MODERN GENETICS WHO DISCOVERED THE STRUCTURE OF DNA? EVERYONE
SEEMS TO KNOW WATSON AND CRICK, BUT WHO IS THIS?
Slide 4
MODERN GENETICS T.H. MORGAN OFFERED FIRST EVIDENCE OF WHAT
SUBSTANCE INSIDE LIVING THINGS CONTROLS THEIR TRAITS LIKE MENDEL,
THE TRICK TO BEING SUCCESSFUL LIED IN WORKING WITH AN ORGANISM THAT
COULD GIVE MANY GENERATIONS QUICKLY!! HENCE, FRUIT FLIES
Slide 5
MODERN GENETICS T.H. MORGANS WORK LED TO THE FOLLOWING
UNDERSTANDING: CHROMOSOMES CONTROL SEX (GENDER) SEX-LINKED TRAITS
GENE LINKAGE
Slide 6
MODERN GENETICS SEX DETERMINATION AND CHROMOSOMES A SPECIFIC
PAIR OF CHROMOSOMES, KNOWN AS THE SEX CHROMOSOMES, DETERMINES THE
GENDER OF ANY INDIVIDUAL
Slide 7
MODERN GENETICS SEX-LINKED TRAITS OBSERVE THE PEDIGREE CHART
WHAT PATTERN DO YOU NOTICE?
Slide 8
MODERN GENETICS SEX-LINKED TRAITS WHEN A TRAIT APPEARS TO BE
DISPLAYED IN ONE GENDER MORE FREQUENTLY THEN ANOTHER, AND THE ONLY
DIFFERENCE BETWEEN EACH GENDER IS THE SEX CHROMOSOMES; THE TRAIT
MUST BE ASSOCIATED/LINKED TO THE SEX CHROMOSOMES X-LINKAGE VS.
Y-LINKAGE
Slide 9
MODERN GENETICS EXAMPLES OF X-LINKED TRAITS: RED-GREEN
COLORBLINDNESS HEMOPHILIA
Slide 10
MODERN GENETICS GENE LINKAGE IT WAS DISCOVERED THAT GENDER AND
TRAITS ARENT THE ONLY THINGS THAT CAN BE LINKED ANY PAIR OF TRAITS
FOUND ON THE SAME CHROMOSOME ARE CONSIDERED LINKED WHAT DATA WOULD
SUGGEST THAT TRAITS ARE LINKED? *HERES A HINT
Slide 11
MODERN GENETICS IF GENES ARE LINKED, HOW CAN THEIR BE PEOPLE
WITH BROWN HAIR AND BLUE EYES? CROSSING OVER!! EXCHANGE BETWEEN
HOMOLOGOUS CHROMOSOMES DURING SYNAPSIS OF MEIOSIS
Slide 12
MODERN GENETICS RANDOM QUESTION IN HUMANS, DOES HEIGHT OCCUR IN
JUST TWO FORMS; TALL VERSUS SHORT? HOW CAN WE EXPLAIN THE LARGE
RANGE OF PHENOTYPES FOR HUMAN HEIGHT? POLYGENIC INHERITANCE MORE
THAN ONE GENE CONTROLS THE SAME TRAIT, CREATING A LARGE NUMBER OF
POSSIBLE PHENOTYPES
Slide 13
MODERN GENETICS AFTER UNDERSTANDING ABOUT THE DIFFERENT
PATTERNS OF INHERITANCE, THIS STILL LEFT AN UNANSWERED QUESTION
WHAT WAS THE ACTUAL SUBSTANCE THAT CONTROLLED THESE TRAITS TO BEGIN
WITH?
