Bio 2 Unit 2 Test

Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements. 1 The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center. 2 The diverse proteins found in and attached to membranes perform many important functions. 3 The kinky tails of some proteins help keep the membrane fluid by preventing the component molecules from packing solidly together. 4 Membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer. 5 Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.

1,2,5

Active Transport

A cell must expend energy to move a solute against its concentration gradient

Which of the following statements regarding membrane function is false? A. The plasma membrane is the control center of the cell B. The plasma membrane plays a role in transferring signals to the cells interior C. The plasma membrane has receptors for chemical messages D. The plasma membrane forms a selective barrier around the cell

A. The plasma membrane is the control center of the cell

Energy Source

ATP

Role that exocytosis has on surface area of cell membrane?

Add too the surface of the cell membrane

Transport proteins

Allow specific ions (particles with charges or molecules to enter or exit the cell)

Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____.

B ... the diffusion gradient there is steeper

Which of the following is a difference between active transport and facilitated diffusion? A. Active transport involves transport proteins, and facilitated diffusion does not. B. Active transport requires the expenditure of cellular energy, and facilitated diffusion does not. C. Facilitated diffusion involves transport proteins, and active transport does not. D. Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot

B. Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.

Which of the following statements regarding membrane protein function is false? A. Membrane proteins serve as enzymes B. Membrane proteins produce phospholipids C. Membrane proteins form junctions between cells D. Membrane proteins act as receptors to molecules like hormones

B. Membrane proteins produce phosolipids

Which of these statements is TRUE with regard to this animation? A. The cell is not expending energy. B. Potassium ions are transported down their concentration gradient. C. Sodium and potassium ions are transported against their concentration gradients. D. The cell does not expend ATP. E. Sodium ions are transported down their concentration gradient.

C. Sodium and potassium ions are transported against their concentration gradients.

Know components of plasma membrane

Cholesterol Phospholipid Protein

You are working on a team that is designing a new drug. In order for this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule enters the cell? A) blood or tissue type of the patient B) non-polarity of the drug molecule C) lack of charge on the drug molecule D) similarity of the drug molecule to other molecules transported by the target cells E) lipid composition of the target cellsʹ plasma membrane

D) similarity of the drug molecule to other molecules transported by the target cells

Passive Transport

Diffusion across a membrane with no energy

Facilitated diffusion

Does not require energy and relies on the concentration gradient

Concentration Gradient

Explain that things are in a higher concentration on side and a lower concentration on the other side. Higher concentration of solvent=lower concentration of solute. High solute=low solvent

Junction Proteins

Form intercellular junctions that attach adjacent cells

What is the importance of cholesterol?

Keeps the whole cell membrane fluid

Which types of molecules will actively transport?

Larger molecules, charged-polar molecules

Diffusion

Passive transport; moving from high to low concentration. Done by CO2, oxygen and glucose

Three types of endocytosis:

Phagocytosis, Pinocytosis and Receptor-mediated

Fluid Mosaic Model

Phospolid bilayer embedded with proteins

Glycoproteins

Serve as ID tags May be recognized by membrane proteins of other cells

Receptor proteins

Signaling molecules bind to receptor proteins Receptor proteins relay the message by activating other molecules inside the cell 3 stages: reception, transduction, and response of the cell

Which types of molecules will passively transport?

Small non-polar molecules; Oxygen, CO2 (by diffusion) , glucose, water (by aquaporins)

Enzymes

Some membrane proteins are enzymes Enzymes may be grouped to carry out sequential reactions

Role that endocytosis has on surface area of cell membrane?

Takes away from the surface of the cell membrane

Osmosis

The diffusion of water across a selectively permeable membrane

Hypotonic

a lower amount of solute and a greater amount of solvent.

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of ________________.

active transport

When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This molecule rapidly enters the cell regardless of whether its concentration is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane?

active transport

Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____.

actively pump water back into their cells to counter its loss due to osmosis

Membrane phospholipids _____________.

are able to drift about in the plasma membrane since they remain fluid due to cholesterol

attachment proteins

attach to extracellular matrix and cytoskeleton Help support the membrane Can coordinate external and internal changes

Which type of proteins help support the membrane and can coordinate external and internal changes?

attachment proteins

Lysed

burst open

Pinocytosis

cell-drinking, or engulfment of extracellular liquid

Tonicity

describes the ability of a surrounding solution to cause a cell to gain or lose water

The first mosaic model describes the plasma membrane as consisting of what?

diverse proteins embedded in a phosolipid bilayer

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via __________.

endocytosis

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of __________.

endocytosis

Isotonic

equal amount of concentration.

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of __________________.

facilitated diffusion

Which type of proteins serve as ID tags and aid in cell to cell recognition?

glycoproteins

The cholesertrol associated with animal cell membranes ____________.

helps to keep phospholipids from being too close to one another, thus remaining fluid

A plant cell placed in a(n) _______________solution will lose water and plasmolyze.

hypertonic

There is a net diffusion of water out of an animal cell when it is placed in a(n) ___________solution.

hypertonic

An animal cell placed in a(n) __________solution will gain water, swell, and possibly burst.

hypotonic

The ideal osmotic environment for a plant cell is a(n) ________ environment.

hypotonic

Plant Cells optimal solution type

hypotonic; in hyper, plasmolysis happens cell membrane separates from cell wall

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

Endocytosis

is used to take in large molecules.

A plant cell surrounded by a(n) _____________ solution will be flaccid (limp).

isotonic

Animal Cells optimal solution type

isotonic

The ideal osmotic environment for an animal cell is a(n) _____________environment.

isotonic

In active transport, _____________________.

molecules move across the plasma membrane against their concentration gradient.

When molecules move down their concentration gradient, they move from where they are ____________ to where they are ________________.

more concentrated; less concentrated

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

osmosis

Diffusion across a biological membrane is called ______________________.

passive transport

Facilitated diffusion is a type of _____.

passive transport

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

phagocytosis

In the fluid mosaic model, where are the kinky tails?

phosolipid bilayer

Most of the function of a cell membrane, including transport and enzymatic fucntion are _______.

proteins

What molecules are responsible in phospholipid bilayer for cellular transport

proteins

Which type of proteins binds with a ligand?

receptor proteins

Hypertonic

solution has more solute and less solvent (water) than the cell.

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?

the difference in water concentration across a selectively permeable membrane

Phagocytosis

the engulfment of a particle by the cell wrapping cell membrane around it, forming a vacuole

How would fatty acids get through the membrane and why?

they travel by passive transport, specfically diffusion. the tails are fatty-acids which allows them to pass through

Water crosses the plasma membrane.

through facilitated diffusion or diffusion.

Which proteins allows specific ions or molecules to enter or exit the cell?

transport proteins

Receptor-mediated

used membrane receptors for specific solutes.

Exocytosis

used to export bulky molecules, such as proteins or polysaccharides.

Aquaporins

very rapid diffusion of water into and out of certain cells is made possible by a protein channel

Aquaporins are proteins that facilitate the transport of __________ across the membrane

water

In the figure below, working from the inside out, what would be the order of components observed?

water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water