Bio Chapter 12

The genetic code consists of ____ codons that specify amino acids, and ____ codons that do not specify amino acids. 20/3 64/3 60/4 61/3 21/3

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

What are similarities and differences between the function of DNA polymerase and that of RNA polymerase?

Both DNA and RNA polymerase use DNA strands as a templaate and connect the nucleotides to each other in a 5' to 3' direction based on complementarity base pairing.One difference is that DNA polymerase needs a preexisting strand,such as an RNA primer to begin DNA replication.Whereas RNA polymerase can begin the syntheis of RNA on a bare template strand.Another key difference is that DNA polymerase connects deoxyribonucleotides,where as RNA polymerase connects ribonucleotides.

what is the direction of flow of genetic infomation?

DNA to RNA to protein

proteins

Denotes function.

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

Initiation

Is a regonition step

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′ Use the following codons and the amino acids they encode. AUG = Start or Met; UUU, UUC = Phe; UUA, UUG = Leu; UCU, UCC = Ser; CCU, CCC = Pro; ACU, ACC = Thr; UGA = Stop. Thr-Phe-Thr Phe-Leu-Ser-Ser-Thr-Pro Met-Phe-Leu-Ser-Ser-Thr-Pro Thr-Phe-Thr-Phe-Leu-Ser-Ser-Thr-Pro Met-Phe-Leu-Ser-Ser

Met-Phe-Leu-Ser-Ser-Thr-Pro

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 are the three enzymes that are required for Argine synthesis?

+Omithine, +Citrulline, Arginine

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? 2 3 4 5 6

4

If a DNA template strand has a sequence of 3′ TACAATGTAGCC 5′, then the RNA produced from it will be which sequence? 3′TACAATGTAGCC5′ 5′ATGTTACATCGG3′ 5′AUGUUACAUCGG3' 3′AUGUUACAUCGG5′ 3′ATGTTACATCGG5′

5′AUGUUACAUCGG3'

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 _________. rRNA pre-mRNA mRNA DNA Protein

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 enhancer response element transcription unit regulatory sequence

promoter

Initiation factors

proteins that facilitate the interactions between components.

Reading frame

refers to the order in which codons are read during translation.

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.

The process that produces mRNA from DNA is called transcription. translation. replication. processing. post-translational modification.

transcription.

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 only a few nucleotides from the ribosomal binding site. The start codon is usually GGA. The start codon is usually AUG. The start codon specifies the amino acid, methionine. The start codon defines the reading frame.

The start codon is usually GGA.

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 carboxyl end. the first tRNA will have the anticodon loop 3'-AUG-5'. the 5' end of an mRNA must start with an A. the stop codons each have their own special tRNAs.

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? helicase topoisomerase aminoacyl-tRNA synthetase ribosome translation factor

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? a. During transcription,DNA codes for polypeptides. b. During transcription,DNA codes for mRNA,which codes for polypeptides during translation. c.During translation,DNA codes for mRNA,which codes for polypeptides during transcription. d.none of the above.

b. During transcription,DNA codes for mRNA,which codes for polypeptides during translation.

The synthesis of a polypeptide occurs during which stage of translation? a.initiation b.elgongation c.termination d.splicing

b.elgongation

During eukaryotic RNA processing,the nontranslated sequences that are removed are called a.exons b.introns c.promoters. d.codons e.ribozymes

b.introns

The____ is the site where the translation process takes place. a.mitochondria b.nucleus c.ribosome d.lysosome e.ribozyme

c.ribosome

Functional protein

compsed of two or more different polypeptides

peptide bonds

connect amino acids together,covalent bonds

snRNPS

containsmall nuclear RNA and a set of proteins

transcription and translation both occur in the same location, where dies 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____. a. The start codon, the stop codon b. A promoter,the stop codon c. the start codon, the terminator d. a promoter, the terminator e.none of the above

d. a promoter, the terminator

During initiation of translation,the frist codon,______, enters the ____ and associates with the initiator tRNA. a.UAG,A site b.AUG,A site c.UAG, P site d.AUG, P site e.AUG,E Site

d.AUG, P site

The functional product of a structural gene is a.tRNA b.mRNA c.rRNA d.a polypeptide e.a,b,and c.

d.a polypeptide

The region of the tRNA that is complementary to a codon in mRNA is a. the acceptor stem b.the codon c.the peptidyl site d.the anticodon e.the adaptor loop.

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 a.peptide bonding b.aminoacyl binding c.translation d.the peptidyl transfer reaction e.elongation

d.the peptidyl transfer reaction

Because more than one codon can specify the same amino acid, the genetic code is said to be repetitive. redundant. reverse. degenerate. wobbly.

degenerate

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 _______. chromosome trait allele gene expression

gene

The processes of transcription and translation are collectively known as RNA processing. gene duplication. protein synthesis. DNA synthesis. gene expression.

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.

where does transcription occur in eukaryotes?

in the nucleus

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 exons. introns. spliceosomes. transposons. transcription factors.

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

polypeptide

linear sequence of amino acid; it denotes structure.

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.

Initiation

a complex is formed between an mRNA molecule,the first tRNA,and ribosomal subunits.

Inborn error of metabolism

a mutation in a gene that is inherited from one or both parents

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 .

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.

Ribosomal RNA(rRNA)

forms part of ribosomes,which provide the site where translation occurs.

What protein influences the ability of RNA polymerase to transcribe genes? DNA polymerases DNA helicases transcription factors snRNPs tRNA

transcription factors

How many nucleotides are contained in a single codon? 1 3 4 6 9

3

________ 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. Reverse transcription Self-splicing Capping Alternative splicing Regulatory splicing

Alternative splicing

Ribozyme

An RNA moecule that catalyzes a chemical reaction.

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.

Transfer RNA (tRNA)

Translates the language of mRNA into that of amino acids.

The small subnit of a ribosome is composed of a.protein b.an rRNA molecule c.many proteins d.many rRNA molecules e.Many proteins and one rRNA molecule.

e.Many proteins and one rRNA molecule.

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.