DNA and RNAChapter 12
Warm Up Exercise Test Corrections– Make sure to indicate your new answerand provide an explanation for why this isthe correct answer. Do this with a redpen in the margins of your original testpaper.
The Components and Structure of DNA DNA is made up of units called nucleotides. Nucleotides are made up of three basiccomponents:– A 5-carbon sugar, called deoxyribose in DNA– A phosphate group– A nitrogen base
The Components and Structure of DNA There are 4 types of nitrogen nes 2 ringsPyrimidines 1 ring
The Components and Structure of DNA The backbone of aDNA chain is formed bysugar and phosphategroups of eachnucleotide. The nucleotides can bejoined together in anyorder.
The Components and Structure of DNAChargaff’s Rules Erwin Chargaff discovered that– The percentages of guanine (G) and cytosine (C)bases are almost equal in any sample of DNA.– The percentages of adenine (A) and thymine (T)bases are almost equal in any sample of DNA. Thus, A pairs with T andG pairs with C.
The Components and Structure of DNAX-Ray Evidence Rosalind Franklin usedX-ray diffraction toobtain informationabout the structure ofDNA.
The Components and Structure of DNAThe Double Helix Using clues fromFranklin’s pattern, JamesWatson and Francis Crickbuilt a model thatexplained how DNAcarried information andhow it could be copied.
The Components and Structure of DNA Watson and Crick’s model of DNA was a doublehelix, in which two strands were wound aroundeach other, like a twisted ladder or spiralstaircase. They discovered that hydrogen bonds formedbetween specific nitrogenous bases and hold thetwo strands together.– This principle is called base pairing, and explainedChargaff’s rules.
The Structure of DNA
Quick Assess- Post It Style What are the four kinds of bases foundin DNA and how do the bases pair?
Warm Up Exercise What are the three parts of a nucleotide? What makes up the backbone of DNA? Whose rules state that A pairs with T and G pairswith C? Who got the credit for the structure of the DNAmolecule?
Prokaryotic DNA Most prokaryotes have a single circular DNAmolecule found in the cell’s cytoplasm. Thislarge DNA molecule is typically referred to as thecell’s chromosome.
Eukaryotic DNA Eukaryotic DNA is located in the nucleus in theform of chromosomes. DNA molecules are very long. The nucleus of ahuman cell contains more than 1 meter of DNA.
Chromosome Structure Eukaryotic chromosomes contain both DNA andprotein packed together to form a substancecalled chromatin. Chromatin consists of DNA that is tightly coiledaround proteins called histones. Together, the DNA and the histone form abeadlike structure called a nucleosome. Nucleosomes pack together to form a thick fiberwhich coils up. Nucleosomes fold huge lengths ofDNA into the tiny space available in the cellnucleus.
DNA Replication Before a cell divides, it duplicates its DNA ina copying process called DNA Replication.– This process ensures that each resultingdaughter cell will have a complete set of DNAmolecules. During DNA replication, the DNA moleculeseparates into two strands, and thenproduces two new complete sets of DNA.– Each strand of the double helix of DNA servesas a template or model for the new strand.
DNA Replication Replication proceeds in both directions untileach chromosome is completely copied. Thesites where separation and replication occurare called replication forks.
DNA ReplicationNew StrandOriginal strandNitrogen BasesGrowthGrowthReplication ForkReplication ForkDNA PolymeraseCopyright Pearson Prentice Hall
Enzymes DNA Helicase- unzips the DNA molecule bybreaking the hydrogen bonds. DNA Polymerase- joins individual nucleotides toproduce a DNA molecule, which is a polymer.DNA polymerase also “proofreads” each newDNA strand, helping to eliminate replicationerrors.
Exit Slip Make a Venn diagram that compares the processof DNA replication in prokaryotes and eukaryotes.Compare the location, steps, and end products ofthe process in each kind of cell.
Advanced Warm Up Exercise Chapter 7 Standardized Test Prep
General Warm Up Exercise During DNA replication, the DNA molecule(separates/combines) into 2 strands. At the end of DNA replication, (four/two)new strands of DNA have been produced, givinga total of (four/six) strands of DNA. New DNA is replicated in strands complementaryto old DNA because production of new DNAfollows the rules of (base pairing/thedouble helix)
RNA and Protein Synthesis Genes- coded DNA instructions that control theproduction of proteins within the cell.– In order to decode genes, the nucleotide sequencemust be copied from DNA to RNA, as RNA containsthe instructions for making proteins. 3 main differences between RNA and DNA:– The sugar in RNA is ribose instead of deoxyribose.– RNA is generally single-stranded.– RNA contains uracil in place of thymine. The main job of RNA is to assemble amino acidsinto proteins!
Types of RNA Messenger RNA (mRNA)- serve asmessengers from the DNA to the rest ofthe cell. They carry the instructions forassembling proteins into amino acids. Ribosomal RNA (rRNA)- help withprotein assembly, which occurs on theribosomes. Transfer RNA (tRNA)- transfers eachamino acid to the ribosome as itspecified by the coded messages inmRNA.
