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cells

The basic unit of all living things

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

nucleus

the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities

nuclear envelope

layer of two membranes that surrounds the nucleus of a cell

Nuclear Pors

located in the envelope, controls the passage of molecules

Nucleoli

dense masses of RNA and protein that manufacture ribosomes, several of these are located in the nucleus.

Chromatin

long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes

Chromosomes

threadlike structures made of DNA molecules that contain the genes

Plasma Membrane

thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings

Hydrophilic

attracts water molecules

Hydrophobic

avoids water molecules

Tight Junctions

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

Desmosomes

specialized junctions that hold adjacent cell together, consist of dense plate at point of adhesion plus extracellular cementing material

Gap Junctions

cell junctions that allow cells to act as one whole unit

Connexons

the tiny, fluid-filled tunnels characteristic of gap junctions that connect neighboring cells

Cytoplasm

The region of the cell between the cell membrane and the nucleus

Cytosol

the semifluid portion of the cytoplasm

Organelles

tiny structures that carry out functions necessary for the cell to stay alive

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

Ribosomes

non membrane bounded organelles responsible for protein synthesis

Rough ER

That portion of the endoplasmic reticulum studded with ribosomes.

Smooth ER

That portion of the endoplasmic reticulum that is free of ribosomes.

Transport Vesicles

vesicles in transit from one part of the cell to another

Golgi Appartus

a cell organelle that helps make and package materials to be transported out of the cell

Secretory Vesicles

carries proteins to the cell membrane so that they can be released into the extracellular fluid

Lysosomes

An organelle containing digestive enzymes

Peroxisomes

membranous sacs containing enzymes used to break down hydrogen peroxide

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Microfilaments

fine, threadlike proteins found in the cell's cytoskeleton

Microtubules

Spiral strands of protein molecules that form a tubelike structure

Centrioles

two tiny structures located in the cytoplasm near the nuclear envelope

Cila

short numerous hair like projections that move in a wavelike motion

Flagella

whip-like structure used for motility

Microvilli

projections that increase the cell's surface area

Solution

A homogeneous mixture of two or more substances

Solvent

substance in which a solute is dissolved to form a solution

Solutes

substances dissolved in a liquid

Inracellular Fluid

Within the cell, are composed of water plus concentration of potassium and phosphates

Interstitial Fluid

liquid found between the cells of the body that provides much of the liquid environment of the body

Selective Permeability

a process in which a membrane allows some molecules to pass through while keeping others out

Diffusion

the process by which molecules move from an area of higher concentration to an area of lower concentration

Concentration Gradient

the difference in the concentration of molecules across a distance

Osmosis

diffusion of water through a selectively permeable membrane

Facilitated Diffusion

the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins

Pressure Gradient

the rate at which atmospheric pressure declines over a given distance

Active Transport

the movement of materials through a cell membrane using energy

Solute Pumps

are protein carriers energized by ATP

Sodium-Potassium Pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

Vesicular Transport

transport of large particles and macromolecules across plasma membranes

Exocytosis

process by which vesicles release their contents outside the cell

Vesicle

A membrane bound sac that contains materials involved in transport of the cell.

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

Phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

Pinocytosis

process by which a cell takes in liquid from the surrounding environment

Interphase

the first stage of the cell cycle

Mitosis

part of eukaryotic cell division during which the cell nucleus divides

Cytokinesis

division of the cytoplasm during cell division

Prophase

the first stage of mitosis or meiosis in eukaryotic cell division, during which the nuclear envelope breaks down and strands of chromatin form into chromosomes

Chromatid

one of two identical "sister" parts of a duplicated chromosome

Centromere

area where the chromatids of a chromosome are attached

Metaphase

second phase of mitosis, during which the chromosomes line up across the center of the cell

Anaphase

a phase of mitosis and meiosis in which the chromosomes separate

Telphase

The phase of cell division during which the nuclear membrane re- appears and the chromosomes disappear

Cleavage Furrow

The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.

Gene

sequence of DNA that codes for a protein and thus determines a trait

Enzymes

proteins that act as biological catalysts

Ribonucleic Acid

RNA

Transfer Ribonucleic Acid

RNA that translates mRNA to amino acids

Ribosomal Ribonucleic Acid

rRNA in full

Messenger Ribonucleic Acid

a transcription of a gene that combines with ribosomal RNA (rRNA) and transfer RNA (tRNA

Transcription

process in which part of the nucleotide sequence of DNA is copied into a complementary sequence in RNA

Triplet

3 line stanza

Codons

three-nucleotide sequence of mRNA that codes for a single amino acid

Translation

decoding of a mRNA message into a polypeptide chain

Anticodon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

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