MODERN GENETICS
description
Transcript of MODERN GENETICS
MODERN GENETICS
MODERN GENETICS WHO DISCOVERED THE
STRUCTURE OF DNA? EVERYONE SEEMS TO
KNOW WATSON AND CRICK, BUT WHO IS
THIS?
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 THATCOULD GIVE MANY GENERATIONSQUICKLY!!
HENCE, FRUIT FLIES
MODERN GENETICS T.H. MORGAN’S WORK LED TO THE
FOLLOWING UNDERSTANDING: CHROMOSOMES CONTROL SEX (GENDER) SEX-LINKED TRAITS GENE LINKAGE
MODERN GENETICS SEX DETERMINATION AND CHROMOSOMES
A SPECIFIC PAIR OF CHROMOSOMES, KNOWN AS THE SEX CHROMOSOMES, DETERMINES THE GENDER OF ANY INDIVIDUAL
MODERN GENETICS SEX-
LINKED TRAITS OBSERV
E THE PEDIGREE CHART…WHAT PATTERN DO YOU NOTICE?
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
MODERN GENETICS EXAMPLES OF X-LINKED TRAITS:
RED-GREEN COLORBLINDNESS HEMOPHILIA
MODERN GENETICS GENE LINKAGE
IT WAS DISCOVERED THAT GENDER AND TRAITS AREN’T 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? *HERE’S A HINT
MODERN GENETICS IF GENES ARE LINKED, HOW CAN THEIR BE
PEOPLE WITH BROWN HAIR AND BLUE EYES? CROSSING OVER!!
EXCHANGE BETWEEN HOMOLOGOUS CHROMOSOMES DURINGSYNAPSIS OF MEIOSIS
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
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?
MODERN GENETICS THE GREAT DEBATE – PROTEIN VS. DNA
BY THE EARLY 1900’S, 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
MODERN GENETICS ENTER “THE MOUSE-KILLER”
SIR FREDERICK GRIFFITH
MODERN GENETICS GRIFFITH’S EXPERIMENTS WEREN’T
ENOUGH FOR THE SKEPTICS…BUT EVEN THE SKEPTICS COULDN’T DENY THE FINDINGS OF…
MODERN GENETICS HERSHEY AND CHASE EXPERIMENT
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
MODERN GENETICS WHILE SCIENTISTS FIGURED OUT THE
BUILDING BLOCKS OF DNA, HOW THOSE BUILDING BLOCKS GOT PUT TOGETHER ELUDED THEM…
MODERN GENETICS ENTER OUR
HERO’S WATSON AND
CRICK CREDITED
WITH IDENTIFYING / DISCOVERING THE STRUCTURE OF DNA!!!
MODERN GENETICS DNA’S STRUCTURE
MODERN GENETICS DNA’S 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)
MODERN GENETICS DNA REPLICATION
MODERN GENETICS LEARNING THE STRUCTURE OF DNA STILL
LEFT AN UNANSWERED QUESTION… HOW WAS DNA THE SUBSTANCE THAT
CONTROLLED AN INDIVIDUAL’S 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…
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?
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 DON’T HAVE TELEPHONES?)
THEY CAN WRITE TO EACH OTHER…WHICH IS EXACTLY WHAT DNA DOES, IT WRITES A MESSAGE TO BE SENT TO THE RIBOSOMES…
ENTER OUR MESSENGER – RNA!!
MODERN GENETICS
RNA VS DNA
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 HAVEN’T MADE A PROTEIN YET…WHERE DO PROTEINS GET MADE?
THE mRNA CAN GO VISIT THE RIBOSOME FACE TO FACE
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
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, G…HOW CAN 4 LETTERS = 20 DIFFERENT BASES?
MODERN GENETICS
MODERN GENETICS I FORGOT TO TELL YOU…RIBOSOMES DON’T
SPEAK PROTEIN (IN OTHER WORDS THEY DON’T KNOW WHAT AMINO ACID MATCHES A CODON)
WE NEED A SPECIAL TRANSLATOR… ENTER tRNA
SPEAKS BOTH CODONAND PROTEIN, SO IT “TRANSLATES” AND “TRANSFERS” THE CORRECT AMINO ACID
MODERN GENETICS LET’S LOOK AT
IT OVERALL PROTEIN
SYNTHESIS TRANSCRIPTIO
N
TRANSLATION
MODERN GENETICS REMEMBER, EVERY CELL IN YOUR BODY HAS
THE EXACT SAME DNA…WHY IS THAT? WE HAVE EXPLAINED HOW DNA ACTS AS THE
INSTRUCTIONS FOR MAKING PROTEINS…SO HOW COME EVERY CELL IN YOUR BODY DOESN’T 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
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 OFF…WHEN THEY ARE ON THEY ARE MAKING PROTEINS, WHEN THEY ARE OFF, THEY AREN’T
MODERN GENETICS WHAT CAN TURN
THE SWITCHES ON OR OFF? OTHER GENES ENVIRONMENTAL
FACTORS **MUST
REMEMBER – THE ENVIRONMENT CAN EFFECT GENE EXPRESSION
MODERN GENETICS UNDERSTANDING GENE EXPRESSION MAY
UNLOCK CURES TO DISEASES SUCH AS CANCER ONCOGENES
MODERN GENETICS WHAT DO WE DO
WITH ALL THIS INFORMATION ON GENES?
APPLIED GENETICS IS NEXT!!