• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

39 Cards in this Set

  • Front
  • Back

Most eukaryotic genes are composed of ___ and ___. Which are coding parts?

exons and intron, exons

RNA splicing involves the removal of __ and splicing of ____ into a continuous reading frame for translation.

introns, exons

Prokaryotes doe not generally have extensive ___ . Exceptions include __ __ __ and __ ___.


group II introns

plasmid introns

More complex organisms have more ___ .


Yeast genes usually have ___ intron(s).


The longest primary transcript is produced by the __ gene


exons are generally ___ than introns


Why must introns be removed before translation in eukaryotes?

The translational machinery can not distinguish between introns and exons.

What is alternative splicing?

When more than one type of mRNA can be produced by one gene (some have over 100)

Introns have a generic ___ ___ to deliniate the intro exon junctions. This includes a ___ spice site and a __ splice site.There is a third conserved element in the middle called the __ __ __.

5', 3', branch point site

The branch point site is followed downstream by a ___ ___

polypyrimidine tract

Splicing occurs through two successive ____ reactions, in which existing ____ bond are transferred from one location to another. Explain.

transesterification, phosphodiester

The 2'OH of the conserved A at the branch site is nucleophillically attacked by a phosphoryl goup on the 5' splice site. To create the three way junction. The 3'OH on the free end attacks the phosphoryl group on the 3' splice site. And the intron is the leaving group.

In splicing of an intron no energy input is required, why?

Because two phosphodiester bonds are broken and two are made.

In alternative splicing, some exons can be ___.


What is trans-splicing?

Exons from different RNA molecules are spliced together

What is the large protein complex that carry out RNA splicing transesterification reactions?


How can RNA carry out some of the events in RNA splicing?

Because they can be catalytic, they can catalyze their own reactions like enzymes.

What are the 5 RNAs in the splicesome (small nuclear RNAs snRNAs)? What are the proteins that they are associated with called?

U1, U2, U4, U5, U6


The snRNPs are responsible for?

1. recognition of the 5' splice site and branch site

2. bringing these regions together

3. helping catalyze the RNA cleavage and joining reaction

What is the sequence of events of the splicesome to form the early complex or E complex?

1. U1 recognizes 5' site

2. U2AF binds to the PY tract AND 3' splice site

3. U2AF recruits BBP to the branch site

Steps to A complex?

1. U2AF aids in binding U2 to the branch site

2. BBP is displaced

Steps to B complex?

1. tri-snRNP are recruited (U4, 5, 6)

2. the three splice sites come together

Steps to C complex?

1. U6 replaces U1

2. U4 is relased, U6 and U2 interact

3. Now there is a functional active site

Steps to remove the lariat?

1. U5 aids in attack between 5'/3' sites

2. lariat is relased and degraded

3. snRNPs are recylced

What kind of introns do not require the splicesome?

self-splicing introns (group I and group II)

How do organism avoid inappropriate splicing?

1. splicesome is only assembled on specific sequences


What are ways that errors can occur in splicing?

1. Exons can be skipped

2. pseudo splice sites are spliced in

In what ways are splice specific selection enhanced?

1. After encountering 5' splice site, proteins on the tail transfer to the RNA and the next 3' splice site is recognized before any downstream site can be transcribed

2. serine-rich SR proteins that bind to ESEs in the exons, promoting more efficient binding of splicesome machinery, SR proteins recruit U2AF

constitutive alternative splicing

more than one product is always produced

regulated alternative splicing

done in response to a specific cellular signal, allows different forms of the transcribed RNA to be produced at diff times

SV40 virus produces what two proteins?

T-ag, t-ag, depending on level of splicing protein

What is an extended exon?

includes a portion of an intron with a stop codon

Othe ways that alternative splicing occurs

1. steric hindrance

2. major and minor splice sites

3. repressor proteins can cause a skip

4. activators can cause a splice

Why are introns absent in bacteria?

1. introns late model, introns were never present, but arose during evolution

2. or introns were originally present and were evolved out to minimize genomes to accomodate selective pressure

Why do eukaryotes have introns?

1. for alternative splicing

2. new genes can be created by shuffling

(each exon codes for a specific domain of a protein, they can be mixed and matched)

What is RNA editing? And what are the two ways it occurs?

When the RNA is changed after transcription

1. site-specific deamination

2. RNA directed uridine insertion or deletion

The mRNA is exported where?

Through the nuclear pore complex

True or false. The bigger the genome the more complex the organism.


So what explains the differences in biological complexity?

1. alternative splicing

2. PTMs

3. protein-protein interactions and their integration into pathways, proteins with a variety of isoforms that carry out more than one function