Cell Science Exam - Long Answer Tasks

Myosin motor proteins move vesicles along actin filaments within the cell, contributing to intracellular transport and cellular organization.

Bcl-2 is a protein that prevents programmed cell death (apoptosis) by inhibiting the intrinsic mitochondrial pathway.

Okazaki fragments are short DNA segments created during DNA replication on the lagging strand.

DNA ligase joins Okazaki fragments, while nucleases break down nucleic acids.

Microtubule polymerization, depolymerization, and motor proteins are essential for cell division and other functions but are not directly involved in DNA replication.

Developing neurons compete for limited survival factors, and those that fail may undergo programmed cell death (apoptosis), not necroptosis.

Calmodulin is a calcium-binding protein that regulates intracellular calcium concentration.

Nucleosomes and their 30nm arrangement create a more compact structure without increasing the overall diameter, due to DNA wrapping.

Cells that can divide indefinitely and differentiate into specialized cell types.

Stem cells derived from embryos at the blastocyst stage, capable of becoming any cell type in the body.

Stem cells found in adult tissues that can differentiate into a limited range of cell types specific to that tissue.

Stem cells generated by reprogramming adult cells to have embryonic stem cell properties.

Conditions that must be maintained for cell growth and survival in culture.

Physical conditions such as temperature, humidity, and oxygen levels that affect cell culture.

Maintaining sterile conditions to prevent contamination in cell culture.

Chemical factors such as growth factors, hormones, and pH that affect cell culture.

Peroxisomes are small organelles that play a crucial role in various metabolic processes, particularly in the detoxification of harmful molecules.

Catalase, an enzyme found within peroxisomes, breaks down hydrogen peroxide (H2O2), a toxic byproduct of cellular metabolism, into water and oxygen, thus protecting the cell from oxidative damage.

Peroxisomes play a vital role in the breakdown of long-chain fatty acids, which are too large for other organelles to handle. They break them down into smaller units, making them usable by the cell.

Peroxisomes break down branched-chain fatty acids, which are a type of fatty acid with a unique structure. This process is essential for the efficient use of lipids within the cell.

Peroxisomes are important for reducing reactive oxygen species (ROS), which are harmful molecules that can damage cells. They neutralize ROS by converting them into less harmful compounds.

The endosymbiotic theory proposes that peroxisomes evolved through a process called engulfment, where a primitive eukaryotic cell engulfed a bacterium capable of performing oxidative reactions. Over time, this bacterium evolved into the peroxisome, becoming a vital part of the cell's metabolic machinery.

Unlike GDP-bound G proteins which are in their inactive form, GTP-bound alpha subunits of G proteins directly activate downstream molecules, such as adenylyl cyclase. This activation triggers a signaling cascade, leading to various cellular responses.

Channels, due to their passive nature and direct passage of solutes through pores, facilitate faster transport compared to transporters. Transporters, particularly those involved in active transport, require ATP and often operate at a slower rate.

The endoplasmic reticulum (ER) is a network of interconnected membranes that plays a crucial role in protein synthesis, folding, and transport. The rough ER (rER) is studded with ribosomes, which are responsible for protein synthesis. The smooth ER (sER) primarily synthesizes lipids and steroids.

Proteins synthesized on ribosomes attached to the rough ER (rER) enter the ER lumen for folding. This process ensures proteins adopt their correct shape and function. In the ER lumen, proteins undergo modifications, such as glycosylation (adding sugar molecules) and quality control checks, to ensure proper function.

The smooth ER (sER) plays a vital role in lipid synthesis, including phospholipids and cholesterol, which are essential components of cell membranes. It also synthesizes steroids, hormonal molecules that regulate various bodily functions.

The sER in the liver is involved in detoxification processes. It metabolizes harmful substances, such as drugs and toxins, converting them into less harmful forms for excretion.

The nuclear lamina is a mesh-like structure that lines the inner surface of the nuclear membrane. It provides structural support for the nucleus and plays a role in regulating gene expression. The nuclear lamina is connected to the outer nuclear membrane via nuclear pore complexes (NPCs).

Stem cells have the remarkable ability to differentiate into various specialized cell types. This regenerative potential makes them promising candidates for treating diseases and injuries, where damaged tissues or organs can be regenerated.

Induced pluripotent stem cells (iPSCs) are derived from adult cells that are reprogrammed to an embryonic-like state. Researchers can use iPSCs to create disease models, helping understand disease mechanisms and develop new therapies.

Terrestrial life is characterized by a set of defining characteristics such as a stable internal environment, organized structure, metabolism, growth and development, reproduction, and adaptability. These features allow organisms to survive and thrive on Earth.

The movement of a cell in response to a chemical gradient of a molecule in the fluid phase.

The movement of a cell in response to a gradient of a surface-bound molecule.

Enzymes that add a phosphate group to a molecule, often a protein, to alter its activity.

The hydrolysis of ATP by dynein, not GTP, provides the energy for microtubule bending in flagella.

The drug Taxol stabilizes microtubules, while colchicine inhibits microtubule assembly.

The inner membrane of mitochondria folds to increase its surface area, allowing for more efficient ATP production.

Mitochondria have their own DNA, separate from the cell's nuclear DNA, which is essential for their function.

A dynamic network of protein fibers that provides structural support and facilitates movement within the cell.

Hollow tubes made of tubulin dimers, responsible for organizing organelles, intracellular transport, and providing structural support.

Rope-like fibers primarily found along the inner surface of the nuclear envelope, crucial for cell strength and integrity.