45a. Know the general structures and functions of DNA, RNA & protein.
512—1 The Components and Structure of DNA What is the overall structure of the DNA molecule?The Components and Structure of DNADNA is made up of ______________________.A nucleotide is a monomer of nucleic acids made up of a five-carbon sugar called ________________, a phosphate group, and a nitrogenous base.
6The Components and Structure of DNA There are ______ kinds of bases in in DNA:adenineguaninecytosinethymineDNA is made up of nucleotides. Each nucleotide has three parts: a deoxyribose molecule, a phosphate group, and a nitrogenous base. There are four different bases in DNA: adenine, guanine, cytosine, and thymine.
7The Components and Structure of DNA The backbone of a DNA chain is formed by ______________ and _______________ groups of each nucleotide.The nucleotides can be joined together in any order.
8The Components and Structure of DNA Chargaff's RulesErwin Chargaff discovered that:The percentages of _________________ [G] and _____________________ [C] bases are almost equal in any sample of DNA.The percentages of ________________ [A] and __________________ [T] bases are almost equal in any sample of DNA.
10The Components and Structure of DNA The Double Helix Using clues from Franklin’s pattern, James Watson and Francis Crick built a model that explained how DNA carried information and could be copied.Watson and Crick's model of DNA was a ___________ _____________ in which _____ strands were wound around each other.
11Who Discovered the DNA molecule? Discovery of DNA:___________: Proposed that DNA is made of 2 chains of nucleotides joined together by the nitrogen basesDouble Helix: DNA composed of 2 strands twisted togetherJames Watson & Francis Crick
12The Components and Structure of DNA DNA Double HelixDNA is a double helix in which two strands are wound around each other. Each strand is made up of a chain of nucleotides. The two strands are held together by hydrogen bonds between adenine and thymine and between guanine and cytosine.
13The Components and Structure of DNA Watson and Crick discovered that ____________________ bonds can form only between certain base pairs—adenine and thymine, and guanine and cytosine.This principle is called ________________.
14From DNA to Protein Why is DNA Important? All of the characteristics that you have are affected by the _____________ that you have in your cells.Controls the color of your eyes, hair, or if you can digest milk.______________ the order of the amino acids Δ’s the kind protein made.
15From DNA to Protein RNA: _____________________ Acid a nucleic acid single strandedSugar in RNA is riboseInstead of Thyamine, Uracil (U) – (A)H
16Three Types of RNA Help to build proteins Messenger RNA (___________): brings info from the DNA in the nucleus to the cell’s factory floor, the cytoplasm.Ribosomal RNA (_________): clamp onto the mRNA and use its info to assemble the amino acids in the correct orderTransfer RNA (___________): transports amino acids to the ribosome to be assembled into protein
17RNA Facts RNA exists in many structural forms mRNA: serves as a __________ during protein synthesistRNArRNA
19ProteinsProteins are ________________ composed of amino acid ______________.Different types of proteins function as enzymes and transport molecules, hormones, structural components of cells, & antibodies that fight infection.
2312-2 Chromosomes and DNA Replication Photo credit: Jacob Halaska/Index Stock Imagery, Inc.
24DNA and Chromosomes DNA and Chromosomes In prokaryotic cells, DNA is located in the __________________.Most __________________ have a single DNA molecule containing nearly all of the cell’s genetic information.
25DNA and Chromosomes E. Coli Bacterium Chromosome Most prokaryotes, such as this E. coli bacterium, have only a single circular chromosome. This chromosome holds most of the organism’s DNA.E. Coli BacteriumBases on the Chromosomes
26DNA and ChromosomesMany eukaryotes have ________ times the amount of DNA as prokaryotes.Eukaryotic DNA is located in the cell ______________ inside chromosomes.The number of chromosomes varies widely from one species to the next.
27DNA and Chromosomes Chromosome Structure Eukaryotic chromosomes contain DNA and protein, tightly packed together to form _______________.Chromatin consists of DNA tightly coiled around proteins called ______________________.DNA and histone molecules form nucleosomes.Nucleosomes pack together, forming a thick fiber.
28DNA and Chromosomes Eukaryotic Chromosome Structure Chromosome NucleosomeDNA double helixCoilsSupercoilsEukaryotic chromosomes contain DNA wrapped around proteins called histones. The strands of nucleosomes are tightly coiled and supercoiled to form chromosomes.Histones
29DNA Replication What happens during DNA replication? DNA Replication Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing.In most prokaryotes, DNA replication begins at a single point and continues in two directions.
