Microbiolgy Lecture 11 Flashcards
What is DNA made of?
sugars
nitrogenous bases
phosphate
DNA replication is semi…
Semi conservative
Describe DNA replication in E Coli
- It starts at ori where DnaA binds to ori and unwinds DNA
- It continues around in both directions
- Replication stops at terminator
What is the coordination at replication fork?
- Helicase unwinds parental DNA/ when enough DNA is unwound, primase synthesizes an RNA primer and lagging strand synthesis begins
- Lagging strand generates Okazaki fragments
- Core enzyme reaches okazaki and is released from DNA template
- Another core enzyme moves in same direction as replication fork and synthesizes DNA
What happens during transcription?
Process of making RNA copy of DNA sequence
- Carried out by RNA polymerase
What happens during translation?
Reading or translation of mRNA to generate protein
- Carried out by ribosomes
What are the parts of RNA synthesis by RNAP
Promoter
Termination
Signma
What is promoter?
DNA sequence that is recognized by sigma
What is terminator?
Sequence of DNA that signals the RNAP to stop transcribing
What is sigma?
A subunit of RNAP that aids in promoter recognition
Bacterial genes are often transcribed as what?
polycistronic mRNA
Why are tRNAs important in translation
They read mRNA to add correct amino acid to polypeptide chain
What carries out translation?
Ribsomes
Ribosomes are made of what?
RNA and protein
What S are ribosome?
70s (30s + 50s)
Ribsomes use .. rRNA
16s rRNA
Why are 16s important in ribosomes?
They recognize shine dalgarno sequence and important for ribosome structure
what reads the genetic code?
tRNA
The ribosome binding site is also known as what?
Shine Dalgarno sequence
What are the parts of the process of translation?
Intitation
Elongation
Termination
What happens during translation
- The tRNA base pairs with start codon and occupies p site
- A tRNA that recognizes next codon fills unoccupied A site
- The ribosome catalyzes the joining of amino acid carried by the tRNA in the p site to the one carried by tRNA in the A site
What happens during Elongation?
- The ribosome advances a distance of one codon/ A tRNA that recognizes the next codon quickly fills the empty A site
- The ribosome continues advancing along the mRNA in 5’ to 3’ direction
What happens during termination?
- Translation continues until a stop codon is reached, signaling the end of the process
- The components disassemble
Which happens first? Transcription or translation
They occur simultaneously
