BCMB 311 Exam 2 – Study Guide, Practice Questions & Revision Notes
What are the benefits of having intracellular compartments? - correct answer ✔✔incompatible
biochemical pathways can be separated into different compartments, avoiding inhibition due to
cross-talk/same intermediates
Recognize that the ER, nuclear envelope, Golgi apparatus, peroxisomes, endosomes and
lysosomes are all thought to have originated by invagination from the plasma membrane in the
earliest eukaryotes. What are the general functions of these organelles? - correct answer ✔✔-
ER: sites of co-translational translocation of proteins (rough); production of steroid hormones,
detoxification of alcohol (smooth)
- nuclear envelope: nuclear pore complexes create pores for regulated transport across
membranes
- Golgi apparatus: modification, sorting, and packaging of proteins
- peroxisomes: oxidative breakdown of toxic molecules
- endosomes: some sort endocytosed material for exocytosis, some fuse to lysosomes to
degrade their contents
- lysosomes: intracellular degradation
Understand that when endocytosis occurs, such as the proposed origin of these organelles, the
cytosolic facing side remains the cytosolic side, and the inside of the organelle membrane is
topologically equivalent to the surface of the cell. - correct answer ✔✔.
When the free-living, aerobic bacterial predecessors of the mitochondria and chloroplasts were
endocytosed, they would have originally been covered in plasma membrane. This membrane
was lost, however. The bacterial inner membrane is the site of the ETC in mitochondria, and this
is equivalent to the mitochondrial inner membrane. What is interesting, is that part of the
specialization that formed the mitochondria expanded the inner membrane into folds to
increase the available surface area for the transmembrane proteins involved in aerobic
respiration. The chloroplasts have a third, inner-most membrane, the thylakoid, in which the
enzymes for photosynthesis and ATP synthesis reside. This membrane is thought to have been
, present prior to endosymbiosis and has similarly undergone considerable expansion of its
surface area to better serve the eukaryotic host. - correct answer ✔✔.
What are the three major strategies by which proteins enter a cellular compartment (slide 9) -
correct answer ✔✔1) transport through nuclear pores
2) transport across membranes (proteins must be unfolded)
3) transport by vesicles
What are signal sequences? What is a sequence motif? - correct answer ✔✔- signal sequences:
short tail of amino acids that directs a protein to a specific cellular compartment
- sequence motif: any of a number of sequences or sequence arrangements that indicate the
likely function of a segment of DNA
What does it mean for a signal sequence to be necessary and sufficient for intracellular
targeting? - correct answer ✔✔signal sequences determine where a protein is going to end up
and are typically cleaved after the protein has been successfully transported
What is the structural relationship between the ER and the nuclear envelope? - correct answer
✔✔the nuclear envelope (specifically the outer nuclear membrane) and the rough ER are
continuous with one another
What is the nuclear lamina and what purpose does it serve? - correct answer ✔✔cytoskeletal
filament meshwork providing structural support
Describe the structure, composition and size of the nuclear pore complex (NPC). - correct
answer ✔✔- nuclear pore complexes are found scattered across the nucleus in order to
facilitate transport
- made up of 400+ individual proteins, 110 megadaltons in size
- proteins lining the inside of the pore form a gel-like mesh and basket that catch large
molecules
What are the benefits of having intracellular compartments? - correct answer ✔✔incompatible
biochemical pathways can be separated into different compartments, avoiding inhibition due to
cross-talk/same intermediates
Recognize that the ER, nuclear envelope, Golgi apparatus, peroxisomes, endosomes and
lysosomes are all thought to have originated by invagination from the plasma membrane in the
earliest eukaryotes. What are the general functions of these organelles? - correct answer ✔✔-
ER: sites of co-translational translocation of proteins (rough); production of steroid hormones,
detoxification of alcohol (smooth)
- nuclear envelope: nuclear pore complexes create pores for regulated transport across
membranes
- Golgi apparatus: modification, sorting, and packaging of proteins
- peroxisomes: oxidative breakdown of toxic molecules
- endosomes: some sort endocytosed material for exocytosis, some fuse to lysosomes to
degrade their contents
- lysosomes: intracellular degradation
Understand that when endocytosis occurs, such as the proposed origin of these organelles, the
cytosolic facing side remains the cytosolic side, and the inside of the organelle membrane is
topologically equivalent to the surface of the cell. - correct answer ✔✔.
When the free-living, aerobic bacterial predecessors of the mitochondria and chloroplasts were
endocytosed, they would have originally been covered in plasma membrane. This membrane
was lost, however. The bacterial inner membrane is the site of the ETC in mitochondria, and this
is equivalent to the mitochondrial inner membrane. What is interesting, is that part of the
specialization that formed the mitochondria expanded the inner membrane into folds to
increase the available surface area for the transmembrane proteins involved in aerobic
respiration. The chloroplasts have a third, inner-most membrane, the thylakoid, in which the
enzymes for photosynthesis and ATP synthesis reside. This membrane is thought to have been
, present prior to endosymbiosis and has similarly undergone considerable expansion of its
surface area to better serve the eukaryotic host. - correct answer ✔✔.
What are the three major strategies by which proteins enter a cellular compartment (slide 9) -
correct answer ✔✔1) transport through nuclear pores
2) transport across membranes (proteins must be unfolded)
3) transport by vesicles
What are signal sequences? What is a sequence motif? - correct answer ✔✔- signal sequences:
short tail of amino acids that directs a protein to a specific cellular compartment
- sequence motif: any of a number of sequences or sequence arrangements that indicate the
likely function of a segment of DNA
What does it mean for a signal sequence to be necessary and sufficient for intracellular
targeting? - correct answer ✔✔signal sequences determine where a protein is going to end up
and are typically cleaved after the protein has been successfully transported
What is the structural relationship between the ER and the nuclear envelope? - correct answer
✔✔the nuclear envelope (specifically the outer nuclear membrane) and the rough ER are
continuous with one another
What is the nuclear lamina and what purpose does it serve? - correct answer ✔✔cytoskeletal
filament meshwork providing structural support
Describe the structure, composition and size of the nuclear pore complex (NPC). - correct
answer ✔✔- nuclear pore complexes are found scattered across the nucleus in order to
facilitate transport
- made up of 400+ individual proteins, 110 megadaltons in size
- proteins lining the inside of the pore form a gel-like mesh and basket that catch large
molecules
