-
Question 1
Incorrect
-
Question 2
Incorrect
-
Inhibition of cell division at the end of G1 occurs through:
Your Answer: p53
Correct Answer: Unphosphorolated retinoblastoma protein (uRb)
Explanation:A cell’s decision to enter, or re-enter, the cell cycle is made before S-phase in G1 at what is known as the restriction point, and is determined by the combination of promotional and inhibitory extracellular signals that are received and processed. Ultimately unphosphorylated Rb acts as an inhibitor of G1.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 3
Correct
-
Cyclic AMP activates the following enzyme
Your Answer: Protein Kinase A
Explanation:Cyclic AMP works by activating protein kinase A (PKA, or cAMP-dependent protein kinase). Protein kinase A can also phosphorylate specific proteins that bind to promoter regions of DNA, causing increases in transcription.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 4
Incorrect
-
The cell membrane:
Your Answer:
Correct Answer: Is a bilayer of amphipathic lipids
Explanation:The cell membrane consists of a bilayer of amphipathic lipids with embedded proteins. The basic function of the cell membrane is to protect the cell from its surroundings. It is selectively permeable to ions and organic molecules. The entire membrane is held together via non-covalent interaction of hydrophobic tails, however the structure is quite fluid and not fixed rigidly in place. Membranes are typically 7.5–10 nm in thickness and typically have a large content of proteins, around 50% of membrane volume.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 5
Incorrect
-
Cell membrane proteins may act as:
Your Answer:
Correct Answer: All of the options
Explanation:Membrane proteins perform a variety of functions including:Membrane receptor proteins relay or carry signals between the cell’s internal and external environments.Transport proteins move molecules and ions (ionic channels) across the membrane. Membrane enzymes may have many activities, such as oxidoreductase, transferase or hydrolase andCell adhesion molecules
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 6
Incorrect
-
The interior of lysosomes is kept at a pH of around 5 by the action of:
Your Answer:
Correct Answer: H+ ATPase
Explanation:The lysosome maintains its pH differential by pumping in protons (H+ ions) from the cytosol across the membrane via proton pumps and chloride ion channels. Vacuolar H+-ATPases are responsible for transport of protons, while the counter transport of chloride ions is performed by ClC-7 Cl−/H+ antiporter.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 7
Incorrect
-
With regards to the Na+/K+ ATPase, which one of the following is correct?
Your Answer:
Correct Answer: 3 Na+ released into the extracellular fluid
Explanation:Na+/K+ pump or sodium–potassium pump is an enzyme found in the plasma membrane. This pumping is active (i.e. it uses energy from ATP) and is important for cell physiology. Its simple function is to pump 3 sodium ions out for every 2 potassium ions taken in and since they both have equal ionic charges, this creates a electrochemical gradient between a cell and its exterior.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 8
Incorrect
-
What is the function of the pro-apoptotic Bcl-2 family of proteins, Bax and Bak?
Your Answer:
Correct Answer: Form permissive pores in the mitochondrial membrane
Explanation:The pro-apoptotic proteins in the BCL-2 family, including Bax and Bak, normally act on the mitochondrial membrane to promote permeabilization and release of cytochrome C and ROS, that are important signals in the apoptosis cascade. Growing evidence suggests that activated BAX and/or Bak form an oligomeric pore, MAC in the mitochondrial outer membrane. This results in the release of cytochrome c and other pro-apoptotic factors from the mitochondria, often referred to as mitochondrial outer membrane permeabilization, leading to activation of caspases.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 9
Incorrect
-
In the presence of oxygen , lactate that was produced under anaerobic conditions is converted to:
Your Answer:
Correct Answer: Pyruvate
Explanation:Lactate can be used in two ways:Oxidation back to pyruvate by well-oxygenated muscle cells, heart cells, and brain cells. Pyruvate is then directly used to fuel the Krebs cycle orConversion to glucose via gluconeogenesis in the liver and release back into circulation.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
-
Question 10
Incorrect
-
What is the function of gap junctions?
Your Answer:
Correct Answer: Diffusion of small molecules between neighbouring cells
Explanation:Gap junctions are a specialized intercellular connection between a multitude of cell-types. They directly connect the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells.
-
This question is part of the following fields:
- Cell Biology
- Medicine
-
SESSION STATS - PERFORMANCE PER SPECIALTY
