BIOL 235 EXAMINATION TEST 2026
QUESTIONS WITH ANSWERS GRADED A+
◉ Cell Junctions . Answer: Points of contact between adjacent plasma
membranes
◉ Tight Junctions . Answer: Weblike strands of transmembrane
proteins that fuse together plasma membranes to form fluid-right seals
between cells. e.g. epithelia tissue that lines stomach, intestines and
bladder
◉ Adherens Junctions . Answer: Contains plaque (dense layer of
proteins on the inside of the plasma membrane that attaches to
membrane proteins and microfilaments of cytoskeleton).
Transmembrane proteins called cadherins join the cells and inserts
plaque from the opposite side of the plasma membrane, partially
crossing the intercellular space, and connecting cadherins of an adjacent
cell. They circle epithelial cells in zones called adhesion belts, to help
resist separation during various contractile activities.
◉ Demosomes . Answer: Contain plaque and cadherins. Unlike adhere
junctions, the plaque attaches to intermediate filaments (which consist of
keratin). This contributes to the stability of the cells and tissues.
,Common among epidermis and cardiac muscles. Prevent separation
under tension.
◉ Hemidesmosomes . Answer: Looks like half a desmosome, but the
transmembrane proteins are integrins not cadherins. Integrins attach to
intermediate filaments on the inside of the membrane, while they attach
to laminin on the outside of the membrane. They anchor cells not to each
other, but to the basement membrane.
◉ Gap Junctions . Answer: Membrane proteins called connexins form
tiny fluid-filled tunnels called connexns that connect neighbouring cells.
The plasma membranes are not fused together so ions and small
molecules can defuse through. Transfer or nutrients and tastes occurs
this way.
Permit electrical and chemical signals to pass between cells
◉ Epithelial Tissue VS Connective Tissue . Answer: Epithelial cells are
tightly packed and connective are widely scattered. Epithelial has no
blood vessels, while connective has significant networks of blood
vessels. Epithelial issue forms surface layers and is not covered by
another tissue.
They are found adjacent to each other because epithelial tissue lacks
blood vessels and connective tissue is blood vessel-rich.
◉ Epithelial Tissue . Answer: Continous sheets in single or multiple
layers. Form coverings and linings throughout the body. Has a free
, surface. It has 3 major functions: (1) selective barrier that limits or aids
the transfer of substances into and out of the body, (2) secretory surface
that releases products produced by the cells onto its free surfaces, and
(3) a protective surface that resists the abrasive influences of the
environment.
- Apical surface: free surface. faces the body surface, cavity, or lumen of
internal organ, or tubular duct. May contain cilia or microvilli.
- Lateral surface: face adjacent cells on either side may contain tight
junctions, adherent junctions, desmosomes, or gap junctions.
- Basal surface: opposite apical suface. Adhere to extracellular materials
such as the basement membrane.
- Basement membrane: thin extracellular layer that commonly consists
of two layers, the basal lamina (closer to epithelial cells) and reticular
lamina (closer to underlying connective tissue).
Divided into two types:
1) Covering and lining epithelium: outer covering of the skin and some
internal organs. Inner lining of blood vessels, ducts, body cavities,
respiratory, digestive, urinary, and reproductive systems.
2) Glandular epithelium: secreting portion of glands and such as the
thyroid, adrenal, and sweat glands.
◉ Epithelial Cell Classification . Answer: 1) Arrangement of cells in
layers
- simple epithelium (single layer - secretion and absorption).
- pseudostratified (appears to have more than one layer but does not)
QUESTIONS WITH ANSWERS GRADED A+
◉ Cell Junctions . Answer: Points of contact between adjacent plasma
membranes
◉ Tight Junctions . Answer: Weblike strands of transmembrane
proteins that fuse together plasma membranes to form fluid-right seals
between cells. e.g. epithelia tissue that lines stomach, intestines and
bladder
◉ Adherens Junctions . Answer: Contains plaque (dense layer of
proteins on the inside of the plasma membrane that attaches to
membrane proteins and microfilaments of cytoskeleton).
Transmembrane proteins called cadherins join the cells and inserts
plaque from the opposite side of the plasma membrane, partially
crossing the intercellular space, and connecting cadherins of an adjacent
cell. They circle epithelial cells in zones called adhesion belts, to help
resist separation during various contractile activities.
◉ Demosomes . Answer: Contain plaque and cadherins. Unlike adhere
junctions, the plaque attaches to intermediate filaments (which consist of
keratin). This contributes to the stability of the cells and tissues.
,Common among epidermis and cardiac muscles. Prevent separation
under tension.
◉ Hemidesmosomes . Answer: Looks like half a desmosome, but the
transmembrane proteins are integrins not cadherins. Integrins attach to
intermediate filaments on the inside of the membrane, while they attach
to laminin on the outside of the membrane. They anchor cells not to each
other, but to the basement membrane.
◉ Gap Junctions . Answer: Membrane proteins called connexins form
tiny fluid-filled tunnels called connexns that connect neighbouring cells.
The plasma membranes are not fused together so ions and small
molecules can defuse through. Transfer or nutrients and tastes occurs
this way.
Permit electrical and chemical signals to pass between cells
◉ Epithelial Tissue VS Connective Tissue . Answer: Epithelial cells are
tightly packed and connective are widely scattered. Epithelial has no
blood vessels, while connective has significant networks of blood
vessels. Epithelial issue forms surface layers and is not covered by
another tissue.
They are found adjacent to each other because epithelial tissue lacks
blood vessels and connective tissue is blood vessel-rich.
◉ Epithelial Tissue . Answer: Continous sheets in single or multiple
layers. Form coverings and linings throughout the body. Has a free
, surface. It has 3 major functions: (1) selective barrier that limits or aids
the transfer of substances into and out of the body, (2) secretory surface
that releases products produced by the cells onto its free surfaces, and
(3) a protective surface that resists the abrasive influences of the
environment.
- Apical surface: free surface. faces the body surface, cavity, or lumen of
internal organ, or tubular duct. May contain cilia or microvilli.
- Lateral surface: face adjacent cells on either side may contain tight
junctions, adherent junctions, desmosomes, or gap junctions.
- Basal surface: opposite apical suface. Adhere to extracellular materials
such as the basement membrane.
- Basement membrane: thin extracellular layer that commonly consists
of two layers, the basal lamina (closer to epithelial cells) and reticular
lamina (closer to underlying connective tissue).
Divided into two types:
1) Covering and lining epithelium: outer covering of the skin and some
internal organs. Inner lining of blood vessels, ducts, body cavities,
respiratory, digestive, urinary, and reproductive systems.
2) Glandular epithelium: secreting portion of glands and such as the
thyroid, adrenal, and sweat glands.
◉ Epithelial Cell Classification . Answer: 1) Arrangement of cells in
layers
- simple epithelium (single layer - secretion and absorption).
- pseudostratified (appears to have more than one layer but does not)
