L5. Gene expression & protein synthesis I Flashcards
explain the cellular control of gene expression
- if cell A in an organism needs protein A, it will make a lot of transcripts for protein A, upregulating it, but not a lot of protein B, deregulating it
- if cell B in the same organism needs protein B, it will up regulate protein B while deregulating protein A
cellular control of gene expression - stem cells
- cells that can differentiate into different kinds of cell
- can do this through up regulation and deregulation of certain proteins
define transcription
an ongoing process which occurs in many places at the same time (even for the same gene)
how is RNA different from DNA
- single strand
- U instead of T
- ribose sugar
how is DNA different from RNA
- double strand
- T instead of U
- deoxyribose sugar
DNA - what is the coding strand
- oriented in a 5’ to 3’ fashion
- looks like the finished mRNA
DNA - what is the template strand
- oriented in a 3’ to 5’ fashion
- strand that is used to make the mRNA
explain the intramolecular base-pairing of RNA
- RNA is not linear, it may go conventional or nonconventional base pairings
- it can form 3D structures to allow things to bind to it and interact with it
- these structures all have different functions
intermolecular base-pairing of RNA - conventional vs nonconventional base pairing
- conventional base pairing: A-U, G-C
- nonconventional: G-U, C-A
explain how RNA polymerase carries out transcription
- since DNA is not hydrogen bounded, it can be easily displaced and allow the RNA pol to transcript the code
- RNA pol uses mRNA molecules from 5’ to 3’
- to begin translation, it jumps onto the promoter region and recognizes the start codon
how is RNA pol different from DNA pol
- uses ribonucleotides
- doesn’t need a primer for transcription
- does not have the capacity for proofreading
- more mistakes
how is DNA pol different than RNA pol
- uses dNTPs
- needs primers for transcription
- does have the capacity for proofreading
- less mistakes
RNA pol vs DNA pol - why did RNA pol evolve to be mistake prone and DNA pol did not
- if there is a mutation in an mRNA, the mutation will be passed onto a small number of proteins
- if there is a mutation in DNA, then the mistake impacts the whole cell and thus all of the protein
- so its less dangerous if there is a mutation in RNA
explain the types of RNA molecules
- messenger RNAs (mRNAs)
- ribosomal RNAs (rRNAs)
- microRNAs (miRNAs)
- transfer RNAs (tRNAs)
- other noncoding RNAs
types of RNA - mRNA function
code for proteins
types of RNA - rRNA function
- form the core of the ribosome’s structure
- catalyze protein synthesis