practice exam 3/3 !

<p>Messenger RNA (mRNA) (A)</p> Signup and view all the answers

<p>Transcription start site (B)</p> Signup and view all the answers

<p>To regulate gene expression and initiate transcription (A)</p> Signup and view all the answers

<p>TATA-binding protein (TBP) (D)</p> Signup and view all the answers

<p>In the 5'-to-3' direction, using the 3'-to-5' strand as a template (C)</p> Signup and view all the answers

<p>The specific types of RNA they transcribe (A)</p> Signup and view all the answers

<p>All general transcription factors are equally necessary (C)</p> Signup and view all the answers

<p>pre-mRNA (D)</p> Signup and view all the answers

<p>Translation (C)</p> Signup and view all the answers

<p>Acts as a scaffold for organizing processing factors (A)</p> Signup and view all the answers

<p>It is identical in length to the DNA template used (A)</p> Signup and view all the answers

<p>Transcription factors (A)</p> Signup and view all the answers

<p>Facilitates ribosomal recognition and binding during translation (B), Increases the stability of the mRNA molecule against decay (D)</p> Signup and view all the answers

<p>Poly A polymerase activity (B)</p> Signup and view all the answers

<p>Methyl groups are added to the terminal ribose of the cap (D)</p> Signup and view all the answers

<p>Downstream of the AUAAA sequence (A)</p> Signup and view all the answers

<p>RNA splicing (C)</p> Signup and view all the answers

<p>Splicesome (B)</p> Signup and view all the answers

<p>It consists of multiple ribosomes bound to a single mRNA. (B)</p> Signup and view all the answers

<p>It facilitates transport of RNA products out of the nucleus. (A)</p> Signup and view all the answers

<p>A ribozyme (A)</p> Signup and view all the answers

<p>It is tightly packed DNA combined with protein complex. (A)</p> Signup and view all the answers

<p>Forms a hydrophobic mesh that regulates macromolecule diffusion (B)</p> Signup and view all the answers

<p>Mature mRNAs are transported as ribonucleoproteins interacting with nucleoporins (D)</p> Signup and view all the answers

<p>Importins bind to Nuclear Localization Signals, while exportins bind to Nuclear Export Signals (C)</p> Signup and view all the answers

<p>Its octagonal symmetry provides a central channel diameter of 20-40 nm (C)</p> Signup and view all the answers

<p>Through specific amino acid sequences known as Nuclear Localization Signals and Nuclear Export Signals (D)</p> Signup and view all the answers

<p>92 chromatids (C)</p> Signup and view all the answers

<p>Has one set of unpaired chromosomes (B)</p> Signup and view all the answers

<p>During mitosis (A)</p> Signup and view all the answers

<p>23 pairs of homologous chromosomes (B)</p> Signup and view all the answers

<p>Chromosome (D)</p> Signup and view all the answers

<p>They bind directly to DNA. (D)</p> Signup and view all the answers

<p>It inhibits the translation of Ferritin mRNA. (A)</p> Signup and view all the answers

<p>Histones (C)</p> Signup and view all the answers

<p>Proteasome (D)</p> Signup and view all the answers

<p>Epigenetics (D)</p> Signup and view all the answers

<p>Each daughter strand contains one parental strand. (A)</p> Signup and view all the answers

<p>S phase (C)</p> Signup and view all the answers

<p>It synthesizes new DNA strands. (A)</p> Signup and view all the answers

<p>Regions where several replicons become active. (D)</p> Signup and view all the answers

<p>It facilitates nucleotide incorporation into new strands. (C)</p> Signup and view all the answers

<p>It extends RNA primers to create Okazaki fragments. (B)</p> Signup and view all the answers

<p>Origin recognition complex (ORC) (C)</p> Signup and view all the answers

<p>Type I topoisomerases (B)</p> Signup and view all the answers

<p>To begin the synthesis of Okazaki fragments. (D)</p> Signup and view all the answers

<p>DnaB helicase (B)</p> Signup and view all the answers

<p>Nonsense mutation (D)</p> Signup and view all the answers

<p>Insertion and deletion mutation (A)</p> Signup and view all the answers

<p>Missense mutation (C)</p> Signup and view all the answers

<p>Altered downstream codons (B)</p> Signup and view all the answers

<p>Point mutation (C)</p> Signup and view all the answers

<p>Formation of protein aggregates leading to toxicity (D)</p> Signup and view all the answers

<p>Genetic mutation (A)</p> Signup and view all the answers

<p>Down Syndrome (C)</p> Signup and view all the answers

<p>By promoting cell growth and proliferation (B)</p> Signup and view all the answers

