Cells, Membranes, and Signaling (U4) Flashcards
What are the three points of the cell theory?
- all organisms are made of cells
- the cell is the basic living unit of organization
- all cells come from pre-existing cells
What are structures all cells have?
plasma membrane, cytosol, chromosomes, and ribosomes
Why can’t a cell be bigger?
volume increases faster than surface area and cells cannot move materials in and out fast enough to support life
How does a cell get bigger?
it divides and becomes multicellular
Ratio
surface area/volume
Prokaryotes
generally smaller/simpler, no nucleus or organelles
Eukaryotes
generally bigger/more complex, nucleus and organelles
Compartmentalization
when internal membranes in eukaryotic cells partition the cell into compartments which creates different local environments
Nuclear envelope
protects DNA, allows for large macromolecules to pass through pores which controls protein synthesis
Nucleolus
within the nucleus, builds ribosomes from rRNA and proteins which exit through the nuclear pores
Ribosomes
create proteins, made of rRNA and protein (2 subunits)
Free ribosomes
suspended in cytosol, synthesize proteins in cytosol
Bound ribosomes
attached to the ER, synthesize proteins for export or the membrane
Endomembrane system
the endoplasmic reticulum, golgi apparatus, lysosomes, and vesicles
Autogenic hypothesis
the origin of the eukaryotic cell is also the prokaryotic cell
Smooth endoplasmic reticulum
synthesizes lipids, hydrolysis, membrane production, and detoxify drugs and poisons
Rough endoplasmic reticulum
contains ribosomes, produces proteins for export out of the cell
Golgi apparatus
sorts, tags and ships cell products through vesicles
Vesicles
transport cell products through the fusing with cell membranes
Lysosomes
found in animal cells, made by rough ER, used to clean up macromolecules and broken down organelles
Mitochondria energy conversion
cellular (aerobic) respiration, breaks down sugars, fats, and fuels in the presence of oxygen
Chloroplast energy conversion
transforms solar energy into chemical energy
Mitochondria
highly folded (cristae) and two membranes, which increases surface area
What are the three parts of the chloroplast?
Stroma, thylakoids, and grana
Endosymbiotic theory
chloroplasts and mitochondria both have circular chromosomes, are semi-autonomous, and contain proteins primarily from free ribosomes in the cytosol
Vacuoles
transferring cell products, storage, turgor pressure in plants
Cytoskeleton
maintains shape of the cell and provides anchorage, regulates and allows for motility
made of microfilaments and microtubules
Phospholipids
hydrophilic head and hydrophobic tail, arranged in a bilayer
Fluid mosaic model
the arrangement of the phospholipid bilayer and proteins together makes a mosaic that can move in “waves” almost like a liquid
Peripheral proteins
proteins loosely bound to the outside of the cell wall (ex. antigens)
Integral/transmembrane proteins
proteins that penetrate the lipid bilayer, usually across the whole membrane (ex. sodium-potassium pump)
Membrane carbohydrates
allows cells to distinguish one another, key in development of organs and immune response
Selectively permeable membrane
the cells ability to let some molecules through and others not
2nd law of thermodynamics
the universe tends towards entropy (disorder)
Simple diffusion (passive transport)
movement from high to low concentration (no energy required)
Facilitated diffusion
diffusion through protein channels (no energy needed)
Osmosis
the diffusion of water
Aquaporins
water channels
Hypotonic
(a cell in fresh water) a high concentration of water around the cell
Hypertonic
(a cell in salt water) a low concentration of water around the cell
Isotonic
a cell in a mild salt solution, no net movement
Passive transport
diffusion of molecules with the concentration gradient
Active transport
diffusion against the concentration gradient
Sodium-potassium pump
enzyme for maintaining osmotic equilibrium
How are large molecules transported through a cell membrane?
through vesicles and vacoules
Phagocytosis
cellular eating
Pinocytosis
cellular drinking
Receptor-mediated endocytosis
when substances enter the cell via inner budding of the plasma membrane
Exocytosis
when substances leave the cell
