HW 3

How does facilitated diffusion differ from simple diffusion?

Membrane proteins help move molecules across the membrane.

Which of the following statements about prokaryotic and eukaryotic cells is FALSE?

Prokaryotic cells usually have internal membranes, and eukaryotic cells usually do not have internal membranes.

One of the ways smooth endoplasmic reticulum (ER) differs from rough endoplasmic reticulum is that rough ER is covered by

ribosomes

What is the difference between passive and active transport?

Active requires energy; passive does not.

What cannot pass directly through the phospholipids of the plasma membrane?

Charged atoms and molecules (ions) cannot pass directly through the phospholipid bilayer. They must pass through membrane transport proteins.

Which of the following is part of the endomembrane system?

Golgi apparatus

Which organelle is responsible for packaging and sending proteins to their appropriate destinations in the cell?

Golgi complex

Which statement is true about the phospholipid bilayer?

The hydrophobic tails face each other in the center of the bilayer.

Which of the following statements about the sodium-potassium pump is true?

Three sodium ions are actively pumped out of the cell, and two potassium ions are pumped into the cell.

Coupled transport differs from primary active transport due to the fact that it uses __________ as a direct source of energy.

an electrochemical gradient

Which major biological molecules make up the plasma membrane?

carbohydrates, proteins, and lipids

Pinocytosis and phagocytosis are types of ________.

endocytosis

You know that this cell is in a(n) _____ solution because it _____.

hypotonic ... lysed

Phagocytosis

involves the engulfing of large particles. This is not an animation of a passive-transport process.

Where in an animal cell is ATP made?

mitochondria

A substance that cannot pass directly through the phospholipids of the plasma membrane must pass through:

transport protein

In exocytosis, what happens?

A transport vesicle fuses with the plasma membrane, attaches, and releases its contents to the extracellular fluid.

Define the term micelle.

It is the structure formed when phospholipid tails join together in the center of a sphere with the hydrophilic heads facing outward.

Which statement about the relationship between carbohydrates and the plasma membrane is true?

Most carbohydrates are attached to proteins in the membrane and thus form glycoproteins

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Which statement about the cell theory is FALSE?

Only eukaryotic cells are a part of the cell theory

Which statement about the diffusion of substances is true

Osmosis is the diffusion of water.

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

Phagocytosis

Some of the cell's ribosomes are found on the surface of the rough endoplasmic reticulum. Which of the following is an immediate result of this anatomical feature?

Proteins for use in lysosomes or outside the cell, and proteins destined to be embedded in the cell membrane are produced.

Solution A has a solute concentration of 10%, and solution B has a solute concentration of 15%. Therefore, which "tonicity" statement is correct?

Solution A is hypotonic to solution B.

Consider this hypothetical situation. Inside the cell you have 357 ions of substance A, 220 ions of substance B, and 520 molecules of substance C (which is a gas). Outside the cell you have 984 ions of substance A, 165 ions of substance B, and 1650 molecules of substance C (which is a gas). If no energy is required for a hypothetical series of actions, and if everything is working "according to the book," what will most likely happen?

Substance A will move into the cell passively; substance B will move out of the cell passively; substance C will move into the cell passively.

If a red blood cell is placed in a beaker containing a salt solution and the red blood cell bursts, what is the most probable relationship between the concentration of salt inside the cell and the concentration of salt in the beaker solution?

The concentration of salt inside the cell is higher than the concentration of salt outside the cell

Saying that the plasma membrane is a fluid mosaic means ________.

The glycoproteins appear to be randomly placed (as in a mosaic) and have a degree of freedom to move about the bilayer. (Fluid means movement.)

Which of the following statements about the plasma membrane is FALSE?

The plasma membrane is not part of the system responsible for the binding together of cells, particularly in multicellular organisms.

Which of the following statements about the sodium-potassium pump is FALSE?

The sodium-potassium pump is used to generate ATP for cellular activities.

What type of transporter would be used to move H+ from low to high into the cell and Na+ from low to high out of the cell?

antiporter (The movement of two different solutes from low to high in opposite directions is mediated by antiporters. In this example, two separate gradients are created: an H+ gradient and a Na+ gradient.)

