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Lecture Objectives
Define Terms:
Transcription, Translation, nucleic acid, amino acid, DNA, RNA, mRNA, cDNA,
“ATCG”, Gene, Genomics, Protein, Proteomics, Exon, Intron, Chromosome,
Nucleus, Ribosome, Diploid, Codon, UTR.
Explain Concepts:
1)
2)
3)
4)
5)
How 24,000 genes in the human genome encode more than 100,000 proteins.
How information flows through Transcription and Translation.
4 points of information control in the cell.
Explain RNA splicing with respect to Exons and Introns.
Explain the difference between a Haploid and a Diploid Cell.
CAGGACCATGGAACTCAGCGTCCTCCTCTTCCTTGCACTCCTCACAGGACTCTTGCTACT
CCTGGTTCAGCGCCACCCTAACACCCATGACCGCCTCCCACCAGGGCCCCGCCCTCTG
CCCCTTTTGGGAAACCTTCTGCAGATGGATAGAAGAGGCCTACTCAAATCCTTTCTGAG
GTTCCGAGAGAAATATGGGGACGTCTTCACGGTACACCTGGGACCGAGGCCCGTGGTC
ATGCTGTGTGGAGTAGAGGCCATACGGGAGGCCCTTGTGGACAAGGCTGAGGCCTTCT
CTGGCCGGGGAAAAATCGCCATGGTCGACCCATTCTTCCGGGGATATGGTGTGATCTTT
GCCAATGGAAACCGCTGGAAGGTGCTTCGGCGATTCTCTGTGACCACTATGAGGGACTT
CGGGATGGGAAAGCGGAGTGTGGAGGAGCGGATTCAGGAGGAGGCTCAGTGTCTGAT
AGAGGAGCTTCGGAAATCCAAGGGGGCCCTCATGGACCCCACCTTCCTCTTCCAGTCC
ATTACCGCCAACATCATCTGCTCCATCGTCTTTGGAAAACGATTCCACTACCAAGATCAA
GAGTTCCTGAAGATGCTGAACTTGTTCTACCAGACTTTTTCACTCATCAGCTCTGTATTCG
GCCAGCTGTTTGAGCTCTTCTCTGGCTTCTTGAAATACTTTCCTGGGGCACACAGGCAA
GTTTACAAAAACCTGCAGGAAATCAATGCTTACATTGGCCACAGTGTGGAGAAGCACCG
TGAAACCCTGGACCCCAGCGCCCCCAAGGACCTCATCGACACCTACCTGCTCCACATG
GAAAAAGAGAAATCCAACGCACACAGTGAATTCAGCCACCAGAACCTCAACCTCAACA
CGCTCTCGCTCTTCTTTGCTGGCACTGAGACCACCAGCACCACTCTCCGCTACGGCTTC
CTGCTCATGCTCAAATACCCTCATGTTGCAGAGAGAGTCTACAGGGAGATTGAACAGGT
GATTGGCCCACATCGCCCTCCAGAGCTTCATGACCGAGCCAAAATGCCATACACAGAGG
CAGTCATCTATGAGATTCAGAGATTTTCCGACCTTCTCCCCATGGGTGTGCCCCACATTG
TCACCCAACACACCAGCTTCCGAGGGTACATCATCCCCAAGGACACAGAAGTATTTCTC
ATCCTGAGCACTGCTCTCCATGACCCACACTA
Central Dogma of Molecular Biology:
DNA acts as a template to replicate itself
DNA is also TRANSCRIBED into RNA
RNA is TRANSLATED into Protein
Human Genome:
Diploid (2 copies of genetic material)
46 Chromosomes (total)
Gender-specific Chromosomes:
XX = Female
XY = Male
Not all cells/organisms are diploid
gametes = haploid (1 copy)
wheat, corn = hexaploid (6 copies)
“Chromosome” literally means “color”
And “body” described by early microscopists
referring to the subcellular structures that stained
by some dyes.
Human Genome:
1st Sequenced (Published) in February 2001
Over 3 Billion base pairs
Estimated 35,000 genes (20% have been patented!).
Genes defined as regions of the genome that encode RNA
that are translated into proteins.
Estimated >100,000 proteins from 35,000 genes (only 1.5% of the genome are “genes”)
Each gene can encode multiple proteins due to “alternative splicing”.
DNA
Transcription
hnRNA
RNA Splicing
mRNA
Translation
Protein
Steps in Transcription:
Promoter
region
1) Double-stranded DNA (gene) is
separated into single strands.
2) RNA Polymerases make exact
RNA template from DNA (hnRNA).
3) Introns are spliced out of hnRNA
to make mRNA.
4) Poly-A tail is added to 3’ end of
mRNA.
“poly-A tail”
5) mRNA moves out of nucleus to
ribosome (in the cytosol) where
protein translation occurs (protein
from mRNA template).
UnTranslated Regions (UTR)
3’ UTR before translation start site
5’ UTR after translation stop site
100-300 “A”
Protein –
“The structural, functional and secreted stuff”
“The stuff you are made of”
“skin, hair, cartilage, tendons, eye color, etc.”
“where genetic information is translated into function”
Made up of 20 different amino acids that each harbor different molecular
characteristics (soluble, insoluble, acidic, basic, etc, etc).
Protein Dogma:
Sequence of amino acids confers specific 3D characteristics
3D characteristics correlates with function
Depiction of a protein in 3D
Protein TRANSLATION from mRNA
The genetic “bit” information to encode a specific amino acid is contained in a
gene’s Codon. A Codon is a 3-base (3-nucleotide) sub-sequence that defines the
amino acid to be incorporated into the protein.
All proteins start with the Codon ATG (DNA notation) or AUG (RNA), which
encodes for the amino acid Methionine.
This start or “initiation” codon sets the “Reading Frame” for Translation.
Many genetic mutations involve the deletion of a single nucleotide, which causes
a “Frame Shift” (aka Frame Shift Mutation), disrupting the Translational process
causing a change in the amino acid composition and alters the stop codon for all
amino acids “Down stream” from this type of mutation.
THEREDCATWASNOTHOTBUTWASWETANDMADYETSADBUT
THEFOXGOTWETANDATEHIM
THEREDCAT_HSDKLSD_WASNOTHOTBUT_WKKNASDN
KSAOJ.ASDNALKS_WASWET_ASDFLKSDOFIJEIJKNAW
DFN_ANDMAD_WERN.JSNDFJN_YETSAD_MNSFDGPOIJ
D_BUTTHEFOX_SDKMFIDSJIR.JER_GOTWET_JSN.DFOI
AMNJNER_ANDATEHIM.
Start with a thin 2 x 4 lego block…
Add a 2 x 2 lego block…
Add a 2 x 3 lego block…
Add a 2 x 4 lego block…
4 points of molecular information control
1) Transcriptional Control
Control of which genes are “used” or “expressed” by the cell.
2) RNA Processing or Splicing
Editing out of introns and sometimes key exons.
3) Translational Control
Control of the amount of protein made from mRNA.
4) Protein Activity Control
Control of how a protein’s activity.