Chapter 3: Cellular Form and Function Flashcards
What is cell theory?
- all organisms are comprised of cells and cell products
- cell is the simplest structural and functional unit of life
- all oranism’s structure and functions are due to the activities of cells
- cells only come from preexisting cells
- cells of all species exhibit biochemical similarities
What are the basic components of a cell and their properties?
cell membrane
- surrounds cell, defines boundaries
- made of proteins and lipids
nucleus
cytoplasm
- organelles
- cytoskeleton
- inclusions (stored or foreign particles)
- cytosol (intracellular fluid, ICF)
What are organelles?
Internal structures of a cell that carry out specialized metabolic tasks.
What are the functions of the plasma membrane?
It is the border of the cell (bilayer). It defines cell boundaries, governs interactions with other cells, and controls the passage of materials in and out of the cell.
What are the membrane lipids?
98% of membrane molecules are lipids
- phospholipids (75%)
- cholestrol (20%)-hold phospholipids still and can stiffen membrane
- glycolipids (5%)
What are the membrane proteins?
These make up 2% of cell membrane molecules but 50% of the weight
- integral proteins: penetrate membrane
- have hydrophilic and hydrophobic regions
- some drift in membrane, others are anchored to cytoskeleton
- peripheral proteins: on the surface of membrane
- adhere to one face of membrane
- usually stuck to cytoskeleton and an integral protein
What are the functions of membrane proteins?
- Receptors (receptor to hormone, lock and key fit)
- second messenger systems
- enzymes
- channel proteins (things go in and out of cell)(hydrophilic solutes need these)
- Carriers (pumps do active transport-e.g. Na/K pump)
- cell identity markers (non-foreign, identify structure)
- cell adhesion molecules (link cell to other cells)
What are the types of channel proteins?
- Some are open, some are gated
- crucial to nerve and muscle function
- ligand gated
- respond to chemical messengers
- (e.g. neurotransmitter)
- voltgate gated
- respond to charge changes
- (e.g. muscle cells contracting, nerve cells for communication)
- mechanically gated
- respond to physical stress on cell
What is the glycocalyx and its functions?
- Fuzzy coat external to plasma membrane
- Made of glycoproteins and glycolipids
- protection, immunity to infection, defense against cancer, transplant compatibility, cell adhesion, fertilization, embryonic development
What are microvilli, cilia, and flagella?
- microvilli
- extensions of membrane (15 to 40x more surface area)
- developed for absorption
- known as brush border
- cilia
- hairlike
- single, nonmotile primary cilium found in nearly every cell (like antenna)
- motile/nonmotile (moving or nonmoving)
- motile: respiratory tract, uterine tubes, ventricles of brain, ducts of testes
- beat material along (power and recovery strokes)
- nonmotile: sensory cells of nose
- motile: respiratory tract, uterine tubes, ventricles of brain, ducts of testes
- flagella
- tail of sperm only one in humans
- whip-like structure
- movement is snakelike (no power and recovery)
How do cilia beat in a saline layer?
- Chloride pumps Cl- into ECF
- Na+ and H2O follow
- Forms a saline layer
- Mucus floats on top of the layer
- Cilia beat the mucus along
- Cystic fibrosis is when the Cl- pump doesn’t work so H2O does not thin mucus (respiratory and pancreatic duct issues)
What are pseudopods?
Continually changing extensions of the cell that vary in shape and size. (Can be used for cellular locomotion, capturing foreign particles)
What are the types of membrane transport?
- Passive mechanisms (require no ATP)
- filtration
- simple diffusion
- facilitated diffusion
- osmosis
- Active mechanisms (consume ATP)
- Primary active transport
- Carrier mediated: use a membrane protein to transport substances across membrane (can be passive or active)
- facilitaton diffusion
- primary active transport
- vesicular transport
What is filtration?
Particles are drive through a membrane by physical pressure. E.g. capillaries (mostly blood pressure)
What is simple diffusion and what are the factors that affect it?
The substances pass directly through the phospholipid bilayer.
Affecting factors: temperature (heat is faster), molecular weight (lighter faster), steepness of concentration gradient (steeper faster), membrane surface area (larger faster), membrane permeability
What is osmosis?
- the diffusion of water through a selectively permeable membrane
- Water moves from where it is more concentrated to where it is less concentrated
- solute particles that cannot pass through the membrane “draw” water from the other side
- Must have membrane, and solutes don’t move
What are some clinical applications of osmosis?
