Nucleic Acids and Protein Synthesis. What are nucleic acids?
Nucleic Acids Genetic Material. Nucleic Acids are macromolecules There are two main types: DNARNA.
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Transcript of Nucleic Acids Genetic Material. Nucleic Acids are macromolecules There are two main types: DNARNA.
Nucleic AcidsNucleic Acids
Genetic MaterialGenetic Material
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Nucleic Acids are macromoleculesNucleic Acids are macromolecules
There are two main types:There are two main types:DNA DNA RNARNA
A Nucleotide is the building A Nucleotide is the building blockblock
It is made up of three partsIt is made up of three parts One part is a 5-carbon sugarOne part is a 5-carbon sugar
This sugar is also called ribose (in RNA)This sugar is also called ribose (in RNA)
Or Deoxy-ribose (In DNA) – Deoxyribose nucleic Or Deoxy-ribose (In DNA) – Deoxyribose nucleic acidacid
What is the difference between What is the difference between Ribose and Deoxy ribose?Ribose and Deoxy ribose?
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Second part of a NucleotideSecond part of a Nucleotide
Nitrogen containing baseNitrogen containing base
There are four different bases:There are four different bases:
Adenine, Cytosine, Guanine, ThymineAdenine, Cytosine, Guanine, Thymine
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3 D3 D
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The Third Component of a The Third Component of a Nucleotide is a Phosphate Nucleotide is a Phosphate
GroupGroup
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Put it all together now…Put it all together now…
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DNA is supercoiledDNA is supercoiled
Think of a Twisted LadderThink of a Twisted Ladder
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In HUMANs and most animals, DNA is In HUMANs and most animals, DNA is always double strandedalways double stranded
RNA is always Single strandedRNA is always Single stranded There are three kinds of RNA…which we will There are three kinds of RNA…which we will
talk about later.talk about later.
The Double HelixThe Double Helix
In 1953 James Watson and Francis Crick In 1953 James Watson and Francis Crick proposed a model for DNA that is still proposed a model for DNA that is still accepted todayaccepted today
Two ExperimentsTwo Experiments
This is an x ray of crystallized DNA taken This is an x ray of crystallized DNA taken by Rosalind Franklin - The Dark Lady of by Rosalind Franklin - The Dark Lady of DNADNA
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Rosalind the CrystallographerRosalind the Crystallographer
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It was Rosalind’s image that led It was Rosalind’s image that led Watson and Crick to the double Watson and Crick to the double
helix model of DNAhelix model of DNA
DNA is made up of two long chains.DNA is made up of two long chains.
Each with a sugar phosphate backboneEach with a sugar phosphate backbone
BUT: The two back-bone’s run in opposite BUT: The two back-bone’s run in opposite direction!direction!
Watson and Crick determined Watson and Crick determined that the four bases pair up very that the four bases pair up very
specificallyspecificallyDiscovered in 1953, won Nobel Prize in Discovered in 1953, won Nobel Prize in 19621962
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Watson and Crick used discoveries Watson and Crick used discoveries of other researchers to build their of other researchers to build their
modelmodelExperiments done by Rosalind Franklin and Experiments done by Rosalind Franklin and
Maurice Wilkins suggested to Watson and Maurice Wilkins suggested to Watson and Crick, that DNA molecules had a Crick, that DNA molecules had a double double helix structurehelix structure
Watson and Crick came up with the Watson and Crick came up with the idea of Base Pairingidea of Base Pairing
Cytosine only pairs with Guanine and vice Cytosine only pairs with Guanine and vice versaversa
Thymine only pairs with Adenine and vice Thymine only pairs with Adenine and vice versaversa
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The Genetic CodeThe Genetic Code
DNA forms the genes – units of genetic DNA forms the genes – units of genetic information that pass from parent to information that pass from parent to offspringoffspring
The human genome is ~ 3 billion base The human genome is ~ 3 billion base pairs long and has been completely pairs long and has been completely mapped mapped
DNA taken with a Scanning DNA taken with a Scanning Tunneling MicroscopeTunneling Microscope
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A single DNA molecule - this is A single DNA molecule - this is a chromosomea chromosome
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Unravelled vs condensedUnravelled vs condensed
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DNA use as evidenceDNA use as evidence
Like a fingerprint DNA is unique to an Like a fingerprint DNA is unique to an individualindividual
Look your right or leftLook your right or left
The person sitting next to you is 99.9% The person sitting next to you is 99.9% similar to you similar to you
How can Forensic Scientists How can Forensic Scientists use DNA?use DNA?
