CH. 4: Cell Structures Flashcards
plasma membrane
outer layer of the cell, composed mainly of lipids and proteins;
encloses the cell contents; regulates what enters and leaves the cell; participates in many activities,
such as growth, reproduction, and interactions between cells
microvilli
short extensions of the cell membrane; absorb materials into the cell
nucleus
large, dark-staining organelle near the center of the cell, composed of DNA and proteins; contains the chromosomes, the hereditary units that direct all cellular activities
nucleolus
small body in the nucleus; composed of RNA, DNA, and protein; makes ribosomes
cytoplasm
colloidal suspension that fills the cell from the nuclear membrane to the plasma membrane; site of many cellular activities. Consists of cytosol and organelles
cytosol
the fluid portion of the cytoplasm; surrounds the organelles
endoplasmic reticulum (ER)
network of membranes within the cytoplasm
Smooth ER
no ribosomes attached to it; involved with lipid synthesis.
Rough ER
has ribosomes attached to it; sorts proteins and forms them into more complex compounds.
ribosomes
small bodies free in the cytoplasm or attached to the ER, composed of RNA and protein;
manufacture proteins
mitochondria
convert energy from nutrients into ATP
Golgi apparatus
makes compounds containing proteins, sorts and prepares these compounds for transport to other parts of the cell or out of the cell
lysosomes
small sacs of digestive enzymes;
digest substances within the cell
peroxisomes
membrane-enclosed organelles containing enzymes; break down harmful substances
vesicles
store materials and move materials into or out of the cell in bulk