<p>Structural abnormalities (A)</p> Signup and view all the answers

<p>Can lead to increased protein-protein interactions (C)</p> Signup and view all the answers

<p>Receptor protein-tyrosine kinases (RTKs) (B)</p> Signup and view all the answers

<p>It can either activate or inactivate the enzyme depending on the protein (A)</p> Signup and view all the answers

<p>Protein stability leading to enhanced cell mobility (A)</p> Signup and view all the answers

<p>Phosphorylate proteins to activate or modify their function (D)</p> Signup and view all the answers

<p>Autocrine signaling (B)</p> Signup and view all the answers

<p>It undergoes a conformational change. (C)</p> Signup and view all the answers

<p>ATP (A)</p> Signup and view all the answers

<p>They activate or inactivate target proteins within the cell. (D)</p> Signup and view all the answers

<p>Paracrine signaling affects nearby cells, while endocrine signaling affects distant targets through the bloodstream. (B)</p> Signup and view all the answers

<p>Gq (D)</p> Signup and view all the answers

<p>cAMP activates PKA by binding to its regulatory subunits. (B)</p> Signup and view all the answers

<p>It acts as a transcription factor that promotes gene expression. (D)</p> Signup and view all the answers

<p>They activate gluconeogenesis via cAMP signaling. (C)</p> Signup and view all the answers

<p>Activation of phospholipase C to generate secondary messengers. (C)</p> Signup and view all the answers

<p>It cleaves phosphatidylinositol di-phosphate (PIP2) to generate second messengers. (C)</p> Signup and view all the answers

<p>It results in membrane hyperpolarization. (A)</p> Signup and view all the answers

<p>cAMP is synthesized by adenylyl cyclase and regulates various cellular processes. (D)</p> Signup and view all the answers

<p>RGS9, which typically helps to inactivate transducin. (C)</p> Signup and view all the answers

<p>Gαt triggers the activation of cGMP phosphodiesterase during light stimulation. (C)</p> Signup and view all the answers

<p>Ligand gated channels (D)</p> Signup and view all the answers

<p>cyclic AMP (cAMP) (B)</p> Signup and view all the answers

<p>Phosphorylating target proteins (D)</p> Signup and view all the answers

<p>IP3 and DAG (C)</p> Signup and view all the answers

<p>Alpha subunit Gs (C)</p> Signup and view all the answers

<p>Activate/inactivate target proteins (C)</p> Signup and view all the answers

<p>Receptor protein-tyrosine kinases (B)</p> Signup and view all the answers

<p>Nerve Growth Factor (NGF) (B)</p> Signup and view all the answers

<p>Ligand-mediated dimerization (A)</p> Signup and view all the answers

<p>It tests positive for human epidermal growth factor receptor 2. (D)</p> Signup and view all the answers

The process of synthesizing RNA from a DNA template in the nucleus.

The enzyme responsible for initiating and carrying out transcription in eukaryotes.

The synthesis of proteins in the cytoplasm using mRNA information.

Messenger RNA; carries the genetic code from DNA to the ribosomes for protein synthesis.

The fundamental concept in molecular biology: DNA -> RNA -> Protein.

Enzyme responsible for synthesizing RNA from a DNA template in eukaryotes.

Proteins that bind to DNA to regulate gene expression by initiating and controlling the rate of transcription, turning a gene 'on' or 'off'.

Essential transcription factors, required for all protein-coding genes to be transcribed, that assemble at the core promoter region of DNA, enabling RNA polymerase II binding and start of transcription.

A crucial subunit of TFIID, a general transcription factor that recognizes and binds to the promoter region of DNA.

The initial RNA transcript produced during transcription, before any processing. It's also called heterogeneous nuclear RNA (hnRNA).

A tail-like structure on RNA polymerase II that acts as a platform for various proteins involved in pre-mRNA processing. It coordinates capping, polyadenylation, and intron removal.

The entire DNA sequence that is transcribed into a single RNA molecule, including the coding region and regulatory regions.

Capping, polyadenylation, and intron removal. These steps are essential for producing a mature mRNA molecule.

A complex of proteins and enzymes that travel with RNA polymerase II during transcription, carrying out mRNA processing steps.

A protective structure added to the 5' end of mRNA, consisting of a guanine nucleotide linked in an unusual 5'-5' triphosphate bridge, with methyl groups added.

The modified guanosine nucleotide that forms the 5' cap, protecting the mRNA and aiding in its transport.

A long string of adenine nucleotides added to the 3' end of mRNA, protecting it from enzymatic degradation and helping it to be exported from the nucleus.

