Cell Theory
1. All organisms are composed of one or more cells, and the life processes of metabolism and heredity occur within these cells
2. cells are
... [Show More] the smallest living things, the basic units of organization of all organisms
3. cells arise only by division of a previously existing cell
surface area-to-volume ratio
as a cell's size increases, its volume increases much more rapidly than its surface area
All cells have
1. a nucleoid or nucleus where genetic material is located
2. cytoplasm
3. ribosomes to synthesize proteins
4. plasma membrane
Prokaryotes
simplest organisms
-archaea
-bacteria
Nucleoid
center of the cell where most of the genetic material lies
nuclear envelope
double-membrane structure
-two phospholipid bilayer structure
cytoplasm
semi-fluid matrix that fills the interior of the cell
organelle
part of the cytoplasm that contains organic molecules and ions in solution called the cytosol
plasma membrane
encloses a cell and separates its contents from its surroundings
transport proteins
help molecules and ions move across the plasma membrane, either from the environment to the interior of the cell or vice versa
receptor proteins
induce changes within the cell when they come in contact with specific molecules in the environment
markers
identify a particular type of cell
ribosomes
carry out protein synthesis
-most lack membrane bound organinelles
peptidoglycan
carbo-hydrate matrix that makes up a bacterial cell wall
flagella
threadlike structures protruding from the surface of a cell that are used in locomotion
central vacuole
membrane-bound sac in plant cells that stores proteins, pigments, and waste materials
vesicles
smaller sacs that store and transport a variety of materials
chromosomes
tightly packaged DNA in the nucleus
cytoskeleton
internal protein scaffold in all eukaryotic cells
chromatin
complex structures of proteins, multiple linear chromosomes
ribosomal RNA (rRNA)
subunits form a functional ribosome to actively synthesize proteins
messenger RNA (mRNA)
carries coding info from DNA
transfer RNA (tRNA)
carries amino acids
RER
structure: pebbly surface with ribosomes, flattened sacs
-proteins synthesized on the surface designed to be exported from the cell
SER
structure: tubules, flattened sacs, higher order tubular arays
-the membrane contains embedded enzymes
-steroid hormones synthesized here
-membrane lipids assembled here
-store the signalling molecule (Ca2+)
-more abundant in testes, brain, and intestines
golgi apparatus
flattened stacks of membranes that sort and package proteins [Show Less]