Human A&P 1 Mastering HW Set 4: Cells

molecular transport through the membrane

Help prevent molecules from passing through the extracellular space between adjacent cells

-Type of anchoring junction -Abundant in tissues subjected to great mechanical stress

-Allows ions and small molecules to pass through from one cell to another -Present in electrically excitable tissues

-simple diffusion -Nonpolar (or lipid-soluble) molecules dissolve into the phospholipid regions of the cell membrane and will pass with no additional protein transporters required.

a) All cells must be motile and divide.

to transport sodium across the membrane The energy from ATP hydrolysis is used to transport sodium and potassium ions across the membrane and thereby establish concentration gradients for each of those ions. The mechanism illustrated does not include an actual chemical reaction between sodium and potassium ions.

Na+/K+ pump This pump is a protein in the membrane that moves these ions only in one direction, and up their concentration gradient. This is active transport, and it requires the use of energy.

receptor-mediated endocytosis

diffusion down a concentration gradient Transport by diffusion of a molecule down its concentration gradient is a spontaneous process that requires no energy input.

Active transport is ATP dependent, whereas passive transport uses only the kinetic energy of the particles for movement across the plasma membrane. In active transport, the cell provides the metabolic energy (ATP) needed to move substances across the plasma membrane (against their concentration gradient). In passive transport, substances cross the plasma membrane (down their concentration gradient) using kinetic energy, without any energy input from the cell.

Phospholipids form a bilayer that is largely impermeable to water-soluble (polar) molecules.

phagocytosis

Decreasing the number of phospholipids in the plasma membrane.

The cells will swell and ultimately burst.

a hypertonic solution

b) During exocytosis, substances from inside the cell are moved outside. Vesicular transport processes that eject substances from the cell interior into the extracellular fluid are called exocytosis. Exocytosis is a form of active transport; thus, it requires energy, usually in the form of ATP.

the disruption of selective permeability allows water molecules that enter these damaged cells to also leave the cytoplasm Skin is an organ made up of tissues, and tissues are made up of cells. Selective permeability requires an intact cell membrane.

swell and burst

A gap junction is a communicating junction between adjacent cells.

osmosis

Na+ diffusing toward the side of the membrane with Cl− and 50% less Na+ A large gradient will provide a greater kinetic energy that will drive and Na+ will be chemically attracted to the Cl− ; this will create an electrochemical gradient. While this will create a large gradient, consider how the Na+ will interact with the K+.

false! In cell biology, phagocytosis is the process by which a cell - often a phagocyte or a protist - engulfs a solid particle to form an internal compartment known as a phagosome

a voltage or electrical charge across the plasma membrane The membrane potential is the electrical potential energy (measured in millivolts) resulting from the separation of oppositely charged ions across the plasma membrane. At rest, membrane potentials are typically negative, ranging from − 50 to minus 100 mV, with more anions (than cations) concentrated along the internal surface of the membrane, and more cations (than anions) concentrated along the external surface.

The resting membrane potential is maintained solely by passive transport processes.

True All cells have a resting membrane potential (RMP), such that the inside (interior surface) of the cell membrane has a net negative charge while the outside (external surface) of the membrane has a net positive charge. Given the different (opposite) charges on either side of the cell membrane, the cell is considered to be polarized. This RMP, which results from separation of charged particles (ions) across the cell membrane, can be measured in millivolts (typically ranging from −50 to −90 mV depending on the cell typ

a phospholipid bilayer surrounding the cell

phospholipids The plasma (cell) membrane is a phospholipid bilayer, composed of two parallel sheets of phospholipid molecules lying tail to tail, with their polar heads exposed to water on either side of the membrane. This allows the plasma membrane to separate the intracellular fluid (the ICF) from the extracellular fluid (ECF).

pinocytosis

messenger RNA

The cell is producing a large amount of proteins. The nucleolus is the site where ribosomal RNA is synthesized and combined with proteins to form ribosomal. These subunits enter the cytoplasm where they form functional ribosomes used for protein synthesis.