Question 1

If experimentally linked $\alpha$/$\beta$ heterodimer integrin subunits are separated,what happens?
A)The molecules bind their ligand tightly
B)The molecules are unable to bind a ligand.
C)The molecules are cleaved.
D)The molecules denature their ligand.
E)The molecules are denatured and degraded.

Accepted Answer

Separating the linked F1F1F1S1F1F1F10/F1F1F1S1F1F1F10 heterodimer integrin subunits would result in the inability of the molecules to bind a ligand. This is because the heterodimer is the functional form of integrin and separation would disrupt its structural integrity and ability to bind ligands.

Question 2

What could be defined as an organized network of extracellular materials found beyond the immediate vicinity of the plasma membrane?
A)intracellular matrix
B)extracellular matrix
C)extracellular netrax
D)intercellular material
E)epicellular matrix

Accepted Answer

The organized network of extracellular materials found beyond the immediate vicinity of the plasma membrane is known as the extracellular matrix. Choice A, intracellular matrix, refers to materials found within the cell. Choices C, D, and E are not commonly used or recognized terms.

Question 3

Which protein below is thought to be secreted into the extracellular matrix that surrounds the lining of mature blood vessels,where it inhibits angiogenesis?
A)tenascin
B)entactin
C)thrombospondin
D)actin
E)laminin

Accepted Answer

Thrombospondin is known to be secreted into the extracellular matrix surrounding the lining of mature blood vessels where it inhibits angiogenesis. The other proteins listed are involved in various cellular functions but not specifically in inhibiting angiogenesis.

Question 4

In an integrin,what structure is it that crosses the lipid bilayer?
A)a transmembrane pleated sheet
B)a transmembrane spear
C)a transmembrane plate
D)a transmembrane helix
E)a bent,curved leg

Accepted Answer

A transmembrane helix is the structure that crosses the lipid bilayer in an integrin.

Question 5

Type I collagen mutations cause a potentially lethal condition characterized by extremely fragile bones,thin skin and weak tendons.This condition is called _______.
A)osteogenesis imperfecta
B)Ehler-Danlos syndrome
C)Alport syndrome
D)dwarfism and skeletal deformities
E)diabetes

Accepted Answer

The condition described in the question - extremely fragile bones, thin skin and weak tendons - is characteristic of osteogenesis imperfecta, which is caused by mutations in the genes that encode type I collagen. Ehler-Danlos syndrome and Alport syndrome are caused by mutations in other genes, and dwarfism and skeletal deformities may have a variety of causes. Diabetes is not related to this condition.

Question 6

All collagen family members consist of _____ chains arranged in a _______.
A)2,double helix
B)3,double helix
C)3,triple helix
D)3,triple lattice
E)2,triple helix

Accepted Answer

All collagen family members consist of three chains arranged in a triple helix.

Question 7

The degradation of the extracellular matrix,along with cell surface proteins,is accomplished mostly by a _____-containing enzyme family called _______.
A)copper,matrix metalloproteinases
B)copper,MMPs
C)zinc,matrix metalloproteinases
D)magnesium,matrix metalloproteinases
E)manganese,MMPs

Accepted Answer

The degradation of the extracellular matrix and cell surface proteins are accomplished mostly by a zinc-containing enzyme family called matrix metalloproteinases (MMPs). Copper and magnesium do not play a significant role in this process, and while manganese is also a possible choice, the term MMPs specifically mentions matrix metalloproteinases.

Question 8

You are investigating the interactions of integrin $\alpha$ and $\beta$ subunits and isolate the extracellular portion of an integrin as a soluble $\alpha$/$\beta$ heterodimer.The heterodimer lacks the associated transmembrane and cytoplasmic domains normally present as part of the molecule.You experimentally link the $\alpha$and $\beta$ subunits at the bases of their legs so that the ligand-binding regions of the $\alpha$and $\beta$subunits approach one another.Which of the following statements is true about the molecules formed?
A)The molecules bind their ligand tightly.
B)The molecules are unable to bind a ligand.
C)The molecules are cleaved.
D)The molecules denature their ligand.
E)The molecules denature and degrade.

Accepted Answer

Integrins bind ligands through a conformational change in the extracellular portion of the molecule. Linking the F1F1F1S1F1F1F10 and F1F1F1S1F1F1F10 subunits would allow for this conformational change and the binding of a ligand. Therefore, the molecules formed would bind their ligand tightly.

