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75 terms

Chapter 3 Key Terms

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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