question

3"splice sequence

answer

question

3'-splice site

answer

question

5'-m7G cap

answer

is a specially altered nucleotide on the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes. This is vital to creating mature messenger RNA, which is then able to undergo translation. Capping ensures the messenger RNA's stability while it undergoes translation in the process of protein synth. (highly regulated in the cell nucleus.) Is called m7G cause the guanosine is methylated on the 7 position after capping by a methyl transferase.

question

5'-splice sequence

answer

question

5'-splice site

answer

question

alternative splicing

answer

is a process by which the exons of the RNA produced by transcription of a gene (a primary gene transcript or pre-mRNA) are reconnected in multiple ways during RNA splicing. The resulting different mRNAs may be translated into different protein isoforms; thus a single gene may code for multiple proteins.

question

branchpoint sequence

answer

question

CTD (c terminal domain)

answer

the carboxyl terminus of a protein.

question

cleavage/polyadenylation site

answer

question

dicer

answer

is an endoribonuclease in the RNase III family that cleaves double stranded RNA and pre-microRNA into short double stranded RNA fragments (siRNA). They catalyze the the first step in RNA interference pathway and initiates formation of the RNA induced silencing complex.

question

exon

answer

is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA (introns) have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing

question

exon definition

answer

question

exon junction complex

answer

has major influences on translation surveillance and localization of the spliced mRNA. It is deposited on mRNA during splicing and is then transported into the cytoplasm. It is believed to provide a a position specific memory of the splicing event. Has a stable heterotetramer core (serves as binding platform)

question

expressed sequence tag (EST)

answer

is a short sub-sequence of a transcribed cDNA sequence. They may be used to identify gene discovery and gene sequence determination.

question

heterogeneous nuclear RNA (hnRNA)

answer

also known as pre-mRNA- is an immature single strand of mRNA. Synthed from a DNA template in the cell nucleus by transcription. Also includes nuclear RNA transcripts that do not end up as cytoplasmic mRNA

question

intron

answer

is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene.

question

intron definition

answer

question

lariat model

answer

is a splicing mechanism where splicesomes create a lariat like structure to remove introns, and join exons.

question

micro RNA (miRNA)

answer

are short RNA molecules (22 nuc. long). Theses are post transcriptional regulators that bind to complementary sequences on target mRNA transcripts, usually resulting in translation repression or gene silencing.

question

N7-methylguanosine (m7G)

answer

it creates the 5' cap, and is part of the transferase family

question

nonsense-mediated decay

answer

is a cellular mechanism of mRNA surveillance that functions to detect nonsense mutations and prevent the expression of truncated or erroneous proteins. Large intron regions increase the probability of stop codons somewhere within the open reading frame. This is a medium for degrading aberrant mRNA.

question

nuclear run-on

answer

it is conducted to identify the genes that are being transcribed at a certain time. Cell nuclei are isolated rapidly, and incubated with labelled nucleotides, and then the results are hybridized to a blot which is exposed to film. You can add things such as a-amanitin to show different effects. (Shows transcription rates)

question

poly(A) polymerase

answer

is an enzyme that catalyzes the reaction of ATP and RNA to diphosphate and RNA with an extra adenosine nucleotide at its 3' end-its a transferase- it creates the poly a tail.

question

poly(A) tail

answer

is the addition of multiple adenosine monophosphates (lots of A bases) It is important for nuclear export, translation and stability of mRNA. It is shortened over time, and when it is short enough it is enzymatically degraded.

question

polyadenylation

answer

is the addition of a poly(A) tail to an RNA molecule. The poly (A) tail consists of multiple adenosine monophosphates- (long stretch of A bases.) -The 3' most segment of the newly made RNA is cleaved of by a set of proteins, which then synth, the poly(A) tail at the 3' end. This is important for nuclear transport, translation and stability. If the poly(A)

question

polyadenylation signal

answer

the upstream signaling region has the sequence AAUAAA which is highly conserved, down stream is a GU rich region

question

poly(A) site

answer

The poly A tail acts as the binding site for poly E binding protein. THis promotes export from the nucleus and translation, and inhibits degradation. This binds to the tail prior to export, and also recruits poly (A) nuclease (what shortens the poly A tail.

