GENETICS 101: DNA
CHAPTER 12
So…How much do YOU know about genetics?
Writing Log today: Take the pre-test in your
notepacket. We will learn about each of the concepts in the pre-test throughout this unit, and then we will take the post-test and see
how well you did on the pre-test.
Section 1: DNA -
What’s this stuff made
of?
What do we find inside the nucleus?
DNA Deoxyribonucleic acid
Genetic Code
Revised 10-10-2006
DNA: Deoxyribonucleic Acid
DNA James Watson and Francis CrickRosalind
Franklin
DNA: Deoxyribonucleic Acid
What do we call this shape?
Watson and Crick:Came up with the model we accept
today as a DOUBLE HELIX • Double helix: where the two
strands are wound around each other
Do you want to build with building blocks?
Did you play with blocks as a kid?
DNA DNA is made up of nucleotides
Nucleotides are the BUILDING BLOCKS of DNA
NUCLEOTIDE: building block of DNA
Three parts of a NUCLEOTIDE:1. Sugar (What the sugar
called?)2. Phosphate group3. Nitrogen Base
Backbone : Deoxyribose Sugar and Phosphate
Inner Molecule: Nitrogen Bases
4 kinds of nitrogen bases
Adenine Guanine
4 kinds of nitrogen bases
Adenine Guanine Both of
these types of
molecules are called
purines
4 kinds of nitrogen bases
Thymine Cytosine
4 kinds of nitrogen bases
Thymine
Cytosine Both of these types
of molecules are called
pyrimidines
LETS MAKE SOME NUCLEOTIDES
Plant CellAnimal Cell
All organisms use the same four bases as a blueprint for that organism.
Plant CellAnimal Cell
All organisms use the same four bases as a blueprint for that organism.
If there are only four types of nitrogen bases, and those nitrogen bases are the blueprint for all organisms, how come we don’t all look the same? Why are there so many different types of organisms?
Before you answer:
Morse Code is a simple code of
only 2 symbols…and yet it can be
used to send complex
information
Base Pairing Edwin Chargaff:
In 1950, he analyzed the amount of each of the bases in the DNA of various species
Erwin ChargaffAustrian BiochemistThe area he was from in now in what is Ukraine
Base Pairing Chargaff’s Data (What do you
notice?)
HumansFruit flyCornBread MoldBacteriaBacteria
Base Pairing Chargaff’s Rule:
Chargaff found that the percentage of A (Adenine) equals the percentage of T (thymine); and C (cytosine)= G (guanine) % of A=% of T and % of C= % of GErwin Chargaff
Austrian Biochemist
Base Pairing Base Pairs: two nucleotides
hydrogen boding together Adenine (A) will bond or pair with Thymine (T)
Cytosine (C) will bond or pair with Guanine (G)
Hydrogen Bonding Turns out purines (Adenine (A) and
Guanine (G)) like to bond with pyrimidines (Cytosine (C) and Thymine (T))
Hydrogen Bonding A (Adenine) and T (Thymine) have
Two Hydrogen Bonds holding those nucleotides together
G (Guanine) and C (Cytosine) have three hydrogen bonds
Lets put our “nucleotides” together
Section 2: What is a
DNA Replication?
What is DNA Replication
https://www.youtube.com/watch?v=27TxKoFU2Nw
DNA Replication Before cell division, DNA is replicated Semiconservative Replication:
parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA.
In other words,Old strands of DNA act as a template
DNA Replication
DNA Replication Steps of DNA Replication:
Helicase unwinds double helix (breaks hydrogen bonds)
DNA Replication
DNA Replication Steps of DNA Replication:
Helicase unwinds double helix (breaks hydrogen bonds)
RNA primase adds a primer to parental/template strands
DNA Replication
DNA Replication Steps of DNA Replication:
Helicase unwinds double helix (breaks hydrogen bonds)
RNA primase adds a primer to parental/template strands
DNA Polymerase adds new nucleotides to create the complimentary strand to parental/template strand
DNA Replicationhttps://www.youtube.com/watch?v=OnuspQG0Jd0
DNA ReplicationLets try DNA Replication:Original DNA StrandATTCGATCCGTTACCATGATAAGCTAGGCAATGGTACT
ATTCGATCCGTTACCATGA
TAAGCTAGGCAATGGTACT
New replicated DNA Strand
New replicated DNA Strand
Original DNA Strand
Section 3: What is a
gene?
Genes
First let’s compare Chromosomes to a
towel
Chromosome
Chromatin = Long strands of DNAChromosome : coiled up strand of chromatin
The “X” shape is where the chromosome has been copied.
Chromatin Chromosome
How many chromosomes do we have in our nucleus?
How many chromosomes do we have in our nucleus of each of our cells?
a. 23b. 52
c. 108d. 46
What is a Gene? Gene: functional unit that
controls inherited trait expression that is passed on from one generation to another generation.
Genes In other words, Genes are pieces of our
DNA that code for our traits.
Proteins from Genes
• Gene: Part of chromosome that codes for a protein
How many genes do we have?
