MCB 2610 Lecture Notes - Lecture 6: Lac Operon, Cistron, Lac Repressor
25 May 2018
School
Department
Course
Professor
Gene centric
What are genes, what do genes do, prokaryote gene control
Goals:
Gene: segment of DNA that encodes -> protein or RNA product (tRNA, rRNA, RNASE)
Francis Crick and Watson determine the helix coil structure of DNA And figure out the central dogma of
molecular biology:
•
DNA ——-> RNA (transcription) ——-> protein (translation) :
•
+ Exceptions:
There are times that DNA can directly make amino acids without going through RNA. Usually these strands
are pretty short.
Reverse Transcription (commonly found in virus) : it’s an important break from central dogma and significant
to biotechnology. The enzyme Reverse Transcriptae
*meta genomics: grind the DNA from the soil -> amplify 16S RNA -> genomes -> identify the genes that were
turned on and off.
Catalytic RNA: it’s an intermediate that can be translated. The act of amino acid added to peptide is catalyzed
by ribosomes RNA. This is why people think that RNA comes before DNA. DNA is super stable; however,
RNA holds information and encodes other things and does chemistry. (Yay RNA)
DNA structure
DNA stands for 2 deoxyribonucleic acid (synthesized from dNTPS = deoxyribonucleotide triphosphates
•
DNA is different from RNA because RNA is not 2-deoxyribo
•
DNA = ribose + Nucleic acid
•
Precursors to DNA are acquired from the environment if available
•
Synthesis of DNA is very complex because it takes dozens of genes and reactions
•
Synthesis from the base + ribose -> dNTP
Bases covalently linked to Ribose
Ribose-5-phosphate: comes from a metabolic cycle -> -> -> Ribonucleotide diphosphate. ———>
Slide : synthesis of dNTPS and NDPs
UTP used in the DNA problems is that it can cause mutation. Evolution helps dUTP to convert into TTP
The new chain: the new base comes into the 3” OH end
1)
All Nucleic acids are made 5’-3’ (new bases go into on the 3’ end)
All Nucleic acids bind each other in a complimentary and anti parallel fashion
2)
B-DNA structure:
10.4 bp per turn
3.4 nm per turn
Minor group can’t really bind anything because the surface area is too small
CAP turns on transcription - by placing on the lac operon of the DNA
Turn the lac gene off. When lactose is around, the LacI falls off and turns the gene on.
Prokaryotes
Eukaryotes
Transcrip
tion
RNA types
1
3
Place
Cytoplasm-nucleoid
nucleus
Transcripti
on site
Same - coupled
transcription and
translation in the
cytoplasm
RNA exported to the Cytoplasm
Gene
organizatio
n
Prokaryotes also have
promoter. However, very
often, prokaryotes have
Promoter drives the transcription of the gene . Every
gene has its own promoter, no sharing of promoter.
Eukaryotic genes are “monocistronic”
MRNA is super long.
Polycistronic
Week 2 Class Material
Friday,)May)11,)2018
8:33)AM
Document Summary
What are genes, what do genes do, prokaryote gene control. Gene: segment of dna that encodes -> protein or rna product (trna, rrna, rnase) Francis crick and watson determine the helix coil structure of dna and figure out the central dogma of molecular biology: Dna -> rna (transcription) -> protein (translation) : There are times that dna can directly make amino acids without going through rna. Reverse transcription (commonly found in virus) : it"s an important break from central dogma and significant to biotechnology. *meta genomics: grind the dna from the soil -> amplify 16s rna -> genomes -> identify the genes that were turned on and off. Catalytic rna: it"s an intermediate that can be translated. The act of amino acid added to peptide is catalyzed by ribosomes rna. This is why people think that rna comes before dna. Rna holds information and encodes other things and does chemistry. (yay rna)