The process of cutting the primary RNA transcript at a specific site near the 3' end, initiating the addition of the poly(A) tail.

The nucleus is the site of transcription, where DNA is transcribed into RNA. It also contains chromatin, a tightly packed complex of DNA and proteins, and the nucleolus, where ribosomes are assembled.

Chromatin is a complex of DNA and proteins found in the nucleus. It's tightly packed to fit within the tiny nucleus and helps control access to the DNA for transcription.

The nucleolus is a region within the nucleus where ribosomes are assembled. These ribosomes are crucial for protein synthesis.

The nuclear envelope is a double membrane that surrounds the nucleus. It regulates what enters and leaves the nucleus, controlling the flow of genetic information.

Lamins are proteins that line the inner membrane of the nuclear envelope. They provide mechanical support and anchor chromatin, helping to organize the nucleus.

A large, intricate protein structure embedded in the nuclear envelope that acts as a gateway for the transport of molecules between the nucleus and cytoplasm.

The protein components that make up the nuclear pore complex (NPC).

A specific amino acid sequence found in certain nucleoporins, forming a hydrophobic mesh that selectively blocks the diffusion of large molecules through the nuclear pore complex.

A short amino acid sequence on a protein that serves as a signal for its import into the nucleus.

A short amino acid sequence on a protein that serves as a signal for its export out of the nucleus.

Proteins that enhance gene expression without directly binding to DNA. They often interact with transcription factors and modify chromatin structure to facilitate transcription.

A protein that regulates iron levels in the cell by binding to iron-responsive elements (IREs) on mRNA. It prevents ferritin mRNA translation when iron levels are high to decrease iron storage.

A cellular mechanism that regulates gene expression by targeting specific mRNA molecules for degradation. It's often used in research to silence gene expression.

A large protein complex responsible for degrading misfolded or damaged proteins, ensuring proper protein quality control in the cell.

The proteasome, a large protein complex, is responsible for degrading peptides and other misfolded proteins.

A tightly packed structure that contains DNA and proteins, allowing the cell to organize and store large amounts of genetic material in a small space. It's like a spool of thread that holds a long strand of DNA.

A cell that contains two sets of chromosomes, one set from each parent. It has a complete set of genetic information, carrying pairs of chromosomes.

Two chromosomes, one from each parent, that carry the same genes but potentially different versions of those genes. They pair up during cell division.

A cell that contains only one set of chromosomes, resulting from meiosis. It carries only half the genetic information found in a diploid cell.

Two identical copies of a chromosome, produced by replication before cell division. They are attached together at the centromere.

The process of DNA replication where each new DNA molecule contains one original strand from the parent DNA molecule and one newly synthesized strand. The two strands of the parent DNA molecule separate, and each serves as a template for the synthesis of a new complementary strand.

The Y-shaped structure formed during DNA replication where the parental DNA strands are unwound and separated, creating a site for DNA synthesis to occur.

During DNA replication, one strand of the newly synthesized DNA molecule is synthesized continuously in the 5' to 3' direction, following the movement of the replication fork.

During DNA replication, one strand is synthesized in discontinuous fragments (Okazaki fragments) in the 5' to 3' direction, moving away from the replication fork.

The process of copying DNA, where one new daughter strand is synthesized continuously (leading strand) and the other is synthesized in small fragments (lagging strand) due to the 5' to 3' directionality of DNA polymerase.

Short DNA segments synthesized on the lagging strand during DNA replication, each requiring a separate RNA primer to initiate.

Helicase uses energy from ATP hydrolysis to break the hydrogen bonds between the two DNA strands, separating them for replication.

SSB proteins coat and stabilize the unwound single strands of DNA during replication, preventing them from re-annealing or becoming damaged.

A single base pair change in the DNA sequence.

A point mutation that results in a change in the amino acid coded for by the DNA sequence.

A point mutation that introduces a stop codon, prematurely ending protein synthesis.

An insertion or deletion of nucleotides that shifts the reading frame of the DNA sequence.

A change in the number of copies of a particular DNA sequence, including insertions, deletions, duplications, and repeat expansions.

A DNA sequence like 'CAG' is repeated many times. Too many repeats can cause problems.

Like having two identical items instead of one, but this can be bad in genes.

The failure of chromosomes to separate properly during cell division, leading to an abnormal number of chromosomes (e.g., Down Syndrome).

The process by which cells communicate with each other using chemical messengers called ligands.

A signaling molecule that binds to a receptor protein on a target cell, initiating a cellular response.

