Bio Chapter 12
How many nucleotides are contained in a single codon?
3
An mRNA sequence is 5′AUG-GGC-ACU-CAU-ACU-UAA3′, where AUG is the start codon and UAA is the stop codon. How many distinct aminoacyl-tRNA synthetases are required to translate the mRNA sequence?
4
If a DNA template strand has a sequence of 3′ TACAATGTAGCC 5′, then the RNA produced from it will be which sequence?
5′AUGUUACAUCGG3'
The genetic code consists of ____ codons that specify amino acids, and ____ codons that do not specify amino acids.
61/3
What promotes the binding between the mRNA and the small ribosomal subunit?
A region near the 5' end of the mRNA is complementary to a region of rRNa is the small subunit.These complementary regions hydrogen-bond with each other to promote the binding of the mRNA to the small ribosomal subunit.
Start codon
AUG
________ enables a single gene to encode two... What process enables a single gene to encode two or more polypeptides that are different in their amino acid sequence.
Alternative splicing
Ribozyme
An RNA moecule that catalyzes a chemical reaction.
what is the direction of flow of genetic infomation?
DNA to RNA to protein
What is the function of an aminoacyl-tRNA synthetase?
Each of these 20 enzymes catalyzes the attachment of a specific amino acid to a specific tRNA molecule.
Capping
IS when mature mRNA of eukaryotes have a modified form of guanine covalently attached at the 5' end. this event occurs while a pre-mRNA is being made by RNA polymerase.After mRNA is in the cytosol the cap structure helps to prevent mRNA degration and is recognized by other cap-binding proteins that enable the mRNA to bind to a ribosome for translation.
How would removing a terminator from a gene affect transcription?where would transcription end?
If a terminator was removed, transcription would occur beyond the normal stopping point.eventually,RNA polymerase would encounter a terminator from an adjacent gene,and transcription would end.
The central dogma of gene expresssion at the molecular level
In bacteria, transcription and translation occur in the cytoplasm In eukaryotes,transcription and RNA processing occur in the nucleus,whereas translation takes place in the cytosol
If an anticodon in a tRNA molecule had the sequence 3'-ACC-5' which amino acid does it carry?
It would bind to a 5'-UGG-3' codon and it would carry tryptophan.
The following mRNA transcript would result in what polypeptide sequence? 5′ ACU-UUC-ACU-AUG-UUU-UUA-UCC-UCC-ACU-CCU-UGA 3′
Met-Phe-Leu-Ser-Ser-Thr-Pro
Self-splicing
RNA itself can catalyze the removal of its own intron.portions of te RNA act like an enzyme to cleave the covalent bonds at the intron-exon boundaries and connect the exons together.
Elongation
RNA polymerase synthesizes the RNA transcript for this to occur thesigma factor is released and RNA polymerase slides along the DNA in a way that maintains an open complex as it goes the DNA strand is used as a template for RNA synthesis .
Which describes the hydrolysis of ATP.why is ATP needed to charge a tRNA?
The attachment of an amino acid to a tRNA is an endergonic reaction.ATP provides the energy to catalyze this reaction.
What is the function of the anticodon?
The function of the anticodon in tRNA is to recognize a codon in an mRNA.
Promoter
The site where transcription begins .signals the beginning of transcription
Which of the following statements about the mRNA start codon is INCORRECT?
The start codon is usually GGA.
Transfer RNA (tRNA)
Translates the language of mRNA into that of amino acids.
End codons/stop condons/termination codons
UAA UAG UGA
Codons for Leu
UUA UUG CUU CUC CUA CUG
Codons for Pheylalanine (Phe)
UUU UUC
C-terminus
a carboxyl group is always found at the end of the polypeptide.
Sigma factor
a protein that binds to RNA polymerase.Also it recognizes the base sequence of promoter ans binds there.
Coding sequence
a region that specified the linear amino acid sequence of a polypeptide.
If a mutation eliminated the start codon from a gene,how would the mutation affect transcription,and how would it affect translation?
a structural gene would still be transcribed into RNA if the start codon was missing.however it would not be translated properly.
There is only one start codon, AUG. This means that all newly-made polypeptides have a methionine at their amino end.
all newly-made polypeptides have a methionine at their amino end.
Alternative splicing
allows a signle gene to encode two or more polypetides with differences in their amino acid sequences/ allows complex eukaryotic species to use the same gene to make different proteins at different stages of development or in different cell types.
