MOLECULAR BIOLOGY 9/27/2015. The study of heredity at the genetic level. Frederick Griffith work with bacteria in 1928

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1 MOLEULR BIOLOY 1 MOLEULR BIOLOY he study of heredity at the genetic level Frederick riffith work with bacteria in 1928 hromosomes ( + proteins) Began the field of molecular biology 2 1

2 HERSHEY & HSE Showed is genetic material using experiments with bacteriophages 1 phage attaches itself to a bacterial cell. 2 he phage injects genetic into the bacterium. 3 he phage genes direct the host cell to make more phage genes and proteins; new phages assemble. he cell lyses and releases the new phages. Bacteriophages viruses that only affect bacteria 3 NULEOIDES Nucleotides are molecules made of a phosphate group, sugar and nitrogenous base one nucleotide (hymine) Phosphate group Nitrogenous base Sugar 4 2

3 MOLEULR BIOLOY OF polynucleotide called deoxyribonucleic acid hymine Phosphate group he sugar in is called (deoxyribose) hymine () ytosine () denine () uanine () Pyrimidines Purines 5 MOLEULR BIOLOY OF has a sugar phosphate backbone that strings nucleotides together Phosphate group Nitrogenous base Sugar Sugar-phosphate backbone 6 3

4 MOLEULR BIOLOY OF forms a double helix Watson and rick end 3 end Hydrogen bond XRY of suggested a double helix structure Proposed that the same base pairs always went together (, ) hargaff s Rules: In any species, the ratio of : and : is 1:1 Sugar phosphate backbones are opposite 3 end 5 end 7 REPLIION replication is semi conservative Semi conservative: Half of the parent molecule is conserved in the daughter molecule Parental molecule Daughter strand Parental strand Daughter molecules 8 4

5 REPLIION Proteins attach at origin of replication Parental molecule Origin of replication Parental strand Bubble forms Daughter created using complementary bases Bubble Daughter strand Bubbles fuse creating two new daughter molecules Daughter molecules 9 REPLIION ENZYMES Polymerases ypes of enzymes that add nucleotides to the daughter Ligases Links pieces of lagging strand together to form 1 continuous strand of Origin of replication 5 end P 4 3 P P Polymerase working in pieces from 5 to 3 of daughter cell Lagging strand Polymerase working continuously from 5 to 3 of daughter cell Leading strand P OH 3 end 5 end 3 end 10 5

6 PROEINS LINK ENOYPE & PHENOYPE ranscription RN NULEUS ranslation YOPLSM Protein 11 RN polynucleotide called ribonucleic acid,, or RN, U, or Sugar (deoxyribose) Sugar (ribose) 12 6

7 PROEIN SYNHESIS RN Proteins serves as a template to transfer genetic information to RN molecule ene 1 RN transfers genetic information using codons ene 2 odons are words made of 3 nucleotides. ranscription RN ranslation U U U U U U U odon ene 3 Polypeptide mino acid 13 RNSLION Multiple words for the 20 different amino acids U start U, U, U stop! First base of RN codon U Second base of RN codon U UUU UU UU UU U Phe yr ys UU U U U Ser UU U U Stop U Stop Leu UU U U Stop U rp UU U U U U His U Leu Pro rg U ln U UU U U U U Ser U sn lle hr U Lys rg U Met or start UU U U U U sp U Val la ly U lu U 14 hird base of RN codon 7

8 ENE RNSRIPION INIIION RN polymerase binds to at a promoter sequence RN polymerase erminator Promoter ELONION he RN strand grows as nucleotides are added ERMINION RN polymerase detaches at the terminator sequence 15 mrn Removes introns, combines exons and ads cap and tail to make mrn Introns filler sequences from that are not expressed as amino acids Exons parts of the gene that are expressed ap & ail help mrn to move into cytoplasm and bind with ribosomes to make proteins 16 8

9 RNSFER RN (trn) he interpreter Unique structure Specific trn for each amino acid nticodon recognizes a specific codon Hydrogen bond RN polynucleotide chain mino acid attachment site Recognizes mrn codons nticodon 17 RIBOSOMES BUILD PROEINS Ribosomes consist of two subunits each made of ribosomal RN (rrn) and proteins. ap Start of genetic message ail Initiator trn mrn U U P site U U End site Large ribosomal subunit Start codon 1 Small ribosomal subunit

10 PROEIN SYNHESIS ranscription NULEUS mrn ranscription ranslation YOPLSM mino acid trn P mrn ranslation Ribosome + trn + mrn rowing polypeptide U U Start codon Polypeptide (protein) odons Polypeptide Stop codon 19 MUENESIS he production of mutations by physical or chemical agents (mutagens) Silent mutations different codon results in correct amino acid Missense mutations results in wrong amino acid Nonsense mutations results in stop codon Frameshift mutations add or subtract base pair (everything shifts) Normal hemoglobin Mutant hemoglobin mrn mrn U Normal hemoglobin Sickle-cell hemoglobin lu Val Sickle cell anemia is an example of a missense mutation 20 10

11 BERIL VIRUSES (PHES) genes in a box that infects prokaryotes or eukaryotes by injecting their genes into a host cell Lytic cycle reproduce and lyse host cell Lysogenic cycle insert into host and stay dormant Lytic cycle Phages cause cell to lyse releasing more phages Phage inserts into host cell Lysogenic cycle Phage and host is replicated Phage reproduces in host cell Prophage inserts into host 21 PLN ND NIML VIRUSES 1. Use glycoprotein spikes to trick a receptor protein 2. Release RN, enzymes and protein into the host cytoplasm 3. Replicate RN, enzymes and proteins 4. loak the virus RN in proteins and plasma membrane and exit host

12 REROVIRUSES RN viruses that reproduce by host molecules HIV looks like a mumps virus but acts very differently ttacks white blood cells resulting in acquired immunodeficiency syndrome (IDS) strand Doublestranded 1 2 Reverse transcriptase NULEUS YOPLSM hromosomal Provirus Patient can die from secondary infections 6 RN 23 BERI N RNSFER Provides a way for bacteria to have new combinations of genes RNSFORMION Uptake from surrounding environment RNSDUION ransfer of from a bacteriophage (virus) ONJUION Physical union and transfer of 2 bacterial cells Donated rossovers Degraded Recipient cell s chromosome Recombinant chromosome 24 12