Transcription Transcription- RNA molecules are produced bycopying part of the nucleotide sequence of DNAinto a complementary sequence in RNA.– Requires RNA polymerase, which uses one strand ofDNA as a template for the construction of the newstrand of RNA.– FIGURE 12.14
Transcription Promoters- specific region of DNA where RNApolymerase will bind. These regions havespecific base sequences.
RNA Editing Introns- DNAnucleotide sequencesthat are not involvedin coding for proteins. Exons- sequencesthat do code forproteins- they are“expressed” in thesynthesis of proteins.
The Genetic Code Codon- consists of three consecutive nitrogenbases that specify a single amino acid that is to beadded to the polypeptide.UCGCACGGUThis sequence would be read three bases at a time as:UCG-CAC-GGUThe codons represent the different amino acids:UCG Serine, CAC Histidine, GGU Glycine
The Genetic Code Because there are four different bases, there are64 possible three-base codons (4x4x4 64). There is one codon, AUG, also known asmethionine, which serves as the “start” codon forprotein synthesis. There are three “stop” codons that do not codefor any amino acids. They signal the end of apolypeptide.
Translation Translation- decoding of an mRNA message toproduce a protein.– Translation takes place on the ribosomes.– Before translation occurs, mRNA is transcribed fromDNA in the nucleus and released into the cytoplasm.
Translation– The rRNA joins the newly synthesized amino acidsand breaks the bond between the amino acid and itstRNA. The tRNA floats away from the ribosome,allowing the rRNA to bind another tRNA.– The ribosome movesalong the mRNA bindingnew tRNA moleculesand amino acids until itreaches a stop codon.
Translation– The tRNA carries 3 unpaired bases that specify for aspecific amino acid. These unpaired bases, calledthe anticodons, are complementary to the mRNAcodon.
Roles of DNA and RNA The cell uses the DNA “master plan” to prepareRNA “blueprints.” The DNA stays in thenucleus. The RNA molecules go to the protein buildingsites in the cytoplasm—the ribosomes.
DNA and RNA The sequence of bases inDNA is used as atemplate for mRNA. The codons of mRNAspecify the sequence ofamino acids in a protein.
Genes and Proteins Genes contain instructions for assemblingproteins. Many proteins are enzymes, which catalyze andregulate chemical reactions.
Exit Slip Analyzing Data- page 296
Warm Up Exercise Complete the worksheet that you picked up asyou came in.
Mutations Mutations- changes in the genetic material.– Mutations that produce changes in a single gene arecalled gene mutations.– Mutations that produce changes in chromosomes areknown as chromosomal mutations.
Mutations Point Mutations- gene mutations involvingchanges in one or a few nucleotides are knownas point mutations, because they occur at asingle point in the DNA sequence.– Ex: substitutions, insertions, and deletions
Mutations Frameshift Mutations- shift the reading frame ofthe genetic message.– May change every amino acid that follows from thepoint of mutation.– Ex: insertions and deletions
Mutations Chromosomal Mutations- involve changes inthe number or structure of chromosomes. Mayeven change the location of genes onchromosomes and the number of copies of somegenes.
Significance of Mutations Some mutations are detrimental, although somecan be beneficial. Mutations in sex cells can be passed along tooffspring and can result in genetic variation. Polyploidy- the condition in which an organismhas an extra set of chromosomes.
Exit Slip Design a chart comparing and contrasting typesof mutations. Make three columns: Definition,Types, and Effects
RNA and Protein Synthesis Genes- coded DNA instructions that control the production of proteins within the cell. – In order to decode genes, the nucleotide sequence must be copied from DNA to RNA, as RNA contains the instructions for making proteins. 3 main differences between RNA and DNA: – The sugar in RNA is ribose instead of .
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AP Biology Exam Review: DNA, Protein Synthesis & Biotechnology Helpful Videos and Animations: 1. Bozeman Biology: DNA Replication 2. Bozeman Biology: DNA and RNA - Part 1 3. Bozeman Biology: DNA and RNA - Part 2 4. Cold Spring Harbor Lab Animation: Griffith / Avery, McCarty, and Macleod Experiments 5. McGraw-Hill Animation: Hershey Chase Experiment
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DNA to Protein: Protein Synthesis Transcription: DNA contains the code necessary for a cell to produce new protein molecules during the process of protein syn-thesis. The sequence of DNA bases determines the type and order of amino acids found
That genes are made of DNA. THE STRUCTURE OF THE GENETIC MATERIAL 10.1 Experiments showed that DNA is the genetic material . INFORMATION FROM DNA TO RNA TO PROTEIN (Protein synthesis) 10.6 -10.16 . 10.6 The DNA genotype is expressed as proteins, which provide the molecular basis for
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OBJECTIVE SHEET NUCLEIC ACIDS AND PROTEIN SYNTHESIS 1. Name the four bases in DNA and describe the structure of DNA. 2. Describe the steps involved in DNA replication. Include in your discussion helicase, DNA polymerase, complementary base-pairs, anti-parallel, semi-conservative replication. 3. Describe three uses for recombinant DNA (rDNA).
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