Transcript Genetics: The Information Broker

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
Introduction
 Why
is an “information broker”
important in living systems?
 What
constitutes a “revolution” in the
sciences?
The Old: Genetics of Inheritance
(1860’s)


Classical or Mendelian genetics (Gregory Mendel)
Competing hypotheses


Blended inheritance versus particulate inheritance
Testing the hypotheses (Scientific Method!!)


Flower color in peas (1 parent with red flowers and 2nd parent with white
flowers)
Results: two classes of flowers




Red (300 seedlings)
White (100 seedlings)
Pink (0 seedlings)
Conclusion
300
100

Hypothesis:
Data support the particulate theory
Data reject blended theory

Specific quantitative data:
3:1 ratio (strange but revealing quantitative
ratio!)
Rules of Classical Mendelian
Genetics (1860’s)

Traits passed from parent to offspring consistent with
particulate inheritance model


Two “copies” of each trait in each individual (3:1 ratio)


Mechanism unknown at the time (now we know)
One from each parent
Some “copies” are dominant and some copies are
recessive


Dominant traits = expressed
Recessive traits = expressed only if both copies recessive
Mendelian Genetics (1860’s) and
Coming Forward


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)






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

Humans: ~20,000 genes
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 Hemoglobin Chemistry
Attached
Brown
O
Individual One (Thee)
Ear Lobe
Eye Color: Brown
Blood Group
Normal
Sickle
Cell
Free
Free
Blue
Blue
B
O
Individual Two (Me)
Genetics of Humans: Sex
Determination


Humans = 46 chromosomes or 23 pairs
Sex determination on one pair of
chromosomes (Pair No. 21)







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

46 chromosomes in each human
(23 pairs)

~20,000 different genes in each
human

Only ~1.5% of genome active
… we think (stay tuned!)

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

Nucleotide: three
components

Sugar
DNA: deoxyribose
 RNA: ribose


Phosphate group

Base (N=4)
Adenine (A)
 Guanine (G)
 Cytosine (C)
 Thymine (T)

DNA Structure

Join nucleotides


DNA



2 strands of nucleotides
Joined by nitrogen base
pairs (A, T, C and G)
Bonding pattern (fidelity!)



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 whopping
number of ___ 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)

Monomer - nucleotides (N = 4 in
DNA)





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

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)

Remember the iphone image
Molecular Genetics: A Single Gene

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

Daily: you experience 10,000’s of mutations but all are corrected
(for the most part)
Molecular Genetics: General Theme
Replication
Molecular Genetics: Replication

Replication:
process of
duplicating DNA
to produce a new
and exact copy
with fidelity

includes “spell
checking”
Molecular Genetics
Replication
Molecular Genetics: Transcription

Information in DNA “transcribed” into another
type of message - mRNA (messenger RNA)

Analogue to transcribing spoken into written language

mRNA made in nucleus and subsequently
shuttled to protoplasm

In protoplasm, mRNA to the ribosome (protein
synthesis)
Compartmentation: Ribosome
Figure 23.22
23-494
Molecular Genetics:
Translation in the Ribosome
Replication
Molecular Genetics: Translation

Information in mRNA “translated” into
polypeptide and then functional protein (new
language and “new letters of the alphabet”!)
Monomer: amino acids
 Location: ribosome for protein synthesis


Genetic code: specificity and fidelity
All organisms and all species use the exact same
process
 Example: genetically modified organisms (GMO’s)

Protein Synthesis and Genetic Code

One gene codes for one protein

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



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

Mutations


Change in sequence of nucleotides in DNA
Causes of mutations






Oxygen (e.g., aging)
Nuclear radiation
X-rays
UV light (e.g., beach time!)
Higher elevations (e.g., mountain tops, airplanes)
DNA Repair



10,000 ‘hits’ per day (you and me!!)
Cells repair damage - excision and repair process
BUT …. 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”




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”




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
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