Question 1

Which tissues below are typically derived from the epithelium on the dorsal surface of a mammalian embryo once some of these cells begin expressing N-cadherins and stop expressing E-cadherins?
A)skin
B)only brain
C)only spinal cord
D)only neural tube
E)brain, spinal cord and neural tube

Accepted Answer

The neural tube, which gives rise to the brain and spinal cord, is derived from the ectoderm on the dorsal surface of the mammalian embryo. Once some of these cells start expressing N-cadherins and stop expressing E-cadherins, they form the neural crest cells, which give rise to various tissues including neurons and glia in the brain and spinal cord. Therefore, the correct answer is E, which includes brain, spinal cord, and neural tube. Skin is not derived from the neural tube or its derivatives and is therefore not included in the answer.

Question 2

Animals lacking the claudin-1 gene suffered from ___________. A)uncontrolled water loss B)high salt loading C)low salt loading D)Mg²⁺ ion permeability E)constant, unremitting pain

Accepted Answer

Claudin-1 gene is responsible for controlling the permeability of tight junctions in the skin of animals. Animals lacking this gene suffered from uncontrolled water loss through their skin, indicating that the claudin-1 gene is important for preventing excessive water loss.

Question 3

Which tissues below are typically derived from the single-celled epithelium on the dorsal surface of a chick embryo after gastrulation?
A)muscle
B)skin, ectodermal tissues and the nervous system
C)only skin
D)only ectodermal tissues
E)only tissues of the nervous system

Accepted Answer

The ectoderm on the dorsal surface of a chick embryo after gastrulation gives rise to skin, ectodermal tissues (such as hair, feathers, etc.), and the nervous system. Therefore, the correct answer is B. Muscle is derived from mesoderm, which is formed during gastrulation and is not derived from the ectoderm. Similarly, choices C, D, and E are too narrow and do not encompass all the tissue types that are derived from the dorsal surface ectoderm.

Question 4

One small region of a human kidney tubule known as the thick ascending limb (or TAL)has tight junctions that are permeable to magnesium (Mg²⁺)ions. What is thought to account for the permeability of this tight junction to magnesium ions? A)The membrane in this region is leaky because of special phospholipids. B)Loops of claudin molecules that extend into the extracellular space form pores in the TAL. C)Loops of claudin molecules that extend into the cytoplasm form pores in the TAL. D)Loops of claudin molecules fully embedded in the TAL membrane form pores in the TAL. E)Claudin molecules form gap junctions that allow the passage of magnesium ions.

Accepted Answer

Tight junctions are composed of claudin molecules, which can form pores that allow the passage of ions and small molecules. In the TAL of the kidney, the tight junctions are permeable to magnesium ions, likely due to loops of claudin molecules that extend into the extracellular space and form pores. Choice A is incorrect because the membrane in this region is not described as leaky due to special phospholipids. Choices C and D are incorrect because the pores are not formed by claudin molecules that extend into the cytoplasm or are fully embedded in the membrane. Choice E is incorrect because gap junctions are a different type of junction that allow for direct communication between cells, not selective permeability.

Question 5

Which tight junction will form a tighter seal?
A)one with a single strand of aligned integral membrane proteins
B)one with a number of parallel, interconnected strands of aligned integral membrane proteins
C)tight junctions containing a special kind of phospholipid
D)tight junctions containing a special kind of carbohydrate
E)one with a number of parallel, interconnected strands of interdigitated integral membrane proteins

Accepted Answer

The answer of Which tight junction will form a tighter...

Question 6

The cadherins of the desmosomes ____________.
A)have a different domain structure from classical cadherins
B)are referred to as desmogleins
C)are called desmocollins
D)all choices are correct

Accepted Answer

All three choices are correct. Desmosomes have unique cadherins with different domain structures compared to classical cadherins. These cadherins are referred to as desmogleins and desmocollins.

Question 7

Which tissues below are NOT typically derived from the cells on the dorsal surface of a mammalian embryo after gastrulation once some of these cells begin expressing N-cadherins and stop expressing E-cadherins?
A)skin
B)brain
C)spinal cord
D)neural tube

Accepted Answer

The cells on the dorsal surface of a mammalian embryo after gastrulation that express N-cadherins and stop expressing E-cadherins typically give rise to neural tissues, such as the brain, spinal cord, and neural tube. The skin is derived from the ectoderm, which is located on the surface of the embryo and does not express N-cadherins or stop expressing E-cadherins.

