30 Questions
What is the purpose of the polypeptide signal sequence in protein synthesis?
To target the polypeptide to the ER membrane
Which cellular structure plays a key role in recognizing the signal sequence during protein synthesis?
Signal recognition particle (SRP)
What happens when the SRP binds to the polypeptide and ribosome during protein synthesis?
Ribosome synthesis is halted
Where is the complex of polypeptide, ribosome, and SRP ultimately recruited during protein synthesis?
Endoplasmic Reticulum (ER) membrane
What is the function of the translocon in ER membrane during protein synthesis?
Polypeptide insertion into ER lumen
How does co-translational translocation differ from post-translational translocation in protein synthesis?
Co-translational translocation deposits proteins into the ER lumen during their synthesis
What is the main function of the lipid bilayer in a cell?
Maintaining internal cell composition
What is the significance of liposomes in membrane research?
Serving as drug delivery vehicles
How do oligosaccharides attach to polypeptide chains in cell membranes?
N-linkages and O-linkages
What determines a person's blood type according to the text?
The carbohydrates on red blood cell glycolipids
What happens in blood type A individuals according to the text?
An enzyme adds N-acetylgalactosamine to the end of the chain
What role do carbohydrate projections play in cell interactions according to the text?
Mediating interactions with the cell's environment
What is the function of Rabs in vesicle transport?
Anchoring vesicles to membranes
Which statement about SNAREs is correct?
SNAREs bring vesicles and target compartments closer together
How do GTP-bound Rabs associate with membranes?
Using a lipid anchor
What triggers the process of exocytosis in cells?
Increase in calcium ion concentration
How many different Rab genes have been identified in humans?
Over 60
Where are v-SNAREs typically found?
In transport vesicles
Which of the following best describes the role of enzymes in cells?
Enzymes facilitate chemical reactions by increasing their rate
Which of the following statements about cellular metabolism is true?
Metabolism is the sum total of all chemical reactions in a cell
What is the primary role of motor proteins in cells?
To facilitate changes in cell shape and movement
How do cells respond to stimuli from their environment?
By interacting with receptors on their surfaces
Which of the following statements about bacterial cells is true?
Bacterial cells are capable of hundreds of chemical transformations
Which of the following is an example of a mechanical activity that cells can perform?
Transporting materials within the cell
What is the main purpose of phagocytosis in mammals?
To engulf and digest invading organisms, damaged cells, and dead cells
How do proteins enter organelles like the nucleus, mitochondria, chloroplasts, and peroxisomes?
They are imported posttranslationally, after complete synthesis on free ribosomes in the cytosol
What is the key difference between the import of proteins into the RER and the import of proteins into organelles like the nucleus and mitochondria?
The RER imports proteins cotranslationally, while the other organelles import them posttranslationally
What is the primary function of the phagosome formed during phagocytosis?
To fuse with a lysosome to form a phagolysosome
What is the key feature that distinguishes 'professional' phagocytes like macrophages and neutrophils from other cells?
Their specialized function of engulfing and digesting invading organisms, damaged cells, and dead cells
What is the main reason why proteins imported into organelles like the nucleus and mitochondria are synthesized on free ribosomes in the cytosol rather than on ribosomes associated with the RER?
To allow for posttranslational import
Explore the various chemical transformations and reactions that occur in cells. Learn how enzymes play a crucial role in speeding up these reactions. Understand how the sum of all chemical reactions in a cell defines its metabolism.
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