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Bio study review
Terms in this set (74)
very large molecules made by assembling smaller molecules together, often using repeating units of the same kind of molecule (monomers) to build a much larger polymer.
removes a water molecule, forming a new bond.
Breaking down complex molecules by the chemical addition of water
are hydrophobic molecules, including the triglycerides, phospholipids, and steroids.
consist of three fatty acids attached to a glycerol molecule by dehydration synthesis, and can be solid (fats) or liquid (oils) at room temperature.
have saturated fatty acids that form straight molecules that can pack closely together.
unsaturated fatty acids that are bent and push each other further apart making them less dense.
a glycerol with two very hydrophobic fatty acid "tails" and one very hydrophilic phosphocholine "head." The balance between these components is just right, making phospholipids amphipathic.
large polymers made by connecting amino acid monomers. The function of a protein is dependent on its shape, so understanding levels of protein structure is critical.
primary structure of a protein
chain of amino acids form by dehydration synthesis, connecting them with peptide bonds.
secondary structure of protein
consequence of hydrogen bonding between the carboxyl and amino groups of the polypeptide backbone. This can either fold short sections of the polypeptide into beta pleated sheets or coil them into alpha helices
Formed by dehydration synthesis, stringing amino acids
Three dimensional folding of sheets and helices of a single peptide. Interactions between R-groups of the same polypeptide.
This creates a single protein made of multiple polypeptides.
Reactions use dehydration when..
atp forms through oxidative phosphorylation
What is one common property lipids have?
Interactions between backbone elements in a polypeptide can twist the chain of amino acids into a coil ("corkscrew") shape. What level of protein structure is this, and what do we call the coiled structure?
That would be Secondary Structure, and the coil structure is an Alpha Helix.
creates a hydrophobic barrier to diffusion between two aqueous (water-filled) compartments. is semipermeable, allowing hydrophobic or small hydrophilic molecules to pass through, but not larger (more than a couple carbons) polar molecules or ions.
The cell membrane gains functionality by
the addition of membrane proteins such as transport proteins, receptors, junction proteins, and cell recognition proteins. These include partially hydrophobic integral membrane proteins that insert into the hydrophobic region of the bilayer, hydrophilic peripheral proteins which associate with either side of the membrane at the phospholipid heads, and lipid-anchored proteins that are hydrophilic but attach to the membrane using a fatty acid molecule that inserts into the hydrophobic layer.
Peripheral Membrane Proteins
In the water next to the membrane, signaling events. Integral proteins insert into the hydrophobic layer in the membrane.
fluid mosaic model
most of the phospholipids and many proteins in the membrane are not covalently lined to other molecules and are free to move around in the membrane. Some molecules may be anchored to the cytoskeleton or extracellular matrix in specialized cells that need structure.
A high proportion of saturated fatty acids or long fatty acids
will make a membrane less fluid (more viscous), while a high proportion of unsaturated fatty acids or short fatty acids will make a membrane more fluid (less viscous).
Adding cholesterol to a membrane
with moderate its fluidity towards average: a viscous membrane will become more fluid, while a fluid membrane will become more viscous.
will make molecules move from an area of higher concentration towards an area of lower concentration.
make cell membranes selectively permeable and allow for the facilitated diffusion of polar molecules and ions across the membrane. This is also called passive transport because it does not cost metabolic energy from the cell.
create aqueous pathways for the diffusion of ions
move molecules across the membrane by changing shape.
If there is a difference in overall solute concentration across a membrane, and diffusion does not happen, a cell will experience a net movement of water
Water will move towards the side of the membrane with higher total solute concentration
from the side with lower total solute concentration
If the total solute concentration is the same on both sides of the membrane
Cells can force transport proteins to change shape and move solutes towards higher concentration using metabolic energy.
can get energy from different sources, either directly from chemical energy in ATP, from high energy electrons, or from energy in a gradient of another solute.
Transport proteins that move a single solute across the membrane
move more than one solute at a time
two molecules travel in the same direction
two substances move in opposite directions
can move many molecules at a time using the membrane itself in the process.
