Gene Expression and Protein Synthesis Flashcards
What do you call the belief wherein information contained in DNA is transferred to RNA and then from RNA the information is expressed in the structure of proteins?
Central dogma of molecular biology
What do you call the turning on, or activation, of a gene?
Gene expression
Transmission of information occurs in two steps. what are they?
Transcription and Translation
what do you call the process in which information encoded in a DNA is copied into an mRNA molecule?
Transcription
what RNA serves as a template on which the amino acids are assembled in the proper sequence?
mRNA
What do you call the process in which information encoded in an mRNA molecule is used to assemble a specific protein?
Translation
What do you call the strand od DNA that serves as the template during RNA synthesis?
Template strand
(-) strand or antisense strand may also be used
What do you call the DNA strand that is not used as a template for transcription but has the same sequence as the RNA produced?
coding strand
or (+) strand or sense strand
Identify the RNA polymerase
catalyzes the formation of most of the rRNA
RNA pol I
Identify the RNA polymerase
catalyzses mRNA formation
RNA Polymerase II
Identify the RNA polymerase
catalyzes tRNA formation as well as one ribosomal subunit and other small regulatory RNA types
RNA polymerase III
a part of the eukaryotic gene that is made up of exons and introns which is transcribed into RNA
structural gene
a part of the eukaryotic gene that is not transcribed but the one who controls the transcription
regulatory portion
not transcribed but has control elements
what do you call the control element that the polymerase recognizes as an initiation signal?
promoter
After inititation, the RNA polymerase zips up the complementary bases by forming a phosphate ester bond between each ribose and the next phosphate group. This process is known as ____.
elongation
What do you call the sequence at the end of the gene that tells the enzyme to stop transcription?
termination sequence
RNA Polymerase II both initiated the transcription and performs the elongation. What are the two forms of the enzyme in this processes?
phosphorylated, unphosphoryled, dephosphorylated
Phosphorylated = elongation
Unphosphorylated = initiation
Pol II is dephosphorylated after termination sequence so it is constantly recycled between the initiation and elongation roles
SImilar to DNA Pol, do RNA Polymerases also move from the 5’ to the 3’ end; that is, does it move along the 3’ to 5’ end of the template strand?
yes or no?
Yes
3’-ATGCTA-5’ (temp strand)
5’-UACGAU-3’ (new strand)
5’-3’ always ang direction ng polymerases kasi they create stuff in this way and travel along d template (or parent, in DNA) 3’-5’.
To ensure that mRNA is functional, the transcribed product is modified (or capped) at both ends. The 5’ end requires what cap?
methylated guanine
7-mG cap
To ensure that mRNA is functional, the transcribed product is modified (or capped) at both ends. The 3’ end requires what cap?
poly-A tail
w’/ 100-200 adenine residues
Once the both of the RNA ends are capped, the introns are spliced out in a process called?
post-transcription process
What types of RNA participate in translation of RNA?
mRNA, tRNA, rRNA
the synthesis of proteins takes place in what organelle of the cell?
ribosome
What do you call the larger ribosomal subunit in higher organisms (humans)? paano d smaller one?
60S ribosome; 40S ribosome
50 30 sa prokaryotes
What RNA binds to the smaller ribosome subunit and is later joined by the larger subunit?
mRNA
forms a unit on which mRNA is stretched out
what do yo ucall the triplets of bases on the mRNA?
codons
After the binding of mRNA to the ribosome, amino acids are brought to the site via RNAs called?
tRNAs
each tRNA has its own amino acid
what enzymes recognize specific tRNA molecules and amino acid and then attaches amino acid to the correct tRNA?
aminoacyl-tRNA synthesases
what do you call the sequence of three nucleotides in mRNA that code for a specific amino acid?
codons
What do you call the sequnce of three nucleotides on tRNA that is complementary to the codon in the mRNA?
anticodons
True or False
the genetic code of bacteria is the same with humans
True
diff lang sa mitochondrial DNA
what are the three stop codons?
- UAA
- UAG
- UGA
What codon is considered the start codon?
AUG
this also codes for methionine
The code on the mRNA is always read in the 5’-3’ direction, and the first amino acid to be linked to the initial methionine is the ____ end of the translated polypeptide chain
N-terminal
what are the 4 stages in protein synthesis?
- Activation
- Initiation
- Elongation
- Termination
The specific recognition by aminoacyl-tRNA synthetase of its proper tRNA and amino acid is often
referred to as the ____
second genetic code
In other words, the anticodon of the tRNA will match up with its matching codon on the mRNA regardless of whether it is carrying the correct amino acid, so the aminoacyl-tRNA synthetases have to get it right.
