Electrophoresis Blood Quiz Questions

Proteins are composed of distinct modules called domains. These domains fold up independently and often represent parts of a protein that function semi-independently. They play a crucial role in protein structure and function, allowing proteins to have different regions with specific functions.

As cells increase in size, their surface area/volume ratio decreases. This is a problem for cells because it hampers their ability to obtain a sufficient amount of nutrients from the environment. With a lower ratio, the cell has less surface area available for nutrient absorption. Additionally, the decrease in surface area/volume ratio compromises the cell's ability to get rid of wastes at a high enough rate. This is because the smaller surface area makes it more difficult for wastes to be expelled from the cell efficiently. Therefore, both options a and b are correct explanations for why the decrease in surface area/volume ratio is problematic for cells.

The correct answer is that the pigment is amphipathic, having polar and nonpolar regions. This is because the pigment is able to congregate between an aqueous environment (water) and a hydrophobic environment (oil). The presence of both polar and nonpolar regions allows the pigment to interact with both the water and oil molecules, resulting in the formation of a blue ring around the droplets of oil.

The correct answer is "information storage" because membranes primarily function to define cell boundaries, regulate transport, compartmentalize cellular components, and facilitate cell-cell communication. Membranes are primarily composed of lipids and proteins that form a selectively permeable barrier, allowing the cell to control the movement of molecules in and out. They also help in organizing cellular structures and organelles, enabling specialized functions within different compartments. Additionally, membranes contain various receptors and signaling molecules that facilitate communication between cells. However, information storage is not a primary function of membranes, as genetic information is stored in the form of DNA within the cell nucleus.

All of the factors mentioned in the options directly or indirectly determine the transition temperature. The ability of lipid molecules to be packed together affects the fluidity and stability of the lipid bilayer, which in turn affects the transition temperature. The saturation or unsaturation of the fatty acid chains determines the presence of double bonds, which affects the fluidity and flexibility of the lipid bilayer. The length of the fatty acid chains also influences the packing and organization of lipids, thereby impacting the transition temperature. Therefore, all of these factors collectively determine the transition temperature.

Tertiary structure in proteins is held together by intermolecular R group interactions. This level of structure involves the folding of the protein chain into a three-dimensional shape, which is stabilized by various interactions between the side chains of amino acids. These interactions can include hydrogen bonding, hydrophobic interactions, ionic interactions, and disulfide bonds. The tertiary structure is crucial for the overall function and stability of the protein.

Cholesterol is a molecule that is found in the cell membrane of animals. It is able to intercalate, or insert itself, between the fatty acid chains within the bilayer of the cell membrane. This intercalation helps to stabilize the cell membrane and maintain its fluidity and integrity. By inserting itself between the fatty acid chains, cholesterol can prevent them from packing too closely together, which would make the membrane too rigid. This allows the cell membrane to remain flexible and functional.

Lowering the temperature of the culture causes the membrane to become less fluid. This is because at lower temperatures, the phospholipids in the membrane move less and become more tightly packed together, resulting in a decrease in fluidity.

The composition of proteins in the lipid bilayer of the cell membrane is described as asymmetrical. This means that the proteins are not evenly distributed or identical on the outer and inner faces of the bilayer. Instead, they are arranged in a non-symmetrical manner, with different types and amounts of proteins present on each side. This asymmetry is important for various cellular processes, such as cell signaling and membrane transport, as it allows for specific protein functions to occur on each side of the bilayer.

The composition of lipids in the outer and inner faces of the lipid bilayer of the cell membrane is asymmetrical. This means that the types and quantities of lipids differ between the two faces of the bilayer. The outer face may contain more glycolipids and sphingomyelin, while the inner face may have more phosphatidylserine and phosphatidylethanolamine. This asymmetry is important for various cellular processes, including membrane trafficking, cell signaling, and membrane fusion.

Membrane proteins are embedded in the cell membrane and play a crucial role in receiving signals from the external environment. These proteins act as receptors and transmit information from outside the cell to the inside, initiating various cellular responses. This allows cells to respond and adapt to changes in their surroundings, including extracellular signals such as hormones, neurotransmitters, and growth factors. Therefore, membrane proteins primarily function in receiving extracellular signals.

The lack of activity of the synthesized enzyme can be best explained by the fact that it was not folded correctly. Folding is a crucial process for enzymes to achieve their functional conformation and catalytic activity. If the enzyme does not fold correctly, it may result in misaligned active sites or improper interactions with substrates, leading to a decrease in activity. Despite having identical amino acid composition, the synthetic enzyme might have encountered difficulties in achieving the proper folding that is essential for its functionality.

