Chap 7- Gene Expression of Bacteria Flashcards
What does “expression” of DNA in Bacteria mean?
the formation of a functional product of DNA
process where info encoded in DNA is copied into RNA
transcription
complete set of genetic info in a cell/ virus
genome/ chromosome
functional unit of GENOME that encodes for a product (product is typically a protein)
gene
In order for cells to multiply, two things must be accomplished: ______
DNA replication and gene expression (transcription & translation)
Transcribing and then translating the information in DNA to produce the encoded protein
gene expression
process where info carried by mRNA is used to synthesize protein
translation
enzyme that synthesizes single strand of RNA from DNA template
RNA Polymerase
RNA made during transcription is _______ and __________ to its DNA template
complementary and antiparallel
Minus strand of DNA is the _________ for RNA , while RNA is complementary to the ______ of DNA
template; plus (Thymine is replaced by Uracil)
RNA transcript that carries one gene; mRNA molecule that carries the information for more than one gene.
monocistronic; polycistronic …. cistron = gene
Nucleotide sequence where RNA polymerase binds to start transcription.
promoter
DNA sequence that stops transcription
terminator
RNA Polymerase can only add nucleotides to what end and synthesize RNA in what direction?
3prime end; 5’ to 3’
Do RNA polymerases need primers to start working?
NOPE
part of RNA polymerase that recognizes and binds to promoters
sigma factor
When does transcription start?
Once RNA polymerase binds to a promoter
Why is it important that a cell can produce various sigma factors?
The various sigma factors recognize different promoters, allowing cells to transcribe specialized sets of genes as needed
How does RNA polymerase recognize promoters in Eukarya and archaea?
Transcription factors
Orientation (position of promoter) dictates
direction of RNA transcription and which DNA strand will be used as template (RNA needs to be transcribed in the 5’ to 3’ direction)
Transcription simplified (initiation, elongation, termination)
RNA Pol binds to promoter to start transcription –>sigma factor dips and allows RNA Pol to transcribe –> RNA synthesized in 5’ to 3’ direction, adding nucleotides to 3’ end —->Once RNA Pol reaches terminator, it falls off and releases the newly synthesized RNA strand
process of synthesizing proteins from mRNA template (turning nucleic acids to amino acids)
translation
RNA molecule that contains genetic info decoded during translation
mRNA
language of mRNA is in the form of
codons
series of 3 nucleotides that code for a specific amino acid
codon
sequence of three nucleotides in a tRNA molecule that is complementary to a codon in mRNA.
anticodon
complementary anticodon is carried by
tRNA
there are _____ possible codon combos but only _____ amino acids
64; 20
redundant codons that code for same amino acids
degenerates
can be translated and code for Amino Acids
sense codons
Translation of mRNA begins at ______ codon , which is
start; AUG
Translation ends at nonsense codons aka _____ which are ; DO NOT encode for amino acid
stop codons; UAA, UAG, UGA
structure where translation takes place; composed of rRNA and proteins
ribosome
Roles of ribosomes in translation
locate sequences on mRNA molecule; maintains correct reading frame
Role of tRNA in translation
delivers correct A.A , has specific anticodon to pair with specific codon, can be recycled once anticodon+A.A is delivered
Translation Process- Initiation
Ribosomal subunit binds to mRNA ; initator tRNA binds to start codon (AUG)
Translation Process- Elongation
tRNA enters with Amino acid, reads codon and pairs its complementary anticodon. ribosome facilitates this pairing and moves along the mRNA as the tRNAs read for codons tRNA then leaves and cycle is repeated while Amino Acids are held together by peptide bonds in a growing polypeptide chain
Translation Process- Termination
Elongation process continues ribosome reaches STOP codons that CANNOT BE READ by tRNA; component disassembles and release newly formed polypeptide
How is termination conducted in translation?
Enzymes free newly composed polypeptide chain by breaking the covalent bond with the tRNA. Ribosome falls off mRNA and splits back into 30S and 50S which can later be reused to start translation at other sites
EPA sites (located on ribosome)
1st binding site (A- acceptors) accept tRNA , 2nd binding site (P-Peptide) holds tRNA, 3rd E site (E-Exit) tRNA leaves ribosome
