 3 billion letter code is read in chunks= GENES. DNA is made via REPLICATION. Genes are coded instructions that control the production of proteins inside the cell. RNA is a copy of 1 gene of DNA. Because DNA is trapped in the nucleus , the RNA is responsible for getting the message of the genes out to the cytoplasm. RNA is made via TRANSCRIPTION.

RNA- Structure Structure of RNA: Made of nucleotides: 3 subunits: 1) Sugar molecule -ribose 2) Phosphate Group (P and O) 3) Nitrogen Base (can be 1 of 4) Guanine Cytosine Adenine Uracil

RNA- Structure & Function STRUCTURE of RNA Single-stranded Nucleic acid made up of repeating units. Sugar molecule is RIBOSE (not deoxyribose) Thymine is replaced with URACIL (U) FUNCTION of RNA Responsible for the movement of genetic information from the DNA (nucleus) to the site of protein synthesis in the cytoplasm.

3 TYPES of RNA Ribosomal RNA (rRNA) Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA) Fill in the RNA strand

1. 2. 3. 4. Transfer of genetic information from DNA to RNA Transfer of genetic information in the RNA to a protein 4.

Transfer RNA (tRNA) transfers each amino acid to the ribosome as the mRNA is read and the protein is built. TYPES of RNA Messenger RNA (mRNA) carries the copy of the instructions to the ribosome. Ribosomal RNA (rRNA) act as the structure for the ribosome. The Gene Scene

T R A N S C I P O RNA is produced by copying part of the nucleotide sequence of DNA into a complementary sequence of RNA, this is called transcription. NUCLEUS

T R A N S C I P O Step 1: Helicase unzips the DNA Step 2: RNA polymerase begins transcription at a DNA sequence called the PROMOTER. Step 3: RNA polymerase builds the complementary RNA Step 4: Polymerase detaches when it reaches a DNA sequence called the TERMINATOR 1st Phase= INITIATION 2nd Phase = ELONGATION 3rd Phase = TERMINATION

RNA Leaves to go to a ribosome Transcription DNA rezips Enzyme (Helicase) Unzips T A A G C RNA Leaves to go to a ribosome T A A G C RNA Strand A T T C G U A A G C A T T C G Enzyme (RNA Polymerase) fills in new nucleotide bases Template Strand

RNA and Transcription Animation

RNA Splicing DNA is composed of both introns and exons Exons are segments of DNA that are expressed as genes Introns are ‘junk DNA.’ They are not expressed and must be removed before the mRNA leaves the nucleus.

I think someone transcribed the wrong gene!

What must happen for Translation to begin? Translation= the process of “interpreting” the code in mRNA to assemble proteins. Converting the 3 letter words of nucleic acids to amino acids, the words of proteins. What must happen for Translation to begin? mRNA leaves the nucleus. mRNA migrates to a ribosome in the cytoplasm. = the site of protein synthesis.

T R A N S L I O The Genetic Code Recall: Proteins are made of smaller pieces called amino acids. The language of mRNA is called the genetic code, the code is read three letters at a time a “word” Each “word” of mRNA is called a codon

T R A N S L I O DNA: AGG – CCG – TAG - GGA mRNA: Amino Acid: UCC – GGC – AUC - CCU Serine– Glycine– Isoleucine– Proline

T R A N S L I O Special CODONS!!! AUG – codes for methionine but is also known as the “Start” codon, this is how the ribosome knows to begin protein synthesis. Stop Codons (use your genetic code to find them) UAA UAG UGA

T R A N S L I O Step 1: A ribosome finds an mRNA strand Step 2: As each codon moves through the ribosome the proper amino acid is brought to the ribosome by a tRNA molecule. The tRNA contains the complementary anti-codon on one end and the amino acid on the other) ANIMATION

T R A N S L I O Step 3: Peptide bonds form between each amino acid Step 4: The stop codon is read and the new protein is released from the ribosome

T R A N S L I O rRNA= Ribosomal RNA A ribosome consists of 2 subunits. Each subunit= 1)Protein 2)rRNA There is an mRNA binding site and a tRNA binding site

Forming Polypeptide Chain Translation Forming Polypeptide Chain Lysine tRNA Anti-codon mRNA Ribosome Codon

Mutations A TAAGTGG T C C C C Mutation – any change in the nucleotide sequence of DNA Mutations can effect anywhere from 1-1000’s of nucleotides Point mutation – occur at a single point. Frameshift mutation- shift the “reading” frame.

MUTATIONS 1) Point Mutations= Substitutions 2) Frameshift Mutations= Insertions (additions) and Deletions DNA DNA T A G A A T C T A T A C T T A G A A A mRNA mRNA A U C U U A G A U A U G A A U C U U U A U G U U A G A U A U C G A A U C U U U

SUBSTITUTIONS: Point Mutations Replacement of one base pair for another Impact on protein synthesis: No impact (if substitution still results in the same amino acid) Nonfunctional protein (if change in amino acid and therefore the protein occurs)

SUBSTITUTIONS- Point Mutations

INSERTIONS & DELETIONS: Frameshift Mutations Insertion – insertion of a base pair in the sequence (shifts all the pairs down one to the right). Deletion – deletion of a base pair in the sequence (shifts all the pairs down one to the left).

INSERTIONS: Frameshift Mutations Notice that the insertion of the base pair has shifted the entire reading frame down – all of the codons after the insertion are different. This usually has disastrous effects on protein synthesis.

DELETIONS: Frameshift Mutations Deletion – deletion of a base pair in the sequence (shifts all the pairs down one to the left).

Insertions and Deletions INSERTIONS & DELETIONS: Frameshift Mutations

Mutations Mutagenesis – production of mutations occurs for many reasons: Spontaneous Mutations occur during replication. Environmental Mutations occur as the result of exposure to a mutagen (physical or chemical agent). Most common are: radiation, tobacco Inherited Mutations are passed down from parents.

MUTATIONS Key Points to keep in mind about mutations !!! Mutations are not always bad – in fact they are often good and are the source of variety in a given population Spontaneous and Environmental Mutations typically occur in one cell in the body – these mutations only effect one area of the body (result in things like cancer) Inherited Mutations occur in every cell in the body – these mutations, if harmful, can result in things like Tay Sachs, Sickle Cell or even ALD.