Question 9

Type II collagen mutations alter the properties of cartilage tissue and are known to cause _______.
A)osteogenesis imperfecta
B)Ehler-Danlos syndromes
C)Alport syndrome
D)dwarfism and skeletal deformities
E)diabetes

Accepted Answer

Type II collagen mutations primarily affect the development and function of cartilage, leading to skeletal dysplasia and dwarfism in affected individuals. This is seen in conditions such as achondrogenesis type II and hypochondrogenesis. None of the other answer choices are associated with type II collagen mutations and cartilage abnormalities.

Question 10

Evidence strongly suggests that the bent conformation of an integrin is _______ and unable to bind its ligand.
A)loose
B)active
C)tight
D)stretched
E)inactive

Accepted Answer

The sentence states that the bent conformation of an integrin is "unable to bind its ligand," which implies a state of inactivity. Therefore, the best choice is E) inactive.

Question 11

What integral membrane protein family made of two membrane-spanning chains ($\alpha$and $\beta$)is involved in attaching cells to their extracellular microenvironment?
A)laminins
B)fibronectins
C)integrins
D)myosins
E)lysins

Accepted Answer

Integrins are the only integral membrane protein family that are made of two membrane-spanning chains (F1F1F1S1F1F1F10 and F1F1F1S1F1F1F10) and are involved in attaching cells to their extracellular microenvironment. Laminins and fibronectins are extracellular matrix proteins, while myosins are motor proteins and lysins are enzymes.

Question 12

Basement membranes contain Type IV collagen,a nonfibrillar collagen organized in a flattened network.The Type IV collagen trimer has some interspersed nonhelical segments.What property does this confer upon basement membranes?
A)strength
B)flexibility
C)extensibility
D)transparency
E)opacity

Accepted Answer

The answer of Basement membranes contain Type IV collagen,a nonfibrillar...

Question 13

The activation of a membrane integrin by the binding of its cytoplasmic portion to molecules in the cytoplasm and the resultant increase in its affinity for an extracellular ligand is called ________.
A)inside-out signaling
B)outside-in signaling
C)right-side-out signaling
D)simple signaling
E)integrination

Accepted Answer

The activation of a membrane integrin by the binding of its cytoplasmic portion to molecules in the cytoplasm and the resultant increase in its affinity for an extracellular ligand is known as inside-out signaling. This process triggers a conformational change in the integrin, leading to its activation and binding to extracellular ligands.

Question 14

Mutations in other collagen genes can lead to a variety of distinct but related defects in collagen matrix structure,one of which causes hyperflexible joints and highly extensible skin.These defects are usually referred to as ______.
A)osteogenesis imperfecta
B)Ehler-Danlos syndromes
C)Alport syndromes
D)Cushing's syndrome
E)diabetes

Accepted Answer

Hyperflexible joints and highly extensible skin are characteristic features of Ehlers-Danlos syndromes, which are caused by mutations in various collagen genes. Osteogenesis imperfecta is another collagen-related disorder, but it primarily affects bone formation and is characterized by brittle bones. Alport syndrome is a genetic disorder that affects the kidneys and hearing. Cushing's syndrome is a hormonal disorder caused by prolonged exposure to high levels of cortisol. Diabetes is a metabolic disorder characterized by high blood sugar levels.

Question 15

What substance joins proteoglycans together into gigantic complexes called proteoglycan aggregates? These complexes can occupy very large volumes.
A)hyaluronidase
B)hyaluronic acid
C)proteoglycase
D)fibronectin
E)laminin

Accepted Answer

Hyaluronic acid joins proteoglycans together into proteoglycan aggregates, which can occupy very large volumes.

Question 16

If antibodies to fibronectin are exposed to an embryo through which neural crest cells are migrating,what happens?
A)Neural crest cell movements are inhibited.
B)Neural crest cell movements are excited.
C)Neural crest cells die.
D)Neural crest cells divide.
E)Neural crest cells convert into muscle cells.

Accepted Answer

Antibodies to fibronectin would likely inhibit neural crest cell movements, as fibronectin is an important component of the extracellular matrix that these cells rely on for migration.