Slide 14
MODERN GENETICS THE GREAT DEBATE PROTEIN VS. DNA BY THE EARLY
1900S, SCIENCE HAD ALREADY LEARNED OF THE EXISTENCE OF CHROMOSOMES
AND THAT THESE CHROMOSOMES WERE COMPOSED OF BOTH PROTEINS AND
NUCLEIC ACIDS LITTLE WAS KNOWN ABOUT NUCLEIC ACIDS, AND PROTEINS
WERE WELL UNDERSTOOD AT THAT TIME AS PROTEINS WERE FOUND TO EXIST
IN EVERY SUBSTANCE INVOLVED IN TRAITS, THEY WERE THE FRONT-RUNNER
FOR THE ACTUAL SUBSTANCE THAT CONTROLLED TRAITS
Slide 15
MODERN GENETICS ENTER THE MOUSE-KILLER SIR FREDERICK
GRIFFITH
Slide 16
MODERN GENETICS GRIFFITHS EXPERIMENTS WERENT ENOUGH FOR THE
SKEPTICSBUT EVEN THE SKEPTICS COULDNT DENY THE FINDINGS OF
Slide 17
MODERN GENETICS HERSHEY AND CHASE EXPERIMENT
Slide 18
MODERN GENETICS ONCE IT WAS ESTABLISHED THAT DNA CONTROLLED
TRAITS, THERE WAS A MAD RUSH TO FIND OUT THE STRUCTURE OF DNA WHY
IN THE WORLD WOULD SCIENTISTS CARE SO MUCH ABOUT THE STRUCTURE OF
DNA? STRUCTURE DENOTES FUNCTION
Slide 19
MODERN GENETICS WHILE SCIENTISTS FIGURED OUT THE BUILDING
BLOCKS OF DNA, HOW THOSE BUILDING BLOCKS GOT PUT TOGETHER ELUDED
THEM
Slide 20
MODERN GENETICS ENTER OUR HEROS WATSON AND CRICK CREDITED WITH
IDENTIFYING / DISCOVERING THE STRUCTURE OF DNA!!!
Slide 21
MODERN GENETICS DNAS STRUCTURE
Slide 22
MODERN GENETICS DNAS STRUCTURE DNA IS A DOUBLE HELIX (TWISTED
LADDER) ADENINE ALWAYS PAIRS WITH THYMINE AND CYTOSINE ALWAYS PAIRS
WITH GUANINE EXPLAINED THE IMMENSE COMPLEXITY OF TRAITS (HOW DOES
IT LEAD TO COMPLEXITY?) UNEXPECTEDLY EXPLAINED WHY DNA CAN MAKE
IDENTICAL COPIES OF ITSELF (IDENTICAL OFFSPRING)
Slide 23
MODERN GENETICS DNA REPLICATION
Slide 24
MODERN GENETICS LEARNING THE STRUCTURE OF DNA STILL LEFT AN
UNANSWERED QUESTION HOW WAS DNA THE SUBSTANCE THAT CONTROLLED AN
INDIVIDUALS TRAITS, IF PROTEINS WERE WHAT WERE PRESENT THAT
ACTUALLY SEEMED TO CONTROL THE APPEARANCE OF THE TRAIT? SOMEHOW,
DNA HAD TO BE CONTROLLING THE SYNTHESIS OF PROTEINS
Slide 25
MODERN GENETICS WHERE IS DNA FOUND? WHERE DOES PROTEIN
SYNTHESIS TAKE PLACE? DOES DNA EVER LEAVE THE NUCLEUS? NO!!! HOW
CAN DNA BE USED TO MAKE PROTEINS IF IT NEVER GOES NEAR THE
RIBOSOMES IN THE CYTOPLASM?
Slide 26
MODERN GENETICS HOW CAN DNA BE USED TO MAKE PROTEINS IF IT
NEVER GOES NEAR THE RIBOSOMES IN THE CYTOPLASM? (HINT - HOW CAN TWO
PEOPLE COMMUNICATE WHO NEVER SEE EACH OTHER AND DONT HAVE
TELEPHONES?) THEY CAN WRITE TO EACH OTHERWHICH IS EXACTLY WHAT DNA
DOES, IT WRITES A MESSAGE TO BE SENT TO THE RIBOSOMES ENTER OUR
MESSENGER RNA !!
