Download Genetics: The Information Broker

Genetics: The Old and the New
(and there is a “Lot” of Newness)
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Introduction
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Analogy to an “information broker”
Radical transformation of the science (i.e.,
what is a revolution in the sciences)
Genetics of inheritance - Mendelian
genetics (> 1860)
Genetics of cell’s operation - molecular
genetics (> 1950)
The “Genetic Code”
Genetics “on the cutting edge”: last five
years
Introduction
 Why
is an “information broker”
important in living systems?
 What
constitutes a “revolution” in the
sciences?
The Old: Genetics of Inheritance
(1860’s)
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Classical or Mendelian genetics (Gregory Mendel)
Competing hypotheses
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Blended inheritance versus particulate inheritance
Testing the hypotheses (Scientific Method!!)
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Flower color in peas (1 parent with red flowers and 2nd parent with white
flowers)
Results: two classes of flowers
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Red (300 seedlings)
White (100 seedlings)
Pink (0 seedlings)
Conclusion
300
100
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Hypothesis:
Data support the particulate theory
Data reject blended theory
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Specific quantitative data:
3:1 ratio (strange but revealing quantitative
ratio!)
Rules of Classical Mendelian
Genetics (1860’s)
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Traits passed from parent to offspring consistent with
particulate inheritance model
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Two “copies” of each trait in each individual
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Mechanism unknown at the time (now we know)
One from each parent
Some “copies” are dominant and some copies are
recessive
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Dominant traits = expressed
Recessive traits = expressed only if both copies recessive
Mendelian Genetics (1860’s) and
Coming Forward
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Gene - trait determined by a sequence of DNA
Allele - alternative forms (“copies”) of the same gene
(e.g., normal hemoglobin vs sickle cell hemoglobin; blue
vs brown eyes)
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No longer called “copies” but alleles!!!
Dominant allele (e.g., brown eyes)
Recessive allele (e.g., blue eyes)
Chromosomes - physical packaging of genes in nucleus
Pairs of chromosomes
Genome - all of the genes of an organism in the nucleus
Question
If you were to cross rabbits that were black with rabbits
that were white and the offspring were gray, this
outcome would support the theory of ___________.
A
B
C
D
E
particulate inheritance
conspicuous inheritance
Lamarckian inheritance
blended inheritance
None of the above
Question
The “unit of inheritance” documented by Mendel
is now called the ___.
A
B
C
D
E
hybrid
parental strain
gene
dominant allele
the “Mendel”
Question
In genetic crosses the re-current quantitative ratio
of 3:1 among offspring supports the presence of
____ copy/copies of each gene in an organism
of all species of eukaryotes.
A
B
C
D
four
three
two
one
Genes and Chromosomes
DNA to Genes to Chromosomes
Gene
Chromosomes, Genes and Alleles
Normal
Attached
Blue
A
Normal
Sickle
Cell
Ear Lobe
Free
Free
Eye Color
Blue
Blue
Blood Group
B
O
Normal Hemoglobin Chemistry
Attached
Brown
O
Individual One (Thee)
Individual Two (Me)
Genetics of Humans: Sex
Determination
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Humans = 46 chromosomes or 23 pairs
Sex determination associated with one pair
of chromosomes (Pair No. 21)
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X and Y chromosome
Female: two “X” chromosomes
Male: one “X” and one “Y” chromosome
Female produces only X chromosome eggs
Male produces both X and Y chromosome
sperm
Who determines the sex of offspring?
Sex-linked traits … examples?
Complexity of the Human Genome
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46 chromosomes in each human
(23 pairs)
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~20,000 different genes in each
human
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Only ~1.5% of genome active
… we think (stay tuned!)
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Millions of nucleotide
differences between any two
people
Affymetrix
Genetics: The Old and the New

Introduction






Analogy to an “information broker”
Radical transformation of the science (i.e.,
revolution)
Genetics of inheritance - Mendelian
genetics (> 1860)
Genetics of cell’s operation - molecular
genetics (> 1950)
The “Genetic Code”
Genetics “on the cutting edge” (> 2005)
Molecular Genetics

Structure of DNA and RNA information storage,
transmission and expression

Replication of the information
- copying/duplication

Transcription of the
information - transcribing

Translation of the
information - expressing as
proteins (requires new
language with new alphabet!)
Watson and Crick: a
Revolution in the Sciences
1953
Double helix
Contribution of Watson and Crick:
Monomer = Nucleotides (A, T, C and G)
Polymer = polynucleotide (nucleic acid)
3 D Structure of Nucleic Acid = DNA Double
Helix
Watson
Crick
Nucleotides: The Building
Blocks of Nucleic Acids
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Nucleotide: three
components
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Sugar
DNA: deoxyribose
 RNA: ribose
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Phosphate group
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Base (N=4)
Adenine (A)
 Guanine (G)
 Cytosine (C)
 Thymine (T)
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DNA Structure
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Join nucleotides
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DNA
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2 strands of nucleotides
Joined by nitrogen base
pairs (A, T, C and G)
Bonding pattern (fidelity!)
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Alternating phosphate and
sugar
Adenine : Thymine
Cytosine : Guanine
Information broker “biological alphabet”
(A,T,C and G)
Question
Nucleic acids such as DNA and RNA are
polymers (macromolecules) of the monomers
called ____.
A
B
C
D
amino acids
monosaccharides
nucleotides
lipids
Question
While the English alphabet contains 26 letters, the
biological alphabet of the DNA is based on ___
nucleotides/”letters”.
A
B
C
D
2
4
6
8
Question
The term “fidelity” in base pairing of nucleotides
in DNA means that the nucleotide thymine
always pairs with nucleotide ___.
A
B
C
D
E
europocil
cytosine
another thymine
guanine
adenine
Genetics: The Old and the New
(and there is a “Lot” of Newness)

