DNA & REPLICATION Practical Ch. 12 Page 286

1. 2. 3. 4.

DNA DNA= DEOXYRIBONUCLEIC ACID Found in the Nucleus of eukaryotic cells. Primary Function= 1. Store and transmit the genetic information. 2. Tells cells which proteins to make and when to make them.

DNA IS…. An ORGANIC compound = NUCLEIC ACID monomers of nucleic acids = 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 are linked creating 2 chains. The Nucleotides are held together by covalent bonds. The 2 chains of DNA are held together by hydrogen bonds connecting the nitrogen bases. DNA is a double helix

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

Complementary Base-Pairing: TWO rules: 1. Cytosine bonds with Guanine 2. Adenine bonds with Thymine

They helped determine that DNA= double stranded Important People!!! They helped determine that DNA= double stranded Chargaff’s Rules: % of A’s= % of T’s % of G’s= % of C’s 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 JAMES WATSON & FRANCIS CRICK discovered the model for the structure of DNA.

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 Replication= copying DNA. Location: Nucleus DNA is complementary because you can use 1 side to make the other (complementary base pairs).

DNA Replication Video Original/Parent Semi conservative Model: After replication each new DNA molecules has: An original strand A new strand Original/Parent Daughter

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

Replication Replication : Where_____________ When______________ 4 Enzymes are involved: 1)Helicase 2) DNA Polymerase

DNA Replication Step 1 Helicase – unzips the DNA strand Breaking Hydrogen Bonds Replication fork=point at which the 2 strands split Step 2: DNA polymerase – building enzyme! Adds new bases one at a time.

DNA POLYMERASE Adds 50–500 pairs per second!! It only makes approximately one mistake in every 10 billion nucleotide pairs. Mistakes in the DNA sequences are called mutations. DNA polymerases proofread the new daughter strands and fix these mistakes.

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

HOW DOES DNA GET THE INFORMATION TO THE RIBOSOME??? Segments of DNA are known as GENES GENE= 1 segment of DNA that codes for 1 protein Proteins are made on RIBOSOMES HOW DOES DNA GET THE INFORMATION TO THE RIBOSOME???

DNA vs. RNA --DNA is trapped in the nucleus… so mRNA is created! RNA can leave the nucleus and take the message to a ribosome!! RNA= 1 gene of DNA RNA is made through: TRANSCRIPTION

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

RNA- Structure & Function Monomer= Nucleotide! RNA is Single-stranded Sugar molecule is RIBOSE (not deoxyribose) Thymine is replaced with URACIL (U) FUNCTION of RNA Moves genetic info from the nucleus to a ribosome to make proteins.

3 TYPES of RNA Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)

Transfer RNA (tRNA) transfers 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 code to the ribosome. Ribosomal RNA (rRNA) makes up part of the ribosome. The Gene Scene

T R A N S C I P O Transcription= process of producing RNA by “transcribing” a portion (gene) of DNA.. Location of TRANSCRIPTION: Nucleus

T R A N S C I P O Step 1: Helicase unzips the DNA Step 2: RNA polymerase adds RNA nucleotides that complement the template DNA Step 3: RNA unattached and leaves the nucleus to go to a ribosome. DNA reconnects and twists back up.

T R A N S L I O Translation= the process of using mRNA to assemble amino acids into proteins. mRNA leaves the nucleus and moves to a ribosome in the cytoplasm. = the site of protein synthesis.

T R A N S L I O The Genetic Code mRNA is read 3 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 = “Start” codon (methionine) this is how the ribosome knows to START making proteins Stop Codons (use your genetic code to find them) UAA UAG UGA

T R A N S L I O Step 1: A mRNA moves to a ribosome. Step 2: As each codon moves through the ribosome the correct amino acid is brought to the ribosome by a tRNA molecule.

T R A N S L I O tRNA= Transfer RNA The tRNA has the anti-codon. This is how tRNA knows what amino acid to bring to the ribosome. ANIMATION

T R A N S L I O rRNA= Ribosomal RNA A ribosome consists of: 1)Protein

Forming Polypeptide Chain Translation Forming Polypeptide Chain 7. Lysine 6. tRNA 4. Anti-codon 5. mRNA 1. 2. Ribosome Codon 3.

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

MUTATIONS 1) Point Mutations= Substitutions 2) Frameshift Mutations= Insertions (additions) and Deletions

SUBSTITUTIONS: Point Mutations Replacement of one base pair for another WHAT CAN HAPPEN: No impact (if substitution still results in the same protein made) Nonfunctional protein if substitution results in a different protein made)

INSERTIONS & DELETIONS: Frameshift Mutations Insertion – inserting an extra base in the sequence (shifts all the pairs down one to the right.) Deletion – deleting a base from the sequence (shifts all the pairs down one to the left.)

Anticodon Codon Template DNA rRNA mRNA tRNA # Paper 1-6 5. 6. 3. Anticodon Codon Template DNA rRNA mRNA tRNA