Membrane Transport
Molecules with high permeability
Small, nonpolar molecules like O2 (without a transport protein), CO2, and N2.
As a cell expands the surface area to volume ratio will...
decrease, if the surface area is too large, there will be a hard time moving things around in the cell, therefore, this ratio will decrease
ex. a small cell with a ratio of 6:1, compared to a large cell with a ratio of 1.5:1
-if a cell began to shrink, the ratio would then increase
Three main fibers that make up the cytoskeleton...
Microtubles: maintains cell shape by resisting compression, moves cells via flagella or cilia, moves chromosomes, forms cell plate during cell division, provides tracks for intracellular transport
Microfilaments: maintain cell shape (resists tension), move cells via muscle contraction, divide animal cells in two, move organelles and cytoplasm
Intermediate filaments: maintain cell shape (resists tension), anchor nucleus and some organelles
Signals can be either hydrophobic or hydrophilic, what are some examples of the two?
Hydrophobic: local mediators (small gases, e.g. nitric oxide), lipid hormones
Hydrophilic: local mediators (neurotransmitters), protein hormones
Cell division results in...
two genetically identical daughter cells
In passive transport, there are two types of transport, what are they? It also requires what type of proteins?
Simple diffusion: does not require energy
Facilitated diffusion: substances move from greater concentration to lesser concentration (down it's conc. gradient)
Channel proteins: allow specific molecules to pass through, ex. aquaporins, ion channels
Carrier proteins: have a slight change in shape when a substance binds, ex. glucose binds to GLUT-1, conformation changes, glucose moves inside cell (facilitated)
There are two general types of cells prokaryotic and eukaryotic, what are some differences between them?
Prokaryotic cells: lack a nucleus, DNA is free floating, contain ribosomes, cell membrane and cytoplasm
Eukaryotic cells: contain membrane-bound organelles like nucleus, endoplasmic reticulum (rough&smooth), golgi apparatus, lysosomes, vacuoles
Types of animal structural ECM elements...
Collagen, forms the fibrous, strongest component of the animal ECM.
Elastin, stretches when tension is exerted and recoils to compact form when tension is released.
Proteoglycans: make up the ground substance in which structural molecules are embedded.
Laminins: in the basal lamina, regulates movement of molecules and cells.
(can reference slides)
Three types of signaling are called...
Direct signaling: where the cytoplasm of adjacent cells are directly connected (gap junctions, plasmodesmata)
Paracrine signaling: a signal that acts on nearby target cells from the secretion of another molecule (ex. growth factor that stimulates nearby cells to grow and divide)
Endocrine signaling: a type of long distance signaling achieved by hormones that travel in the circulatory system (hormones are secreted into bodily fluid like blood)
All DNA in the cell constitutes the cells genome... the genome consists of... and is packed into...
a number of DNA molecules and are packed into chromosomes
Red blood cells in pure water will cause them to swell and burst, putting them in a salty solution makes them shrink and shrivel, these are examples of?
hypotonicity; hypertonicity
in this example, in pure water the concentration is higher inside the red blood cell, water will diffuse through and cause the cell to swell and burst. In a salty solution, the water leaves the red blood cell causes it to shrivel.
The Endoplasmic Reticulum can be divided into two distinct regions.... what are their functions and things they synthesize... why are ribosomes important on the rough ER?
Smooth ER: lacks ribosomes, synthesizes lipids (phospholipids, steroids!, triglycerides), stores calcium ions,
Rough ER: surface studded with ribosomes, is one site of protein synthesis
ribosomes allow for translation of RNA to synthesize proteins, RNA -> proteins
Types of junctions...
Desmosomes: hold together animal cells and provide high strength that is resistant to mechanical stress
Tight junctions: form (almost) watertight seals that block the flow of fluids and molecules
Gap junctions: connects the cytoplasm of two animal cells, this lets ions, small molecules, and electrical signals to pass through
Cells that receive signals undergo these three processes...
Reception: Detection of the signal (in the membrane or cytoplasm), the binding of a signal molecule to the receptor is highly specific, there is usually a change in shape.
Transduction: Conversion of signal to a cellular response, via signal transduction pathway. The activated receptor activates another molecule, then another, until the target protein produces a response.
Response: A cellular activity in response to the signal, leads to the regulation of one or more cellular activities.
Each chromosome is comprised of two... they are joined in the middle by the....
Active transport differs from passive in that... An example of active transport is...
this transport requires energy, it also utilizes protein pumps to move substances against their concentration gradients.
the Sodium-Potassium Pump requires NA+ to be removed from the protein before K+ enters and binds to the pump, cleaving phosphate, K+ then enters the cell
Functions of the golgi apparatus...
Functions of lysosomes...
Functions of vacuoles...
Golgi modifies products from the ER, manufactures macromolecules, sorts and packages materials into transport vesicles (modifies and sorts proteins)
Lysosomes contain hydrolytic enzymes that digest macromolecules, the acidic environment helps with digestion.
Vacuoles are large vesicles that can take up food (in animal cells), pump out excess water (protists), and store things like seed protein or toxins/poisons (in plants)
The structure that connects the ECM to the cell surface and intracellular environment...
integrins
- these connect actin (component of cytoskeleton) to laminin (component of ECM)
The three types of plasma membrane receptors are G protein-coupled receptors, ligand-gated ion channel, enzyme-linked receptors, give the function of each...
G-protein: The signal molecule causes the receptor to contact the G-protein. GDP is released and GTP is picked up. Once active the shape changes and subunits separate producing a signal.
Ligand-gated: Acts as "gate" for ions when receptor changes shape. Where a signal molecule binds, the gate will change and allows through specific ions. These are most important in the nervous system.
Enzyme-linked: Start a chain of phosphorylation events to bring about a cell signal. The ligand will bind, change receptor shape, and auto-phosphorylate, can then phosphorylate other proteins.
Stages of the cell cycle...
Mitotic (M) phase: includes mitosis and cytokinesis
Interphase: includes cell growth and copying of chromosomes, prepares cell for dividing
within interphase is:
- G1 phase: metabolic activity and growth
- S phase: when chromosomes are duplicated
- G2 phase: preparation for cell division
Cells also utilize bulk transport for larger molecules, the two types are...
Exocytosis: allows for export of products by fusing with the membrane to release content
Endocytosis: takes in molecules by forming vesicles from the plasma membrane, three types: phagocytosis, pinocytosis, receptor mediated
This type of transport also requires energy, ex. of large molecules are polysaccharides and proteins
Eukaryotic organelles outside the endomembrane system and their functions
Chloroplasts: contain chlorophyll and other enzymes and molecules that function in photosynthesis
Peroxisomes: metabolic compartments that produce hydrogen peroxide and convert to water
Examples of movement caused by actin-myosin interactions...
Cytokinesis in animals, cytoplasmic streaming in plants
What are two molecular switches used in signaling pathways?
Protein kinases: A kinase adds another phosphate group to a protein. On the other hand, a phosphotase removes a phosphate.
G-proteins: these switch between an inactive state (bound to GDP) and an active state (bound to GTP). ATP is not involved and a phosphate group is not being donated to a target molecule. Instead, GDP is replaced by GTP (to activate the protein) and GTP is hydrolyzed to GDP (inactivation of protein).
Mitosis and meiosis are different in that...
Mitosis allows for cell division, the same DNA is kept, resulting in genetically identical cells.
In Meiosis, DNA is reduced by half, the daughter cells are not identical.