Chapter 12 DNA

12.2 & 12.3 Vocabulary DNA – page 18 & 48 Nucleotide – building blocks of DNA and RNA; composed of a simple sugar, a phosphate group, and a nitrogen base Complementary base pairing – page 348 Double helix – two strands of DNA nucleotides that spiral together; resembles a twisted-ladder shape Chromosome – glossary Replication DNA polymerase Telomere

Section 2 & 3 Structure of DNA & DNA Replication Standards: 2A.1, 4A.1, 4A.2 Objectives: Diagram and label the basic structure of DNA. Summarize the role of the enzymes involved in the replication of DNA. Compare/contrast DNA replication in prokaryotes and eukaryotes.

DNA Deoxyribonucleic Acid  type of nucleic acid Genetic code  instructions for making proteins Found in nucleus Building blocks  nucleotide (G, A, T, C)

How Many Nucleotides?

Structure of DNA Adenine Covalent bond between nucleotides Guanine Cytosine Thymine Covalent bond between nucleotides

DNA Watson & Crick discovered DNA is a double helix (two strands of nucleotides spiraled together). P and Sugar alternate on outside N bases on inside

DNA Complementary base pairing – adenine bonds with thymine and guanine bonds with cytosine Hydrogen bond holds bases together

DNA Antiparallel

DNA Nucleotides  Double Helix  Chromatin  Chromosome

Complementary DNA Strands

DNA Replication Replication – copying process of duplicating DNA Occurs during S phase of interphase Each strand of DNA serves as a template for the new strand  produces two identical complete sets of DNA molecules from mitotic cell divisions. Enzymes involved in DNA replication Occurs in 3 steps

DNA Replication

Step 1: Unwind Double Helix DNA Helicase (an enzyme) unwinds and unzips DNA into two separate strands  H bonds break  leaving single strands of DNA.

Step 2: Add New Base Pairs DNA Polymerase (an enzyme) adds nucleotides to produce new strand of DNA. New bases added to parental DNA strand Proofreads  exact copy of original Follows the base-pair rule: (A-T, G-C)

Step 3: Join Base Pairs At the end of replication  2 new strands of daughter DNA are produced. Each is made of ½ old DNA and ½ new DNA replication fork DNA polymerase Direction of replication Direction of replication new nucleotides being added DNA Replication

Telomere Telomere – tips of eukaryotic chromosomes; protective cap. Telomerase (enzyme) adds DNA sequences to each end. Telomere

DNA Replication Prokaryotes/Eukaryotes Circular DNA strand  replicated in one section 2 directions DNA is shorter Eukaryotes Replicated in several sections DNA is longer

Chapter 13 RNA & Protein Synthesis

13.1 Vocabulary RNA – nucleic acid that directs the production of proteins Messenger RNA - glossary Ribosomal RNA - glossary Transfer RNA - glossary Transcription RNA Polymerase - glossary

Section 1 RNA Standards: 2A.1, 4B.1 Objectives: Compare/Contrast DNA and RNA. Explain the process of transcription.

Why Proteins are Important DNA  “code of life” or “genetic code” because it contains the code for each PROTEIN. Sequence of DNA nucleotides determines type of protein to be synthesized. Proteins determine how an organism looks & functions.

Why Proteins are Important Gene – segment of DNA that contains instructions for making a protein. Specific location on a chromosome Controls inherited trait expression that is passed on for generations. Ribosomes make proteins

Why Proteins are Important Each organism has unique nucleotide sequences. Organisms closely related have more common nucleotide sequences  similar DNA. Oak Tree Red Maple Trees Worm

Why Proteins are Important

DNA  RNA Problem: DNA contains instructions for making proteins but DNA can’t leave the nucleus. Solution: RNA will take DNA’s instructions to the ribosomes for protein synthesis.

RNA Ribonucleic Acid  type of nucleic acid Directs production of proteins Single stranded Building blocks  nucleotides Uracil and NO thymine (G, A, C, U)

RNA – 3 Types mRNA (messenger RNA) – carries copies of instructions to make proteins; complementary to DNA rRNA (ribosomal RNA) – form ribosomes tRNA (transfer RNA) – carries amino acids to ribosome Messenger RNA Ribosomal RNA Transfer RNA

RNA

Protein Synthesis Part 1: Transcription (template of DNA  mRNA) occurs in nucleus gene for a specific protein is turned ON and that gene is copied into mRNA Example: (DNA) T A C G G T A STOP codon (mRNA) A U G C C A U STOP RNA Polymerase (an enzyme) – links RNA nucleotides as DNA strand unwinds and unzips. mRNA detaches and leaves nucleus and enters cytoplasm. TWO DNA strands rejoin.

