Cellular neuro final

What is the primary function of RNA polymerase II (POL II)?

It binds to the TATA box and recruits transcription factors like TFII to the promoter region.

What are the two main components of the CRISPR system used for gene editing?

The Cas9 enzyme and a guide RNA.

What is the role of the guide RNA in the CRISPR system?

It directs the Cas9 enzyme to a specific, matching sequence of DNA.

If a neuron has voltage-gated calcium channel mRNA in the nucleus but no proteins are found, what is a likely cause?

A failure in nuclear export of the mRNA into the cytoplasm.

Why do neurons have higher transcription levels and larger nuclei compared to many other cells?

To meet the high demand for constant protein synthesis required for cellular communication.

What is a nucleosome?

A structural unit of DNA consisting of a length of DNA coiled around core proteins called histones.

What term describes the active, uncoiled region of DNA that is available for transcription?

Euchromatin

How do adenine (A) and thymine (T) bind to each other in a DNA double helix?

They are held together by two hydrogen bonds.

How do guanine (G) and cytosine (C) bind to each other in DNA?

They are held together by three hydrogen bonds.

Which base pair is easier to break, A-T or G-C, and why?

A-T pairs, because they only have two hydrogen bonds compared to the three in G-C pairs.

What type of bond links the 5' end of one deoxyribose sugar to the 3' end of the next in a DNA strand?

Phosphodiester bond

Which nucleotide base is found in RNA but not in DNA?

Uracil (U)

What are the three main components of a DNA nucleotide?

A five-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base.

What is the primary significance of RNA having a ribose backbone while DNA has a deoxyribose backbone?

The deoxyribose backbone makes DNA more stable, which is necessary for protecting the 'master copy' of genetic information.

What is the specific function of transfer RNA (tRNA)?

It delivers specific amino acids to the ribosomes during protein translation.

What are the building blocks that make up the structure of ribosomes?

Ribosomal RNA (rRNA)

What is the sequence rich in thymine and adenine found in the promoter region of a gene?

TATA box

What occurs during the 'Initiation' step of transcription?

Transcription factors (TFII) bind the promoter region and recruit RNA polymerase II to pull apart the DNA strands.

During transcription elongation, which strand of DNA does RNA polymerase II read?

The template strand

What is the function of the 5' cap (GMP) added to developing mRNA?

It distinguishes mRNA from other RNA, regulates nuclear export, and prevents degradation.

What are the roles of Cleavage Stimulation Factors (CstF) and Polyadenylation Specificity Factor (CPSF)?

They bind to the end of the mRNA to signal termination and initiate polyadenylation.

What is the 'poly-A tail' added to the end of mRNA during termination?

A sequence of adenine nucleotides added to regulate export, prevent degradation, and promote translation.

What is the process of removing non-coding regions and joining coding regions in mRNA called?

Splicing

What are 'introns' in the context of gene expression?

Non-coding sequences of a gene that are removed from the mRNA transcript during splicing.

What are 'exons' in the context of gene expression?

Coding sequences of a gene that remain in the mature mRNA and are translated into protein.

What is 'alternative splicing'?

A process where different combinations of exons are joined, allowing a single gene to code for multiple related proteins.

What is epigenetics?

The mechanism by which gene expression is controlled by outside means, such as DNA methylation, without changing the DNA sequence.

Through what structure does mRNA exit the nucleus to reach the cytoplasm?

Nuclear pore complexes

What is the 'Nissl body' in a neuron?

A complex specific to neurons formed by the rough endoplasmic reticulum and free ribosomes.

Where does most protein synthesis occur in a neuron?

The cell body (soma).

What are the three main steps of protein translation?

Initiation, elongation, and termination.

What is the final functional ribosome complex involved in translation initiation?

80S complex

What defines the 'A site' within a ribosome?

The acceptor site where the amino-acid tRNA first enters the ribosome.

What defines the 'P site' within a ribosome?

The peptidyl site where the growing polypeptide chain is held.

What defines the 'E site' within a ribosome?

The exit site where empty tRNAs leave the ribosome.

What enzyme is responsible for linking amino acids together in the ribosome?

Peptidyl transferase

When does translation elongation end?

When the ribosome encounters a stop codon.

What is protein phosphorylation?

The addition of a phosphate group to Serine, Threonine, or Tyrosine residues to alter protein function or localization.

What is glycosylation?

The post-translational addition of oligosaccharides to a protein, often occurring in the ER or Golgi.

What type of proteins are specifically synthesized on the Rough Endoplasmic Reticulum (RER)?

Integral (membrane-bound) proteins or proteins destined for secretion.

