Transcript The control of complexity in the human genome

Exciting Developments in
Molecular Biology
As seen by an amateur
Dr. Ray Sepeta
631-7421
[email protected]
DNA
sequences of nucleotides
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A – Adenine
C – Cytosine
G – Guanine
T – Thymine
N – any nucleotide base
R – A or G
Y – C or T
- none (gap)
RNA
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A – Adenine
C – Cytosine
G – Guanine
U - Uracil
Central Dogma
DNA
RNA
transcription
Protein
translation
Proteins
strings of amino acids
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G – Glycine – Gly
A - Alanine – Ala
L – Leucine – Leu
M – Methionine – Met
F - Phenylalanine-Phe
W – Tryptophan – Trp
K – Lysine – Lys
S – Serine – Ser
N – Asparagine – Asn
D – Aspartic acid – Asp
B – Aspartate - Asx
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P – Proline – pro
V – Valine – Val
I – Isoleucine – Ile
C – Cysteine – Cys
Y – Tyrosine – Tyr
H – Histidine – His
R – Arginine – Arg
T – Threonine – Thr
Q – Glutamine – Gln
E – Glutamic acid – Glu
Z – Glutamate - Glx
5’ Base
U
U
phe
phe
leu
leu
Genetic Code
Middle Base
C
A
ser
tyr
ser
tyr
ser
quit
ser
quit
G
cys
cys
quit
trp
3’ Base
U
C
A
G
C
leu
leu
leu
leu
pro
pro
pro
pro
his
his
gln
gln
arg
arg
arg
arg
U
C
A
G
A
ile
ile
ile
met
thr
thr
thr
thr
asn
asn
lys
lys
ser
ser
arg
arg
U
C
A
G
G
val
val
val
val
ala
ala
ala
ala
asp
asp
glu
glu
gly
gly
gly
gly
U
C
A
G
gene
chromosome
DNA
base pairs
RNA
Watson and Crick
Avery
Hershey and Chase
proteins
amino acids
genetic code
codon
central dogma
sequence of DNA that codes for a protein
contiguous stretch of DNA, contains many genes
double helix of base pairs A, C, T, G
A – T, G - C
ribosomal, messenger, transfer (U for T)
discovered structure DNA
discovered transforming principle of DNA
blender experiment
sequence of amino acids,
selected by codons and tRNA for proteins
codon => amino acid
three base pairs-together
see slide
virus
bacteria
prokaryote
eukaryote
nucleus
cytoplasm
exons
introns
number of genes
c.elegans
corn
insects
humans
DNA (or RNA) in protein coat
cell-metabolizes food to function
cell without nucleus
cell with a nucleus
where mRNA is transcribed from DNA
outside nucleus, proteins formed
stretches of DNA converted to genes
DNA excised, “junk” DNA
19,000
40,000
13,500
27,000
In prokaryotes there is no nucleus so transcription
and translation occur almost simultaneously. So
there is no time to splice out RNA segments
Among eukaryotes as their complexity increases
generally so too does the proportion of their junk
DNA that does not code for protein
Arguably the most important advance in
biology in decades has been the discovery
that RNA molecules can regulate the
expression of genes. - Sharp
The failure to recognize the importance of introns may
well go down as one of the biggest mistakes in the history
of molecular biology
Less than 1.5 % of the human genome
encodes for protein.
Either the human genome (and that of other complex
organisms) is replete with useless transcription, or
these nonprotein-coding RNAs fulfill some unexpected
function
Generating complexity is easy,
controlling it is not.
Sources
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Censors of the Genome, Sci. Am, Aug 03
Unseen Genome, Sci. Am, Nov 03
RNAi Revolution, Nature, Jul 04
Hidden Genetic Program, Sci. Am, Oct 04
Alternate Genome, Sci. Am, Apr 05