A cell biologist compared the properties of rough endoplasmic reticulum (ER) and smooth ER. She found that one type of ER is used for protein storage, and the other is used for lipid storage. What accounts for this difference?
a
Smooth ER works with the nucleus to synthesize protein.
b
Rough ER has ribosomes on its surface.
c
Rough ER forms proteins and transports them to the mitochondria.
d
Smooth ER creates amino acids for ribosomes to form into proteins.
b
Rough ER has ribosomes on its surface.
Review the responses below; then SELECT ALL the reasons why we use scientific models.
a
Models allow exploring very small or very large systems.
b
Models are used when systems are too expensive, expansive or impossible to use.
c
Models help you understand complex systems.
d
Models are always expensive.
a
Models allow exploring very small or very large systems.
b
Models are used when systems are too expensive, expansive or impossible to use.
c
Models help you understand complex systems.
If a living plant were moved from a freshwater aquarium to a saltwater aquarium, which of the following would occur?
a
The plant's cells would take in extra water.
b
The plant's cells would block sodium movement.
c
The plant's cells would lose sodium.
d
The plant's cells would lose water.
d
The plant's cells would lose water.
You're looking at a sample from your patient under the microscope. Does your patient have a virus?
a
Yes, my patient has a virus, as this a typical viral structure.
b
No, my patient does not have a virus, this is a fungal cell.
c
No, my patient does not have a virus, this is a bacterial cell.
d
Yes, my patient has a virus, since this is not a cell.
It is not possible to determine whether the patient has a virus based solely on looking at a sample under the microscope.
The table lists the diameters of common viruses and bacteria. A single micrometer (µm) is equivalent to 1000 nanometers (nm).
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Using the table as evidence, which argument can be made about the size of viruses compared to the size of bacteria?
a
Viruses are smaller than most bacteria.
b
Viruses are both smaller and larger than bacteria.
c
Bacteria and viruses are about the same size.
d
Bacteria are smaller than most viruses.
a
Viruses are smaller than most bacteria.
The correct answer is b: Rough ER has ribosomes on its surface.
To understand why rough ER is used for protein storage while smooth ER is used for lipid storage, it's important to understand the structure and function of these organelles.
The rough endoplasmic reticulum (ER) is so named because it has ribosomes attached to its surface, giving it a rough appearance under a microscope. These ribosomes are responsible for protein synthesis. When a cell needs to produce proteins, the ribosomes on the rough ER synthesize proteins directly into its lumen (the internal compartment of the rough ER). The rough ER then processes and modifies these proteins before sending them to their correct destinations within the cell. This makes the rough ER an integral part of the cell's protein synthesis and sorting machinery.
On the other hand, smooth ER lacks ribosomes on its surface. It appears smooth under a microscope. The smooth ER is involved in a variety of functions, including lipid metabolism and detoxification of drugs and toxins. It plays a crucial role in the synthesis of lipids, such as phospholipids, cholesterol, and steroid hormones. The smooth ER also aids in the storage and release of calcium ions, which are important for various cellular processes.
In summary, the key difference between rough ER and smooth ER is the presence of ribosomes on the surface of rough ER, which allows it to be involved in protein synthesis and storage. Smooth ER, on the other hand, is involved in lipid synthesis and storage, as well as other cellular functions such as detoxification and calcium regulation.