Genetics and Society PowerPoint revised from: hum.utah.edu/~bbenham/ 2510%20Spring%2008/cla ss%203%20central %20dogma.ppt
Jan 24, 2016
Genetics and Society
PowerPoint revised from: hum.utah.edu/~bbenham/251
0%20Spring%2008/class%203%20central%20dogma.ppt
OutlineWhat is a gene?
Central dogmaReplication (DNA makes DNA)Transcription (DNA makes RNA)Translation (RNA makes Protein)
5' 3'
“Watson”
“Crick”
5' 3'
?
http://giant-panda.com/
5' 3'
“Watson”
“Crick”
5' 3'
genes
http://giant-panda.com/
What is a gene?
http://cmgm.stanford.edu/biochem201/Slides/Chromatin%20Structure/01%20Human%20Chromosome.JPG
A gene is a section of DNA(usually several 10,000’s of base pairs long)
A gene is a section of DNA
chromosome gene
What is a gene?
http://cmgm.stanford.edu/biochem201/Slides/Chromatin%20Structure/01%20Human%20Chromosome.JPG
A gene is a section of DNA(usually several 10,000’s of base pairs long)
A gene makes a protein.
Proteins do things
EnzymesEnzymes are a type of protein (or RNA molecule) that speed up metabolic reactions in plants and animals.
They are not permanently changed or destroyed when they do so.
A gene “makes” a protein.
How?
The Central Dogma
The Central DogmaI called this idea the central dogma, for two reasons, I suspect. I had already used the obvious word hypothesis in the sequence hypothesis, and in addition I wanted to suggest that this new assumption was more central and more powerful. ... As it turned out, the use of the word dogma caused almost more trouble than it was worth.... Many years later Jacques Monod pointed out to me that I did not appear to understand the correct use of the word dogma, which is a belief that cannot be doubted. I did apprehend this in a vague sort of way but since I thought that all religious beliefs were without foundation, I used the word the way I myself thought about it, not as most of the world does, and simply applied it to a grand hypothesis that, however plausible, had little direct experimental support.
-Francis Crick
Complementarity is the secret of life
A T
G C
Central Dogma:
DNA
RNA
Protein
Complementarity
Central Dogma
DNA
RNA
Protein
Replication
DNA is the long-term storage medium
DNA is copied when cells divide
"It has not escaped our notice that the specific pairing that we have postulated immediately suggests a possible copying mechanism for the genetic material"
Complementarity allows DNA to be copied exactly
Replication
AGC TAG C A C TAC T GA A G T G C G C CTCG ATC G T G ATG A CT T C A C G C G G
AGC TAG C A C TAC T GA A G T G C G C C
TCG ATC G T G ATG A CT T C A C G C G G
TCG ATC G T G ATG A CT T C A C G C G G
AGC TAG C A C TAC T GA A G T G C G C C
Central Dogma
DNA
RNA
Protein
Replication
Transcription
RNA is a temporary copy of the DNA information
DNA RNA
RNA is copied from 1 DNA strand
TranscriptionAGC TAG C A C TAC T GA A G T G C G C CTCG ATC G T G ATG A CT T C A C G C G G
AGC TAG C A C TAC T GA A G T G C G C C
TCG ATC G T G ATG A CT T C A C G C G G
DNA
AGC UAG C A C UAC U GA A G U G C G C C RNA
(Complementarity again)
RNA is copied from 1 DNA strand
TranscriptionAGC TAG C A C TAC T GA A G T G C G C CTCG ATC G T G ATG A CT T C A C G C G G
AGC TAG C A C TAC T GA A G T G C G C CTCG ATC G T G ATG A CT T C A C G C G G
DNA
AGC UAG C A C UAC U GA A G U G C G C C RNA
(mRNA- messenger)
RNA vs. DNA
http://www.mun.ca/biology/scarr/Ribose_sugar.html
RNA uses U in place of T
About 1/10,000,000 C bases decompose to U per day.
Because DNA uses T, not U, the cell automatically assumes that U is the result of a C gone bad and removes all U bases from DNA.
