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MCAT Biology #1
Cell Structure
| Term | Definition |
|---|---|
| Amino acid | composed of an amino group, an acidic carboxyl group, a hydrogen atom, and a side chain; they make up proteins |
| Chiral | there are 4 different substituents attached to the alpha-carbon |
| Enantiomers | non-superimposable mirror images |
| Proteases | enzymes that degrade protein |
| Two important amino acid modifications | hydroxylation and methylation |
| Physiological pH | 6.5-8.0 |
| Zwitterionic | having two charges, or dipolar |
| Ampholytes | molecules that can act either as an acid or a base |
| Henderson-Hasselbalch Equation | pH = pKa + log([A-]/[HA]) |
| Isoelectric point | the pH at which a molecule carries no net electric charge |
| pI (formula) | (pKa1+pKa2)/2 |
| cathode | the negative electrode, where positive charges go towards |
| anode | the positive electrode where negative charges towards |
| electrophoresis | a technique of separating amino acids based on isoelectric points |
| buffer | ability to resist changes in pH |
| peptide linkage | an amide bond between amino acids |
| polypeptide | a term used for any length of a polymer of amino acids |
| oligopeptide | 10 or more amino acids linked together |
| protein | 100 or more amino acids linked together, into a functional entity |
| disulfide bonds | cysteine residues that are joined together covalently, through oxidation |
| alpha helix | secondary structures of polypeptides stabilized by hydrogen bonding, and with 3.6 aa per turn, 1.5 angstroms vertical rise per turn, and 100 degrees rotation per turn |
| beta sheet | secondary structure of polypeptides that occurs via hydrogen bonding between strands of polypeptide, connected by beta-turns |
| heme group | a crevice within myoglobin and hemoglobin subunits that can bind to oxygen |
| primary structure | the sequence of amino acids, and the location of disulfide bonds |
| secondary structure | the spatial arrangement of amino acids that are close to one another |
| tertiary structure | the spatial arrangement of amino acids that are far from one another and is determined by the primary structure |
| quaternary structure | the spatial structure of various subunits |
| enzymes | proteins that catalyze reactions in cells |
| active site or catalytic site | the crevice that a substrate come into contact with where it is bound in such a way that the enzyme can do chemistry on it |
| allosteric site | an alternate site on an enzyme where regulation can occur via binding |
| aldehyde | a molecule in which the carbonyl group is terminal |
| ketone | the molecule in which the carbonyl group is internal |
| reference carbon | the chiral carbon in a monosaccharide that is farthest from the carbonyl carbon |
| pyranose | six membered sugar ring |
| furanose | five membered sugar ring |
| anomer | cyclic sugars that differ only in the configuration of the C-1 carbon |
| anomeric carbon | the carbon on a sugar ring that determines the alpha or beta form of the sugar ring |
| beta sugar rings | the hydroxyl group is on the same side (drawn as a ring) as the CH2OH group |
| alpha sugar rings | the hydroxyl group is on the opposite side (drawn as a ring) as the CH2OH group |
| hemiacetal | a half acetal. One of the oxygens is still bonded to a hydrogen. |
| Hemiketal | a half ketal. One of the oxygens is still bonded to a hydrogen. |
| Tollen’s reagent | a reagent used to identify reducing sugars that will precipitate silver if they are present |
| Benedict’s reagent | a reagent used to identify reducing sugars, in which case a brick-red precipitate will form |
| Sugar with “ide” ending | the sugar is not a reducing sugar |
| Acetal group | a fully oxidized aldehyde, where both oxygens are not bound to hydrogens |
| Ketal group | a fully oxidized ketone, where both oxygens are not bound to hydrogens |
| Saturated fatty acids | fatty acids with no double bonds and all single bonds |
| Unsaturated fatty acids | fatty acids with specific double bonds |
| Triacylglycerol | fatty acids esterified to a glycerol backbone |
| Glycerophosopholipids | a glycerol backbone with two fatty acid chains and one phosphoryl group with another molecule attached to it |
| Sphingolipids | lipids derived from amino alcohols |
| Ceramide | the structural reside common to all sphingolipids |
| Cerebroside | a ceramide with a monosaccharide attached to the C-1 carbon |
| Sphingoglycolipids | sphingolipids with sugar attached |
| Gangliosides | ceramide with several sugar residues attached. |
| Progesterone | steroid hormone that prepares the uterine lining for implantation of an ovum, and the maintaining of endometrial lining of the uterus |
| Cortisol | steroid hormone made and secreted from cells in the adrenal gland to increase both glycogen synthesis and gluconeogenesis |
| Aldosterone | steroid hormone that increases readsorption of sodium ions |
| Testosterone | steroid hormone that facilitates sperm maturation and promotes male secondary characteristics |
| Estradiol | steroid hormone the control a number of female characteristics |
| Nucleotides | molecules composed of a nitrogenous base, pentose sugar, and phosphoric acid |
| Purines | nitrogenous bases with two rings, adenine and guanine |
| Pyrimidines | nitrogenous bases with one ring, thymine, guanine, uracil |
| Phosphodiester bond | an ester bond with a phosphate group in the middle |
| Cell cycle | the sum of all events that occur between the completion of one cell division and the next |
| Interphase of cell cycle | intermediate phase of cell cycle |
| G1 phase of cell cycle | the first growth phase, where RNA and proteins are actively being synthesized, the centriole pairs separate |
| S phase of cell cycle | synthetic phase, where the DNA is replicated once, and centrioles are replicated |
| G2 phase of cell cycle | second growth phase, where the chromatin begins to condense |
| Aster | starlike structure of microtubules that form during prophase of mitosis |
| Centrosome | the region from which microtubules extend outwards during mitosis |
| MTOC | the region from which microtubules extend outwards during mitosis |
| Mitotic spindle | a structure involved in the separation of the chromosomes during anaphase |
| Kinetochore | a specialized area closely associated with the centromere |
| Reductive division | another name for what happens in meiosis I |
| Leptotene | first part of prophase I in meiosis I where replicated chromosomes have started to condense |
| Zygotene | second part of prophase I in meiosis I where homologous chromosomes begin to pari up logintudinally to prepare for crossing over |
| Synapsis | the overlapping regions of chromosomes during crossing over |
| Synaptonemal comlex | a specialized protine and RNA scaffold that facilitates crossing over |
| Pachytene | the third part of prophase I in meiosis I where crossing over takes place |
| Diplotene | the fourth part of prophase I in meiosis I where the chromosomes begin to pull apart. Human eggs are arrested at this stage during development |
| Diakinesis | the fifth and last part of prophase I in meiosis I where the nuclear envelope breaks down and the homologous chromosomes are moving apart |
| Micelles | spherical strcutures that are formed when enough phospholipids congregate together such that heads are outside and tails are inside |
| Liposome | a lipid bilayer folded back on itself |
| Lateral diffusion | phospholipids exchanging places in a single layer of the membrane |
| Transverse diffusion | phospholipids moving from one lipid plane to another, very rare |
| Glycolipids | membrane lipid attached to a carbohydrate, usually found on the exterior surface of the membrane |
| Glycoproteins | membrane proteins attached with carbohydrates |
| Uniport | transporter protein involved in facilitated diffusion of one type of solute molecule |
| Symport | transporter protein involved in facilitated diffusion of two types of solute molecules going in the same direction |
| Antiport | transporter protein involved in facilitated diffusion of two types of solute molecules going in opposite directions |
| Permeases | protein transporters that allow for the movement of a solute across a membrane |
| