TRANSLATION Flashcards
- DNA Is transcribed into _.
- mRNA is translated into _
- Each _ corresponds to amino acid.
- Amino acids form _.
- Polypeptide chains fold into _.
PROTEIN SYNTHESIS (TRANSLATION OF m RNA)
- mRNA
-amino acids
- codon
- polypeptide chains
- proteins
is the collection of codons that specify all the amino acids found in proteins
genetic code
IS Usually triplet bases which are carried by mRNA
CODONS
carries anti-codon, together with mRNA they will connect to create _ to create _
tRNA
- polypeptide
- proteins
is non-overlapping (i.e., each _ is used only once)
a. It begins with a start codon () near the 5’ end of the mRNA.
b. It ends with a termination (stop) codon (, ,) near the 3’ end.
The code is _ (i.e., there are no breaks or markers to distinguish one codon from the next).
The code is nearly universal.
The same codon specifies the same amino acid in almost all species studied; however, some differences have been found in the codons used in .
The start codon () determines the reading frame.
PROTEIN SYNTHESIS (TRANSLATION OF MESSENGER RNA)
- genetic code
- nucleotide
- AUG ( also called methionine)
- UGA, UAG, or UAA
- commaless
- mitochondria
-AUG
- occur when a base or a number of bases are added to DNA.
>They can result in a protein with more or fewer amino acids than normal.
Insertions
- occur when a base or a number of bases are removed from DNA.
>They can result in a protein with fewer or more amino acids than normal.
Deletions
occur when the number of bases added or deleted is not a multiple of three.
Frameshift mutations
In eukaryotes, ___________ binds to the ______________.
a. The _binds to the small subunit, and the first AUG codon base pairs with the anticodon on the
methionyl-tRNAiMet.
b. The _ that initiates protein synthesis is subsequently removed from the N terminus of the
polypeptide.
Initiation of translation (1)
- methionyl-tRNAiMet
- small ribosomal subunit
-5’ cap of the mRNA
-methionine
In bacteria, the methionine that initiates protein synthesis
is formylated and is carried by __. Prokaryotes do not contain a _ on their mRNA.
>An mRNA sequence upstream from the translation start site
(the __) binds to the _ to position the small ribosomal subunit on the mRNA
Initiation of translation (1)
- tRNAfMet
- 5’ cap
- Shine-Dalgarno sequence
- 3’ end of 16S ribosomal RNA (rRNA)
The large ribosomal subunit binds, completing the initiation complex.
a. ___ is bound at the P (peptidyl) site of the complex.
b. The __ site of the complex is unoccupied.
Initiation of translation (2)
Methionyl-tRNAiMet
A (acceptor or aminoacyl)
,,_ are required for formation of the initiation complexes.
a. PROKARYOTES ,,_
b. EUKARYOTES
c. Release of the initiation factors involves hydrolysis of GTP
to _ and _
Initiation of translation (4)
- Initiation factors (IFs), ATP, and guanosine triphosphate (GTP)
- IF-1, IF-2, and IF-3
- eIF-1, eIF-2, until eIF-7
- guanosine diphosphate (GDP) and inorganic phosphate
discuss the process of initiation of translation
tRNA will always connect to A site (acceptor) will give the
amino acid they carried to P site large ribosomal unit will
move backward to the right IRIKS & OVARY Page 3
tRNA that has been removed of the amino acid will now go
to the E site repeat until it elongate -> polypeptide production -> protein production
> tRNA has CCA sequence that contains amino acids. That amino acid is attached to its corresponding RNA via _
FORMATION OF AMINOACYL-TRANSFER RNA’s (tRNA)
aminoacyl- tRNA Synthetase
type of bond that connects amino acid together to form polypeptide bonds
- creates protein
PEPTIDE BOND
When a termination codon (UGA, UAG, or UAA) occupies the
_, release factors cause the newly synthesized _
to be released from the ribosome.
_ indication that protein protein synthesis is done
UGA, UAG, UAA
2. The _ dissociate from the mRNA.
TERMINATION OF TRANSLATION
- A site
-polypeptide
- Stop codon
-ribosomal subunits
Amino acids are activated and attached to their corresponding tRNAs by highly specific enzymes known as _____________.
FORMATION OF AMINOACYL-TRANSFER RNA’s (tRNA)
-aminoacyl-tRNA synthetases
An amino acid first reacts with _, forming an activated amino acid
_ and _, which is cleaved to _
FORMATION OF AMINOACYL-TRANSFER RNA’s (tRNA)
adenosine triphosphate (ATP)
- (aminoacyl-adenosine monophosphate [AMP]) and pyrophosphate
- 2 inorganic phosphates (Pi)
The aminoacyl-AMP then forms an ester with the 20 - 30-hydroxyl of tRNA specific for that amino acid, producing an ___and _________.