What enzyme catalyzes the attachment of amino acids to tRNA molecules?
aminoacyl-tRNA synthetase
What is the enzyme that catalyzes that attachment of amino acids to tRNA?
aminoacyl-tRNA synthetases
Gene
an organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product.
Transcription factors
are proteins influenced by the ability of RNA polymerase to transcribe genes
Poly A tail
at the 3' end,most mature eukaryotic mRNAs have a string of adenine nucleotides. the poly A tail is not encoded in the gene sequence.A long poly A tail aids in the export of mRNAS from the nucleus.
Which of the following best represents the centreal dogma of gene expression?
b. During transcription,DNA codes for mRNA,which codes for polypeptides during translation.
The synthesis of a polypeptide occurs during which stage of translation?
b.elgongation
During eukaryotic RNA processing,the nontranslated sequences that are removed are called
b.introns
The____ is the site where the translation process takes place. a.mitochondria
c.ribosome
Functional protein
compsed of two or more different polypeptides
peptide bonds
connect amino acids together,covalent bonds
snRNPS
contain small nuclear RNA and a set of proteins
transcription and translation both occur in the same location, where does this occur and what type of cell is this ?
cytoplasm, bacteria
In what region does translation occur?
cytosol
Transcription of gene begins at a site on DNA called_____ and ends at a site on DNA known as____.
d. a promoter, the terminator
During initiation of translation,the frist codon,______, enters the ____ and associates with the initiator tRNA.
d.AUG, P site
The functional product of a structural gene is
d.a polypeptide
The region of the tRNA that is complementary to a codon in mRNA is .
d.the anticodon
The movement of polypeptide from the tRNA in the p Site to the tRNA in the A site is referred to as
d.the peptidyl transfer reaction
Because more than one codon can specify the same amino acid, the genetic code is said to be
degenerate
The small subnit of a ribosome is composed of
e.Many proteins and one rRNA molecule.
Ribosomal RNA(rRNA)
forms part of ribosomes,which provide the site where translation occurs.
An organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product is called a _______.
gene
The processes of transcription and translation are collectively known as
gene expression.
Coding strand
has the same sequence of bases as the resulting mRNA,except for thymine in the DNA is substituted for uracil in the RNA.It carries information that codes the polypeptide.
RNA splicing
introns are removed and the remaining exons are connected to eachother.
Intervening sequences that are transcribed, but not translated into protein are called
introns.
Anticodon
is a three-based sequence in tRNA molecule that is complementary to a codon in mRNA bind to each other.
spliceosome
is comprised of several different subunits knowns as snRNPS(pronounced "snurps").they bind to specific sequences at three locations
Messenger RNA (mRNA)
is created from structural genes ,it's function is to carry infomation from the DNA to cellular components called ribosomes
where does transcription occur in eukaryotes?
nucleus
Transcribed region
part of this region contains the infomation that specifies an amino acid sequence.
Ribosomes
play a key role in the synthesis of polypepties.
The transcription process in a eukaryotic gene directly produces _________.
pre-mRNA
Structural genes
produce RNA molecule that contains the information to specify a polypeptide with a particular amino acid sequence.
Transcription
produces an RNA copy of a gene, transcription literally means the act of making a copy.
Transcription begins near a site in the DNA called the ______.
promoter
Initiation factors
proteins that facilitate the interactions between components.
N-terminus
refers to the presence of a nitrogen atom(N)
Exons
sequences contained in the mature mRNA.they are expressed in regions whereas introns are intervening regions that are not expressed because they are removed from the mRNA.
Regulatory sequence
site for the binding of regulatory proteins.the role of regulatory proteins is to influence the rate of transcription.
Terminator
specifies the end of transcription.signals the end of transcription
Genetic Code
specifies the relationship between the sequence of nucleotides in the mRNA and the sequences of amino acids in a polypeptide.
RNA processing
the RNA transcript, termed pre-mRNA is modified in ways that make it functionally active mRNA.
elongation
the covalent bonding of amio acids to each other,one at a time,to produce a polypeptide.
RNA polymerase
the enzyme that synthesizes strands of RNA.
Codons
the groups of three nucleotide bases read
Template strand
the portion of the DNA strand that is used as a template for RNA synthesis
Translation
the process of synthesizing a specific polypeptide on a ribosome.
release factor
the three-dimmensional structure of a release factor protein mimics the structure of tRNAs which allows it to fit into the A site.
Introns
transcribed but not translated into proteins.
What protein influences the ability of RNA polymerase to transcribe genes?
transcription factors
The process that produces mRNA from DNA is called
transcription.