Question 8

What forms the barrier of the tight junctions that seals off the space between adjacent cells?
A)paired rows of aligned integral membrane proteins
B)paired rows of aligned phospholipids
C)paired rows of carbohydrates
D)paired rows of polynucleotides
E)interdigitating integral membrane proteins

Accepted Answer

Tight junctions are composed of paired rows of integral membrane proteins, such as claudins and occludins, that interlock with each other and seal off the space between adjacent cells. Phospholipids, carbohydrates, and polynucleotides do not form the barrier of tight junctions. Interdigitating integral membrane proteins are a feature of desmosomes, not tight junctions.

Question 9

The opening in the center of a connexon that allows the passage of solutes between cells is called a(n)________.
A)connexin
B)annulus
C)cumulous
D)lunulus
E)limulus

Accepted Answer

The correct term for the opening in the center of a connexon that allows the passage of solutes between cells is "annulus." Connexons are structures that form gap junctions between cells, facilitating communication and the transfer of small molecules.

Question 10

Each connexon in a gap junction is constructed of ___ connexin subunits.
A)2
B)4
C)6
D)8
E)10

Accepted Answer

Each connexon in a gap junction is constructed of 6 connexin subunits, allowing for the direct transfer of ions and small molecules between cells.

Question 11

Which animal cell structure do plasmodesmata in plants most closely resemble?
A)maculae adherens
B)spot desmosomes
C)zonulae adherens
D)gap junctions
E)zonulae occludens

Accepted Answer

Plasmodesmata in plants are similar in function to gap junctions in animal cells, as both allow for direct communication and transport of molecules between neighboring cells.

Question 12

The blood-brain barrier is very restrictive, preventing even water and small ions from crossing. However, _______ can pass through the blood-brain barrier by sending a signal that opens up the junction.
A)red blood cells
B)immune system cells
C)platelets
D)complement cells
E)epithelial cells

Accepted Answer

Immune system cells, specifically white blood cells, are able to pass through the blood-brain barrier by sending a signal that triggers the opening of the tight junctions between brain endothelial cells. This allows them to enter the brain and respond to infections or injuries.

Question 13

Patients with abnormal claudin-16 gene suffered from ___________. A)uncontrolled water loss B)high salt loading C)low salt loading D)excessive Mg²⁺ ion permeability E)constant, unremitting pain

Accepted Answer

The claudin-16 gene is involved in the regulation of magnesium and calcium ions in the kidney. Mutations in this gene can lead to abnormal permeability of these ions, particularly magnesium, hence the correct answer is related to excessive magnesium ion permeability.

Question 14

The human disease pemphigus vulgaris __________.
A)is characterized by a loss of epidermal cell-cell adhesion
B)is an autoimmune disease
C)is characterized by severe blistering of the skin
D)is caused by the production of antibodies against one of the desmogleins
E)all of these are correct

Accepted Answer

Pemphigus vulgaris is characterized by a loss of epidermal cell-cell adhesion, is an autoimmune disease, and is characterized by severe blistering of the skin. It is caused by the production of antibodies against one of the desmogleins.

Question 15

What kind of molecule does NOT pass through a gap junction?
A)ions
B)cAMP
C)inositol phosphates
D)ribosomal RNA
E)cGMP

Accepted Answer

Ribosomal RNA is a large molecule that does not pass through gap junctions. Gap junctions are only permeable to small molecules such as ions, cAMP, inositol phosphates, and cGMP.

Question 16

During gap junction formation, connexons in apposing cells become tightly connected through extensive noncovalent interactions of __________.
A)connexin subunit intracellular domains
B)connexin subunit extracellular domains
C)connexin carbohydrates
D)connexin lipids
E)polynucleotides

Accepted Answer

Connexons in apposing cells become tightly connected through extensive noncovalent interactions of connexin subunit extracellular domains. This interaction facilitates the direct cytoplasmic connection between neighboring cells, allowing for the passage of ions and small molecules.

