Chapter 4: Cell Flashcards
The major components of the cell
- plasma membrane
- cytoplasm
- nucleus
Plasma membrane
the selectively permeable barrier separating internal contents from the external environment
Cytoplasm
cellular contents between the plasma membrane and nucleus; includes:
- cytosol (fluid of the cytoplasm)
- inclusions
- organelles
Nucleus
the largest structure in the cell that’s enclosed by a nuclear envelope; contains genetic material (DNA); also contains a nucleus
Organelles
“little organs”; complex organized structures within cells
Membrane-bound organelles
- endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes, mitochondria
Non-membrane-bound organelles
- ribosomes
- cytoskeleton
- centrosome
- proteasomes
Cell functions
- maintain integrity and shape of the cell
- obtain nutrients and form chemical building blocks
- dispose of wastes
- some are capable of cell division
Mitochondria
“powerhouse of the cell’; complete digestion of fuel molecules to synthesize ATP
Golgi apparatus
“warehouse of the cell”; modification, packaging, and sorting proteins; formation of secretory vesicles and lysosomes
Rough endoplasmic reticulum
peroxisomes produced here; protein production by ribosomes, inserted into ER
Smooth endoplasmic reticulum
- synthesis, transport, and storage of lipids
- carbohydrate metabolism
- detoxification of drugs and poisons
Bound ribosomes
attached to the external surface of the ER membrane; synthesize proteins for export, become part of plasma membrane, or serve as enzymes in lysosomes
Free ribosomes
suspend within cytosol; all other proteins within cell synthesized here
Lysosomes
contain digestive enzymes formed by golgi; participate in the digestion of unneeded substances
Passive transport
do not require energy; depend on substances moving down the concentration gradient; two types:
1- diffusion
2- osmosis
Diffusion
movement of solutes; end result: equal distribution
Osmosis
movement of water; end result: equal concentration
Active transport
requires energy; movement of a solute against its concentration gradient
Types of active transport
- ion pumps
- Na+/K+ pumps
Ion pumps
maintain internal concentrations of ions
Na+/K+ pumps
continuously exports Na+ out of the cell and moves K+ into the cell
Exocytosis
large substances secreted from the cell
Endocytosis
cellular uptake of large substances from external environment
Phagocytosis
“cellular eating”; occurs when a cell engulfs a large particle external to the cell
Pinocytosis
“cellular drinking”; internalization of droplets of interstitial fluid containing dissolved solutes
Isotonic solutions
both cytosol and solution have same relative concentration of solutes
Hypotonic solution
gains water through osmosis; extracellular fluid has a lower concentration of solutes, higher concentration of water than in cytosol
Hypertonic solution
loses water through osmosis; extracellular fluid has a higher concentration of solutes than cytosol, a lower concentration of water than in cytosol