The structural framework in a cell is the

cytoskeleton (the structural framework in a cell)

Pancreatic lipase is secreted from the pancreas and is charged with the breakdown of fat molecules in the human digestive system. Which process is used to secrete this protein from pancreatic cells?

exocytosis

You have a U-shaped tube with a selectively permeable membrane that allows water to pass but not solutes. On the left side of the tube you have a 40% NaCl solution and on the right a 15% NaCl solution. The left side of the tube is considered __________, while the right side of the tube is considered

hypertonic; hypotonic (The side with 40% has a greater solute concentration compared to 15%. This means the 40% solution is hypertonic compared to the hypotonic 15% solution.)

The major difference between diffusion and endocytosis is that ________.

in endocytosis, larger particles are engulfed; in diffusion, smaller particles pass through the membrane

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

Which of the following represents the digestion center of the cell responsible for breakdown macromolecules and worn-out organelles?

lysosome is the stomach of the cell responsible for breaking down macromolecules and worn-out/damaged organelles

Which of the following organelles breaks down worn-out organelles?

lysosomes

What carries instructions for making proteins from the nucleus into the cytoplasm?

mRNA

Where is the genetic information of the cell stored?

nucleus (DNA is the genetic information of the cell, and it is stored in the nucleus.)

Which of the following is not associated with all cell types?

nucleus (The nucleus is exclusive to eukaryotic cells and is an important distinguishing characteristic between the two cell types.)

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

osmosis

Facilitated diffusion is a type of _______.

passive transport During facilitated diffusion, the cell is not expending energy to move the particles across the membrane; therefore, facilitated diffusion is a form of passive transport.

A __________ uses phagocytosis to engulf and destroy foreign pathogens in the body.

phagocyte

Engulfing bacteria could be described as an example of ________.

phagocytosis

Which of the following represents the bulk import of solids from the environment?

phagocytosis

Which is the hydrophilic portion of the phospholipid molecule?

phosphate

Which of the following makes up the largest part of the cell membrane?

phospholipid molecules

You know that this process is _____ because _____

pinocytosis ... the cell is engulfing extracellular fluid

What structure acts as a selective barrier, regulating the traffic of materials into and out of the cell?

plasma membrane

Which of the following molecules will not be able to easily pass directly through the phospholipid portion of the cell membrane?

polar molecules The phospholipid portion of the cell membrane is largely nonpolar, so nonpolar substances generally can pass through, but polar molecules cannot and instead typically go through protein channels.

While exploring a local wooded area, you encounter what you believe to be a previously uncharacterized organism. Upon microscopic evaluation, you notice a single-celled organism about 1 micrometer, lacking a nucleus. What type of cell is this?

prokaryote (The lack of a nucleus is indicative of a prokaryotic cell.)

Which type of molecule forms channels through the cell membrane?

protein

You have a U-shaped tube with a selectively permeable membrane that allows water to pass but not solutes. On the left side of the tube you have a 40% NaCl solution and on the right a 15% NaCl solution. Which way will water move in this scenario?

right to left

A patient enters your office complaining of excessive stiffness and cramps after vigorous exercise. Tests reveal the patient has Brody disease, a muscle disorder characterized by impairment of skeletal muscle relaxation due to the inability of the muscle cells to regulate calcium levels in the cytoplasm. Which organelle is most likely affected in this patient?

rough ER (The smooth ER is responsible for a variety of functions, including calcium balance in muscle cells. The ability to clear calcium from the cytoplasm and into the smooth ER allows muscle cells to relax.)

The __________ produces plasma-membrane-associated proteins, which are then sent to the __________ for sorting and processing.

rough ER; Golgi complex (Ribosomes bound to the rough ER are responsible for producing proteins for secretion, membrane-associated proteins, and proteins for other organelles. Upon completion, the protein is sent to the Golgi, where it is modified and shipped off to the plasma membrane.)

Where are lipids made in the cell?

smooth endoplasmic reticulum (ER)

You have a U-shaped tube with a selectively permeable membrane that allows water to pass but not solutes. On the left side of the tube you have a 40% NaCl solution and on the right a 15% NaCl solution. The NaCl in this example is considered the __________.

solute

When particles are engulfed by endocytosis, what is the wall of the vesicle made of?

the plasma membrane

Which of the following is the best definition of passive transport?

the spontaneous movement of molecules from high to low concentrations

True or False. Regarding the proteins and cholesterol in the animal plasma membrane, some proteins are embedded in the bilayer, other proteins are only on one side, and the cholesterol is scattered throughout the inner parts of the membrane.

true Some proteins are embedded in the bilayer, and some proteins are located only on one side. Cholesterol molecules are found scattered between the lipid tails.