How Cells Work (Central Dogma) pt. 1b Flashcards
An ________ (in procaryotes) consists of a promoter, genes, and a terminator
operon
Initiation begins with binding of _____ to _______ region of DNA.
sigma factor
promoter region
____ vary in binding affinity for the sigma factor.
Promoters
When the sigma factor is released, ____ begins
elongation
m-RNA synthesis stops when RNA polymerase encounters a _____ (specific sequence of bases) (can vary in strength also).
terminator
_____ can be polygenic (multiple genes controlled by one promoter).
Prokaryotic transcription
______ do not do polygenic messages
Eukaryotic
In procaryotes, _____ occur simultaneously because they don’t have nuclear membrane.
transcription and translation
m-RNA in eukaryotes can have nonsense segments, called ______.
Opposite is _____
introns (non-coding, remove through splicing)
exon (coding)
- m-RNA in eukaryotes undergo further _____.
- m-RNA ______.
processing
splicing
_____ make it more difficult to transfer eucaryotic genes to procaryotes.
Introns
Other mRNA processing steps:
- Do not occur in _____.
- ________ – 5’ end is modified by the addition of a guanine nucleotide with a methyl group attached.
- ____ – a string of adenine nucleotides is added to the 3’ end.
These processes are thought to increase m-RNA stability and facilitate transport across the _______.
prokaryotes
RNA capping
Polyadenylation
nuclear membrane
Translation (making protein)
Three translation substeps
Initiation, elongation, and termination
In prokaryotes, initiation is the formation of a _______ rRNA initiation complex
30s and 50s
____ means ribosomal RNA, 30s and 50s are the sizes of two parts of the ribosome.
If they are joined, they are called ________
Aside from that, 3 proteins called _______, and the _______ energy from GTP should also be present.
r-RNA
70s ribosome
initiation factors
phosphate bond
Translation: Making Proteins
In ____, m-RNA must first bind to the ribosomes
eukaryotes
Translation: Making protein
All protein synthesis begins with the _____ initiation codon.
AUG
_____ encodes for N-formyl methionine
(special amino acid)
Initial AUG
_______ encodes regular methionine.
middle AUG
________ ; ten nucleotides upstream the initial AUG.
Shine-Dalgarno box (AGGAGGU sequence)
Elongation uses tRNA with attached amino acids as _______.
decoders
“____” of tRNA match the codons on
mRNA
anti -codons
Three letter “words” of four possible letters (_____) form “______” on mRNA (64 possible, many redundant).
UCAG
“codons”
Process of Translation (making protein)
The _____ approaches the ribosome then the ribosome reads the _______.
Upon reading, the ribosome produces ________.
Once the 5’ enters the ribosome, the ______ helps to produce polypeptide.
mRNA
message
polypeptides
tRNA
_____, _____ and _____ signals to stop
____ is the initiation
UAA, UAG, UGA,
AUG
Three codons (_____) do not code for amino acids and are stop codons. Translation stops or translation terminations sequence.
(UAA, UAG, and UGA)
Translation start codon is
_____.
AUG
Two sites on the ribosome for the tRNA called
P and A
the ribosome is moving to balance the elongating polypeptide chain
Rachet mechanism
When a nonsense codon is reached, the protein is released from the ribosome with a _______.
release factor
A _____ can be read simultaneously by 10 to 20 ribosomes at once.
single m-RNA
Post-translational processing:
- ______ from ribosome undergoes further processing before becoming truly useful.
- Sometimes several proteins must associate to form _______ or ________.
Polypeptides
enyzme or structural protein
chaperones (proteins) that assist in ____
folding
signal sequence = a sequence of 20-25 amino acids on the front of a protein that directs protein to be secreted out of the cell. The signal sequence is clipped off during ________
Secretion
secretion through the cytoplasmic membrane.
Procaryotes
transport vesicles – bud around the proteins and transport to the membranes.
It can be transport thru ______, ______, or by _____
Eukaryotes
nuclear pores, across membranes, or by vesicles.
