From molecules to cells lecture 14: Epithelia and cell-cell junctions

Which of the following is NOT one of the four main tissue types?

A) Connective tissue

B) Epithelial tissue

C) Nervous tissue

D) Vascular tissue

D

Which tissue type consists of few cells with lots of extracellular matrix providing strength?

A) Epithelial tissue

B) Connective tissue

C) Nervous tissue

D) Muscular tissue

B

What is a characteristic feature of epithelial tissue?

A) Contains a large amount of extracellular matrix

B) Comprised of scattered cells with abundant ECM

C) Organised into sheets, often a monolayer of cells

D) Often forms a bilayer of cells

C

The base of epithelial tissue sits on which structure?

A) Apical lamina

B) Basal lamina

C) Intercellular matrix

D) Connective tissue

B

Which type of junction forms a seal between epithelial cells to stop diffusion across the epithelial sheet?

A) Tight junctions

B) Gap junctions

C) Desmosomes

D) Adherens junctions

A

Tight junctions are primarily formed by which proteins?

A) Occludin and claudin

B) Cadherin and integrin

C) Actin and myosin

D) Collagen and elastin

A

Epithelial sheets are usually polarised with a free surface facing either air or liquid known as the:

A) Basal side

B) Lateral side

C) Apical side

D) Luminal side

C

The functional polarisation of epithelial membranes allows for:

A) Random transport of molecules

B) Equal distribution of proteins on both sides

C) Different protein compositions in basal and apical membranes

D) Uniform secretion from both surfaces

C

Which tissue types are found in the gut?

A) Connective, epithelial, and muscular tissues

B) Nervous, epithelial, and connective tissues

C) Muscular, nervous, and epithelial tissues

D) Epithelial, connective, and vascular tissues

A

In epithelial tissues, secretion most commonly occurs from:

A) Basal surface

B) Lateral surface

C) Both apical and basal surfaces

D) Apical surface

D

Which type of junction links the cytoskeleton of epithelial cells to their neighbours using cadherins?

A) Tight junctions

B) Hemidesmosomes

C) Adherens junctions

D) Gap junctions

C

Which type of junction links the cytoskeleton of epithelial cells to the basal lamina using integrins?

A) Tight junctions

B) Desmosomes

C) Adherens junctions

D) Hemidesmosomes

D

Cadherins are dependent on which ion for their interaction with identical cadherins in neighbouring cells?

A) Na+

B) K+

C) Mg2+

D) Ca2+

D

Cadherins primarily mediate which type of cellular attachment in epithelial tissues?

A) Attachment to the extracellular matrix

B) Attachment to neighboring epithelial cells

C) Attachment to muscle cells

D) Attachment to nerve cells

B

At adherens junctions, cadherins link to which type of cytoskeletal filaments?

A) Microtubules

B) Intermediate filaments

C) Actin filaments

D) Keratin filaments

C

Which of the following structures is a continuous band of adherens junctions that forms an actin network across the epithelium?

A) Adhesion belt

B) Desmosomes

C) Tight junctions

D) Hemidesmosomes

A

The invagination of epithelial sheets is caused by organized tightening along which specific structure?

A) Desmosomes

B) Hemidesmosomes

C) Adhesion belts

D) Tight junctions

C

Desmosomes link which type of filaments in adjacent epithelial cells to provide strength?

A) Intermediate filaments

B) Microtubules

C) Actin filaments

D) Laminin filaments

A

Desmosomes are particularly abundant in which of the following?

A) Brain tissue

B) Lung tissue

C) Heart muscle

D) Adipose tissue

C

Hemidesmosomes differ from desmosomes in that they use which type of proteins to connect to the basal lamina?

A) Cadherins

B) Integrins

C) Occludins

D) Claudins

B

Integrins in hemidesmosomes bind to laminin in the basal lamina and to which other structures inside the cell?

A) Actin filaments

B) Intermediate filaments

C) Microtubules

D) Desmin filaments

B

Which cadherin type is expressed by epithelial cells?

A) N-cadherin

B) P-cadherin

C) E-cadherin

D) M-cadherin

C

Muscle cells express which cadherin type?

A) E-cadherin

B) N-cadherin

C) P-cadherin

D) C-cadherin

B

Which statement is true regarding the interaction of cadherins?

A) E-cadherin can interact with P-cadherin

B) N-cadherin can interact with E-cadherin

C) N-cadherin can interact with P-cadherins

D) E-cadherin can only interact with other E-cadherins

D

Why do cancer cells become highly motile when they express N-cadherin instead of E-cadherin?

A) N-cadherin is stronger than E-cadherin

B) N-cadherin allows cells to adhere more tightly

C) N-cadherin makes cells less adhesive and more motile

D) N-cadherin makes cells larger

C

What percentage of cancers begin in epithelial tissues?

A) 50%

B) 65%

C) 75%

D) 85%

D

What protein forms the narrow cytosolic channel in gap junctions?

A) Cadherin

B) Integrin

C) Connexon

D) Claudin

C

Gap junctions allow the direct transfer of which types of molecules between adjacent cells?

A) Large proteins and carbohydrates

B) Inorganic ions and small water-soluble molecules

C) DNA and RNA

D) Lipids and cholesterol

B

Gap junctions are essential for which physiological function?

A) Urine production

B) Bone formation

C) Regular heartbeat

D) Cell division

C

What is the equivalent of gap junctions in plant cells?

A) Plasmodesmata

B) Desmosomes

C) Tight junctions

D) Hemidesmosomes

A

Which types of molecules can pass through plasmodesmata?

A) Only ions and small molecules

B) Only water and nutrients

C) Proteins and regulatory mRNAs

D) Only lipids and carbohydrates

C