In the human genome there are certain In the human genome there are certain places where there are known sequencesplaces where there are known sequences
We can use these parts as markers and We can use these parts as markers and we can use specific enzymes to cut the we can use specific enzymes to cut the DNA strand at this spotDNA strand at this spot
Restriction Enzymes are used Restriction Enzymes are used to cut DNAto cut DNA
These enzymes are produced by certain These enzymes are produced by certain types of virusestypes of viruses
What these enzymes do is recognize What these enzymes do is recognize specific patterns in a DNA sequence and specific patterns in a DNA sequence and cut the DNA like a pair of scissorscut the DNA like a pair of scissors
Viruses are an enemy of bacteria and people, Viruses are an enemy of bacteria and people, and they can infect us by cutting our DNA, and and they can infect us by cutting our DNA, and inserting THEIR DNA!!inserting THEIR DNA!!
Once their DNA is in we become Virus factoriesOnce their DNA is in we become Virus factories
They have hijacked our cells, and they force us They have hijacked our cells, and they force us to produce more of them…this leads to us being to produce more of them…this leads to us being sick and spreading them.sick and spreading them.
Restriction Enzymes Cut DNA Restriction Enzymes Cut DNA at a palindromeat a palindrome
What is a palindrome ?What is a palindrome ?
A sequence that reads the same A sequence that reads the same backwards as forwards…Do you see the backwards as forwards…Do you see the palindrome in the below sequence?palindrome in the below sequence?
GTAGAATTCATTCACGCAGTAGAATTCATTCACGCA
CATCTTTAAGTAATGCGT CATCTTTAAGTAATGCGT
Now do you see it?Now do you see it?
GTA G-AATTC ATTCACGCAGTA G-AATTC ATTCACGCA
CAT CTTTAA-G TAATGCGTCAT CTTTAA-G TAATGCGT
This is the region where a restriction This is the region where a restriction enzyme would recognize and CUT or enzyme would recognize and CUT or CLEAVE the DNACLEAVE the DNA
The actual name of this enzyme is Eco RIThe actual name of this enzyme is Eco RI
Restriction Fragment Length Restriction Fragment Length PolymorphismPolymorphism
This is the ability to cut DNA at a specific code This is the ability to cut DNA at a specific code using Restriction Enzymesusing Restriction Enzymes
These regions that scientists can cut, will These regions that scientists can cut, will result in varying segment lengths for result in varying segment lengths for different people,different people,
The Digested DNA will then be run using Gel The Digested DNA will then be run using Gel Electrophoresis… This is how we can Electrophoresis… This is how we can visualize the different DNA segment lengthsvisualize the different DNA segment lengths
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A molecule of DNA has an A molecule of DNA has an extremely negative chargeextremely negative charge
So we can use this to run an electric So we can use this to run an electric charge through an electophoresis cell--- charge through an electophoresis cell--- see belowsee below
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As the electrical charge occurs we have a As the electrical charge occurs we have a current of positive ions flowing through our current of positive ions flowing through our gel.gel.
The DNA will migrate down the gel toward The DNA will migrate down the gel toward the positive end of the cellthe positive end of the cell
The negative DNA is attracted to the The negative DNA is attracted to the Positive end of the electrophoresis cellPositive end of the electrophoresis cell
Do you see the different band Do you see the different band patterns? They are all different patterns? They are all different
size DNA piecessize DNA pieces
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After the DNA has been chopped up by After the DNA has been chopped up by enzymes, the shorter pieces will move enzymes, the shorter pieces will move down the gel faster than the longer piecesdown the gel faster than the longer pieces
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Is it possible that two different people Is it possible that two different people would have the same lengths strands after would have the same lengths strands after the DNA samples have been cut?the DNA samples have been cut?
Yes!!! - So this method would be a good Yes!!! - So this method would be a good way to eliminate suspects.way to eliminate suspects.This method alone could not incriminate a This method alone could not incriminate a suspectsuspect
In a criminal case where DNA In a criminal case where DNA evidence is available an evidence is available an
electrophoresis would be one of electrophoresis would be one of the first techniques usedthe first techniques used
In actuality Forensic scientists don’t use In actuality Forensic scientists don’t use electroporesis anymore…but it was one of electroporesis anymore…but it was one of the original DNA fingerprinting techniquesthe original DNA fingerprinting techniques
Why do you think this is?Why do you think this is?
Because we the process is relatively Because we the process is relatively inexpensive and quick to do, and suspects inexpensive and quick to do, and suspects whose bands were very different could be whose bands were very different could be immediately eliminatedimmediately eliminated
Suspects who had similar banding Suspects who had similar banding patterns would have to be further analyzed patterns would have to be further analyzed …Their DNA would probably be …Their DNA would probably be sequenced to determine if the sequences sequenced to determine if the sequences matchedmatched
DNA can be sequenced using DNA can be sequenced using PCRPCR
The Polymerase Chain ReactionThe Polymerase Chain Reaction