A protein on a cell surface that binds to a specific ligand, triggering a signal transduction pathway within the cell.

The process by which a signal from outside the cell is converted into a cellular response, often involving a cascade of events within the cell.

A small molecule that helps relay a signal from the cell surface to intracellular targets, amplifying the original signal.

The process by which cells communicate with each other through signaling molecules and receptors. This allows cells to coordinate their actions and respond to changes in their environment.

A series of molecular events that occur in a specific order, starting with a signaling molecule and ending with a cellular response. Each step in the pathway involves a protein that changes conformation.

Phosphorylation, adding a phosphate group to a protein, can activate or inactivate enzymes, alter protein-protein interactions, change the location of a protein within the cell, or trigger protein degradation.

G-protein coupled receptors are a large family of cell surface receptors that are involved in a wide range of cellular processes, including sensing light, odorants, and hormones. They are activated by binding to a signaling molecule, which triggers a conformational change that activates a G protein.

Receptor protein-tyrosine kinases are cell surface receptors that have intrinsic tyrosine kinase activity. They are activated by binding to a signaling molecule, which triggers dimerization and autophosphorylation.

A second messenger molecule produced by the breakdown of PIP2 by phospholipase C. It triggers the release of calcium ions from intracellular stores, leading to various cell responses.

Diacylglycerol, a second messenger produced along with IP3, that activates protein kinase C (PKC) by binding to its regulatory domain.

Protein Kinase C, a family of serine/threonine-specific protein kinases activated by DAG and calcium ions. It plays a key role in cell signaling pathways involved in cell growth, differentiation, and apoptosis.

A signaling pathway triggered by the activation of phospholipase C, which breaks down PIP2 into IP3 and DAG. IP3 mobilizes calcium from intracellular stores, while DAG activates PKC, leading to downstream signaling events.

The breakdown of PIP2 by phospholipase C generates two crucial second messengers, IP3 and DAG. This event acts as a 'signal amplifier' and triggers various downstream signaling pathways involved in cell growth, differentiation, and other important cellular processes.

Rhodopsin is a light-sensitive receptor protein found in rod cells of the retina. It's activated by photons of light, triggering a signaling cascade leading to vision.

cGMP is a second messenger that keeps sodium and calcium channels open in rod cells in the dark. When light activates rhodopsin, it triggers a decrease in cGMP, causing the channels to close and the cell to hyperpolarize, signaling to the brain.

Transducin is a G protein (Gαt) that is activated when light activates rhodopsin. It then activates cGMP phosphodiesterase, leading to a decrease in cGMP.

Bradyopsia is a condition characterized by slow vision, often caused by mutations in the RGS9 gene, which usually helps inactivate transducin during light termination. This leads to slower cGMP increase and slower membrane depolarization.

PLC is an effector enzyme activated by Gαq. It cleaves PIP2 into two second messengers, IP3 and DAG, which further relay signals within the cell.

This pathway starts with a ligand binding to an RTK, triggering its dimerization and autophosphorylation. This activates downstream signaling proteins, including MAPKs, which relay the signal further into the cell, ultimately resulting in diverse cellular responses.

Dimerization is the process by which two identical molecules, like RTKs, come together and bind to each other. This binding is often triggered by a ligand and can lead to activation of the molecules.

Autophosphorylation is the process by which a protein 'phosphorylates' itself, meaning it adds a phosphate group to its own amino acids. This often happens within RTKs, activating the protein and enabling it to activate downstream signaling pathways.

Ligand binding to RTKs can cause receptor dimerization, either by ligand-mediated dimerization (one ligand binds to both receptors) or receptor-mediated dimerization (two ligands bind to two separate receptors). This dimerization brings the tyrosine kinases in close proximity, allowing them to phosphorylate each other.

Once dimerized, the tyrosine kinase domains of RTKs become active and phosphorylate tyrosine residues on each other. This autophosphorylation creates docking sites for other signaling proteins, initiating a cascade of downstream events.

RTKs are activated by a variety of ligands, including insulin, VEGF (Vascular Endothelial Growth Factor), PDGF (Platelet-Derived Growth Factor), EGF (Epidermal Growth Factor), and FGF (Fibroblast Growth Factor). Each ligand triggers specific downstream signaling events, contributing to diverse cellular processes.

RTKs play a vital role in normal cell growth, proliferation, and differentiation. Dysregulation of RTK signaling can lead to uncontrolled cell growth, which is a hallmark of cancer. For example, in HER2-positive breast cancer, the HER2 protein, an RTK, is overexpressed, leading to increased growth of tumor cells.