Cells and Cell Membranes Flashcards
Which of the following are principles of cell theory or cell doctrine?
All living organisms are composed of one or more cells, cells are the smallest units of life, and new cells come only from pre-existing cell division.
Which two scientists are credited with figuring out the structure of DNA?
Schleiden and crick
lack a true nucleus
Which of the following structures distinguishes plant cells from animal cells?
Plasma membranes are a feature of
During a period of low water availability, which structure would protect a cell from dessication (drying out)?
Which of the following might account for the general structural and functional differences between a nerve and smooth muscle cell within an individual?
The proteome and the relative amounts of certain proteins differ between muscle and nerve cells.
FtsZ, MreB, adn CreS proteins regulate the shape and structure of bacterial (prokaryotes)cells. These proteins are homologous to what structure in eukaryotes?
Which of the statements about the synthesis ofpolypeptides (proteins)is INCORRECT?
The systhesis of proteins is a catabolic process.
Which cytoskeletal structures represent a highly diverse group of tension-bearing fibers important to the maintenance of cell shape?
The cytoskeleton and motor proteins are important for which of the following processes?
2)whipping motion of sperm flagella
3)movement of amoeba by lamellopodia
Which of the following is NOT true for cilia or flagella?
They are composed of microfilaments.
Large numbers of ribosomes are present in cells that produce which of the following molecules?
In animal cells microtubules grow from which structure?
centrosomes containing centrioles
Which would be the most accurate endomembrane route through which a protein is secreted from a cell?
rough endoplasmic reticulum -->Golgi apparatus --> vesicles-->plasma membrance
Which one of the following pairs is mismatched?
Due to the lack of an enzyme to break down lipids, excess accumulation of lipids in the brain leads to a human disease called Tay Sachs syndrome. Which organelle is likely to be the one that lacks the proper enzyme needed for lipid breakdown?
This organelle is important for the detoxification of alcohol in the liver.
smooth endoplasmic reticulum
In eukaryotes, which of the following is NOT a function of the plasma membrane?
Which of the following organelles can grow and divide to reproduce themselves?
both mitochondria and chloroplasts
Cyanide binds and impairs one of the molecules involved in the production of ATP. Which organelle does cyanide act upon?
Tissues that are metabolically active and utilize large amounts of energy would be rich in
Cellular membrances are
Which of the following is the major lipid found in membranes?
Scientists unearth a Wooly Mammoth from the Siberian Ice Sheath and discover that a cell is still alive. Which component of the cell membrane might contribute to maintaining the fluidity of plasma membranes under freezing conditions?
high levels of unsaturated fatty acyl tails within the lipid bilayer
Which of the following statements is CORRECT about biomembranes?
Membrane proteins are globular, and some span the phospholipid bilayer and project from both side of the membrane.
A scientist produces an artificial membrane from phospholipids and notices that oxygen, but not glucose readily moves through the membrane. What might account for the inability of glucose to move through the artificial membrane?
The artifical membrance lacked a protein meeded for glucose transport.
Which of the following is NOT a component of plasma membranes?
glycosylated nucleic acids
Around what percentage of all genes encode membrance proteins?
The following affect membrance fluidity EXCEPT
Which of the following is TRUE of phospholipids that flip-flop across the lipid bilayer?
The process requires energy and the flippase enzyme.
How might a plant cell compensate for the excessive membrane fluidity that occurs during prolonged exposures to elevated temperature?
Alter the lipid composition to have longer fatty acyl tails and fewer double bonds.
Which of the following is important for allowing large, charged molecules to pass through the membrane?
Placing celery sticks in fresh water will make the more turgid and harder. This is because
the celery is hypertonic to fresh water
Of the following molecules, which passes through a lipid bilayer most readily?
Animal cells are permeable to water and urea but NOT to sucrose. Initially, the inside of a cell contains 1M sucrose and 1M urea and the outside 1M sucrose and 2M urea. After the system reaches equilibrium, what changes are observed?
The molarity of sucrose would be similar inside and outside the cell and water would move out of the cell causing the cell to shrivel.
Which of the following statements is CORRECT about active transport?
1)It requires energy
2)It is an active process in which molecules move from a region of lower concentration to one of higher concentration.
3)It requires integral proteins.
4)It is necessary to maintain solute gradients across a membrance.
Which of the following is NOT true of passive diffusion?
Passive diffusion requires the presence of a transmembrane protein.
The pressure required to stop water from moving across the membrance by osmosis is called
is a carbohydrate-containing coating on the outside of a cell membrance
An organelle that helps break fats and amino acids
A large macromolecule is most likely to be degraded by a:
Vesicles are controlled by tagging their membranes during synthesis with
A lipid anchored membrane protein
have fatty acyl tails that anchor a protein to a membrane.
Phospholipids are Amphipathic
Unsaturated fatty acids make membranes more flexible.
Which of the following is involved in the first step in fatty acid synthesis?
The process of attaching a carbohydrate to a lipid or protein is called:
A molecule synthesized on the inside of a cell membrane may be transferred to the outside by a protein called:
Integral membrane proteins usually contain