Question 17

Collagen fibrils are strengthened by covalent cross-links between _____ and ____ residues on adjacent collagen molecules.
A)lysine,hydroxylysine
B)proline,hydroxyproline
C)lysine,hydroxyproline
D)proline,hydroxylysine
E)proline,lysine

Accepted Answer

Collagen fibrils are strengthened by covalent cross-links that form between lysine and hydroxylysine residues on adjacent collagen molecules. This cross-linking is crucial for the structural integrity and tensile strength of collagen fibers.

Question 18

In the corneal stroma,the uniformity of collagen fiber size and the ordered packing of the fibers confers what property on the corneal stroma?
A)strength
B)flexibility
C)extensibility
D)transparency
E)opacity

Accepted Answer

The uniformity of collagen fiber size and the ordered packing of the fibers in the corneal stroma helps in the transmission of light through the cornea, which gives it the property of transparency.

Question 19

You place mammary gland epithelial cells in culture and then treat them with enzymes that digest the surrounding extracellular matrix.What happens?
A)The secretory and synthetic activities of the cells decrease.
B)The secretory and synthetic activities of the cells increase.
C)The cells die.
D)The cells enunciate.
E)The secretory and synthetic activities of the cells do not change.

Accepted Answer

The answer of You place mammary gland epithelial cells in...

Question 20

What would be the effect on primordial germ cells when an embryo is exposed to laminin-specific antibodies?
A)They arrive at the developing gonad more quickly.
B)Their movement to the developing gonad is disrupted.
C)They begin to divide rapidly.
D)They increase greatly in size.
E)Their nuclei disintegrate.

Accepted Answer

Laminin is an extracellular matrix protein that helps regulate cell movement and adhesion. If an embryo is exposed to laminin-specific antibodies, it could disrupt the movement of primordial germ cells to the developing gonad, potentially causing developmental abnormalities or infertility. Therefore, option B is the best choice. None of the other options are likely effects of exposure to laminin-specific antibodies on primordial germ cells.

Quiz 7: Interactions Between Cells and Their Environment

If experimentally linked $\alpha$ / $\beta$ heterodimer integrin subunits are separated,what happens?

What could be defined as an organized network of extracellular materials found beyond the immediate vicinity of the plasma membrane?

Which protein below is thought to be secreted into the extracellular matrix that surrounds the lining of mature blood vessels,where it inhibits angiogenesis?

In an integrin,what structure is it that crosses the lipid bilayer?

Type I collagen mutations cause a potentially lethal condition characterized by extremely fragile bones,thin skin and weak tendons.This condition is called _______.

All collagen family members consist of _ chains arranged in a ___.

The degradation of the extracellular matrix,along with cell surface proteins,is accomplished mostly by a _-containing enzyme family called ___.

Type II collagen mutations alter the properties of cartilage tissue and are known to cause _______.

Evidence strongly suggests that the bent conformation of an integrin is _______ and unable to bind its ligand.

What integral membrane protein family made of two membrane-spanning chains ( $\alpha$ and $\beta$ ) is involved in attaching cells to their extracellular microenvironment?

Basement membranes contain Type IV collagen,a nonfibrillar collagen organized in a flattened network.The Type IV collagen trimer has some interspersed nonhelical segments.What property does this confer upon basement membranes?

The activation of a membrane integrin by the binding of its cytoplasmic portion to molecules in the cytoplasm and the resultant increase in its affinity for an extracellular ligand is called ________.

Mutations in other collagen genes can lead to a variety of distinct but related defects in collagen matrix structure,one of which causes hyperflexible joints and highly extensible skin.These defects are usually referred to as ______.

What substance joins proteoglycans together into gigantic complexes called proteoglycan aggregates? These complexes can occupy very large volumes.

If antibodies to fibronectin are exposed to an embryo through which neural crest cells are migrating,what happens?

Collagen fibrils are strengthened by covalent cross-links between _ and residues on adjacent collagen molecules.

In the corneal stroma,the uniformity of collagen fiber size and the ordered packing of the fibers confers what property on the corneal stroma?

You place mammary gland epithelial cells in culture and then treat them with enzymes that digest the surrounding extracellular matrix.What happens?

What would be the effect on primordial germ cells when an embryo is exposed to laminin-specific antibodies?