The Human Genome
• How many paired nucleotides do we have? (i.e. how many base pairs do we have?)
3 billion base pairs
In 1964, Friedrich Vogel estimated that the total number of genes in the human genome
to be ~ 6.7 million
What is a Trait?
Trait = Any characteristic
Trait
Inherited Trait
Inherited trait = a characteristic that you get from your biological parents and….
• a trait you are born with. • It’s in your DNA!• What are some examples?
EX: (Write down one of your inherited traits)
Acquired Trait
Acquired trait = a characteristic that you develop in your lifetime
• a trait you learn or pickup after you are born (not inherited from your parents)
• What are some examples?
EX: (Write down one of your acquired traits)
Section 4: transcriptio
n and translation
What are grandmas good for?
What is DNA good for?
PROTEIN SYNTHESIS:
How proteins are made…
which are coded from DNA
AKA: Transcription and Translation
Protein Synthesis
DNA RNA
Transcription
Protein Synthesis
DNA RNA Protein
Transcription Translation
DNA vs. RNA
DNA
-Double strand
-Sugar called
deoxyribose
-Bases are
C G A T
RNA
-Single strand
-Sugar called ribose
-Bases are
C G A U
DNA vs. RNA
DNA
Double strand
Sugar called
deoxyribose
Bases are
C G A T
RNA
Single strand
Sugar called ribose
Bases are
C G A U
U = Uracil
Transcription• Using DNA to make RNA• Happens inside the nucleus
Translation• Using RNA to make protein• Happens outside the nucleus
Protein:
A chain of amino acids
• Each amino acid is coded for by three nucleotides called…..
Codon:
Three bases that code for a specific amino acid
(Anticodon)
Anticodon:
The three opposite bases
A T G AA T A G C T G G A G G G A T T A A
T A C T T A T C G A C C T C C C T A A T T
Transcription (inside the nucleus)
A T G AA T A G C T G G A G G G A T T A A
A UG A A U A G CU G G A G G GA U U A A
T A C T T A T C G A C C T C C C T A A T T
A UG A A U A G C U G G A G G GA U U AA
A UG A A U A G C U G G A G G GA U U AA
ASPA
MET ASP SER TRY ARG
So WHY DNA, the real purpose?
To make PROTEIN!!
Section 5: Mutations
Mutations
Evr made a mitsake
in yourr spelng?
MUTATIONS!A mess up in the DNA
sequence
Where do mutations occur?
IN THE DNA!!
(not the RNA)
When do mutations occur?
During replication
MUTATIONS!Gene Mutations (2 types)Changes in a single base
Chromosomal Mutations (4 types)Changes in whole chromosomes
Gene MutationsPoint Mutations
Frameshift Mutations
Point Mutation
A T G AA T A G C T G G A G G G A T T T T
T A C T T A T C G T C C T C C C T A A A A
A T G AA T A G C T G G A G G G A T T T T
A UG A A U A G C A G G A G G GA U U UU
T A C T T A T C G T C C T C C C T A A A A
Point Mutation
These happen at only ONE POINT or base
Usually one base is replaced by a different base
End result:
ONE amino acid in the protein chain is wrong
A UG A A U A G C A G G A G G GA U U UU
Point Mutation
MET ASP SER ARG ARG ASPA
PHE
These happen at only ONE POINT or base
Usually one base is replaced by a different base
End result:
ONE amino acid in the protein chain is wrong
A UG A A U A G C A G G A G G GA U U UU
Point Mutation
MET ASP SER ARG ARG ASPA
PHE
A T G AA T A G C T G G A G G G A T T T T
T A C T T A T C G T C C T C C C T A A A A
Frameshift
A T G AA T A G C T G G A G G G A T T T T
A UG A A U A G C A G G A G G GA U U UU
T A C T T A T C G T C C T C C C T A A A A
Frameshift
A UG A A U A G GU G G U G G GA U U UU
Frameshift
A UG A A U A G G G G U G G G A U U UU
Frameshift
A UG A A U A G C U G G A G G GA U U UU
MET ASP SER TRY ARG ASPA
PHE
Frameshift
Frameshift
This causes a SHIFT in the rest of the sequence following the mutationEnd result:Every amino acid after the mutation is wrong!
A UG A A U A G C G G A G G GA U U UU
MET ASP SER GLY GLY ISO
MUTATIONS!
Chromosomal Mutations (4)
Changes in whole chromosomes
Chromosomal Mutations1. Deletion:
part of the chromosome is lost
Chromosomal Mutations1. Deletion:
part of the chromosome is lost
2. Duplication:
part of the chromosome is repeated
Chromosomal Mutations1. Deletion:
part of the chromosome is lost
2. Duplication:
part of the chromosome is repeated
3. Inversion:
part of the chromosome gets reversed
Chromosomal Mutations1. Deletion:
part of the chromosome is lost
2. Duplication:
part of the chromosome is repeated
3. Inversion:
part of the chromosome gets reversed
4. Translocation:
two chromosomes that are NOT pairs switch information