CHAPTER 3: Cell Structures and Their Functions

secretory vesicle

contains materials produced in the cell, formed by the Golgi apparatus, secreted by exocytosis

centrioles

facilitate the movement of chromosomes during cell division

diffusion

Solutes, such as ions or molecules, tend to move from an area of higher concentration of a solute to an area of lower concentration of that same solute in solution. E..g., O2, CO2, Cl−, urea

osmosis

With the concentration gradient (for water) through the lipid portion of the cell membrane or through membrane channels

facilitated diffusion

With the concentration gradient by carrier molecules.E.g, Glucose in most cells

active transport

Against the concentration gradient* by carrier molecules. E.g., Na+, K+, Ca2+, H+, and amino acids

Secondary active transport

Against the concentration gradient by carrier molecules; the energy for this of one substance comes from the concentration gradient of another. E.g., glucose and amino acid

endocytosis

movement into cells by vesicle. E.g., Ingestion of particles by phagocytosis and liquids by pinocytosis

exocytosis

movement out of cells by vesicles. E.g.,secretion of proteins

leak channels

Some channels constantly allow ions to pass through. These channels are called

gated channels

Other channels limit the movement of ions across the membrane by opening and

closing. These channels are called g

osmotic pressure

is the force required to prevent the movement of water across a selectively permeable membrane. Thus, this is a measure of the tendency of water to move by osmosis across a selectively permeable membrane

hypotonic solution

usually has a lower concentration of solutes and a higher concentration of water relative to the cytoplasm of the cell. Thus, the solution has less tone, or osmotic pressure, than the cell. Water moves by osmosis into the cell, causing it to swell.

isotonic solution

the concentrations of various solutes and water are the same on both sides of the cell membrane. The cell therefore neither shrinks nor swells

hypertonic solution

the solution usually has a higher concentration of solutes and a lower concentration of water relative to the cytoplasm of the cell. Water moves by osmosis from the cell, resulting in cell shrinkage, or crenation

vesicle

is a small, membrane-bound sac that transports or stores materials within cells

microvili

are specialized extensions of the cell membrane that are supported by microfilaments , but they do not actively move as cilia and flagella do. Microvilli are numerous on cells that have them, and they increase the surface area of those cells. They are abundant on the surface of cells that line the intestine, kidney, and other areas in which absorption is an important function.

gene expression

DNA contains the information that directs protein synthesis. This process is called

messenger RNA

travels from the nucleus to the ribosomes in the cytoplasm, where the information in the copy is used to construct a protein by means of translation.

transfer RNA

carry the amino acids to the ribosome to synthesize protein

interphase

Cell life cycle stage: the DNA (located in chromosomes in the cell’s nucleus) is replicated. The two strands of DNA separate from each other, and each strand serves as a template for the production of a new strand of DNA

cell division

is the formation of daughter cells from a single parent cell. The new cells necessary for growth and tissue repair are formed through mitosis, and the sex cells necessary for reproduction are formed through meiosi

autosome

The remaining 22 pairs of chromosomes are called __ determine most other characteristics except the individual’s sex

mitosis

a parent cell divides to form two daughter cells with the same amount and type of DNA as the parent cell. Because DNA determines the structure and function of cells, the daughter cells, which have the same DNA as the parent cell, can have the same structure and perform the same functions as the parent cell.

prophase

Cell life cycle stage: the chromatin condenses into chromosomes. Each chromosome consists of two chromatids joined at the centromere. The centrioles move to the opposite ends of the cell, and the nucleolus and the nuclear envelope disappear.

metaphase

Cell life cycle stage: the chromosomes align in the center of the cell in association with the spindle fibers.

anaphase

Cell life cycle stage: the chromatids separate to form two sets of identical chromosomes. The chromosomes, assisted by the spindle fibers, move toward the centrioles at each end of the cell. The cytoplasm begins to divide.

telophase

Cell life cycle stage: the chromosomes disperse, the nuclear envelopes and the nucleoli form, and the cytoplasm continues to divide to form two cells.

apoptosis

programmed cell death is a normal process by which cell numbers within various tissues are adjusted and controlled.

free radical

which are atoms or molecules with an unpaired electron