30DNA ReplicationIn eukaryotic chromosomes, DNA replication occurs at hundreds of places. Replication proceeds in both directions until each chromosome is completely copied.The sites where separation and replication occur are called ____________________.
31DNA Replication Duplicating DNA Before a cell divides, it duplicates its DNA in a process called ____________________.Replication ensures that each resulting cell will have a complete set of DNA.During DNA replication, the DNA molecule separates into ______ strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template for the new strand.
32DNA Replication New Strand Original strand Nitrogen Bases Growth During DNA replication, the DNA molecule produces two new complementary strands. Each strand of the double helix of DNA serves as a template for the new strand.Replication ForkReplication ForkDNA Polymerase
33DNA Replication How Replication Occurs DNA replication is carried out by enzymes that “unzip” a molecule of DNA.Hydrogen bonds between base pairs are broken and the two strands of DNA unwind.The principal enzyme involved in DNA replication is _______________________.DNA polymerase joins individual nucleotides to produce a DNA molecule and then “proofreads” each new DNA strand.
34DNA Replication__________________ breaks up the hydrogen(H+) bonds between the nitrogen bases that holds the 2 strands together—unzips the DNA moleculeFree floating _______________ bond to the single strands by base pairingAnother _______________ bonds these new nucleotides into a chain
35DNA Replication4. This process continues until the entire molecule has been unzipped and replicated.5. Each new strand formed is a _________________ of the original, or parent, strands.6. The result is the formation of two DNA molecules, each of which is __________________ to the original DNA molecule.
3712–3 RNA and Protein Synthesis _______________ are coded DNA instructions that control the production of proteins.Genetic messages can be decoded by copying part of the nucleotide sequence from DNA into RNA._______________ contains coded information for making proteins.
38The Structure of RNA The Structure of RNA RNA consists of a long chain of nucleotides.Each nucleotide is made up of a ___-carbon sugar, a phosphate group, and a nitrogenous base.There are three main differences between RNA and DNA:The sugar in RNA is ribose instead of deoxyribose.RNA is generally single-stranded.RNA contains ______________ in place of thymine.
39Types of RNA What are the three main types of RNA? Types of RNA There are three main types of RNA:_________________ RNAribosomal RNA_______________ RNA
40Types of RNAThe three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA.Messenger RNA (mRNA) carries ______________ of instructions for assembling amino acids into proteins.
41Types of RNARibosomeRibosomal RNAThe three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Ribosomal RNA is combined with proteins to form ribosomes.Ribosomes are made up of proteins and ribosomal RNA (rRNA).
42Types of RNAAmino acidThe three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA.Transfer RNADuring protein construction, transfer RNA (tRNA) transfers each amino acid to the _________________.
43Transcription What is transcription? Transcription RNA molecules are produced by copying part of a nucleotide sequence of DNA into a complementary sequence in RNA. This process is called ______________________.Transcription requires the enzyme ___________________________.
44TranscriptionDuring transcription, RNA polymerase binds to DNA and separates the DNA strands.RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.RNA polymerase binds only to regions of DNA known as ______________________.Promoters are signals in DNA that indicate to the enzyme where to bind to make RNA.
45Transcription Steps __________________ unzip the molecule of DNA Free RNA nucleotides pair with complementary DNA nucleotides on one of the DNA strandsAGC TAA CCG ______ strandUCG AUU GGC _____ strandWhen the base pairing is completed, the mRNA molecule breaks away as the DNA strands rejoin.The ______________ leaves the nucleus and enters the cytoplasm
46Transcription RNA RNA polymerase DNA During transcription, RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA.
47RNA Editing RNA Editing The DNA of eukaryotic genes contains sequences of nucleotides, called __________________, that are not involved in coding for proteins.The DNA sequences that code for proteins are called _________________.When RNA molecules are formed, introns and exons are copied from DNA.
48RNA Editing The ____________ are cut out of RNA molecules. ExonIntronDNAThe ____________ are cut out of RNA molecules.The _____________ are the spliced together to form mRNA.Pre-mRNAmRNAMany RNA molecules have sections, called introns, edited out of them before they become functional. The remaining pieces, called exons, are spliced together. Then, a cap and tail are added to form the final RNA molecule.CapTail