BIO307 Lecture 4: Cell Communication

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Questions and Answers

What type of junction allows for the passage of calcium ions between cells to facilitate action potential transmission?

Gap junction (correct)

Tight junction

Adheren junction

Desmosome

Which junction type is primarily responsible for preventing water and molecules from passing between cells?

Gap junction

Desmosome

Adheren junction

Tight junction (correct)

In which type of signaling do surface protein molecules on one cell membrane bind to receptor molecules on another cell's membrane?

Paracrine signaling

Autocrine signaling

Endocrine signaling

Contact-dependent signaling (correct)

What role do desmosomes play in cellular communication?

Link the cytoskeletons of adjacent cells Signup and view all the answers

What results from neurotransmitters being secreted into a synapse?

Eliciting a response in the target cell Signup and view all the answers

Which of the following best describes adheren junctions?

They mediate cell-cell adhesion. Signup and view all the answers

What allows for localized communication in cell-cell signaling?

Local direct contact or signaling Signup and view all the answers

Which statement correctly describes the function of tight junctions in epithelial cells?

They prevent paracellular transport. Signup and view all the answers

What role do exosomes play in cancer progression?

They transfer oncogenes and growth factors to other cells. Signup and view all the answers

Which protein is considered a building block of gap junctions?

Connexin 43 Signup and view all the answers

In co-culture experiments, what is assessed?

The interaction between different cell types through direct communication and paracrine signaling. Signup and view all the answers

What does the scrape loading and dye transfer assay primarily measure?

The gap junction direct communication between adjacent cells. Signup and view all the answers

Which technique is NOT mentioned as a method for investigating cell communication?

Gas chromatography Signup and view all the answers

Exosomes are involved in which of the following processes?

Cell-to-cell communication. Signup and view all the answers

What type of communication can be assessed by tracking a signaling molecule in co-culture experiments?

Paracrine communication. Signup and view all the answers

Which of the following statements about exosome research is correct?

Exosome research presents both challenges and opportunities. Signup and view all the answers

What is the initial event in the process of atherosclerosis?

Endothelial cell dysfunction Signup and view all the answers

Which component is primarily involved in the formation of atherosclerotic plaque?

Lipids and calcium Signup and view all the answers

What type of cells are responsible for plaque stability in atherosclerosis?

Smooth muscle cells Signup and view all the answers

What are foam cells primarily derived from?

Macrophages engulfing lipids Signup and view all the answers

Which factor is NOT associated with endothelial dysfunction in atherosclerosis?

High-density lipoprotein (HDL) cholesterol Signup and view all the answers

What cellular process is linked to the development of atherosclerosis?

Cellular senescence Signup and view all the answers

Which of the following best describes the fibrous cap in an atherosclerotic plaque?

A protective layer made by smooth muscle cells Signup and view all the answers

What kind of damage is primarily associated with the development of atherosclerosis?

DNA damage Signup and view all the answers

What is a key focus in the development of radioprotective drugs?

Understanding molecular mechanisms Signup and view all the answers

Which molecular mechanism is related to atherosclerosis?

Inflammation response Signup and view all the answers

What is likely a target for radioprotectant development?

Molecular antioxidants Signup and view all the answers

How does oxidative stress relate to atherosclerosis?

It contributes to endothelial damage Signup and view all the answers

What represents a component of the problem description in drug development?

Characterizing experimental designs Signup and view all the answers

In the context of atherosclerosis, what does Ca2+ overload typically lead to?

Increased inflammation Signup and view all the answers

What is a potential outcome of targeting molecular mechanisms in drug development?

Improved therapeutic efficacy Signup and view all the answers

What is often a result of damaged endothelium in relation to atherosclerosis?

Vascular inflammation Signup and view all the answers

What is the primary role of the transduction stage in a signal transduction pathway?

To convert the signal into a specific cellular response Signup and view all the answers

Which of the following is true regarding the signal transduction pathway?

It leads to either a nuclear response or a cytoplasmic response Signup and view all the answers

What may occur as a result of the cascade initiated during the transduction stage?

Amplification of signals through a series of reactions Signup and view all the answers

In the example of epinephrine signaling, which enzyme is ultimately activated to release glucose monomers?

Glycogen phosphorylase Signup and view all the answers

What is the process of activating a sequence of relay molecules in signal transduction often referred to as?

Signal cascade Signup and view all the answers

What is the effect of one receptor protein in the context of hormone signaling?

It can activate approximately 100 molecules of G protein Signup and view all the answers

What initiates the transduction process in the signal transduction pathway?

Binding of a signaling molecule to a receptor Signup and view all the answers

What is a possible cellular response after the transduction stage?

Regulation of gene expression in the nucleus Signup and view all the answers

What is the first event in the atherosclerotic process?

Endothelial cell dysfunction Signup and view all the answers

Which type of cell communication is affected by radiation according to the content?

Gap junction communication Signup and view all the answers

What are connexins primarily associated with in endothelial cells?

Hemichannel formation Signup and view all the answers

What are potential outcomes of endothelial cell dysfunction?