- Crucial for IV fluids (0.9% is isotonic to blood plasma)
- Osmotic imbalances underlie diarrhea, conspitation, and edema
- Osmosis is enhanced by aquaporins, channel proteins in membrane specialized for water passage
What is osmolarity?
The measure of total concentration of solute particle.
What is tonicity?
The ability of a surrounding solution to affect fluid volume and pressure in a cell. (remember tonicity is relative)
What are the 3 mechanisms of carrier mediated transport?
- Uniport: carries one type of solute (e.g. calcium pump)
- symport–carries two or more solutes simultaneously in the same direction (cotransport) (e.g. sodium-glucose transporters)
- antiport–carries two or more solutes in opposite directions (countertransport) (e.g. Sodium/potassium pump)
What are the three mechanisms of carrier mediated transport?
- Facilitated diffusion
* carries moves solute down its concentration gradient, does not require ATP - Primary active transport
- carrier moves a solute through a membrane up (against) its concentration gradient (requires ATP)
- e.g. Sodium/Potassium pump, Calcium pump
- Secondary active transport
What is the structure and function of the Sodium Potassium Pump?
- pumps 3 Na out and 2 K in
- Keeps K concentration higher and Na lower than in the ECF
- necessary because Na and K constantly leak through membrane
- regulates cell volume
- produces heat
- Half of daily calories used on this pump
What is vesicular transport and its types?
- moves large particles, fluid droplets, or numerous molecules at once through the membrane in vesicles
- endocytosis: transport into cell
- exocytosis: transport out of cell
- trafficking: transport from one area or organelle to another
- transcytosis: transport into and out of the cell
What are the types of endocytosis?
- Phagocytosis: “cell eating,” used by white blood cells, forms a phagosome
- Pinocytosis: “cell drinking,” bring in fluid, used by all human cells
- Receptor mediated: more selective, enables cells to take in specific molecules to bind to extracellular receptors
What are the functions of exocytosis?
- ejection of wastes
- release of neurotransmitters
- hormone secretion
- mucus secretion
What are the membranous/nonmembranous organelles?
- membranous: nucleus, mitochondria, lysosomes, peroxisosomes, endoplasmic reticulum, and Golgi complex
- non-membranous: ribosomes, centrosomes, centrioles, basal bodies
What is the function of the cytoskeleton?
- network of protein filaments and cylinders
- Microfilaments maintain shape and microvilli
- Intermediate fibers anchor organelles
- Microtubules move organelles and make centrioles
What is the function of the nucleus?
- genetic control center (shelters DNA)
- makes proteins
What is the function of the Rough ER and the Smooth ER?
Rough ER: make proteins
Smooth ER: make lipids, detoxification, calcium storage
What is the function of the ribosome?
interpret genetic code and make polypeptides
What is the function of the Golgi Complex?
- receives and modifies and packages proteins
- makes carbs
- packages products into vesicles
What is the function of the lysosome?
contains enzymes for digestion, autophagy (recycling organelles), cell death, and glucose mobilization
What is the function of the peroxisome?
contains enzyme for detoxification of free radicals and drugs
What is the function of a mitochondria?
ATP synthesis
What is the function of a centriole?
forms microtubules of cytoskeleton and mitotic spindle
What are inclusions?
storage products (glycogen, fat droplets) and foreign matter (viruses, bacteria, dust particles)
What is the difference between cytoplasm and cytosol?
Cytoplasm includes organelles. Cytosol is ICF only.
What are the components of the plasma membrane?
- intracellular and extracellular face
- membrane lipids
- phospholipid bilayer
- cholesterol
- glycolipids
- membrane proteins
- integral proteins
- transmembrane proteins
- Glycocalyx
- Microvilli, Cilia, Flagella
- Pseudopods
What is the difference between simple and facilitated diffusion?
Facilitated used a carrier / channel protein.
Surrounds cell, defines boundaries and is made of proteins and lipids?
Plasma(cell) membrane
Define permeability, passive transport, and active transport
- Permeability: a membrane is selectively permeable, meaning it has standards and will only let some substances in
- Passive transport: involves substances moving down the gradient, requires no energy
- Active transport: substances move against the gradient, require ATP
Contents of the cell, excluding the nucleus?
*Organelles
*Cytoskeleton
*Inclusions (stored or foreign particles)
*Cytosol (intracellular fluid, ICF)
Cytoplasm
