BIOL 235 COMPREHENSIVE EXAM 2026 FULL
QUESTIONS AND SOLUTIONS GRADED A+
◉ Cytoplasm . Answer: Cellular contents between the plasma
membrane and nucleus. 2 main components: cytosol and organelles.
◉ Nucleus . Answer: Large. Contains most of the cell's DNA and
chromosomes that house DNA associated with several proteins, and
thousands of genes that control cellular structure and functions.
◉ Structure of Plasma Membrane . Answer: - Lipid bilayer
- Membrane proteins
◉ Lipid Bilayer . Answer: Made up of phospholipids (~75%),
cholesterol (~20%) and glycolipids (~5%). Hydrophilic "head" and
hydrophobic "tail".
"Heads" face outward on either side, "tails" face inward.
◉ Amphipathic . Answer: Having both polar and non-polar parts.
- hydrophobic: water hating
- hydrophilic: water loving
,◉ Membrane Proteins . Answer: - Integral
- Peripheral
◉ Integral Proteins . Answer: Amphipathic proteins which extend into
or through the lipid bilayer. Hydrophilic regions protrude into either
watery extracellular fluid or the cytosol. Most are transmembrane
proteins and glycoproteins.
◉ Transmembrane Proteins . Answer: Span entire lipid bilayer and
protrude into both the cytosol and extracellular fluid
◉ Glycoproteins . Answer: Have carbohydrate groups attached to the
ends that protrude into the extracellular fluid. These carbohydrates are
called oligosaccharides (2 - 60 monosaccharides, either straight or
branched). They form glycocalyx.
◉ Glycocalyx . Answer: Extensive sugary coating formed by the
carbohydrate parts of glycoproteins and glycolipids. Acts as a molecular
"signature" that enables cells to recognize each other. e.g. detect
"foreign" glycocalyx to destroy invading organisms.
◉ Peripheral Proteins . Answer: Not firmly embedded in the
membrane. Attached to the polar heads of membrane lips or to integral
proteins at the inner or outer surface of the membrane. Help support
, plasma membrane, anchor integral proteins, participate in mechanical
activities.
◉ Ion Channel . Answer: Integral proteins. Pores or holes that specific
ions can flow through. Most are selective.
◉ Carriers . Answer: Integral proteins. Selectively moves a polar
substance or ion from one side of the membrane to the other. Also
known as transporters.
◉ Receptors . Answer: Integral proteins. Serve as cellular recognition
sites. Each type recognizes/binds a specific type of molecule. The
specific molecule that binds to a receptor is called a ligand.
◉ Enzymes . Answer: Integral or peripheral proteins. Catalyze specific
chemical reactions.
◉ Linkers . Answer: Integral or peripheral proteins. Anchor proteins in
the plasma membrane of neighbouring cells to one another or to protein
filaments inside and outside of the cell.
◉ Cell-identity markers . Answer: glycoproteins and glycolipids.
Enable a cell to (1) recognize cells of the same kind during tissue
formation or (2) recognize/respond to potentially dangerous foreign
cells. e.g. wrong blood types clumping together.
QUESTIONS AND SOLUTIONS GRADED A+
◉ Cytoplasm . Answer: Cellular contents between the plasma
membrane and nucleus. 2 main components: cytosol and organelles.
◉ Nucleus . Answer: Large. Contains most of the cell's DNA and
chromosomes that house DNA associated with several proteins, and
thousands of genes that control cellular structure and functions.
◉ Structure of Plasma Membrane . Answer: - Lipid bilayer
- Membrane proteins
◉ Lipid Bilayer . Answer: Made up of phospholipids (~75%),
cholesterol (~20%) and glycolipids (~5%). Hydrophilic "head" and
hydrophobic "tail".
"Heads" face outward on either side, "tails" face inward.
◉ Amphipathic . Answer: Having both polar and non-polar parts.
- hydrophobic: water hating
- hydrophilic: water loving
,◉ Membrane Proteins . Answer: - Integral
- Peripheral
◉ Integral Proteins . Answer: Amphipathic proteins which extend into
or through the lipid bilayer. Hydrophilic regions protrude into either
watery extracellular fluid or the cytosol. Most are transmembrane
proteins and glycoproteins.
◉ Transmembrane Proteins . Answer: Span entire lipid bilayer and
protrude into both the cytosol and extracellular fluid
◉ Glycoproteins . Answer: Have carbohydrate groups attached to the
ends that protrude into the extracellular fluid. These carbohydrates are
called oligosaccharides (2 - 60 monosaccharides, either straight or
branched). They form glycocalyx.
◉ Glycocalyx . Answer: Extensive sugary coating formed by the
carbohydrate parts of glycoproteins and glycolipids. Acts as a molecular
"signature" that enables cells to recognize each other. e.g. detect
"foreign" glycocalyx to destroy invading organisms.
◉ Peripheral Proteins . Answer: Not firmly embedded in the
membrane. Attached to the polar heads of membrane lips or to integral
proteins at the inner or outer surface of the membrane. Help support
, plasma membrane, anchor integral proteins, participate in mechanical
activities.
◉ Ion Channel . Answer: Integral proteins. Pores or holes that specific
ions can flow through. Most are selective.
◉ Carriers . Answer: Integral proteins. Selectively moves a polar
substance or ion from one side of the membrane to the other. Also
known as transporters.
◉ Receptors . Answer: Integral proteins. Serve as cellular recognition
sites. Each type recognizes/binds a specific type of molecule. The
specific molecule that binds to a receptor is called a ligand.
◉ Enzymes . Answer: Integral or peripheral proteins. Catalyze specific
chemical reactions.
◉ Linkers . Answer: Integral or peripheral proteins. Anchor proteins in
the plasma membrane of neighbouring cells to one another or to protein
filaments inside and outside of the cell.
◉ Cell-identity markers . Answer: glycoproteins and glycolipids.
Enable a cell to (1) recognize cells of the same kind during tissue
formation or (2) recognize/respond to potentially dangerous foreign
cells. e.g. wrong blood types clumping together.
