Cell Membrane And Transport Trivia

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Lindsey Block, PhD (Cellular & Molecular Biology) |
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Lindsey, Ph.D. in cellular and molecular biology from the University of Wisconsin-Madison, specializes in Zika's impact on conception and preterm birth biomarkers. She completed courese on Advanced Cell Biology at the University of Illinois at Urbana-Champaign and Advanced Virology at University College Cork. Lindsey's accolades include three first-author papers, three fellowships, and active participation in five conference presentations. Currently associated with the University of Pennsylvania through a T32 NIH Postdoctoral Fellowship, she continues to contribute significantly to her field, combining academic rigor with practical research to advance understanding in reproductive health and prenatal care. Currently, she is a full time lecturer at Northwestern University - The Feinberg School of Medicine.
, PhD (Cellular & Molecular Biology)
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What is the cell membrane composed of?

Answer: Phospholipid bilayer with many other organic compounds
The cell membrane is composed of a phospholipid bilayer, which consists of two layers of phospholipids. These phospholipids have a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail, which arrange themselves in a way that the heads face outward towards the watery environment both inside and outside the cell, while the tails face inward, creating a barrier. In addition to phospholipids, the cell membrane also contains many other organic compounds such as proteins, cholesterol, and carbohydrates, which play various roles in maintaining the structure and function of the membrane.

"That only certain things may enter or exit the cell, whereas others are not permitted to cross the cell membrane" is the best definition for what word?

Answer: Selective permeability
The term "Selective permeability" refers to the property of the cell membrane that allows certain substances to enter or exit the cell while restricting others. This means that the cell membrane acts as a selective barrier, controlling the movement of molecules and ions. It only permits the passage of specific substances through various mechanisms such as diffusion, facilitated diffusion, and active transport. Therefore, "selectively permeable" is the best definition for the given word.

What is the polar head of a phospholipid made of?

Answer: Glycerol
The polar head of a phospholipid is made of glycerol. Phospholipids are composed of a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail. The head group is typically made up of glycerol, which contains hydroxyl (-OH) groups that interact with water molecules. This polar head allows phospholipids to form the outer layer of cell membranes, with the hydrophobic tails oriented towards the interior of the membrane and the polar heads facing the aqueous environment.

This specific structure can be part of the cell membrane, depending on the function of the cell. Whereas some cells do not need these. What biomolecule is being referred to?

Answer: Proteins
The specific structure of the cell membrane depends on the function of the cell. Proteins play a crucial role in cell membrane structure and function. They are embedded within the phospholipid bilayer and serve various functions such as transporting molecules across the membrane, acting as receptors for signaling molecules, and providing structural support. Different cells have different protein compositions in their cell membranes, depending on their specific functions and needs. Therefore, certain cells may not require the same types or amounts of proteins as other cells.

In the phospholipid bilayer, which ways do the nonpolar tails face?

Answer: Towards the interior
The nonpolar tails of phospholipids in the bilayer face towards the interior. This is because the nonpolar tails are hydrophobic, meaning they repel water. By facing towards the interior, they are shielded from the surrounding aqueous environment, which is polar and water-filled. This arrangement helps to stabilize the bilayer structure and maintain the integrity of the cell membrane.

What is the cytoplasm made of?

Answer: The liquid cytosol
The cytoplasm is made up of the liquid cytosol. The cytosol is a gel-like substance that fills the cell and surrounds the organelles. It contains various molecules such as proteins, ions, and nutrients that are essential for cell functions. The cytosol provides a medium for cellular processes to occur and supports the organelles within the cell. It also acts as a transportation system, allowing molecules to move within the cell. Therefore, the liquid cytosol is a major component of the cytoplasm.

Where are peripheral proteins attached?

Answer: The surface of the cell membrane
Peripheral proteins are attached to the surface of the cell membrane. These proteins are not embedded within the lipid bilayer of the membrane, but rather loosely bound to it through non-covalent interactions. They can be easily detached from the membrane without disrupting its integrity. Peripheral proteins play various roles in cell signaling, transport of molecules across the membrane, and structural support. Their attachment to the cell membrane allows them to interact with other molecules on the cell surface and participate in important cellular processes.

Integral/ transmembrane proteins include what structure?

Answer: Protein channels and carrier proteins
Integral/transmembrane proteins are proteins that are embedded within the cell membrane. They span across the lipid bilayer, with parts of the protein exposed on both sides of the membrane. These proteins play crucial roles in transporting molecules and ions across the membrane. Protein channels are specific integral proteins that form pores or channels, allowing the selective passage of molecules or ions. Carrier proteins, on the other hand, bind to specific molecules and undergo conformational changes to transport them across the membrane. Therefore, the correct answer is protein channels and carrier proteins.

What organic compound is often attached to integral proteins?

Answer: Carbohydrates
Carbohydrates are often attached to integral proteins in a process known as glycosylation. This modification plays a crucial role in various cellular processes, including cell adhesion, signaling, and immune response. By attaching carbohydrates to integral proteins, cells can enhance their functionality and recognition by other cells. Therefore, carbohydrates are the organic compound that is commonly attached to integral proteins.

What is the main purpose of a cell?

Answer: To maintain homeostasis
The main purpose of a cell is to maintain homeostasis. Homeostasis refers to the ability of an organism or cell to maintain a stable internal environment despite external changes. Cells regulate various factors such as temperature, pH, and nutrient levels to ensure optimal conditions for their functioning. This balance is crucial for the survival and proper functioning of the cell and the organism as a whole.
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