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THE MOLECULAR BIOLOGY OF THE GENE. EXPERIMENTS HAVE SHOWN THAT DNA IS THE GENETIC MATERIAL – DNA HAS BEEN KNOWN ABOUT FOR OVER 100 YEARS; HOWEVER, KNOWLEDGE.

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Presentation on theme: "THE MOLECULAR BIOLOGY OF THE GENE. EXPERIMENTS HAVE SHOWN THAT DNA IS THE GENETIC MATERIAL – DNA HAS BEEN KNOWN ABOUT FOR OVER 100 YEARS; HOWEVER, KNOWLEDGE."— Presentation transcript:

1 THE MOLECULAR BIOLOGY OF THE GENE

2 EXPERIMENTS HAVE SHOWN THAT DNA IS THE GENETIC MATERIAL – DNA HAS BEEN KNOWN ABOUT FOR OVER 100 YEARS; HOWEVER, KNOWLEDGE OF ITS ROLE AS GENETIC MATERIAL IS RELATIVELY NEW – ORIGINALLY, IT WAS THOUGHT THAT PROTEIN WAS IN CHARGE OF TRAITS (WHY DO YOU THINK THEY BELIEVED PROTEINS WERE THE ANSWER?)

3 THE MOLECULAR BIOLOGY OF THE GENE GRIFFITH’S EXPERIMENT

4 THE MOLECULAR BIOLOGY OF THE GENE GRIFFITH’S SETUP – INVOLVED A TYPE OF BACTERIA (STREPTOCOCCUS) – UTILIZED HEAT SHOCK TO DENATURE PROTEINS GRIFFITH’S RESULTS – HARMLESS FORM (R FORM) WAS TURNED INTO HARMFUL FORM (S FORM) WHEN HEAT-SHOCKED “S” WAS MIXED WITH NORMAL “R” – IDENTIFIED DNA IS GENETIC CARRIER

5 THE MOLECULAR BIOLOGY OF THE GENE SCIENTISTS WERE RESISTANT TO GRIFFITH’S FINDINGS SCIENTISTS KNEW ABOUT CHROMOSOMES – CHROMOSOMES ARE MADE UP OF PROTEINS (VERSATILE SUBSTANCES, 20 DIFFERENT AMINO ACIDS) NUCLEIC ACIDS (ONLY 5 DIFFERENT NUCLEOTIDES)

6 THE MOLECULAR BIOLOGY OF THE GENE HERSHEY AND CHASE EXPERIMENT

7 THE MOLECULAR BIOLOGY OF THE GENE HERSHEY AND CHASE SETUP – USED T2 BACTERIOPHAGES (PHAGE = VIRUS THAT ATTACKS/EATS BACTERIA) – GREW PHAGES IN RADIOACTIVE ELEMENTS SULFUR FOR PROTEIN / PHOSPHOROUS FOR DNA – TRACING RADIOACTIVITY ALLOWED THEM TO DETERMINE THE GENETIC CARRIER RESULTS – RADIOACTIVE PHOSPHOROUS ONLY WAS PRESENT IN BACTERIAS; CONCLUSIVELY SHOWING THAT DNA (NUCLEIC ACIDS) ARE CONTROLLING TRAITS/GENETICS

8 THE MOLECULAR BIOLOGY OF THE GENE NOW THE RACE WAS ON TO STUDY DNA/RNA DNA / RNA – POLYMERS OF NUCLEOTIDES NUCLEOTIDE?? POLYNUCLEOTIDE?? – SUGAR-PHOSPHATE BACKBONE REPEATING PATTERN OF SUGAR (PENTOSE) AND PHOSPHATE

9 THE MOLECULAR BIOLOGY OF THE GENE DNA – DEOXYRIBONUCLEIC ACID DEOXYRIBOSE  ?? NUCLEIC  ?? ACID  ?? – 4 TYPES OF BASES IN DNA (2 GROUPS) PURINES (2 RINGS) – ADENINE / GUANINE PYRIMIDINES (1 RING) – CYTOSINE / THYMINE RNA – RIBONUCLEIC ACID RIBOSE  ?? NUCLEIC  ?? ACID  ?? – 4 TYPES OF BASES IN RNA (2 GROUPS) PURINES (2 RINGS) – ADENINE / GUANINE PYRIMIDINES (1 RING) – CYTOSINE / URACIL