To initiate protein synthesis, a tRNA bonded to the smaller ribosomal subunit forms the pre-initation complex, along w/ GTP. What do you call this tRNA?
tRNAfMet
this carries the formylated Met residues and is solely used for the initation step
The pre-initiation complex binds to the mRNA by recognising a special RNA sequence called what?
this is complementary to a sequence on the smaller subunit
Shine-Dalgarno sequence
The complete ribosome carries how many units (or sites)?
3 sites:
- P site (Peptidyl site)
- A site (Aminoacyl site)
- E site (Exit)
the growing peptide chain will bind at what site in a ribosome?
P site
what site in a ribosome accepts the incoming tRNA bringing the next amino acid?
A site
Acceptor
E is end site ata
The binding of tRNA to A site takes place with the aid of proteins called?
elongation factors
this occurs when A site is vacant and aminoacyl-tRNA molecules try to fit in
What do you call the enzyme that creates a peptide bond between the naunang amino acid and the next amino acid?
peptidyl transferase
During translocation, the dipeptide is translocated from what site to where?
from A site to P site
empty tRNA will move to E site then empty tRNA will be ejected then go back to the pool of tRNA available for activation w amino acid
After translocation, what ribosomal site is associated with the next codon on the mRNA?
A site
After the final translocation, what do you call the codon wherein no more amino acids can be added?
stop codon
UAA, UGA, UAG
anticodon of 5’ AAG 3’?
5’ CUU 3’
What do you call the process wherein the expression of the gene is turned on or off?
Gene regulation
Transcription is regulated by three entities namely:
- promoters
- enhancers
- response elements
what do you call the transcription factor that form a complex with RNA polymerase and DNA to help position RNA pol correctly and stimulate the initiation of transcription?
General Transcription Factor
What do you call the entity defined by an initiator and conserved sequences such as TATA box?
located adjacent to the transcription site
Promoters
What do you call the transcription factors that speed up the transcription process by binding DNA sequences that may be located thousan nucleotides away from the transcription site?
Enhancers
What do you call the transcription factors that activate in response to an outside stimulus?
stimulus may be heat shock, heavy metal toxicity, or hormonal signal
response elements
What do you call the enzyme that is responsible for the attachment of the proper amino acid to its tRNA?
aminoacyl-tRNA synthetase
Stop codons must be recognized by release factors, leading to the release of the ____ chain and allowing the recycling of ____.
polypeptide; ribosomes
What do you call the enzyme that cleaves the peptide bond between the methionine residue at the N-terminus and the next amino acid?
observed in most proteins
methionine aminopeptidase
What do you call the proteins that recognize the hydrophobic regions exposed on unfolded proteins and bind to them?
they then assist the proteins to the biologically desirable folding as well as to their local destinations w/in the cell
chaperones
What do you call the cylindrical assemblies that include a number of protein subunits with proteolytic activity in its core?
If rescue by chaperones fail, these degrade the misfolded protein
proteasomes
On an average, it has been estimated that one error occurs for every how many bases?
for every 1010 bases
What do you call the error in the copying of a sequence of bases that can occur during replication or during transcription?
Mutation
What do you call the mutation wherein the same protein is manufactured but the codons used are different?
silent mutation
what do you call the organic compounds that can induce mutations by reacting with DNA?
mutagens
What do you call the mutagens that causes cancer when introduced to our body?
Carcinogens
Most of the carcinogens are mutagens but the reverse is not true
What do you call the process where you remove incorrect nucleotides immediately after they are added to the growing DNA during replication?
Proofreading
What mutagen creates pyrimidine dimers and will cause a distortion in the normal shape of the DNA?
pi electrons from 2 carbons on each of the 2 pyrimidines will form a cyclobutyl ring
Ultraviolet light
mutagens = exogenous factors
ano yung apat na repair mechanisms mentioned sa ppt?
- Mismatch repair
- Nucleotide-excision repair
- Base-excision repar
- Nonhomologous DNA end-joining
repair system wherein enzymes recognize the incorrect pairing of bases
area of incorrect pairing is removed and replicated by DNA polymerases
Mismatch repair
repair system wherein damaged base is removed by DNA glycosylase leaving an AP site
AP = apurinic/apyrimidinic
DNA Pol I fills the gap then ligase comes in to seal phosphodiester backbone
Base-excision repair
used when bases are attacked by hydrolysis, oxidation, or alkylation
repair system that is common for DNA lesions caused by UV
Nucleotide-excision repair
repair system utilized in double-stranded breaks where DSBs pose a big threat to the stability of the genome
Chemical agents & Ionizing Radiation may induce double-stranded breaks
Nonhomologous DNA end-joining
NHEJ
What do you call the natural process in which genetic information is rearranged to form new associations?
Genetic recombination
recombination may be homologous or nonhomologous
What do you call the introduction of a gene for a missing protein?
this may be used to alter somatic cells (introduction of virus)
gene therapy
What do you call the changes in DNA that are not reflected in the actual base sequence?
Epigenetics
Two different pathways to damage DNA
- Endogenous
- Exogenous