Question 17

Desmosomes are particularly numerous in tissues _____________.
A)that are subjected to mechanical stress
B)like cardiac muscle
C)like the epithelial layers of the skin
D)like the epithelial layers of the uterine cervix
E)all of these are correct

Accepted Answer

Desmosomes are specialized structures that anchor cells together, particularly in tissues that are subjected to mechanical stress. Therefore, they are particularly numerous in tissues like cardiac muscle, epithelial layers of the skin, and epithelial layers of the uterine cervix.

Question 18

A new type of communication system has been discovered that consists of thin, highly elongated tubules capable of conducting cell-surface proteins, cytoplasmic vesicles and calcium signals from one cell to another. This system is referred to as ________.
A)T tubules
B)scanning tunneling EMs
C)tunneling nanotypes
D)tunneling nanotubes
E)sarcoplasmic tubules

Accepted Answer

The communication system described is known as "tunneling nanotubes" (TNTs). This term specifically mentions the thin, elongated tubules that conduct various signals between cells. The other choices, such as T-tubules or scanning tunneling EMs, do not accurately describe the system mentioned in the statement.

Question 19

What is thought to promote the release of future mesoderm cells from an epithelium and their transformation into mesenchymal cells?
A)a reduction in the expression of E-cadherin genes
B)an increase in the expression of E-cadherin genes
C)degradation of the cell membrane
D)the cytoplasm taking on an anti-adhesive character
E)autophagy of the nucleus

Accepted Answer

A reduction in the expression of E-cadherin genes is thought to promote the release of future mesoderm cells from an epithelium and their transformation into mesenchymal cells. E-cadherin is a cell adhesion molecule that holds cells together in epithelial tissues. Its reduction results in the loss of cell-cell adhesion and allows cells to detach from the epithelium and become mesenchymal cells.

Question 20

Attachment of an integrin to its ligand can induce which of the following responses within a cell? A)changes in cytoplasmic pH B)changes in cytoplasmic C2⁺ ion concentration C)protein phosphorylation D)gene expression E)all of these are correct

Accepted Answer

Attachment of an integrin to its ligand can induce a variety of responses within a cell, including changes in cytoplasmic pH, changes in cytoplasmic ion concentration, protein phosphorylation, and gene expression. Integrins are transmembrane receptors that facilitate cell-extracellular matrix (ECM) adhesion. Upon binding to their ligands, integrins can activate signal transduction pathways that lead to these cellular responses.

Quiz 7: Interactions Between Cells and Their Environment

Which tissues below are typically derived from the epithelium on the dorsal surface of a mammalian embryo once some of these cells begin expressing N-cadherins and stop expressing E-cadherins?

Animals lacking the claudin-1 gene suffered from ___________.

Which tissues below are typically derived from the single-celled epithelium on the dorsal surface of a chick embryo after gastrulation?

One small region of a human kidney tubule known as the thick ascending limb (or TAL) has tight junctions that are permeable to magnesium (Mg²⁺) ions. What is thought to account for the permeability of this tight junction to magnesium ions?

Which tight junction will form a tighter seal?

The cadherins of the desmosomes ____________.

Which tissues below are NOT typically derived from the cells on the dorsal surface of a mammalian embryo after gastrulation once some of these cells begin expressing N-cadherins and stop expressing E-cadherins?

What forms the barrier of the tight junctions that seals off the space between adjacent cells?

The opening in the center of a connexon that allows the passage of solutes between cells is called a(n) ________.

Each connexon in a gap junction is constructed of ___ connexin subunits.

Which animal cell structure do plasmodesmata in plants most closely resemble?

The blood-brain barrier is very restrictive, preventing even water and small ions from crossing. However, _______ can pass through the blood-brain barrier by sending a signal that opens up the junction.

Patients with abnormal claudin-16 gene suffered from ___________.

The human disease pemphigus vulgaris __________.

What kind of molecule does NOT pass through a gap junction?

During gap junction formation, connexons in apposing cells become tightly connected through extensive noncovalent interactions of __________.

Desmosomes are particularly numerous in tissues _____________.

A new type of communication system has been discovered that consists of thin, highly elongated tubules capable of conducting cell-surface proteins, cytoplasmic vesicles and calcium signals from one cell to another. This system is referred to as ________.

What is thought to promote the release of future mesoderm cells from an epithelium and their transformation into mesenchymal cells?

Attachment of an integrin to its ligand can induce which of the following responses within a cell?