Introduction






Analogy to an “information broker”
Radical transformation of the science (i.e.,
what is a revolution in the sciences)
Genetics of inheritance - Mendelian
genetics (> 1860)
Genetics of cell’s operation - molecular
genetics (> 1950)
The “Genetic Code”
Genetics “on the cutting edge”: last five
years
Molecular Genetics: General Theme
Molecular Genetics: Structure of DNA
and RNA

DNA - Deoxyribonucleic acid
(nucleus; double strand)

RNA - Ribonucleic acid
(protoplasm; single strand)
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Monomer - nucleotides (N = 4 in
DNA)
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Guanine (always binds to Cytosine - G:C)
Adenine (always binds to Thymine - A:T)
Cytosine (always binds to Guanine - C:G)
Thymine (always binds to Adenine - A:T)
Polymer - polynucleotide (DNA &
RNA)
Sequence of Nucleotides and Genes
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Linear sequences of nucleotides
1150

431
1225
102
Number of nucleotides
954
653
1580
Gene: sequence of nucleotides responsible for a specific
trait (e.g., eye color; hemoglobin; attached ear lobes,
carbon metabolism, sickle cell anemia, enzyme)
Molecular Genetics: A Single Gene
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Exact sequence of nucleotides is important
ATTAGCGGTA
T G C C G G T TAAGAT C C G
ATTAGCGGTA
C G C C G GT TAAGAT C C G
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Any change in sequence changes the information (“RAT to
CAT”) and constitutes a mutation
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Daily: you experience 10,000’s of mutations but all are corrected
Molecular Genetics: General Theme
Replication
Molecular Genetics: Replication
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Replication:
process of
duplicating DNA
to produce a new
and exact copy
with fidelity
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includes “spell
checking”
Molecular Genetics
Molecular Genetics: Transcription
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Information in DNA “transcribed” into another
type of message - mRNA (messenger RNA)
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Analogue to transcribing spoken into written language
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mRNA made in nucleus and subsequently
shuttled to protoplasm
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In protoplasm, mRNA to the ribosome (protein
synthesis)
Compartmentation: Ribosome
Figure 23.22
23-494
Molecular Genetics:
Translation in the Ribosome
Molecular Genetics: Translation
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Information in mRNA “translated” into
polypeptide and then functional protein (new
language and “new letters of the alphabet”!)
Monomer: amino acids (e.g., lab exercise)
 Location: ribosome for protein synthesis
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Genetic code: specificity and fidelity
All organisms and all species use the exact same
process
 Example: genetically modified organisms (GMO’s)
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Protein Synthesis and Genetic Code
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One gene codes for one protein
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Protein drives chemical process in cell (e.g., enzymes)
Original source of information = DNA
Intermediate source of information = RNA
All living things on Earth use the absolute same genetic code
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Transcription, Translation and
Protein Assembly
http://www.youtube.com/watch?v=983lhh20rGY
Question
In the following figure, the process linking the
DNA to RNA (see white arrow) is called
_______.
A
B
C
D
replication
transcription
translation
gene splicing
Question
Making a copy of DNA is called ___.
A
B
C
D.
replication
transcription
translation
photocopying
Question
The sum of all information contained in your
DNA and copied in each cell in your body is
called your ___.
A
B
C
D.
gene base
gene traits
genome
genetic material
Mutations and DNA Repair
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Mutations
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Change in sequence of nucleotides in DNA
Causes of mutations
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Oxygen (e.g., aging)
Nuclear radiation
X-rays
UV light (e.g., beach time!)
Higher elevations (e.g., mountain tops, airplanes)
DNA Repair
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10,000 ‘hits’ per day (you and me!!)
Cells repair damage - excision and repair process
Repair not equal in all individuals
Molecular Genetics: A Single Gene
(Single Strand)

Exact sequence of nucleotides is important
ATTAGCGGTA
T G C C G G T TAAGAT C C G
ATTAGCGGTA
C G C C G GT TAAGAT C C G

Any change in sequence changes the information (“RAT to
CAT”) and constitutes a mutation

Excision and repair
Genetics: The Old and the New

Introduction






Information broker
Radical transformation of the science (i.e., revolution)
Genetics of inheritance - Mendelian genetics (> 1860)
Genetics of cell’s operation - molecular genetics (> 1950)
The “Genetic Code”
Genetics “on the cutting edge” (last five years)
Genetics “on the Cutting Edge”




Genetic counseling (probability of offspring with
particular traits)
Forensic sciences (e.g., CSI TV series)
Genetic engineering : GMO’s (Genetically Modified Organisms)
Genetic “Sleuthing”
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Human applications (e.g., ice man in the Alps + 5,000 years)
Genetic basis of autism
Genetics, mutations and cancer (next week’s lecture)
Editing of genes
Genetic Counseling
Genetic Counseling using “Gene Chips”
Forensic Sciences
Genetics “on the Cutting Edge”



Genetic counseling (probability of offspring with
particular traits)
Forensic sciences (e.g., CSI TV series)
Genetic engineering (e.g., “starlight” strain of corn)


Genetic “Sleuthing”



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GMO’s (Genetically Modified Organisms)
Human applications (e.g., ice man in the Alps + 5,000 years)
Genetic basis of autism
Genetics, mutations and cancer (next week’s lecture)
Editing of genes