Lesson 3.3 Glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
Adenine – One of the four bases in DNA. It pairs only with thymine.
C
Cell membrane – The semipermeable membrane enclosing the cytoplasm of a cell.
Cell wall – The membranous covering of a cell secreted by the cytoplasm in growing
plants.
Cells – The ultimate functional unit of an organic structure, plant, or animal. It
consists of a microscopic mass of protoplasm which includes a nucleus surrounded
by a membrane.
Centriole – A structure that appears during mitosis in animal cells.
Centrosome – A dark body containing a centriole in animal cells, but not plant cells;
spindle fibers radiate from the centrosome in preparation for mitosis.
Chloroplast – Minute objects within plant cells which contain the green pigment,
chlorophyll.
Chromosome – A microscopic, dark-staining body, visible in the nucleus of the cell
at the time of nuclear division, which carries the genes, arranged in linear order. Its
number in any species is usually constant, and it serves as the bridge of inheritance,
i.e., the sole connecting link between two succeeding generations.
Cytoplasm – The living substance within a plant or animal cell excluding the
nucleus.
Cytosine – One of the four bases of DNA; it pairs only with guanine.
Cytoskeleton – A network of long protein strands in the cytosol that helps maintain
the shape and size of a eukaryotic cell.
Cytosol – The gelatin-like aqueous fluid that bathes the organelles on the inside of
the cell membrane.
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D
Deoxyribonucleic acid (DNA) – A genetic proteinlike nucleic acid on plant and
animal genes and chromosomes that controls inheritance. Each DNA molecule
consists of two strands in the shape of a double helix.
E
Eukaryote cell – A cell that contains genetic information or DNA in the nucleus like
most organisms.
G
Genes – The simplest unit of inheritance. Physically, each gene is apparently a
nucleic acid with a unique structure. It influences certain traits.
Golgi apparatus – A system of membranes in eukaryotic cells that modifies proteins
for export by the cell.
Guanine – One of the four bases of DNA; it pairs only with cytosine.
I
Inheritance – The transmission of genetic factors from parent to offspring.
L
Lysosome – An organelle containing digestive enzymes, existing primarily in animal
cells.
M
Mitochondria – Organelles that are the site of aerobic respiration in eukaryotic cells.
Molecule – The smallest part of a substance that can exist separately and still retain
its chemical properties and characteristic composition; the smallest combination of
atoms that will form a given chemical compound.
N
Nuclei – Plural for nucleus.
Nucleolus – A small, rounded body within the cell nucleus, functioning in ribosome
manufacture.
Nucleotide – Each strand of DNA is a linear arrangement of repeating similar units
called nucleotides, which are each composed of one sugar, one phosphate, a
nitrogen base.
Nucleus – The central portion of the cell protoplast surrounded by a very thin
membrane. It consists of nucleoplasm and includes within itself variously arranged
chromatin, nuclear sap, and nutritive substances. It is of crucial significance in
metabolism, growth, reproduction and the transmission of the determiners of
hereditary characters.
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O
Organelle – The inside parts of a cell such as the Golgi apparatus, nucleus,
ribosomes, microtubules, and storage particles.
P
Peroxisome – A cell organelle containing enzymes that catalyze the production and
breakdown of hydrogen peroxide.
Precipitant – A substance that causes a precipitate to form when it is added to a
solution.
Prokaryote – A unicellular organism that lacks a nucleus and membrane-bound
organelles.
Protein synthesis – The formation of proteins using information coded on DNA and
carried by RNA.
R
Ribonucleic acid (RNA) – The substance in the living cells of all organisms that
carries genetic information needed to form protein in the cell.
Ribosome – An organelle that functions in the synthesis of proteins.
Rough endoplasmic reticulum – The portion of the endoplasmic reticulum that
contains attached ribosomes.
S
Secretory vesicle – Membrane bounded vesicle derived from the Golgi apparatus
and containing material that is to be released from the cell.
Smooth endoplasmic reticulum – The portion of the endoplasmic reticulum that
actively transports K+ ions into and Na+ ions out of cells.
Synthesis – The forming or building of a more complex chemical substance or
compound from elements or simpler compounds.
T
Thymine – One of the four bases of DNA; it pairs only with adenine.
Traits – An inherited feature or characteristic.
V
Vacuole – A fluid-filled organelle that stores enzymes or metabolic wastes in a plant
cell.
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