What component directs an mRNA/ribosome complex to the RER membrane?

The Signal Recognition Particle (SRP) binding to a signal sequence on the forming protein.

What happens when the SRP binds to the signal sequence during RER protein synthesis?

Translation is temporarily halted until the complex binds to an SRP receptor on the RER.

What is the function of 'signal peptidases' in the RER?

They remove the N-terminal signal sequence from the growing polypeptide chain.

What specific protein coating allows a vesicle to be targeted from the RER to the Golgi complex?

COPII

What is the role of the Trans-Golgi Network (TGN)?

It sorts and targets proteins to their final destinations, such as the plasma membrane or organelles.

What is 'retrograde transport' in the context of the Golgi apparatus?

The movement of vesicles from the Golgi back to the RER, often mediated by COPI coating.

What small GTP-binding protein triggers the budding of COP I vesicles by binding to the Golgi membrane?

ARF (ADP-ribosylation factor)

What must happen to the COP I coat before a vesicle can fuse with a target membrane?

The coat must depolymerize (uncoat), triggered by the hydrolysis of ARF-GTP to ARF-GDP.

What are SNARE proteins?

Specific surface proteins exposed after uncoating that mediate the fusion of a vesicle with its target membrane.

What is the difference between v-SNAREs and t-SNAREs?

v-SNAREs are located on the vesicle membrane, while t-SNAREs are on the target membrane.

What is the function of Rab proteins in vesicle trafficking?

They act as regulators of vesicle targeting and fusion.

After being sorted in the Golgi, what does a vesicle attach to in order to travel to the axon terminal?

Microtubules

What is 'fast axonal transport'?

The rapid movement of membrane-bound organelles and vesicles along microtubules.

What are gap junctions?

Direct physical connections between cells that allow the passage of ions and small molecules for fast, coordinated signaling.

What is the structural unit contributed by a single cell to a gap junction?

A hemichannel (or connexon).

What specific proteins make up gap junctions in vertebrate species?

Connexins

What specific proteins make up gap junctions in invertebrate species?

Innexins

Where are newly synthesized connexins assembled into hemichannels?

In either the RER or the Golgi apparatus.

Where is the greatest diversity found among members of the gap junction channel family?

The cytoplasmic C-terminal region.

How are hemichannels removed from the cell membrane?

Through internalisation into the cytoplasm.

How many hydrogen bonds form between Guanine and Cytosine?

3

What is the sugar found in the backbone of RNA?

Ribose

What is the process of copying a DNA sequence into an RNA sequence called?

Transcription

What modification at the 3' end of mRNA helps prevent enzymatic degradation?

Polyadenylation (Poly-A tail).

What enzyme is responsible for the removal of introns from pre-mRNA?

The spliceosome (consisting of snRNAs and proteins).

Which specific modification to histones can lead to the silencing or activation of genes?

Methylation (or phosphorylation/ubiquitination).

Where in the cell does the 80S ribosome complex form?

In the cytoplasm (on the RER or as free ribosomes).

What molecule carries the anticodon and the corresponding amino acid to the ribosome?

tRNA

Proteins synthesized on free ribosomes are generally destined for where?

The cytoplasm (or organelles like mitochondria/peroxisomes).

What is the function of the Signal Recognition Particle (SRP) receptor?

It resides on the RER membrane and docks the SRP-ribosome-nascent protein complex.

Which side of the Golgi apparatus receives vesicles from the RER?

The Cis-Golgi Network (CGN).

What is the role of COPI coatomer proteins?

They facilitate the budding of vesicles for retrograde transport or intra-Golgi transport.

Which protein complex catalyzes the dissociation of the SNARE complex after vesicle fusion?

NSF and alpha-SNAP.

How do gap junctions facilitate coordinated responses in a group of cells?

By allowing the direct spread of electrical signals and small second messengers between interconnected cells.

What determines if a protein will be cytoplasmic or membrane-embedded?

The presence or absence of a signal sequence that targets the ribosome to the RER.

What is the primary biological concern mentioned regarding CRISPR technology?

Ethical concerns and risks associated with experimental therapies in humans.

What is the role of 'shuttle proteins' in gene expression?

They help transport mature mRNA out of the nucleus through nuclear pore channels.

In neurons, what is 'slow axonal transport' used for?

The movement of cytosolic and cytoskeletal proteins.

What is the 'Cisface' of the Golgi apparatus?

The side of the Golgi stack that is oriented toward the nucleus/ER.

What is the 'Transface' of the Golgi apparatus?

The side of the Golgi stack that faces away from the nucleus, toward the plasma membrane.