C U T
Central Dogma
DNA
RNA
Protein
Replication
Transcription
Translation
Protein is the final product of the information
mRNA ProteinTranslation
Proteins are made of 20 different amino acids
Amino acids can be linked together
Proteins are long chains of amino acids
Protein(a real protein would have hundreds of amino acids)
Proteins are long chains of amino acids
Hemoglobin
Protein chains fold into complex shapes that depend on the sequence of amino acids
Protein
An RNA “adapter” is used to convert RNA to Protein
U A C
tRNA
Amino Acid
Complementarity is used to convert the information in RNA
into protein
mRNAUCU AUC G U G AUA C CU U C A C G C
Amino Acids
tRNAAGA UAG C A C UAU G GA A G U G C G U G A
Complementarity is used to convert the information in RNA
into protein
U A CCU U
UCC
UC GAU U G A A
C G C
Protein
mRNAAGA UAG C A C UAU G GA A G U G C G U G A
AUG is the translation startUAA UAG or UGA are stop
U A CCU U
UCC
UC GAU U G A A
C G C
Protein
mRNAAGA UAG C A C UAU G GA A G U G C G U G A
START STOP
Where do these events occur in the cell?
Replication
Transcription TranslationmRNA mRNA
Protein
Nucleus
Not all of the DNA gets copied into RNA
DNA
A gene is a piece of DNA that
makes a protein
RNA
Not all of the DNA gets copied into RNA
DNA
RNA
•Some of the DNA encodes when, where and how much of the RNA to make. This is called the promoter.
promoter
A gene is a piece of DNA that
makes a protein
Different cells copy different parts of the DNA into RNA
Hemoglobin
Insulin
Different cells copy different parts of the DNA into RNA
Hemoglobin
Insulin
Blood cell
mRNA hemoglobin
Different cells copy different parts of the DNA into RNA
Hemoglobin
Insulin
Pancreas cell
mRNA insulin
Genes in some well known organisms
<10 m12 M base pairs6,300 genes
~1 mm97 M base pairs19,100 genes
http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml#genomesize
http://elegans.swmed.edu/http://www.genomenewsnetwork.org/articles/12_03/yeast_screen.shtml
Genes in some well known organisms
~1 cm180 M base pairs13,600 genes
~10 cm 125 M base pairs 25,500 genes
http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml#genomesize
http://www.rhone-alpes-genopole.com/index.php?pageID=52&tabNum=2http://www.cofc.edu/~bernardoj/Genetics%20Lab/212Lhome.htm
Genes in some well known organisms
2,500 M base pairs~30,00 genes
2,900 M (~3 billion) base pairs~30,000 genes
http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml#genomesize
http://www.bcgsc.ca/gc/mouse/http://www.thatsweird.net/picture32.shtml
The exact types and amounts of protein made by our DNA
make us what we are.
5' 3'
“Watson”
“Crick”
5' 3'
http://giant-panda.com/
DNA
RNA
Protein
Identical twins share the same DNA
Lech and Jaroslaw Kaczynski, president and prime minister of Poland
http://english.pravda.ru/news/world/10-07-2006/83163-poland-0
Genes provide possibilities
•Hemoglobin genes make it possible to have normal blood
•A large number of genes make it possible to have a properly wired brain.
Genes provide possibilities
Can you name other examples of things that are possible or not possible because of genes?
Genes provide probabilities
•A particular set of genes will make it probable that someone will be tall.
•DNA repair genes make it probable that a person will not get cancer.
Environment will affect the odds
Genes provide probabilities
Can you name other traits that are affected by both genes and the environment?
Genes for…
Right:
A gene for hemoglobinA gene for insulin
Wrong:
A gene for mathA gene for alcoholismA gene for loyalty
Genes affect traits, but still a gene makes a protein, not a trait
What is a gene?
What is the central dogma?
What is the central dogma?
How does complementarity fit into the central dogma?
DNA
RNA
Protein
A T
G C
Postscript: Central Dogma Exceptions
DNA
RNA
Protein
RNA viruses (RNA > Protein, no DNA)Retroviruses (RNA > DNA)Prions (Protein > Protein)Catalytic RNA (DNA > RNA, no Protein)RNAi (RNA > RNA, no DNA or Protein)