Question 1

If extracellular matrix materials are added back to the cells described in question #2,what happens?
A)Nothing happens.
B)Everything happens.
C)The differentiated state of the cells is restored and the cells produce their usual products.
D)The cells die.
E)The cells dedifferentiate.

Accepted Answer

Addition of extracellular matrix materials can help restore the differentiated state of the cells and promote normal cellular function. This is because extracellular matrix provides important cues and signals that help regulate cell behavior and maintain tissue structure. Therefore, choice C is the best answer.

Question 2

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 3

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 definition given describes the extracellular matrix. The intracellular matrix refers to the materials found inside the cell, while the other options (extracellular netrax, intercellular material, epicellular matrix) are not accurate terms used in biology.

Question 4

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 maintenance of cartilage tissue, which can result in skeletal deformities and dwarfism.

Question 5

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 extracellular matrix provides structural and biochemical support to cells. Digesting it can disrupt cell signaling and attachment, leading to decreased secretory and synthetic activities.

Question 6

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

The experimental linking of the F1F1F1S1F1F1F10 and F1F1F1S1F1F1F10 subunits and their approach to one another should result in a properly folded, functional ligand-binding site. Therefore, the molecules formed should be able to bind their ligand tightly.

Question 7

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 (alpha chains) arranged in a triple helix.

Question 8

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

The hyperflexible joints and highly extensible skin are characteristics of Ehler-Danlos syndromes, which are caused by mutations in collagen genes. Osteogenesis imperfecta, Alport syndrome, Cushing's syndrome, and diabetes are not associated with these specific symptoms.

Question 9

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

The integral membrane protein family made of two membrane-spanning chains (F1F1F1S1F1F1F10 and F1F1F1S1F1F1F10) that is involved in attaching cells to their extracellular microenvironment is integrins. Laminins and fibronectins are extracellular matrix glycoproteins, myosins are motor proteins involved in muscle contraction, and lysins are enzymes that can digest bacterial cell walls.

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 term "bent" suggests a conformational change that is not active or stretched, implying that it is inactive. Additionally, the statement that the integrin is "unable to bind its ligand" supports the conclusion that it is in an inactive state. Therefore, choice E, inactive, is the best answer.

Question 11

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

Type I collagen is the most abundant collagen in the body and mutations in this gene can cause osteogenesis imperfecta, which is characterized by weakened bones, thin skin, weak tendons, and other connective tissues. Ehler-Danlos syndrome is also a genetic disorder affecting collagen, but it is caused by mutations in other types of collagen genes and has different symptoms. Alport syndrome affects proteins in the kidneys, ears, and eyes, not collagen. Dwarfism and skeletal deformities are caused by various genetic and environmental factors, not exclusively collagen mutations. Diabetes is a metabolic disorder and not directly related to collagen.

Question 12

The basal lamina of which structure may thicken abnormally in long-term diabetics causing kidney failure?
A)the dermis
B)the epidermis
C)the glomerulus
D)the bladder epithelium
E)the pericardium

Accepted Answer

The glomerulus is a part of the kidney that is responsible for filtering blood. Long-term uncontrolled diabetes can lead to thickening of the basal lamina of the glomerulus, causing an abnormal filtration process and ultimately leading to kidney failure.

Question 13

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 is a long, unbranched glycosaminoglycan that can form large complexes with proteoglycans, creating proteoglycan aggregates. These aggregates can occupy large volumes and are important components of extracellular matrix in connective tissues.

Question 14

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

The transmembrane region of an integrin consists of a single helical chain that crosses the lipid bilayer.

Question 15

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 plays a critical role in cell adhesion and migration. Primordial germ cells rely on laminin to properly migrate to the developing gonad. Exposure to laminin-specific antibodies would disrupt the ability of these cells to effectively migrate, potentially resulting in developmental abnormalities or even loss of these cells. Therefore, choice B, that their movement to the developing gonad is disrupted, is the best answer.

Question 16

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 integrins by binding of cytoplasmic molecules is called inside-out signaling, which leads to an increase in the integrin's affinity for extracellular ligands. This is in contrast to outside-in signaling, which occurs when an extracellular ligand binds to the integrin and triggers intracellular signaling pathways. Choices C, D, and E are not valid terms used in discussing integrin activation.

Question 17

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 extracellular matrix and cell surface proteins is mostly accomplished by a zinc-containing enzyme family called matrix metalloproteinases (MMPs). Copper, magnesium, and manganese are not commonly associated with MMPs. Additionally, MMPs is the full term for the enzyme family, not just the abbreviation MMPs.

Question 18

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 interspersed nonhelical segments in Type IV collagen provide flexibility to the basement membranes, allowing them to be more pliable and adaptable to changes in shape and pressure.

Question 19

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 confers the property of transparency. This arrangement allows for the passage of light through the cornea, which is essential for vision.

Question 20

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 can inhibit or disrupt the migration of neural crest cells, as fibronectin plays a critical role in the cell interactions and movements required for neural crest cell migration.

Quiz 7: Interactions Between Cells and Their Environment

If extracellular matrix materials are added back to the cells described in question #2,what happens?

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

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

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

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

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

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

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

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

The basal lamina of which structure may thicken abnormally in long-term diabetics causing kidney failure?

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

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

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

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 ________.

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

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?

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

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