BIOL 235 MIDTERM 1 EXAMPREP 2026
STUDY GUIDE WITH SOLVED QUESTIONS
AND ANSWERS
⩥ 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)
- stratified epithelium (two plus layers that protect underlying tissue)
2) Cell shapes
STUDY GUIDE WITH SOLVED QUESTIONS
AND ANSWERS
⩥ 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)
- stratified epithelium (two plus layers that protect underlying tissue)
2) Cell shapes