Hydrophobic interactions are nonpolar interactions between hydrophobic molecules or regions that are driven by the tendency of water to exclude nonpolar substances. The core of a water-soluble protein is where hydrophobic amino acid residues are typically found, as they are repelled by water molecules and tend to cluster together to minimize their exposure to water. This allows the protein to fold into a stable, compact structure. Therefore, hydrophobic interactions are most likely to occur in the core of a water-soluble protein.

A phosphoglyceride, specifically phosphatidic acid, is composed of glycerol, one phosphate group, and two fatty acids. This composition allows for the molecule to have a hydrophilic head (the phosphate group) and hydrophobic tails (the fatty acids), making it ideal for forming the lipid bilayer of cell membranes.

Disulfide bonds are often found to stabilize the tertiary level of protein structure. Tertiary structure refers to the three-dimensional folding of a protein, which is crucial for its proper functioning. Disulfide bonds form between two cysteine residues, creating a covalent bond that helps to maintain the protein's overall structure and stability. These bonds can occur within a single polypeptide chain or between different chains, contributing to the folding and stability of the protein in its native conformation. Therefore, disulfide bonds play a significant role in stabilizing the tertiary structure of proteins.

SDS-PAGE is a technique commonly used in molecular biology and biochemistry to separate proteins based on their size. In this technique, proteins are denatured and coated with sodium dodecyl sulfate (SDS) which gives them a uniform negative charge. The proteins are then loaded onto a polyacrylamide gel and subjected to an electric field. Since the gel has pores of different sizes, smaller proteins migrate faster through the gel while larger proteins migrate slower. This separation based on size allows for the differentiation of proteins, making SDS-PAGE the correct answer in this case.

The α-helix is a common secondary structure in proteins, characterized by a right-handed coil. It is stabilized by hydrogen bonds formed between the carbonyl oxygen of one amino acid and the amide hydrogen of an amino acid four residues ahead. These hydrogen bonds run parallel to the molecular axis of the helix, contributing to its stability and structure.

Region 2 is hydrophobic because it contains the amino acids Alanine, Glycine, Tryptophan, and Valine. These amino acids have nonpolar side chains, which are hydrophobic in nature and tend to avoid water.

During SDS polyacrylamide gel electrophoresis, proteins are separated based on their size. Smaller proteins have less mass and are able to move through the gel matrix more easily, resulting in them traveling the farthest. Therefore, the smallest proteins move the farthest during SDS polyacrylamide gel electrophoresis.

A selectively permeable membrane is important to living things because it provides a good barrier between the inside and outside of the cell. This barrier allows the cell to control the movement of substances in and out of the cell, ensuring that only necessary molecules are allowed to enter or exit. This regulation is crucial for maintaining the cell's internal environment and carrying out essential cellular processes.

Sphingolipids are not the predominant phospholipid in membranes.

Carbon atoms are most likely to form covalent bonds with one another, not ionic bonds. Ionic bonds involve the transfer of electrons between atoms with opposite charges, while covalent bonds involve the sharing of electrons between atoms. Since carbon atoms have four valence electrons, they are able to share electrons with other carbon atoms, forming stable covalent bonds.

GPI-anchor proteins are a type of protein that are associated with either the extracellular or cytoplasmic surface using a lipid tail. These proteins have a glycosylphosphatidylinositol (GPI) anchor attached to their C-terminus, which allows them to be embedded in the lipid bilayer of the cell membrane. This anchor helps to anchor the protein to the membrane and allows it to function in various cellular processes, such as cell signaling and cell adhesion. Therefore, GPI-anchor proteins are the correct answer to the question.

Amphoteric molecules have the ability to both accept and donate protons. This means that they can act as both an acid (donate protons) and a base (accept protons) depending on the reaction conditions. This characteristic is important in various chemical reactions and allows these molecules to participate in a wide range of chemical processes.

In a glacier environment, where temperatures are extremely low, the plasma membrane of an organism needs to be flexible and fluid to function properly. Unsaturated fatty acids have double bonds in their carbon chains, which introduce kinks and prevent the fatty acids from packing tightly together. This results in a more fluid and flexible plasma membrane, making it easier for the organism to survive in the cold conditions. Therefore, it is expected to find a predominance of largely unsaturated fatty acids in the plasma membrane of the organism isolated from the glacier.

