Biomedical Science Exam 1 Questions
and Answers
What effect does the presence of cholesterol have on the plasma membrane? -
ANSWER-Cholesterol disrupts the packing of the long phospholipid fatty acid chains
and therefore increases the fluidity of the membrane
Pinocytosis - ANSWER-Cell drinking (comes into the cell)
extracellular fluid and soluble material
Receptor Mediated Endocytosis I - ANSWER-• Receptors for many substances are
located on the cell surface, they can be widely distributed or localized to specialized
coated pits.
• Binding of ligands to receptors causes receptors to accumulate in coated pits.
• The cytoplasmic surface of the PM at these locations contain many proteins,
particularly clathrin. These proteins form a lattice meshwork.
• The coated pit invaginates and pinches off forming a coated vesicle which contains the
receptor plus the bound ligand.
• Coated vesicles lose their clathrin and fuse with endosomes. Clathrin detaches and
recycles back to the PM.
Properties of the mitochondria - ANSWER-contains cristae which increases the SA
matrix contains dna, tRNA, mRNA, and rRNA
very high protein to lipid ratio
new mitochondria arise by the fusion of existing mitochondria
responsible for the production of the cell's ATP and carries out most cellular oxidation.
Endoplasmic reticulum enclose a ______________ - ANSWER-cisterna
SER in muscle cells - ANSWER-Called sarcoplasmic reticulum
involved in the sequestration and release of ca2+ during contraction.
Ribosomes - ANSWER-Electron-dense particles, 20 X 30 nm in size.
Composed of 4 types of RNA and >80 proteins.
In eukaryotic cells the RNA is synthesized in the nucleus and ribosomes comprise 2
different subunits, 60S and 40S.
Ribosomes stain blue with haemotoxylin.
Individual ribosomes are held together by mRNA to form polyribosomes.
mRNA encode for amino acids and ribosomes decode this and translate it into protein.
and Answers
What effect does the presence of cholesterol have on the plasma membrane? -
ANSWER-Cholesterol disrupts the packing of the long phospholipid fatty acid chains
and therefore increases the fluidity of the membrane
Pinocytosis - ANSWER-Cell drinking (comes into the cell)
extracellular fluid and soluble material
Receptor Mediated Endocytosis I - ANSWER-• Receptors for many substances are
located on the cell surface, they can be widely distributed or localized to specialized
coated pits.
• Binding of ligands to receptors causes receptors to accumulate in coated pits.
• The cytoplasmic surface of the PM at these locations contain many proteins,
particularly clathrin. These proteins form a lattice meshwork.
• The coated pit invaginates and pinches off forming a coated vesicle which contains the
receptor plus the bound ligand.
• Coated vesicles lose their clathrin and fuse with endosomes. Clathrin detaches and
recycles back to the PM.
Properties of the mitochondria - ANSWER-contains cristae which increases the SA
matrix contains dna, tRNA, mRNA, and rRNA
very high protein to lipid ratio
new mitochondria arise by the fusion of existing mitochondria
responsible for the production of the cell's ATP and carries out most cellular oxidation.
Endoplasmic reticulum enclose a ______________ - ANSWER-cisterna
SER in muscle cells - ANSWER-Called sarcoplasmic reticulum
involved in the sequestration and release of ca2+ during contraction.
Ribosomes - ANSWER-Electron-dense particles, 20 X 30 nm in size.
Composed of 4 types of RNA and >80 proteins.
In eukaryotic cells the RNA is synthesized in the nucleus and ribosomes comprise 2
different subunits, 60S and 40S.
Ribosomes stain blue with haemotoxylin.
Individual ribosomes are held together by mRNA to form polyribosomes.
mRNA encode for amino acids and ribosomes decode this and translate it into protein.