Transcription

Transcription

Transcription Practice DNA C G T T A G C A A C T G STOP mRNA 2. DNA A C G T C A A C G T T A STOP

13.2 Vocabulary Polypeptide – glossary Genetic Code – glossary Codon – glossary Translation Anticodon – glossary Gene Expression - glossary

Section 2 Ribosomes and Protein Synthesis Standards: 4A.1, 4B.1 Objectives: Explain the process of translation. Transcribe & translate DNA  mRNA  proteins.

Genetic Code Polypeptides – long chains of amino acids Amino acids make up proteins 20 amino acids total Genetic Code  mRNA codons Codon – 3 base code (N base) 1 codon = 1 amino acid

This section of DNA represents a gene. CODON T A C G This section of DNA represents a gene. How many codons do you see in this gene? How many amino acids total make this protein?

Genetic Code

Genetic Code

Practice Converting mRNA  Amino Acids AUG = CUC = AAG = GGU = UAC = CAC = CAA = UGA =

Protein Synthesis Part 2: Translation (mRNA  Protein) Occurs at ribosome in the cytoplasm Interprets genetic message and builds proteins mRNA attaches to a ribosome (rRNA) and is read 3 bases (codon) at a time

Protein Synthesis Part 2: Translation (mRNA  Protein) tRNA is activated by enzyme and carries amino acid to the ribosome 20 different types of tRNA molecules tRNA structure: Anticodon site – 3 nucleotide base complementary to the codon of mRNA; end of tRNA molecule Amino acid attached on other end

Protein Synthesis Part 2: Translation (mRNA  Protein) Amino acids joins together in a chain by peptide bonds  forming a protein. Continues until STOP codon is read on the mRNA  last amino acid is added  protein breaks away from ribosome  protein synthesis ends.

Gene Expression Gene Expression – process by which gene produces its product and the product carries out its functions.

Central Dogma of Molecular Biology

Central Dogma of Molecular Biology

13.3 Vocabulary Mutagen Mutation – glossary Point Mutation – glossary Frameshift Mutation – glossary Mutagen Polyploidy

Section 3 Mutations Standards: 4B.1, 4D.1 Objectives: Summarize the various types of mutations.

Gene Regulation Ability of an organism to control which genes are transcribed.

Mutation Mutation – change (or alteration) in DNA Changes vary from… Single gene (gene mutations)  large segments of DNA (chromosomal mutations) Beneficial  harmful Unnoticeable  disorders or death

Examples of Gene Mutations Affects a single gene  small section of DNA. Huntington’s Disease Sickle-Cell Disease Albinism

Examples of Chromosomal Mutations Affects groups of genes or entire chromosome. Down Syndrome

Examples of Beneficial Mutations Results in traits that are favored by natural selection  species evolve (CHANGE)  increase population size. Polyploidy – extra sets of chromosomes

Mutation If mutant cell is a body cell (somatic cell) then daughter cells can be affected but mutation will not be passed to offspring  aging and/or cancer. If mutant cell is a gamete (sex cell) then mutation will be passed to offspring  genetic disorders.

Point Mutations Change in one base pair (or one nucleotide) Missense Mutation – codes for wrong amino acid Normal: AUG CAU UAC Mutated: AUG GAU UAC Nonsense Mutation – change amino acid codon to a stop codon; terminates translation early Normal: AUG CAU UAC Mutated: AUG UGA histidine

Frameshift Mutations Shifts the “frame” of the amino acid sequence by adding or deleting nucleotides  changes codons Deletion Mutation – loss of a nucleotide Normal: AUG CAU UAC GUA Mutated: AUG AUU ACG UAU Insertion Mutation – addition of a nucleotide Mutated: AUG CCA UUA CGU A

Duplication Mutations Entire codon(s) repeat; increases the number of amino acids Normal: AUG CAU UAC GUA Mutated: AUG CAU CAU CAU CAU UAC GUA

Review: Types of Mutations Point, Frameshift, or Duplication Mutation? Missense, Nonsense, Deletion, or Insertion Mutation?

Review: Types of Chromosomal Mutations Inversion  genes reversed Duplication  extra copies Translocation  parts break off and reattach somewhere else Deletion  loss of genes

How Mutations Occur Errors in genetic processes (DNA replication, Transcription, Translation) Mutagens – substances which cause mutations; certain chemicals and radiation. Most mutations repaired  no effect

Effects of Mutations The shape of a protein controls how it works. Shape is determined by amino acids. Incorrect amino acids change protein’s shape  protein may not work properly.