Journal  Sketch a model of DNA and list three facts about DNA.

Characteristics of DNA  Location: inside a eukaryotic cell’s nucleus

Molecular Genetics

Structure of DNA  Made up of: Nucleotides 1. Sugar 2.Phosphate Group 3.Nitrogenous base

4 Types of Nitrogenous Bases

Molecular Genetics Chargaff  Chargaff’s rule: C = G and T = A

Molecular Genetics Wilkins & Franklin  X-ray Diffraction  Helped solve the structure of DNA  Indicated that DNA was a double helix

Watson & Crick (1953)

Double Helix “twisted ladder”  Backbone – alternating sugar and phosphate  Base Pair Rules:  Adenine always pairs with Thymine (A = T)  Guanine always pairs with Cytosine (G = C)

 On the top rail, the strand is said to be oriented 5 ′ to 3 ′.  The strand on the bottom runs in the opposite direction and is oriented 3 ′ to 5 ′. Orientation

Molecular Genetics Mr. W’s DNA Fantastic Rap

1. A 2. B 3. C 4. D FQ 2 Molecular Genetics Chapter A. A—G and C—T B. A—T and C—G C. C—A and G—T D. C—U and A—G What is the base-pairing rule for purines and pyrimidines in the DNA molecule? Section 1 Formative Questions

1. A 2. B 3. C 4. D FQ 3 Molecular Genetics Chapter Section 1 Formative Questions A.chromatin and histones B. DNA and protein C. DNA and lipids D. protein and centromeres What are chromosomes composed of?

1. A 2. B 3. C 4. D CAQ 1 Molecular Genetics Chapter Look at the following figure. Identify the proteins that DNA first coils around. Chapter Assessment Questions A. chromatin fibers B. chromosomes C. histones D. nucleosome

DNA Replication  Semiconservative Replication Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA

1. Unwinding  DNA helicase, an enzyme, is responsible for unwinding and unzipping the double helix.  RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand. DNA Replication

Molecular Genetics 2. Base pairing  DNA polymerase adds appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand.

Molecular Genetics  One strand is called the leading strand and is elongated as the DNA unwinds.  The other strand of DNA, called the lagging strand, elongates away from the replication fork.  The lagging strand is synthesized discontinuously into small segments, called Okazaki fragments.

3. Joining  DNA ligase links the two sections.

Practice  During DNA replication, a DNA strand that has the bases CTAGGTCAAG would produce a complementary strand with what base order? GATCCAGTT CTAGGTCAA

For your viewing pleasure…  Amoeba Sisters Wsuc Amoeba Sisters Wsuc  Mr. W’s DNA Replication Song fantastic/

1. A 2. B 3. C 4. D CDQ 2 Chapter Diagnostic Questions A. ligase B. Okazaki fragments C. micro RNA D. helicase Name the small segments of the lagging DNA strand.

1. A 2. B 3. C 4. D FQ 2 A. A—G and C—T B. A—T and C—G C. C—A and G—T D. C—U and A—G What is the base-pairing rule for purines and pyrimidines in the DNA molecule? Section 1 Formative Questions

1. A 2. B 3. C 4. D FQ 3 Section 1 Formative Questions A.chromatin and histones B. DNA and protein C. DNA and lipids D. protein and centromeres What are chromosomes composed of?

1. A 2. B 3. C 4. D FQ 5 Section 2 Formative Questions A. DNA ligase B. DNA polymerase C. DNA helicase D. RNA primer Which is not an enzyme involved in DNA replication?

1. A 2. B 3. C 4. D CAQ 1 Look at the following figure. Identify the proteins that DNA first coils around. Chapter Assessment Questions A. chromatin fibers B. chromosomes C. histones D. nucleosome

1. A 2. B 3. C 4. D STP 1 What does this diagram show about the replication of DNA in eukaryotic cells? Standardized Test Practice A. DNA is replicated only at certain places along the chromosome. B. DNA replication is both semicontinuous and conservative. C. Multiple areas of replication occur along the chromosome at the same time. D. The leading DNA strand is synthesized discontinuously.

RNA and Protein Synthesis  DNA gives coded instructions for making proteins. The cell has to “break” the code before making proteins.

Central Dogma DNARNAPROTEIN

RNA  Structure  3 Differences from DNA: 1) Sugar = Ribose 2) Single-stranded 3) Uracil in place of Thymine ( A pairs with U)

3 Types of RNA  Messenger RNA (mRNA) – Long strands of RNA nucleotides that are formed complementary to one strand of DNA  Ribosomal RNA (rRNA) - Associates with proteins to form ribosomes in the cytoplasm  Transfer RNA (tRNA) – transfers amino acids to ribosomes

Transcription  Process that produces mRNA (in the nucleus) by reading the DNA code  mRNA is read 3 letters (codon) at a time. Each codon matches up to an amino acid  Example:  mRNAAGGCUCAUC is read AGG – CUC - AUC

RNA Processing  The code on the DNA is interrupted periodically by sequences that are not in the final mRNA.  Intervening sequences are called introns.  Remaining pieces of DNA that serve as the coding sequences are called exons.

Practice  For the following DNA strand, write the complementary mRNA strand  DNA: CCA GAC TCA GGT ATC  mRNA: GGU CUG AGU CCA UAG

Translation  tRNA “translates” the Genetic Code from mRNA to attach the corresponding amino acids  Example:  mRNA: AGG – CUC – AUC  Amino acidarginine –leucine – isoleucine

The Genetic Code

Practice  Use this DNA strand to code for mRNA and its matching amino acid  DNA: CCA GAC TCA GGT ATC  mRNA: GGU CUG AGU CCA UAG  Amino acid: Glycine – Leucine – Serine – Proline - STOP

Journal – Part 2  Write down three NEW facts about DNA that we talked about this class.