bio ch 5 questions

important in holding the components of a biological membrane together?

- hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane - hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane - hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane - polar interactions among the phospholipid head groups on the same surface of the membrane

glycoprotein

A protein with one or more carbohydrates covalently attached to it.

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

Amphipathic nature Detergents form micelles around the grease, which are then washed away because the polar head groups facing outward on the micelle are water-soluble.

passive transport

Diffusion across a biological membrane

How can a lipid be distinguished from a sugar?

Lipids are mostly nonpolar, whereas sugars are polar.

Which of the following particles could diffuse easily through a cell membrane?

Oxygen (O2) Small nonpolar molecules such as oxygen can diffuse across cell membranes.

Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of a transport protein?

Small, nonpolar, lipid-soluble molecules can pass rapidly through the phospholipids of the plasma membrane. Ions, such as hydrogen ions, and hydrophilic molecules, such as water and glucose, cannot rapidly pass directly through the phospholipids of the membrane. To move rapidly through the membrane, they must pass through membrane transport proteins.

The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.

Which of the following factors does not affect membrane permeability?

The polarity of membrane phospholipids

Which of the following statements about osmosis is correct?

The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis. Aquaporins facilitate water movement across membranes and thus speed up the process of osmosis.

Which factors affect the rate of osmotic movement of water?

The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane. The rate of osmosis varies with a number of factors, including temperature, pressure, and the difference in solute concentrations between two solutions separated by a selectively permeable membrane.

Which of the following factors affects membrane permeability?

The saturation of hydrocarbon tails in membrane phospholipids Temperature the amount of cholesterol in the membrane

In facilitated diffusion, what is the role of the transport protein?

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium?

Water molecules move between the two solutions, but there is no net movement of water across the membrane. Water molecules are constantly in motion and will continually move across the membrane. However, becuase the solutions are in equilibrium, there is not net movement across the membrane.

Which of the following molecular movements is due to diffusion or osmosis?

When a plant cell is placed in concentrated salt water, water moves out of the cell. If the salt water is hypertonic to the plant cell's contents, water moves out of the cell by osmosis, a form of diffusion.

Which of the following factors would tend to increase membrane fluidity?

a greater proportion of unsaturated phospholipids

If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol?

active transport For the cell to accumulate phosphate, it must move calcium against the concentration gradient. This process requires energy

Which of the following is least likely to be important in holding the components of a biological membrane together?

covalent interactions between the phospholipid and protein components of the membrane; there are rarely covalent bonds between the phospholipids and integral membrane proteins.

Osmosis

diffusion of water across a selectively permeable membrane.

receptor protein

has a binding site for a signal protein and can emit a second messenger.

Hydrophobic interactions among the fatty acid tails of the phospholipids

hold the phospholipids together.

Defensive proteins are manufactured by the _____ system.

immune

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

A carbon atom and a hydrogen atom form what type of bond in a molecule?

nonpolar covalent bond

atomic number

number of protons in the nucleus.

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

Which of these does NOT contain a structural protein? tendons muscles ligaments spider silk ovalbumin

ovalbumin

Which of the following processes includes all the others? transport of an ion down its electrochemical gradient osmosis passive transport diffusion of a solute across a membrane facilitated diffusion

passive transport

Facilitated diffusion is a type of _______.

passive transport; the cell is not expending energy to move the particles across the membrane

A white blood cell engulfing a bacterium is an example of _____.

phagocytosis

Oxygen is more electronegative than hydrogen.

polar covalent bond

What type of bond joins the carbon atom to each of the hydrogen atoms?

single (nonpolar) covalent Each carbon-hydrogen bond involves a single pair of equally shared electrons

function of cholesterol

stabilization of the phospholipids/structure of the plasma membrane.

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

mass number

the sum of the number of neutrons and protons in an atomic nucleus

The permeability of a biological membrane to a specific polar solute may depend on which of the following?

the types of transport proteins in the membrane. The lipid bilayer will be impermeable or very poorly permeable to polar or charged solutes. The presence of the correct transport protein will determine the permeability.

Which of the following best describes the structure of a biological membrane?

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers. The membrane proteins can be found either embedded in or attached to the surface of the phospholipid bilayer.