Oxidative stress and inflammation Signup and view all the answers

How does radiation exposure impact the cardiovascular system based on the content?

It induces cell death and promotes atherosclerosis. Signup and view all the answers

Which experimental variable is mentioned in assessing the effect of radiation?

Exposure to X-rays Signup and view all the answers

Which of the following is NOT a consequence of endothelial cell dysfunction?

Enhanced gap junction communication Signup and view all the answers

Which factor is critical when formulating a hypothesis related to radiation effects?

Understanding the underlying cellular mechanisms Signup and view all the answers

Study Notes

Molecular and Cellular Biology [BIO307]

Course title: Molecular and Cellular Biology
Course code: BIO307
School: Biotechnology

Lecture 4: Cell Communication and Signaling I

Topic: Cell communication and signaling
Focus: Fight-or-flight response
Source: Campbell Biology, 11th edition, Chapter 11, pages 212-233

The Fight-or-Flight Response

Body's natural response to perceived danger.
Physiological changes coordinated by the nervous and endocrine systems.

Cell Communication and Signaling

Brain detects stressful situation.
Stress hormones (adrenaline, cortisol) released from adrenal glands.
Hormones travel through blood to target cells.
Target cells respond to hormones via signaling pathways (receptor binding).
Diverse physiological responses: increased heart rate, fast breathing, pupils dilate, etc.

Physiological Changes (Response)

Heart rate increases.
Breathing quickens.
Blood flow to the brain increases.
Alertness and focus increase.
Digestion slows.

Cell-to-Cell Communication

Body relies on complex communication between cells.
Cells communicate via chemical messengers.
These messengers include small molecules, hormones, and neurotransmitters

Types of Cell Signaling

Local signaling: Occurs between nearby cells
- Gap junctions: Direct contact between cells. Allows passage of ions and small molecules.
- Contact-dependent signaling: Requires direct contact between cell membranes. Molecules on one cell surface interact with receptors on another.
- Synaptic signaling: Nerve cells release neurotransmitters into a small gap called a synapse; these bind to receptors on the target cell.
- Paracrine signaling: Secretory cells release local regulators that influence nearby cells.
- Autocrine signaling: Secretory cells act on themselves.
Long-distance signaling: Occurs in distant parts of an organism.
- Endocrine signaling: Signaling molecules (hormones) are secreted into the bloodstream and travel to target cells.
- Nervous system: Neurons release neurohormones into the blood for actions on distant target cells.

Examples

Wound healing: Cytokines, local signaling molecules, attract immune cells. Growth factors promote cell proliferation and new blood vessel growth.
Fight-or-flight response: Nervous system stimulates hormonal release triggering a cascade of effects.

Exosomes

Tiny, membrane-bound vesicles released from cells.
Carry proteins, nucleic acids, and lipids.
Involved in local and long-distance cell-cell communication.
Play an important role in physiological and pathological processes like cancer, neurological diseases, and cardiovascular disease.

Molecular Techniques to Investigate Cell Communication

Detecting and Measuring Gene/Protein Expression: Using techniques like qPCR and Western blotting to examine levels of specific genes or proteins important for communication.
Co-culture Experiments: Culturing different cell types together to study direct cell-to-cell or paracrine interactions. Track signaling molecules using dyes or sensitive assays (ELISA).
Scrape Loading and Dye Transfer: Used to measure gap junction communication.
Live-Cell Imaging: Study real-time cell function responses to direct or paracrine signals.

Signal Transduction Pathway

Series of steps converting a signal on a cell's surface into a cellular response.
Three main stages: reception, transduction, and response.
- Reception: Signal molecule (ligand) binds to a receptor protein. This binding triggers a conformational change initiating the transduction phase.
- Transduction: Signal is relayed through a sequence of intermediary molecules. This often involves a cascade of enzymatic reactions and a "domino effect" where signal intensity increases.
- Response: Final molecule in the pathway activates a cellular response like activating enzymes, transcription factors, or structural changes in the cell.

Experimental Design and Hypothesis Testing

Scientific research process: describe a problem, propose hypotheses, test hypotheses, form conclusions, communicate conclusions.
Process of radioprotective drug development for breast cancer radiotherapy.
Role of endothelial cells in radiation-induced atherosclerosis.

Atherosclerosis

Cardiovascular disease.
Endothelial cell dysfunction is the initial step.
Oxidative stress, inflammation, and DNA damage contribute.

Radiation-induced Atherosclerosis

Radiation exposure can damage endothelial cells causing atherosclerosis.
Understanding the damage mechanisms and cell-cell communication.

Application of findings

New research questions arise from the study.

Next steps/lecture

Further details on G-protein coupled receptors and the MAPK pathway.

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Description

This quiz focuses on Lecture 4 of the Molecular and Cellular Biology course, specifically covering cell communication and signaling related to the fight-or-flight response. You will explore how the body reacts to stress through the release of hormones and the physiological changes that occur. Test your understanding of these critical biological processes and their importance in survival.