question

pre-mRNA

answer

is an immature single strand of mRNA. Is synthed from a DNA template in the cell nucleus by transcription. Comprises the bulk of heterogeneous nuclear RNA. pre-mRNA has not been spliced, or had the 5' cap added, or a poly (a) tail

question

RISC loading complex

answer

This is a protein that loads miRNA to proteins

question

RNA editing

answer

describes the process by which the information content in an RNA molecule is altered through a chemical change in the base makeup. This occurs in the nucleus and cytosol, as well as in mitochondria and plastids.

question

RNA induced silencing complex (RISC)

answer

is a multiprotein complex that incorporates one strand of a small interfering RNA or micro RNA. It uses siRNA or miRNA as a template for recognizing complementary mRNA. When it finds a complementary strand it activates RNase and cleaves the RNA. This is important against viral infections, which uses double stranded RNA as an infectious vector.

question

RNA interference (RNAi)

answer

is a system within living cells that takes part in controlling which genes are active and how active they are. miRNA and siRNA are central to this. They can bind to other RNA and either increase or decrease their activity by preventing or producing a protein.

question

short interfering RNA (siRNA)

answer

(sometimes known as silencing RNA) is a class of double stranded RNA molecules (20-25 nuc) that are involved in RNA interference pathway, where it interferes with the expression of a specific gene. They are processed by a dicer, which converts long dsRNAs or small hairpin RNAs into siRNA

question

snRNA

answer

(small nuclear RNA) is a class of small RNA molecules that are found within the nucleus of eukaryotic cels. (Transcribed by RNA poly II or III and involved in RNA splicing, regulation of transcription factors or RNA poly II and maintaining telomeres.

question

snRNP

answer

are RNA protein complexes tat combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA protein molecular complex upon which splicing of pre-mRNA occurs. It is essential to the removal of introns from pre-mRNA. IT is composed of protein molecules and RNA.

question

spliceosome

answer

is a complex of specialized RNA and protein subunits that removes introns from a transcribed pre-mRNA (hnRNA) segment. It is composed of five snRNPs.

question

splicing

answer

is a modification of an RNA after transcription in which introns are removed and exons are joined. This is needed for the typical eukaryotic messenger RNA before it can be used to produce a correct protein through translation.

question

split gene

answer

is simply a strand of DNA that contains both introns and exons. These are found mainly in higher level eukaryotes.

question

trans-splicing

answer

is a special form of RNA processing in eukaryotes where exons from two different primary RNA transcripts are joined end to end and ligated . (Normal cis-splicing processes a single molecule.the car

question

After transcription begins what is added to the 5' end of mRNAs

answer

a 7-methylguanosine cap

question

Spliceosomes contain what that are responsible for splicing?

answer

snRPS

question

Polyadenylation occurs how? The pre mRNA is cleaved to do what

answer

Cotranscriptionally, it is cleaved to generate a new 3' end to which the poly A tail is added.

question

In mRNA editing _____ editing is specfic for spliced transcripts and _____ editing occurs on pre-mRNAs with introns still present.

answer

C-U, A-I,

question

How can gene expression be silenced? What does this require and how does it work

answer

RNA interference- Short RNAs (siRNA and miRNAs) are incorporated into RNA induced silencing complexes.

question

hnRNA has a broad size range and is composed of what? What must happen to it?

answer

It is composed of pre-mRNA, they have to be trimmed to form shorter RNAs.

question

T or F Eukaryotic pre-mRNAs are also polyadenylated

answer

true

question

mRNA's are capped where and by what

answer

at the 5' end by 7-methylguanosine

question

The ____ is attached early in transcription, when the nascent pre-mRNA chain is only 20-30 nucleotides long

answer

5' cap

question

Why does CTD play a role in capping?