Slide 27
MODERN GENETICS RNA VS DNA
Slide 28
MODERN GENETICS THE PROCESS OF DNA WRITING A MESSAGE IN THE
FORM OF RNA IS CALLED: DNA TRANSCRIPTION DNA mRNA ALL WE HAVE IS A
MESSAGE, WE HAVENT MADE A PROTEIN YETWHERE DO PROTEINS GET MADE?
THE mRNA CAN GO VISIT THE RIBOSOME FACE TO FACE
Slide 29
MODERN GENETICS THE RIBOSOME USES THE mRNA AS THE INSTRUCTIONS
ON HOW TO MAKE A PROTEIN WHAT IS THIS PROCESS OF MAKING A PROTEIN
CALLED? PROTEIN SYNTHESIS WHAT DOES A PROTEIN LOOK LIKE? A LONG
CHAIN OF AMINO ACIDS HOW DOES PROTEIN SYNTHESIS WORK? THE mRNA
TELLS THE RIBOSOME WHAT THE ORDER OF AMINO ACIDS SHOULD BE IN
BUILDING A PROTEIN
Slide 30
MODERN GENETICS PROTEINS ARE MADE UP OF AMINO ACIDS; STUDIES
HAVE SHOWN THAT THERE ARE 20 DIFFERENT AMINO ACIDS THERE ARE ONLY 4
NITROGENOUS BASES IN mRNA; A, U, C, GHOW CAN 4 LETTERS = 20
DIFFERENT BASES?
Slide 31
MODERN GENETICS
Slide 32
I FORGOT TO TELL YOURIBOSOMES DONT SPEAK PROTEIN (IN OTHER
WORDS THEY DONT KNOW WHAT AMINO ACID MATCHES A CODON) WE NEED A
SPECIAL TRANSLATOR ENTER tRNA SPEAKS BOTH CODON AND PROTEIN, SO IT
TRANSLATES AND TRANSFERS THE CORRECT AMINO ACID
Slide 33
MODERN GENETICS LETS LOOK AT IT OVERALL PROTEIN SYNTHESIS
TRANSCRIPTION TRANSLATION
Slide 34
MODERN GENETICS REMEMBER, EVERY CELL IN YOUR BODY HAS THE EXACT
SAME DNAWHY IS THAT? WE HAVE EXPLAINED HOW DNA ACTS AS THE
INSTRUCTIONS FOR MAKING PROTEINSSO HOW COME EVERY CELL IN YOUR BODY
DOESNT MAKE THE EXACT SAME PROTEINS DIFFERENT CELLS USE DIFFERENT
PARTS OF DNA WE CONTROLS/DETERMINES WHAT PARTS OF DNA ARE USED? WE
CALL THIS FIELD OF STUDY GENE EXPRESSION
Slide 35
MODERN GENETICS GENE EXPRESSION IS ONE OF THE MOST
COMPLICATED/LEAST UNDERSTOOD AREAS OF GENETICS/SCIENCE TODAY THE
SIMPLE EXPLANATION IS THAT MOST GENES ARE LIKE LIGHT SWITCHES, THEY
CAN BE ON OR OFFWHEN THEY ARE ON THEY ARE MAKING PROTEINS, WHEN
THEY ARE OFF, THEY ARENT
Slide 36
MODERN GENETICS WHAT CAN TURN THE SWITCHES ON OR OFF? OTHER
GENES ENVIRONMENTAL FACTORS **MUST REMEMBER THE ENVIRONMENT CAN
EFFECT GENE EXPRESSION
Slide 37
MODERN GENETICS UNDERSTANDING GENE EXPRESSION MAY UNLOCK CURES
TO DISEASES SUCH AS CANCER ONCOGENES
Slide 38
MODERN GENETICS WHAT DO WE DO WITH ALL THIS INFORMATION ON
GENES? APPLIED GENETICS IS NEXT!!