10 THE MOLECULAR BIOLOGY OF THE GENE STRUCTURE DENOTES ____________ – THEREFORE LEARNING THE STRUCTURE OF DNA BECAME OF EXTREME IMPORTANCE

11 THE MOLECULAR BIOLOGY OF THE GENE DNA IS A DOUBLE STRANDED HELIX – DOUBLE HELIX  TWO STRANDS OF DNA, COILED AROUND EACH OTHER (*TWISTED LADDER*) – EXPLAINED BY WATSON AND CRICK – USED DATA FROM WILKINS AND FRANKLIN X-RAY CRYSTALLOGRAPHY

12 THE MOLECULAR BIOLOGY OF THE GENE WATSON AND CRICK EXPLAINED THE DOUBLE HELIX – USING DATA FROM ERWIN CHARGAFF (EXPERIMENT THAT SHOWED # OF A’S AND T’S WAS ALWAYS EQUAL, AND # OF C’S AND G’S WAS ALWAYS EQUAL) – AS WELL AS DATA THAT SHOWED DNA STRANDS WERE ALWAYS THE SAME DISTANCE APART

13 THE MOLECULAR BIOLOGY OF THE GENE DISCOVERED STRUCTURE SUGGESTED AN EXPLANATION OF DNA REPLICATION SPECIFIC BASE PAIRING IS HOW DNA IS COPIED SPECIFIC BASE PAIRING IS HOW DNA IS COPIED

14 THE MOLECULAR BIOLOGY OF THE GENE WHILE THE CONCEPT OF REPLICATION IS SIMPLE, ACTUAL PROCESS IS COMPLEX

15 THE MOLECULAR BIOLOGY OF THE GENE DNA REPLICATION: A CLOSER LOOK – REPLICATION BEGINS AT SPECIFICS POINTS CALLED ORIGINS OF REPLICATION (O.R.’S) ORIGINS OF REPLICATION

16 THE MOLECULAR BIOLOGY OF THE GENE DNA REPLICATION: A CLOSER LOOK – THERE ARE MULTIPLE O.R.’S ALONG THE DNA STRAND (WHY IS THAT??) – REPLICATION BUBBLES WHERE DNA SPLITS AND REPLICATION OCCURS IN BOTH DIRECTIONS (WHY IS THAT??) – THE STRANDS OF DNA ARE ORIENTED IN OPPOSITE DIRECTIONS!!! HOW WILL THIS AFFECT REPLICATION? REMEMBER, ENZYMES HAVE SPECIFIC SHAPES!!

17 THE MOLECULAR BIOLOGY OF THE GENE DNA REPLICATION: A CLOSER LOOK – ENZYMES OF IMPORTANCE ENZYMES OF IMPORTANCE DNA POLYMERASE – ENZYME THAT ADDS NUCLEOTIDES TO GROW DAUGHTER STRAND

18 THE MOLECULAR BIOLOGY OF THE GENE DNA REPLICATION: A CLOSER LOOK DNA LIGASE – TIES/GLUES PIECES OF DNA TOGETHER INTO A SINGLE CONTINUOUS STRAND DNA HELICASE – UNZIPS THE DOUBLE STRANDED HELIX TOPOISOMERASE – RELIEVES THE PRESSURE/TENSION PLACED ON PARTS OF DNA STRAND THAT ARE STILLED COILED

19 THE MOLECULAR BIOLOGY OF THE GENE DNA REPLICATION: A CLOSER LOOK – ENSURES THAT EXACT COPIES OF DNA ARE PASSED ALONG TO ALL SOMATIC CELLS – AMAZINGLY ACCURATE; ONLY ONE MISTAKE EVERY BILLION NUCLEOTIDES PLACED!!

20 THE MOLECULAR BIOLOGY OF THE GENE THE STRUCTURE OF DNA ALSO OFFERS AN EXPLANATION AS TO HOW IT CAN CONTROL YOUR TRAITS THE DNA GENOTYPE (NUCLEOTIDE MAKEUP) IS EXPRESSED AS PROTEINS, WHICH ACTS AS THE MOLECULAR MAKEUP FOR PHENOTYPIC EXPRESSION!!

21 THE MOLECULAR BIOLOGY OF THE GENE DNA  RNA  PROTEIN = PHENOTYPE – TRANSCRIPTION PROCESS BY WHICH DNA IS CONVERTED TO RNA – TRANSLATION PROCESS BY WHICH RNA IS CONVERTED TO PROTEIN PROTEINS CONTROL THE PHENOTYPE (TRAITS) OF AN ORGANISM

22 THE MOLECULAR BIOLOGY OF THE GENE BEADLE AND TATUM EXPERIMENT – SHOWED THAT MUTANT MOLD, DEFICIENT IN ONLY ONE GENE; COULDN’T GROW ON MEDIA THAT IT COULD GROW ON WITH NORMAL GENE – ONE GENE : ONE POLYPEPTIDE HYPOTHESIS

23 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – PRODUCES GENETIC MESSAGES IN THE FORM OF RNA – ONLY OCCURS IN THE NUCLEUS (WHY??) – SIMILAR TO REPLICATION 2 STRANDS SPLIT BUT; ONLY STRAND SERVES AS TEMPLATE

24 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – REQUIRES THE FOLLOWING: RNA POLYMERASE – ENZYME THAT PLACES AND LINKS NUCLEOTIDES BEING TRANSCRIBED PROMOTER – SPECIFIC REGION OF DNA FOR RNA POLYMERASE TO BIND

25 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – OCCURS IN 3 STAGES INITIATION ELONGATION TERMINATION

26 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – INITIATION ????

27 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – ELONGATION ????

28 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – TERMINATION ????? TERMINATOR  SPECIFIC SEQUENCE ON DNA THAT SIGNALS THE RNA POLYMERASE TO DETACH

29 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – EUKARYOTIC RNA IS PROCESSED BEFORE LEAVING THE NUCLEUS mRNA = MESSENGER RNA; CARRIES MESSAGE OF DNA TO RIBOSOME FOR PROTEIN SYNTHESIS IN EUKARYOTES, THE mRNA MUST BE PROCESSED (CLEANED UP) BEFORE IT CAN LEAVE

30 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – EUKARYOTIC mRNA PROCESSING ONE TYPE OF PROCESSING IS ADDING A “CAP” AND “TAIL” WHY DOES THIS HAPPEN??

31 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – EUKARYOTIC mRNA PROCESSING SECOND TYPE OF PROCESSING IS REMOVAL OF NON-CODING REGIONS = RNA SPLICING TWO TYPES – EXONS » ??? – INTRONS » ???

32 THE MOLECULAR BIOLOGY OF THE GENE TRANSCRIPTION : A CLOSER LOOK – EUKARYOTIC mRNA PROCESSING RNA SPLICING – REMOVAL OF INTRONS TO PRODUCE FINAL mRNA PRODUCT – SPLICEOSOMES (A.KA. snRNP’S = PRONOUNCED SNURPS) SPLICEOSOMES

33 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – RIBOSOMES BUILD POLYPEPTIDES – RIBOSOMES ARE COMPOSED OF PROTEINS AND rRNA – RIBOSOMES COORDINATE mRNA, tRNA, AND AMINO ACIDS TO ALLOW PROTEIN SYNTHESIS – RIBOSOME STRUCTURE TWO SUBUNITS (LARGE VS SMALL) P SITE = PEPTIDYL – tRNA BINDING A SITE = AMINOACYL – tRNA BINDING

34 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – tRNA MOLECULES SERVE AS INTERPRETERS DURING TRANSLATION – AMINO ACIDS ARE READILY AVAILABLE IN THE CELL FROM DIGESTED FOOD – tRNA PICKS UP THE APPROPRIATE AMINO ACID AND BRINGS IT TO THE MATCHING CODON OF THE mRNA

35 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK TRANSLATION : A CLOSER LOOK – CODONS THREE NITROGENOUS BASE “WORD” THAT SPECIFIES A PARTICULAR AMINO ACID

36 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – CODONS – 4 “UNIQUE” CODONS AUG  START CODON, ALSO CODES FOR METHIONINE 3 STOP CODONS  SIGNAL END OF TRANSLATION – “WOBBLE” HYPOTHESIS MORE THAN ONE CODON CAN CODE FOR THE SAME AMINO ACID (OVERLAP)

37 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK

38 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – TRANSLATION CAN BE DIVIDED INTO THREE STAGES INITIATION ELONGATION TERMINATION

39 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – INITIATION

40 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – INITIATION 2 STEPS – mRNA BINDS TO SMALL SUBUNIT OF RIBOSOME; tRNA WITH THE STARD CODON BINDS (MET = AUG) – LARGE RIBOSOMAL SUBUNIT ATTACHES, CREATING A FUCNTIONAL RIBOSOME; INITIATOR tRNA FITS INTO “P” SITE