answer

Capping enzymes bind directly to the CTD but the CTD must be phosphorylated on Ser-5 of the heptapeptide repeats

question

Eukaryotic pre-mRNAs have what that must be removed?

answer

introns.

question

Coding regions are found where?

answer

In the exons (exons mean where the things that are expressed reside)

question

What are generally not well conserved?

answer

Introns and non coding regions

question

Pre-mRNAs that are alternatively spliced produce what? In this what happens with the exons?

answer

Different RNAs- Constitutive exons are included in all, but regulated exons is retained in only some mRNAs

question

What happens in trans-splicing

answer

exons from two different mRNAs are spliced together.

question

What specific sequences does splicing require?

answer

the 5' splice site, the 3' splice site, and the branchpoint sequence.

question

snRNP do what

answer

they assemble to form a spliceosome that excises introns and joins the exons.

question

How are U snRNPs formed?

answer

The snRNAs are exported to the cytoplasm, where they are processed and joined to the Sm proteins. The snRNP is then transported back into the nucleus

question

Splicing can be regulated through what

answer

Intronic and exonic splicing enhancers or silencers.

question

Splicing beings when, and what stimulates spliceosome assembly

answer

During transcription, and CTD stimulates assembly

question

Pre-mRNA are________

answer

polyadenylated

question

Polyadenylation occurs in two stages, what are they

answer

The pre-mRNA is cleaved at a poly(A) site, and a poly (A) tail is added at the newly generated 3' end

question

the CTD does what

answer

it binds certain factors for polyadenylation

question

What takes place after cleavage and take place downstream of the poly A site

answer

transcription termination

question

____ editing can occur in spliced transcripts

answer

C-U

question

What must happen to mRNAs for translation to occur

answer

They must be transported to the cytoplasm

question

______ editing can occur in unspliced transcripts

answer

A-I

question

How are splicing and export coupled?

answer

The RNA export factor is recruited to the spliceosome, and the mRNA is targeted for export to the cytoplasm through the nuclear pores

question

______ is gene silencing through double stranded RNA

answer

RNA interference

question

A dicer enzyme does what?

answer

It converts double stranded RNA into siRNA molecules that are incorporated into a RISC

question

miRNAs do what, and what are they assembled into

answer

They regulate mRNA translation or cause mRNA degradation. They are assembled into RISC

question

What sequences would you specifically look for to spot an intron

answer

5' GU, 3' AG, some where between UACUAAC

question

Eukaryotic mRNA and hnRNA both have _____ at their 3' ends

answer

poly (A) tails

question

Eukaryotic mRNA molecules have ____ at their 5' end

answer

m7G caps

question

T or F Eukaryotes use a variety of pathways to form 5' m7G caps

answer

false

question

The carboxy terminal domain of the largest subunit of RNA polymerase II must be ____ on Ser-5 to target a transcript for capping

answer

phosphorylated

question

Amino acid coding regions within eukaryotic genes may be interrupted by ____ regions

answer

noncoding

question

T or F- Exons tend to be conserved during evolution whereas introns usually are not as tightly conserved.

answer

True

question

Two splicing intermediates resemble _____

answer

lariats

question

_____ permits a cell to recode genetic information in a systematic and regulated fashion.

answer

RNA editing

question

Pre-mRNA requires specific sequences for precise ____ to occur

answer

splicing

question

A single ___- can be processed to produce two or more different mRNA molecules

answer

pre-mRNA

question

____ assemble to form a spliceosome, the splicing machine that excises introns

answer

snRNPs

question

Transcription termination takes place downstream from the ____

answer

poly (A) site

question

____ molecules can silence gene expression

answer

Short RNA

question

the ____ pathway blocks mRNA translation or causes mRNA degradation

answer

miRNA

question

T or F Splicing begins as a cotranscriptional process and continues as posttranscriptional process

answer

True

MMBIO 240 Ch 17 – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards