Question 1

Which of the following is not a characteristic that chloroplasts and mitochondria share?

Accepted Answer

Chloroplasts and mitochondria are not part of the endomembrane system, which includes the endoplasmic reticulum, Golgi apparatus, and vesicles. They are considered organelles that are separate entities within the cytoplasm. A, B, and D are characteristics that both chloroplasts and mitochondria share.

Question 2

Why are lysosomes considered part of the endomembrane system?

Accepted Answer

Lysosomes are formed from products synthesized by the endoplasmic reticulum and then processed by the Golgi, making them part of the endomembrane system.

Question 3

Mitochondrial DNA codes for about 13 proteins (depending on the species of organism).These 13 proteins account for a small proportion of the proteins present in mitochondria.The remaining proteins are coded for by nuclear DNA.What is the most likely explanation for how these proteins find their way to the mitochondria?

Accepted Answer

Signal sequences are specific amino acid sequences that act as molecular tags directing proteins to their correct subcellular location. In the case of mitochondrial proteins, a mitochondria-targeting signal sequence directs the protein to be imported into the organelle via specialized transport proteins. Nuclear-encoded mitochondrial proteins have such signal sequences that are recognized by specialized receptor proteins on the mitochondrial outer membrane.

Question 4

You arrive late to lecture and your professor is describing a feature of the nucleus that provides it with structural support.You are not sure which feature is being discussed,but because you read the book before you came to class,you are fairly certain that it is

Accepted Answer

The nuclear lamina is a mesh-like network of intermediate filaments that provides structural support to the nucleus. The nucleoplasm is the liquid inside the nucleus, the nuclear pore is a protein-lined channel in the nuclear envelope that allows for the movement of molecules in and out of the nucleus, and the nucleolus is a structure within the nucleus that produces ribosomes. Only the nuclear lamina provides structural support to the nucleus.

Question 5

What is the site of synthesis of proteins for export (secretion from the cell)?

Accepted Answer

Ribosomes that attach to the endoplasmic reticulum are responsible for synthesizing proteins that are meant for export or secretion from the cell. These proteins are synthesized onto the lumen of the endoplasmic reticulum and then transported through the secretory pathway for eventual release outside the cell.

Question 6

What is the function of the nuclear pore complex?

Accepted Answer

The nuclear pore complex regulates movement of materials across the nuclear envelope, allowing certain molecules to enter or exit the nucleus while preventing others from doing so. This helps to control gene expression and maintain the integrity of the nuclear environment.

Question 7

Which of the following components would you expect to find in any type of living organism?

Accepted Answer

All living organisms have genetic material organized into chromosomes, although the structure and location of chromosomes can vary between prokaryotes and eukaryotes.

Question 8

The small intestine is the site of digestion and absorption of nutrients.A single layer of epithelial cells lines the small intestine.In the duodenum (the first section of the small intestine),these epithelial cells secrete large quantities of digestive enzymes.Which of the following features would be typical of these epithelial cells?

Accepted Answer

Epithelial cells in the duodenum secrete large quantities of digestive enzymes, which are proteins. Therefore, they would contain large quantities of rough endoplasmic reticulum, which is responsible for protein synthesis and modification. Smooth endoplasmic reticulum is involved in lipid metabolism, so it would not be as abundant in these cells. Lysosomes contain hydrolytic enzymes responsible for breaking down cellular waste and foreign substances, but they are not directly involved in protein synthesis or secretion. The size of the nucleus would not necessarily be related to the type or amount of secretions produced by a cell.

Question 9

Which of the following organelles contains receptors for the products of the rough endoplasmic reticulum?

Accepted Answer

The smooth endoplasmic reticulum (SER) does not contain receptors for the products of the rough endoplasmic reticulum (RER). The lysosomes contain enzymes that help break down and digest cellular waste and debris, so they are not involved in the processing of products from the RER. The mitochondria are responsible for producing energy in the form of ATP, and the peroxisomes are involved in breaking down fatty acids and neutralizing harmful substances, so neither of these organelles are involved in the processing of RER products. Therefore, the best choice is the smooth endoplasmic reticulum, which contains receptors for the products of the RER.

Question 10

How is the nuclear membrane related to the endoplasmic reticulum?

Accepted Answer

The nuclear membrane is composed of two bilayers, the inner and outer nuclear membranes, which are separated by a space that is continuous with the space inside the endoplasmic reticulum. This provides a direct physical connection between the two structures. Ribosomes that exit the nucleus through the nuclear pore complex also attach to ribosome receptor locations on the endoplasmic reticulum, but this is not the primary reason for the connection between the nuclear membrane and the endoplasmic reticulum. The nucleolus is a structure within the nucleus and does not directly communicate with the endoplasmic reticulum. The nuclear lamina provides structural support to the nucleus, but it does not directly anchor the endoplasmic reticulum.

Question 11

You have a distant cousin,age 4,who is always tired and fatigued and is not able to play games and sports like other healthy children.He is most likely to have an enzyme deficiency or defect associated with which intracellular organelle?

Accepted Answer

Mitochondria are responsible for producing energy in the form of ATP through oxidative phosphorylation. A deficiency or defect in the enzymes involved in this process can lead to fatigue and inability to perform physical activities. Lysosomes, Golgi stacks, and peroxisomes are not directly involved in energy production and are therefore less likely to be associated with this type of symptom.

Question 12

What can you infer about high-molecular-weight proteins that cannot be transported into the nucleus?

Accepted Answer

High-molecular-weight proteins that cannot be transported into the nucleus lack nuclear localization signals (NLS). NLS are necessary for proteins to be recognized and transported into the nucleus by the nuclear pore complex. Therefore, the absence of NLS would prevent their transport into the nucleus.

Question 13

What is the most likely role of a cell that contains an extensive smooth ER?

Accepted Answer

Smooth ER is involved in lipid synthesis and storage. Thus, a cell containing an extensive smooth ER is most likely involved in the synthesis of large quantities of lipids.

Question 14

You are studying an organism and note that its proteins fail to be glycosylated.A deficiency in which of the following organelles is likely the cause?

Accepted Answer

The Golgi apparatus is responsible for modifying, sorting, and packaging proteins, including glycosylation, which is the addition of sugar molecules to proteins. A deficiency in the Golgi apparatus would lead to proteins not being glycosylated.

Question 15

Which of the following represents a major difference between prokaryotic cells and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a more complex structure, with a nucleus and membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Prokaryotic cells lack a nucleus and membrane-bound organelles and have a simpler structure. While some prokaryotes may have a cell wall, not all do, and some eukaryotes such as plants also have cell walls. Prokaryotes can carry out aerobic respiration, but they do not have the same complex inner-membrane system as eukaryotes. The grouping of prokaryotes and eukaryotes does not necessarily relate to their differences in structure and function.

Question 16

Which of the following organelles is involved in the oxidation of fatty acids or ethanol?

Accepted Answer

Peroxisomes are involved in the oxidation of fatty acids or ethanol through a series of enzymatic reactions. These reactions produce hydrogen peroxide, which is then broken down by the enzyme catalase present in the peroxisomes. Mitochondria are involved in cellular respiration and energy production, while the Golgi apparatus is involved in processing and sorting proteins. The rough endoplasmic reticulum is involved in the synthesis and modification of proteins.

Question 17

What is a purpose of the cell wall for both prokaryotes and plant cells?

Accepted Answer

The cell wall serves to protect the cell from a hypotonic environment, which would cause water to enter the cell and potentially burst it. This is important for both prokaryotes and plant cells.

Question 18

One function of peroxisomes is alcohol detoxification.In which of the following locations would you expect to find large quantities of peroxisomes?

Accepted Answer

Peroxisomes are responsible for the detoxification of alcohol in the liver. Therefore, you would expect to find large quantities of peroxisomes in the liver tissue of people who drink large quantities of alcohol. The other options are not directly related to peroxisome function in alcohol detoxification.

Question 19

As part of our immune system,neutrophil cells engulf micro-organisms or foreign particles.The process by which the neutrophil does this is known as

Accepted Answer

Phagocytosis is the process by which neutrophil cells engulf micro-organisms or foreign particles. Exocytosis involves the release of materials from the cell, pinocytosis involves the uptake of fluids and small molecules, while receptor-mediated endocytosis involves the selectively uptake of specific molecules via specific receptors on the cell membrane.

Question 20

Mitochondria are separated into two compartments,the matrix and the intermembrane space,by their inner and outer membranes.How does the presence of two compartments contribute to the function of mitochondria?

Accepted Answer

The two compartments permit different but complementary functions to be accomplished in the organelle. The outer membrane allows for the exchange of molecules and ions between the cytosol and the intermembrane space, whereas the inner membrane is highly folded to increase surface area and contains the electron transport chain and ATP synthase. The matrix compartment contains enzymes necessary for the Krebs cycle and other metabolic processes. Having two separate compartments allows these different functions to be carried out without interference. Option A is incorrect because mitochondrial DNA and ribosomes are found within the matrix compartment, not separated from it. Option C is incorrect because mitochondria are not involved in glycosylation of proteins.

Quiz 7: Inside the Cell