FORMATION OF AMINOACYL-TRANSFER RNA’s (tRNA)
- aminoacyl-tRNA and AMP
The addition of each amino acid to the growing polypeptide chain involves
- binding of an _____________at the A site - formation of a_ - translocation of the __________ to the P site
ELONGATION OF POLYPEPTIDE CHAINS
- aminoacyl-tRNA
- peptide bond
- peptidyltRNA
Binding of aminoacyl-tRNA to the - A site
a. The _ at the A site determines which aminoacyl-tRNA will bind.
b. An elongation factor for prokaryotes _ and for eukaryotes _ and _ are required for binding.
ELONGATION OF POLYPEPTIDE CHAINS
- mRNA codon
- (EF) (EF-Tu in prokaryotes and
EF-1 in eukaryotes) and
hydrolysis of GTP
forms between the amino group of the aminoacyl-tRNA at the A site and the carbonyl of the aminoacyl group attached to the tRNA at the P site.
Formation of it catalyzed by _, which is _.
b. The _ at the P site now does not contain an amino acid. It is ‘‘uncharged.’’
c. The growing polypeptide chain is attached to the in the _ site
Formation of a peptide bond
- peptide bond
- peptidyl transferase
-rRNA
trna
- A
a. The _(along with the attached mRNA) moves from the A site to the P site, and the uncharged tRNA is released from the ribosome.
B. An elongation factor (_in eukaryotes or _ in prokaryotes) and the _ are required for this.
Translocation of peptidyl-tRNA
- peptidyl-tRNA
-EF-2
-EF G
hydrolysis of GTP
After synthesis is completed, proteins can be modified by ,,,,_
Post-translational processing
- phosphorylation, glycosylation, ADPribosylation, hydroxylation, and addition of other groups.
destined for release from the cell, are synthesized on ribosomes attached to the _ in eukaryotic cells.
- Secretory proteins
-rough endoplasmic
reticulum (RER)
A _________at the N terminus of a secretory protein causes the nascent protein to pass into the lumen of the RER. The signal sequence is cleaved from the N terminus, and the protein may be glycosylated within the _.
- hydrophobic signal sequence
- RER
The protein travels in vesicles to the _, where it may be glycosylated further and is packaged in _
Golgi
secretory vesicles.
Secretory vesicles containing the protein travel from the
Golgi to the cell membrane. The protein is released from the
cell by _.
exocytosis
SYNTHESIS AND RELEASE OF SECRETORY PROTEINS
- Secretory proteins
- A hydrophobic signal sequence at the N terminus
- The protein travels in vesicles to the Golgi
- Secretory vesicles containing the protein travel from the
Golgi to the cell membrane.
describes how one amino acid can be coded for by several codons.
__ The third nucleotide in a codon
There are two main properties of this nucleotide. The cognate tRNA’s binding to a codon in an mRNA is substantially more “loose” in the codon’s third position.
5. The third codon position can now accommodate a variety of _
Wobble effect
Wobble Hypothesis
WOBBLE POSITION
non-Watson–Crick base pairings
- Relationship of protein synthesis to _
- Prokaryotes, such as Escherichia coli, require a source of
_ for sugar - A source of _ is also required for the synthesis of
amino acids - The process by which synthesis of the enzymes is regulated is
called _.
>uses different type of sugar as the source of sugar
REGULATION OF PROTEIN
Regulation of Protein Synthesis in Prokaryotes
1 nutrient supply
carbon
nitrogen
induction
Responsible for having gram positive and gram negative
bacteria
LAC OPERON
- lactose fermenters ad non lactose fermenters
metabolite of lactose and
inducer
Lactose Operon Inducible
o Responsible genes: ,,_
o Has rapid and slow fermenters because of the
presence/absence of these 3 enzymes
Lactose fermenters
b-galactosidase, lactose
permease, and transacetylase
The _ is inducible.
is induced only in the absence of _. It exhibits _
(1) A metabolite of lactose, _, is the inducer.
(2) Proteins produced by the genes of the lac operon allow the cell to oxidize lactose as a source of energy.
_produces a b-galactosidase;
_, a lactose permease; and
_, a transacetylase.
lactose (lac) operon
- glucose
- catabolite repression
- allolactose
- Gene Z
- gene Y
- gene A
_______ is a set of genes that are adjacent to one another in the genome and are coordinately controlled; that is, the genes are either all turned on or all turned off
An operon
_ begins near a promoter region, which is located upstream from the group of structural genes.
Transcription
Associated with the promoter is a short sequence, the _______, which determines whether or not the genes are expressed.
operator
Binding of a _________to the operator region prevents binding of _ to the promoter and inhibits transcription of the structural genes of the operon.
repressor protein
RNA polymerase
___________ are encoded by regulatory genes, which may be located anywhere in the genome.
Repressor proteins
a. Cells preferentially use glucose when it is available.
b. The lac operon exhibits this
Catabolite repression
a. In bacterial cells, _ and _ occur simultaneously.
b. __ occurs by a mechanism by which rapid translation of the nascent transcript causes termination of transcription
- Ability of the body to know whether a mechanism is
happening slow or very fast
can Terminates transcription
can Terminates translation
transcription and translation Attenuation
which are small, basic proteins associated with the DNA of eukaryotes, act as nonspecific repressors.
b. The expression of specific genes is stimulated by __
c. _ (e.g., steroid hormones) enter cells, bind to protein receptors, interact with chromatin in the nucleus, and activate specific genes.
d. Some genes have more than one _. Thus, that is used can differ
under different physiologic conditions or in different cell types.
