Cell Biology Quiz on Membrane Dynamics

Molecules move across the membrane without energy input, from high to low concentration.

A type of endocytosis where specific molecules bind to receptors on the cell membrane, triggering their internalization.

Increases in unsaturated fatty acids and short-chain fatty acids, as well as a decrease in cholesterol, contribute to membrane fluidity.

The process of collagen molecules assembling into fibers, occurring outside the cell in the extracellular space.

A transmembrane protein that plays a crucial role in cell-matrix adhesion.

The first cell membrane was simple and lacked specialized regions for signaling.

The extracellular matrix (ECM) provides structural support and influences cell behavior.

Fibronectin and elastin are two major proteins found in the extracellular matrix (ECM).

The glycocalyx is a layer of carbohydrates attached to the outer surface of the plasma membrane. It plays a role in cell recognition and communication.

The plasma membrane's selective permeability allows certain molecules, such as lipids, to move laterally within the membrane more easily than others.

Active transport mechanisms move molecules against their concentration gradient, requiring energy. This process is usually very specific, meaning a particular transporter protein is responsible for moving a specific type of molecule.

Myosin is a protein primarily found in muscle cells, responsible for muscle contraction, not in the extracellular matrix (ECM).

Macrophages and neutrophils, types of white blood cells, are specialized cells in the immune system that carry out phagocytosis - the engulfment of foreign particles and cellular debris.

Viruses are not cells; they are acellular particles that require a host cell to replicate. They possess genetic material (either DNA or RNA) but lack the complex machinery needed for independent life.

Collagen is a fibrous protein responsible for providing structure and strength to tissues, including bones. A deficiency in collagen can cause fragile bones, leading to increased risk of fractures.

Small, nonpolar molecules like oxygen (O2) and carbon dioxide (CO2) can easily pass through the cell membrane without any special transport mechanism.

Different biological membranes contain varying amounts of proteins, influencing their specific functions.

During receptor-mediated endocytosis, the receptor and its bound ligand (molecule) are internalized together within a vesicle. This vesicle then travels to an endosome, where the lower pH environment leads to the separation of the receptor and ligand.

The sodium-potassium pump, a type of active transport, moves sodium ions from a low concentration area to a higher concentration area, requiring energy expenditure.

Clathrin is a protein that forms a cage-like structure around vesicles during endocytosis. This helps to create a more controlled and efficient internalization process.

The extracellular matrix (ECM) provides structural support and helps to create a framework for cells. It is found in all animal tissues, but its composition and density can vary.

Collagen fibrils, composed of assembled collagen molecules, are strong and resist stretching. They contribute to the overall mechanical strength of tissues.

The ECM interacts with cells through integrins, which are transmembrane proteins that connect the cytoskeleton to the ECM. This interaction helps to regulate cell behavior and movement.

The endoplasmic reticulum (ER) is an extensive network of interconnected membrane-bound sacs and tubules that plays a vital role in protein synthesis, processing, and folding.

A mutation that changes a codon for a specific amino acid into a stop codon, leading to a truncated and often non-functional protein.

A type of mutation that causes the insertion or deletion of a small number of nucleotides in the DNA sequence, leading to a frameshift in the reading frame.

A mutation that affects multiple phenotypic traits.

A condition where different mutations in the same gene can cause the same or similar phenotypes.

Genetic alterations that can lead to uncontrolled cell growth and tumor development.

The loss of chromosomal DNA.

A type of genetic mutation that affects the production of a specific protein that plays a role in muscle function.

The process of gene expression being modified without changes in the DNA sequence.

Lipids in cell membranes are amphipathic, meaning they have both a hydrophilic head (attracted to water) and one or two hydrophobic tails (repelled by water). This structure allows them to form the bilayer, where the heads face the watery environment and the tails hide inside.

The extracellular matrix (ECM) is a complex network of molecules outside the cell's membrane. It's not just a support structure, but also influences cell behavior. This is due to the presence of various proteins like fibronectin and elastin, which play crucial roles in cell adhesion and tissue elasticity.

The distribution of lipids and proteins within a cell membrane is asymmetrical. For instance, phosphatidylserine is mainly found on the inner leaflet of the cell membrane, while sugar residues are primarily on the outer surface.

The transporter proteins responsible for glucose transport across the cell membrane are integral membrane proteins. This means they are embedded within the membrane, allowing them to move molecules across. They also undergo conformational changes to facilitate this transport. Importantly, they are specific for glucose, meaning they don't transport just any molecule.

Exocytosis is the process where cells release substances outside their membrane by fusing vesicles (small sacs) with the cell membrane. This is a regulated process, meaning it requires energy (ATP) and specific signals. One important signal is the presence of calcium ions, which trigger the fusion of vesicles.

The plasma membrane is semipermeable, allowing some molecules to pass through easier than others. This is particularly true for lipids. Their hydrophobic tails allow them to move laterally within the membrane, making it more fluid.

A process where a cell uses pseudopods to engulf solid particles, enclosing them in a vesicle that then fuses with lysosomes for digestion.

Caveolae-mediated endocytosis is characterized by small, flask-shaped invaginations of the plasma membrane that are rich in caveolin, a specific protein.

It is FALSE to say that phagocytosis occurs in all types of cells. Only specialized cells, like macrophages and neutrophils, are capable of this.

Endocytosis is the process by which cells take in materials from the extracellular space. This process can involve both solid and liquid substances.

Down syndrome is caused by having an extra copy of chromosome 21. Since Guillermo's brother and sister both have Down syndrome, it is likely that Guillermo also has the extra chromosome 21, making him a carrier for Down syndrome.

Since her sister died from Tay-Sachs disease, an autosomal recessive disorder, there is a 2/3 chance that the woman is a carrier. This is because she has a 1/2 chance of inheriting the faulty gene from her mother and a 1/2 chance of inheriting it from her father. Since her sister was affected, both parents must have been carriers. This means she has a 2/3 chance of being a carrier.

Autosomal recessive disorders require two copies of the faulty gene to cause the disease. Since Antia's father had the condition, he must have been homozygous for the faulty gene. This means that Antia has a 50% chance of inheriting a copy of the faulty gene from her father and a 50% chance of being a carrier. The probability depends on whether her mother was also a carrier.