4th Period Membrane Protein Quiz 1

The outer boundary of the cell is known as the plasma membrane. It is a thin, semi-permeable barrier that surrounds the cell and separates its internal environment from the external environment. The plasma membrane controls the movement of substances in and out of the cell, allowing nutrients to enter and waste products to exit. It also plays a role in cell signaling and communication. The nuclear membrane, lysosome, and nucleolus are all internal structures within the cell and are not part of the outer boundary.

The fluid-mosaic model of the plasma membrane structure describes a phospholipid bilayer with embedded proteins. This model suggests that the plasma membrane is composed of a double layer of phospholipids, with the hydrophilic heads facing outward and the hydrophobic tails facing inward. The proteins are embedded within this phospholipid bilayer, either partially or completely spanning the membrane. This model accounts for the fluidity and flexibility of the plasma membrane, as well as the mosaic-like arrangement of different proteins within it.

The correct answer is A, B, AB, O. This is because in our blood typing system, there are four main blood types: A, B, AB, and O. Each blood type is determined by the presence or absence of specific antigens on the surface of red blood cells. Type A blood has A antigens, type B blood has B antigens, type AB blood has both A and B antigens, and type O blood has neither A nor B antigens. Therefore, individuals can be typed as A, B, AB, or O based on the antigens present in their blood.

Hormones and other molecules are able to attach to specific proteins because the proteins have a specific shape that matches the shape of the hormone. This is similar to how a lock and key work - the hormone is the key and the protein is the lock. The hormone can only attach to proteins that have the correct shape to fit it, just like a key can only open a lock that has the right shape. This specificity allows hormones to target specific cells and carry out their functions effectively.

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Rods and cones are photoreceptor cells that are responsible for vision. They are found in the retina of the eye. Rods are more sensitive to dim light and are responsible for peripheral and night vision, while cones are responsible for color vision and visual acuity in bright light. Therefore, the correct answer is the eye.

The polar heads of phospholipid molecules in the plasma membrane are hydrophilic, not hydrophobic. Hydrophilic means they have an affinity for water, while hydrophobic means they repel water. The polar heads of phospholipids are attracted to the watery environment both inside and outside the cell, while the nonpolar tails are repelled by water and face inward, creating a hydrophobic interior of the plasma membrane.

Marker proteins in the plasma membrane distinguish cells from each other. These proteins act as identification tags, allowing cells to recognize and interact with one another. They play a crucial role in cell recognition and communication, as well as in immune responses and tissue development. Marker proteins can be specific to certain cell types or tissues, helping to maintain the integrity and functionality of different cell populations within an organism.

Receptor proteins are responsible for binding hormones and other molecules to the outside of the cell. These proteins act as signal receptors and initiate specific cellular responses when they bind to their respective ligands. They play a crucial role in cell communication and are involved in processes such as hormone signaling, neurotransmission, and immune responses.

Cones are receptor proteins that pick up color images. Cones are specialized cells found in the retina of the eye and are responsible for color vision. They contain pigments that absorb different wavelengths of light, allowing us to perceive different colors. When light enters the eye, it stimulates these cone cells, which then send signals to the brain to interpret the color information. Therefore, cones are receptor proteins that play a crucial role in our ability to see and distinguish colors.

Blood type O does not have any proteins on its phospholipid bilayer. This is because blood types are determined by the presence or absence of certain proteins called antigens on the surface of red blood cells. Type O blood lacks both A and B antigens, hence there are no proteins present on the membrane surface.

People who have B blood produce anti-A antibodies because B blood type contains the B antigen on the surface of red blood cells. When a person with B blood type is exposed to the A antigen, their immune system produces anti-A antibodies to attack and eliminate the foreign A antigen. This is a natural defense mechanism in the blood system to prevent incompatible blood transfusions or reactions between different blood types.