(Inside) brings assemblages of molecules into a cell and can involve different processes. "cell-eating"
Creates large vesicles and can bring in large amounts of material.
creates small vesicles that are used to transport water. "cell-drinking" transports water
receptor mediated endocytosis
uses transmembrane receptor proteins to selectively bring in large amounts of the same solute very specifically.
need to constantly transport many different solutes at the same time using systems of multiple transport proteins working together.
occurs when a ligand binds to a receptor protein, causing a change in the shape of the protein.
occurs when proteins inside the cell recognize the change in shape of a receptor bound by ligand and trigger a signal transduction cascade. Information passes membrane
amplify signals, meaning small amounts of ligand outside the cell can cause a large response inside the cell.
Cascades can create
diversity, allowing different cells to have different responses to the same ligand.
Cascades can allow
plasticity, so that the same cell can change how responds to a ligand depending on other information or conditions within the cell.
Signal transduction is
is a key feature of transmembrane receptors, but some other types such as nuclear hormone receptors or gated ion channels respond directly to ligand binding and do not use a signal transduction cascade.
Receptor tyrosine kinases
are transmembrane receptors that have the ligand binding part outside the cell and an enzyme part inside the cell on a single protein.
dimerize, with at least two ligand molecules causing two receptor proteins to pair up, forming a dimer.
growth factor receptors
also called rtks because most of their ligands cause a response that promotes cell division.
two nearby ligands together change shape to stick together.
When RTKs dimerize...
they begin the process of signal transduction with autophosphorylation, phosphorylating tyrosine amino acids on their own polypeptides. These are recognized by cytoplasmic enzymes that trigger the signal transduction cascade.
phosphorylation of an enzyme by itself
G-protein coupled receptors
are transmembrane receptors that have separate proteins for ligand binding and enzymatic response. These proteins are "coupled" by a G-protein that becomes activate on ligand binding by the receptor and in turns activates an enzyme that triggers a signal transduction cascade.
GPCRs respond to ligand binding
by activating G-proteins, causing them to exchange a GDP for a GTP. When the G-protein activates an enzyme the GTP is hydrolyzed back to GDP and the G-protein is inactivated.
If you take a bacteria that normally lives in the ocean and drop it in the freshwater pond in your backward, would you expect the cell to be hypertonic, hypotonic, or isotonic compared to the environment? In terms of osmosis, what would you expect to happen in this situation?
The bacteria would be HYPERTONIC relative to freshwater, so water would go into the cell.
Which of the following would be a characteristic GPCR activation, specifically?
Exchange of GTP for GDP
is the sum of all anabolic and catabolic reactions in a cell, connected in a network of reaction pathways.
makes things, dehydration synthesis, energy is absorbed Endergonic
(Break things down)
Hydrolysis releases energy
1st Law of Thermodynamics
Energy can be converted from one form to another, but can not be created or destroyed.
2nd law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe.
A measure of disorder or randomness.
Free energy (G)
is chemical energy available to do work and is expressed as the difference between enthalpy (total energy) and entropy.
are proteins that reduce the activation energy of a reaction.
interact with enzymes at the active site, forming an enzyme-substrate complex with a close interaction through induced fit.
Enzyme activity can be reduced
by competitive inhibitors that compete with substrates for the active site.
Enzymes can also
be regulated by allosteric effectors that bind somewhere other than the active site (called the allosteric site) and alter the shape of the protein to either inhibit or activate enzyme function.
Negative feedback (aka Feedback inhibition)
loops use the product of a pathway to inhibit an enzyme at the beginning of the pathway.
State the First Law of Thermodynamics in your own words. Give an example from class illustrating the first law in action.
Energy can be transformed from one form to another but not created or destroyed. For example with active transport using a cotransport protein, chemical energy from ATP is transformed into energy in a gradient, which is then transformed into kinetic energy of moving solutes.
Briefly explain the difference between enthalpy and free energy of a molecule.
Enthalpy is the total potential energy stored in a molecule, while free energy is the portion we can use (the rest goes to entropy).
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