The property of fluidity in membranes allows interactions to take place within the membrane, including the assembly of membrane protein clusters at particular sites and the formation of specialized structures. This means that the lipids and proteins in the membrane are able to move laterally and interact with each other, facilitating various cellular processes. This fluidity also allows for the dynamic rearrangement of membrane components, which is crucial for membrane function and adaptability.

Compounds that react with free hydrogen or hydroxyl ions, thereby resisting changes in pH, are called buffers. Buffers are important in maintaining the pH stability of a solution or environment. They can absorb excess hydrogen ions (acidic conditions) or release hydrogen ions (basic conditions) to maintain a relatively constant pH. Buffers play a crucial role in protecting cells and organisms from fluctuations in pH, which could be harmful to their biochemical processes. Therefore, the correct answer is "are called buffers."

Ionic bonds are formed between ions, which are atoms that have gained or lost electrons, resulting in a positive or negative charge. These bonds are strong and require the presence of opposite charges. In a living organism, ionic bonds are most likely to be found deep in a protein's core where water is excluded. Proteins are complex molecules that play critical roles in the structure and function of cells. The core of a protein is typically hydrophobic, meaning it repels water. This hydrophobic environment allows for the formation of stable ionic bonds between charged amino acid residues, contributing to the stability and structure of the protein.

Lipids would be the best compound to couple with a new drug in order to achieve better uptake by cells. Lipids are a major component of cell membranes and have hydrophobic properties, which allow them to easily pass through the hydrophobic interior of the cell membrane. By coupling the drug with lipids, it can be effectively transported across the cell membrane and into the cells, enhancing its uptake and potential efficacy.

Phenylalanine is most likely to be found in the core of a protein because it is a nonpolar amino acid with a bulky aromatic side chain. Nonpolar amino acids tend to be found in the hydrophobic core of proteins, away from water, while polar amino acids like asparagine, serine, threonine, and glutamic acid are more likely to be found on the surface of the protein where they can interact with water molecules.

The tertiary structure of proteins is held together by intramolecular R group interactions. This refers to the three-dimensional arrangement of the protein molecule, which is stabilized by bonds and interactions between the R groups of amino acids. These interactions can include hydrogen bonding, hydrophobic interactions, disulfide bonds, and electrostatic interactions. The tertiary structure is crucial for the overall folding and function of the protein.

Treating cells with high-salt solutions can result in the extraction of peripheral proteins. Peripheral proteins are proteins that are loosely attached to the cell membrane and can be easily removed or extracted without disrupting the lipid bilayer. High-salt solutions disrupt the ionic interactions between the peripheral proteins and the cell membrane, allowing them to be extracted. This is why peripheral proteins can be obtained by treating cells with high-salt solutions.

Chaperones were first identified as heat shock proteins and they do not require hydrophobic interactions to occur. Heat shock proteins are a class of chaperones that are produced in response to cellular stress, such as high temperatures. They assist in protein folding and prevent the aggregation of misfolded proteins. While hydrophobic interactions can play a role in protein folding, chaperones do not rely on these interactions for their function. Instead, they use other mechanisms, such as binding to exposed hydrophobic regions, to assist in protein folding.

Peripheral proteins are proteins that are located on the outer surface of the cell membrane, but are not embedded within it. They play various roles in maintaining the structure and function of the cell membrane. Receptors, mechanical support for the membrane, and enzymes are all known functions of peripheral proteins. However, molecules that serve in signal transmission are not typically associated with peripheral proteins. These molecules are more commonly associated with integral proteins, which are embedded within the cell membrane.

Phospholipase is the correct answer because it is an enzyme that is known to release certain membrane proteins from a membrane. This property of phospholipase makes it instrumental in the discovery of GPI-anchored proteins, as it can cleave the glycosylphosphatidylinositol (GPI) anchor that attaches these proteins to the membrane. Therefore, phospholipase plays a crucial role in the identification and study of GPI-anchored proteins.

The word "Hydrophilic" characterizes the amino acids that are found in an α-helical segment that spans a membrane. Hydrophilic amino acids are attracted to water and are typically found on the outer surface of a protein, interacting with the aqueous environment. On the other hand, "Hydrophobic" amino acids are repelled by water and are commonly found in the interior of a protein, away from the aqueous environment. Therefore, both hydrophilic and hydrophobic amino acids play a crucial role in stabilizing the α-helical structure within the membrane.