Regulation of the level of transcription
Histones
positive mechanisms
Inducers
promoter
a. Regulatory mechanisms that occur during _, , can alter the amino acid sequence or the quantity of the protein produced from the mRNA.
>Editing of mRNA also occurs, and the rate of degradation of mRNA is also regulated.
b. _ sites can be used to produce different mRNAs.
*Note: The use of different splice sites results in the production of _ in the C cells of the thyroid or, alternatively, in the brain, the
_
Regulation during processing and transport of mRNA
- capping, polyadenylation, and splicing
- Alternative splice
- calcitonin
- neuropeptide calcitonin gene–related peptide (CGRP)
is the process whereby an inducer (a small molecule) stimulates transcription of an operon.
Induction
The _ is frequently a sugar (or a metabolite of the sugar), and the proteins produced from the _ allow the sugar to be metabolized
inducer
inducible operon
The inducer binds to the _, inactivating it.
o The inactive repressor does not bind to the _.
o _, therefore, can bind to the promoter and transcribe the operon.
o _ encoded by the operon are produced.
repressor
operator
RNA polymerase
structural proteins
undergo differentiation, and the organisms go through various
developmental stages.
Eukaryotic cells
Eukaryotes contain _. Therefore, transcription is separated from translation.
nuclei
In _, transcription and translation occur simultaneously.
prokaryotes
_ is complexed with histones in eukaryotes, but not in prokaryotes.
DNA
- Regulation can result from changes in genes or from mechanisms that affect _, _, and _
Regulation of protein synthesis in eukaryotes
- transcription,
processing, and transport of mRNA, mRNA translation, or mRNA stability.
Changes in genes
a. Genes can be lost (or partially lost) from cells, so that _ can no longer be produced (e.g., during differentiation of red blood cells).
b. Genes can be _
c. _ can move from one location to another on the genome, associating with each other in various ways so that different proteins are produce
d. Modification of the bases in DNA affects the_ of a gene.
(1) _ can be methylated at its 5 position.
(2) The greater the extent of _, the less readily a gene is transcribed.
Regulation of protein synthesis in eukaryotes
-functional proteins
- amplified
Segments of DNA
transcriptional activity
Cytosine
methylation
is a sequence of 3 bases (triplet) in messenger RNA (mRNA) (50 to 30) that specifies (corresponds to) a particular _
Each of the _ has at least one codon; many amino acids have numerous codons.
codon
-amino acid
-20 common amino acids
mRNA needs _ to prevent degradation
CAP
where process of replication and transcription
NUCLEUS
site for Process of translation (protein synthesis)
RIBOSOME
discuss pathway of protein synthesis
mRNA leaves the nuclear pore from nuclear pore, it will
leave to the cytoplasm in cytoplasm, it will find the
ribosomes protein synthesis will start
– tRNA that carries methionine
methionyl-tRNAiMet
diff of codon and anti codon
Codon AUG – methionine (inside the mRNA)
Anti-codon methionyl-tRNAiMet (inside the tRNA)
bacteria andarchaea’s small ribosomal subunit
SHINE-DALGARNO SEQUENCE
large ribosomal subunit is composed or 3 areas
o E area – exit area
o P area – peptidyl area
o A area – aminoacyl area, acceptor area
mRNA that contain series/multiple ribosomes
POLYSOME
b. The structural genes of an operon code for a series of different _.
>A single _ is transcribed from an operon. This single mRNA codes for all the proteins of the operon.
(2) A series of _ on the polycistronic mRNA allows a number of different proteins to be produced at the translational level from the single mRNA.
proteins
- polycistronic mRNA
- start and stop codons
The _ contains about 1000 times more DNA than E. coli _
mammalian genome
(109 versus 106 base pairs)
Most mammalian cells are _.
diploid
The major part of the genome of mammalian cells does not code for _.
proteins
Some eukaryotic genes, like most bacterial genes, are unique (i.e., they exist in _ of copies per genome).
one or a small number
- Other eukaryotic genes, unlike bacterial genes, have _ in the genome (e.g., genes for ,,_ ).
many copies
tRNA, rRNA, histones
Relatively short, repetitive DNA sequences are dispersed throughout the _.
They do not code for proteins (e.g., _).
eukaryotic genome
- Alu sequences
- Eukaryotic genes contain _. Bacterial genes do not.
introns
Bacterial genes are organized in _ (sets that are under the control of a single promoter). Each eukaryotic gene has its own _.
operons
promoter