41 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – ELONGATION ADDS NUCLEOTIDES TO POLYPEPTIDE CHAIN 3 STEPS TO ELONGATION – CODON RECOGNITION – PEPTIDE BOND FORMATION – TRANSLOCATION

42 THE MOLECULAR BIOLOGY OF THE GENE TRANSLATION : A CLOSER LOOK – TERMINATION ELONGATION CONTINUES UNTIL A “STOP” CODON ENTERS THE “A” SITE

43 THE MOLECULAR BIOLOGY OF THE GENE REVIEW

44 THE MOLECULAR BIOLOGY OF THE GENE MUTATIONS CAN CHANGE THE MEANING OF GENES – MUTATION  ANY RANDOM CHANGE IN THE NUCLEOTIDE SEQUENCE OF DNA – CAN BE CLASSIFIED 3 WAYS SUBSTITUTIONS INSERTIONS (ADDITIONS) DELETIONS

45 THE MOLECULAR BIOLOGY OF THE GENE SUBSTITUTIONS – A BASE SUBSITUTION MAY CHANGE AN AMINO ACIDIN A POLYPEPTIDE, CHANGING THE PROTEIN – “WOBBLE” HYPOTHESIS??

46 THE MOLECULAR BIOLOGY OF THE GENE INSERTIONS AND DELETIONS – CAN BE MORE SEVERE – THEY CHANGE THE “READING FRAME”

47 THE MOLECULAR BIOLOGY OF THE GENE MUTAGENESIS – THE FORMATION OF MUTATIONS – 2 COMMON WAYS SPONTANEOUS MUTATION – ERRORS IN DNA REPLICATION/TRANSCRIPTION – UNKNOWN ORIGINS MUTAGEN – PHYSICAL (RADIATION) OR CHEMICAL AGENT *WHILE MUTATIONS ARE USUALLY HARMFUL; THEY CAN ALSO BE EXTREMELY USEFUL – PROMOTES EVOLUTION – IN THE LAB, PROVIDES A USEFUL TOOL FOR GENETIC RESEEARCH

48 THE MOLECULAR BIOLOGY OF THE GENE VIRUSES – IN A SENSE, VIRUSES ARE NOTHING MORE THAN PACKAGED GENES

49 THE MOLECULAR BIOLOGY OF THE GENE VIRUSES USE HOST CELL MACHINERY TO REPRODUCE VIRUSES USE HOST CELL MACHINERY TO REPRODUCE – HOW CAN THIS LEAD TO DISEASE? – WHY ARE VIRUSES DIFFICULT TO TREAT WITH ANTI-BIOTICS? – HOW DO WE TREAT VIRUSES?

50 THE MOLECULAR BIOLOGY OF THE GENE VIRUSES – TWO REPRODUCTIVE CYCLES LYTIC CYCLE

51 THE MOLECULAR BIOLOGY OF THE GENE VIRUSES – TWO REPRODUCTIVE CYCLES LYSOGENIC CYCLE  **CAN LEAD TO A PROPHAGE LYSOGENIC CYCLE

52 THE MOLECULAR BIOLOGY OF THE GENE EMERGING VIRUSES – AIDS (HIV) – FLU – EBOLA – HANTA HOW DO VIRUSES ARISE? – UNKNOWN!!!! – POSSIBLE THEORIES??

53 THE MOLECULAR BIOLOGY OF THE GENE AIDS – HIV IS A RETROVIRUS (UNIQUE) – MAKES DNA FROM AN RNA TEMPLATE

54 THE MOLECULAR BIOLOGY OF THE GENE AIDS – REQUIRES THE USE OF REVERSE TRANSCRIPTASE – TURNS HOST CELL INTO A “PROVIRUS” – WHAT IS THE DIFFERENCE BETWEEN AIDS & HIV?? – WHY IS HIV SO DIFFICULT TO TREAT?

55 THE MOLECULAR BIOLOGY OF THE GENE THE STRUCTURE OF DNA CAN TELL US HOW IT COPIES ITSELF AND HOW IT CAN GET CONVERTED INTO PROTEIN; BUT HOW COME IF EVERY CELL HAS THE SAME DNA, THEY CAN ALL LOOK DIFFERENT THAN EACH OTHER? YOU JUST HAVE TO STICK AROUND TO FIND OUT MORE!!

56 THE MOLECULAR BIOLOGY OF THE GENE


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