Lecture #20

Question 1

The pattern of ______ removal can allow for multiple protein products from the same gene from alternative splicing.

Answer 1

intron

Question 2

Alternative splicing allows different combinations of ______ in the final mRNA product

Answer 2

exons

Question 3

The particular ______ pathway that is followed may depend on the stage of development, cell, or tissue type.

Answer 3

splicing

Question 4

The ______ gene encodes a family of cell-adhesion molecules that function in axon guidance during early neuronal development in fruit flies. This gene consists of 24 exons but includes multiple alternative versions of exons 4, 6, 9, and 17 leading to 38,106 different cell-adhesion molecules.

Answer 4

Dscam

Question 5

______ splicing enhancers serve as binding sites for regulatory proteins

Answer 5

Exonic

Question 6

Specific nucleotides can be converted to other nucleotides through ______ _______

Answer 6

mRNA editing

Question 7

____ ______ can create new splice sites, generate stop codons, or lead to amino acid substitutions

Answer 7

RNA editing

Question 8

A typical eukaryotic non-dividing nucleus in housed by an envelope and contains:
- Chromosomes as extended fibers of ________.
- ______ for rRNA synthesis.
- ________ as the fluid where solutes are dissolved.
- The _____ _____, which is the protein-containing fibrillar network.

Answer 8

chromatin, Nucleoli, Nucleoplasm, nuclear matrix

Question 9

Two membranes separated by a _______ space; and membranes are fused at sites forming nuclear _____.

Answer 9

nuclear, pores

Question 10

Inner surface of the nuclear envelope is lined by the ______ ______ and it contains around 60 distinct transmembrane proteins.

Answer 10

nuclear lamina

Question 11

The ______ _____ supports the nuclear envelope and is composed of lamins. Its integrity is regulated by phosphorylation/dephosphorylation of _______ _______

Answer 11

nuclear lamina, intermediate filaments

Question 12

The nuclear envelope is the ______ between the nucleus and cytoplasm, and nuclear pores are the gateways.

Answer 12

barrier

Question 13

Proteins synthesized in the _______ and transported across the nuclear envelope. mRNAs, tRNAs, and ribosomal subunits are manufactured in the nucleus and transported to the ________.

Answer 13

cytoplasm, cytoplasm

Question 14

The ? is a doughnut-shaped structure that straddles the nuclear envelope, projecting into both the cytoplasm and nucleoplasm; and is composed of ~30 proteins called ________

Answer 14

Nuclear Pore Complex (NPC), nucleoporins

Question 15

The _____ is not static, as many of its proteins are replaced over a period of seconds to minutes. It is a huge complex (15–30X mass of a ribosome) that exhibits octagonal symmetry.

Answer 15

NPC

Question 16

Cytoplasmic proteins are targeted for the nucleus by the ? (NLS) (+ charged aa)

Answer 16

nuclear localization signal

Question 17

Transport receptors include:
- ______ to move molecules from the cytoplasm into the nucleus.
- ______ to move molecules in the opposite direction.

Answer 17

importins, exportins

Question 18

mRNAs, rRNAs, snoRNAs, miRNAs, and tRNAs are synthesized in the nucleus and function in the cytoplasm or are modified in the cytoplasm and return to function in the _______. These RNAs move through the NPC as ___________(RNPs).

Answer 18

nucleus, ribonucleoproteins

Question 19

Only mature, fully processed mRNAs are capable of nuclear export, as an mRNA with an unspliced _______ is retained in the nucleus.

Answer 19

intron

Question 20

3 main aspects of translational control: ?

Answer 20

localization of mRNAs, controlling whether or not a mRNA is translated and how often, controlling the half-life of the mRNA.

Question 21

Translational control operates through interactions between specific mRNAs and various proteins/microRNAs present within the _________.

Answer 21

cytoplasm

Question 22

UTRs contain nucleotide sequences used by the cell to mediate ________ control

Answer 22

translational

Question 23

Iron concentrations ____ → iron regulatory protein (IRP) binds to the iron-response element (IRE) -→ ______ translation.

Answer 23

low, prevent

Question 24

Iron becomes ______ → it binds to the IRP → changing its conformation and causing it to _______ from the IRE → allowing the translation of the mRNA to form ferritin

Answer 24

available, dissociate

Question 25

mRNA produced during fruit fly oogenesis:
______ mRNA localized in anterior end cytoplasm.
______ mRNA localized in posterior end cytoplasm.

Answer 25

bicoid, oskar

Question 26

Around ___% of all mRNAs are localized in specific regions.

Answer 26

70

Question 27

The lifetimes of eukaryotic mRNA vary ______

Answer 27

widely

Question 28

The poly(A) tail length may influence the ______ of mRNA. As an mRNA remains in the cytoplasm, its poly(A) tail tends to be ______.

Answer 28

longevity, reduced

Question 29

Typical mRNA leaving the nucleus, around 200 adenosine residues. Effect on mRNA stability is observed when the tail is reduced to around ____ A residues

Answer 29

30

Question 30

Certain destabilizing proteins in the 3’ UTR may affect the ____ of poly(A) tail shortening

Answer 30

rate

Question 31

Short-lived mRNA 3’ UTRs have AU-____ regions

Answer 31

rich

Question 32

Deadenylation, decapping, and 5’→ 3’ degradation occur within small transient cytoplasmic granules (__-_____)

Answer 32

P-bodies

Question 33

P-bodies can also serve to store mRNAs for later _______

Answer 33

translation

Question 34

Double-stranded RNA is very effective in ______ gene expression

Answer 34

stopping

Question 35

Phenomenon known as RNA ________ (RNAi)

Answer 35

interference

Question 36

siRNA – small antisense effectors of RNA _________

Answer 36

silencing

Question 37

Dicer and Argonaute involved for ________ the RNAi.

Answer 37

maturing

Question 38

Drug development: Instead of making a small chemical that inhibits a target enzyme by binding in its active site, one could potentially get the same result by using ______ to target the gene encoding the enzyme.

Answer 38

RNAi

Question 39

miRNAs – regulatory roles in development:
- Patterning of the ______ system
- Control of cell __________ and death.
- Leaf and flower development in ______.

Answer 39

nervous, proliferation, plants

Question 40

miRNAs act by binding to site in the ___ UTR of their target mRNAs

Answer 40

3’

Question 41

miRNAs suppress gene expression by:
- promoting deadenylation and ________.
- inhibiting the initiation of __________.
- inhibiting ________.
- possibly activating degradation of nascent _______.

Answer 41

degradation, translation, elongation, peptides

Question 42

________ stability may be determined by the amino acids on the N-terminus

Answer 42

Protein

Question 43

Degradation of proteins is carried out within hollow, cylindrical __________

Answer 43

proteasomes

Question 44

Proteasomes recognize proteins linked to _______

Answer 44

ubiquitin

Question 45

Ubiquitin is transferred by ______ _____ to proteins being degraded

Answer 45

ubiquitin ligases

Question 46

Once polyubiquitinated, a protein is recognized by the ____ of the proteasome

Answer 46

cap

Question 47

Once degraded, the component amino acids are released back into the _______

Answer 47

cytosol