44 terms

9th Grade Cell Structure and Function Vocabulary

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cells
the basic unit of life
cell theory
a fundamental concept of biology
objective lens
located just above the specimen
ocular lens
magnifies the image further
transmission electron microscope
uses electron beams to pass through thin slices of specimens
scanning electron microscope
uses pencil like beam of electrons to scan over the surface of the specimen, creating a three-dimensional picture
cell membrane
thin flexible barrier that surrounds all cells
nucleus
large membrane-enclosed structure that contains genetic material in the form of DNA
Eukaryotes
cells that enclose their DNA in nuclei
Prokaryotes
cells that do not enclose their DNA in nuclei
cytoplasm
portion of the cell outside the nucleus
organelles
literally "little organs"; perform functions in a cell
vacuole
large, saclike, membrane-enclosed structures; store materials like water, salts, proteins, and carbohydrates
contractile vacuole
specialized vacuole that pumps excess water out of the cell
vesicles
membrane-enclosed structures that store and move materials between cell organelles, as well as to and from the cell surface
lysosomes
small organelles filled with enzymes; break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell; are also involved in the breakdown of organelles that have outlived their usefulness.
cytoskeleton
a network of protein filaments that give shape and internal organization to Eukaryotic Cells; helps maintain the cells shape and is also involved in movement
microfilaments
threadlike structures made up of a protein called actin; they form extensive networks in some cells and produce a tough flexible framework that supports the cell
microtubules
hollow structures made up of proteins called tubulins; they play critical roles in maintaining cell shape; also important in cell division
centrioles
located near the nucleus and help to organize cell division; not found in plant cells
ribosomes
small particles of RNA and protein found throughout the cytoplasm in all cells; produce proteins by following instructions from the DNA
endoplasmic reticulum
an internal membrane system; where lipid componenets of the cell membrane are assembled, as well as proteins and other materials that are exported from the cell
golgi apparatus
modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell
chloroplasts
bological equivalents of solar power plants; capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis
mitochondria
the power plants of the cell; converts the chemical energy stored in food into compounds that are more convenient for the cell to use
cell wall
strong supporting layer for the cell
lipid bilayer
gives cell membranes a flexible structure that forms a strong barrier between the cell and its surroundings
cell membrane
regulates what enters and leaves the cell and also protects and supports the cell
selectively permeable
some substances can pass across them and others cannot
passive transport
the movement of materials across the cell membrane without using cellular energy
diffusion
process by which molecules of a substance move from an area of higher concentration to an area of lower concentration
facilitated diffusion
process in which molecules that cannot directly diffuse across the membrane pass through special protein channels
aquaporins
water channel proteins
osmosis
the diffusion of water through a selectively permeable membrane
isotonic
same strength
hypertonic
above strength
hypotonic
below strength
endytosis
when a particle enters the cell through active transport
exocytosis
when a particle exits the cell through active transport
homeostasis
a relatively constant internal physical and chemical conditions
tissue
a group of similar cells that performs a particular function
organ
many tissues work together to make this
organ system
many organs work together to make this
receptor
specific protein whose shape fits that of a specific molecular messenger, such as a hormone