the ability of the plasma membrane to let

some substances in and keep others out, and is essential for

maintaining cellular homeostasis.

(a)  

maintenance of a relatively constant internal

environment despite fluctuations in the external environment.

(a)  

Downhill transport of solutes across the membrane.

(a)  

Molecules tend to move randomly

(due to spontaneous molecular

motion) from areas where they are

highly concentrated to areas of

lower concentration, until they are

evenly distributed in a state of

dynamic equilibrium.

This process accounts for most of

the short-distance transport of substances moving into and out of the cells.

(a)  

For polar molecules (not soluble in lipids),

diffusion may occur through protein

channels (pores) in the lipid bilayer.

Protein channels offer a continuous

pathway for specific molecules to move

across the plasma membrane so that they

never come into contact with the

hydrophobic layer or its polar surface.

Large molecules and some of those not

soluble in lipids require assistance in

passing through the plasma membrane.

This process called facilitated diffusion

also requires no energy input to occur.

To pass through the membrane, a

molecule temporarily binds with a carrier protein in the plasma membrane and is

transported from an area of higher to one of lower concentration.

(a)  

(also called carriers, permeases, or transporters)

• undergo a series of conformational changes to transfer the

bound solute across the membrane.

(a)  

allow specific solutes (usually inorganic ions of appropriate

size and charge) to pass.

• transport occurs in much faster rate

(a)  

It is the diffusion of water through a selectively

permeable membrane from an area of higher

concentration to an area of lower

concentration.

(a)  

refers to the relative

concentration of solutes in the water

inside and outside the cell.

(a)  

solution, the solute

concentration is the same inside and

outside the cell. The concentration of

water molecules is also the same inside

and outside the red blood cell; thus,

water molecules move through the

plasma membranes at the same rate in

both directions, and there is no net movement of water in either direction.

(a)  

the solute concentration is higher outside the red blood

cell than inside it. Because there is a higher concentration of water molecules

inside the cell than outside, water moves out of the cell, which shrinks. This

condition is called crenation in red blood cells.

(a)  

the solute concentration is lower outside the red blood

cell than inside. Conversely, the concentration of water molecules is higher outside

the cell than inside. As a result, water moves into the cell, which swells and may

burst.

(a)  

It is a process that forces small molecules through selectively permeable

membranes with the aid of hydrostatic (water) pressure (or some other externally

applied force, such as blood pressure).

(a)  

The diffusion of dissolved solutes through a semi-permeable membranes with the

movement towards down the concentration gradient.

(a)  

processes move molecules and other substances through a

selectively permeable membrane against a concentration gradient – that is, from

an area of lower to one of higher concentration. Because the movement is against

the concentration gradient, ATP energy is required.

The active transport process is similar to facilitated diffusion, except that the

transport protein (carrier protein) in the plasma membrane must use energy to

move the molecules against their concentration gradient.

(a)  

couple the uphill transport of one solute across the

membrane to the downhill transport of another.

(a)  

couple uphill transport to the hydrolysis of ATP.

(a)  

which are found mainly in bacterial cells, couple uphill

transport to an input of energy from light, as with bacterio-rhodopsin.

(a)  

keeps the calcium concentration many hundred times lower

inside the cell than outside.

(a)  

(“cell drinking”)

nonspecific uptake of small

droplets of extracellular fluid.

(a)  

(“cell eating”) the

material taken into the cell is solid

rather than liquid. Commonly, an

organelle called a lysosome

combines with the vesicle to form

a phagolysosome (“digestion

vacuole”), and lysosomal

digestive enzymes

(a)  

refers to the complete sequence of events involving interphase, cell

division, cell growth, cell senescence/aging, and cell death.

(a)  

called the metabolic stage of the cell cycle, although there are no signs

of cell division at this stage.

(a)  

a process of indirect cell division. Indirect in the sense that the products

generated after the process are two similar daughter cells, each with the

same number of chromosomes.

(a)  

first stage of mitosis, during which the chromosomes are

condensed and attached to the mitotic spindle.

(a)  

the stage of chromosome alignment at the metaphase or

equatorial plate.

(a)  

the stage of chromosome separation and migration to the

opposite poles.

(a)  

the stage of nuclear reconstitution, the stage of cytoplasmic

division.

(a)  

refers to the division of the cytoplasm of an animal cell into two.

(a)  

occurs in the male gonads or testes and involves steps

or changes leading to the production of

spermatids, which

differentiate into mature male gametes (sperm cells). Four haploid

spermatids are

produced after meiosis of one spermatogonium.

(a)  

occurs in the female gonads or ovaries. It is composed of steps

leading to the polar bodies and ootids.

A haploid ootid matures into a female gamete (egg cell). Three polar bodies

and one functional egg cell are produced after meiosis of one oogonium.

(a)  

a direct type of cell division which involves the constriction of the cytoplasm

and of the nucleus into two or more parts or cells, with approximately equal

amounts of nuclear and cytoplasmic materials.

- chromosomes are not formed and the chromatin material is not divided in a

strict quantitative way.

(a)  

the body of the parent is divided into two approximately

equal parts, each of which grows into an individual similar to the parent.

- common among protozoans.

(a)  

involves the unequal division of the organism. The new individual

arises as an outgrowth (bud) from the parent. The bud develops organs like

that of the parent and then detaches itself.

(a)  

The bud is formed on the surface of the parent, e.g.,

hydra.

(a)  

The bud is formed within the parent’s body (called

gemmules/internal buds). Several gemmules may be formed, surrounded

by a dense covering in the body wall. When the body of the parent

disintegrates, each gemmule gives rise to a new individual, e.g., freshwater

sponge.

(a)  

most active during embryonic development in injured tissues, and in the

production of tumors like cancer.

(a)  

is a nucleotide with three phosphate groups

instead of one phosphate group.

(a)  

is the process by which ATP is produced by cells by the

complete oxidation of organic compounds using oxygen.

(a)  

The remaining two carbons from the pyruvate feed into a complicated set of

reactions

(a)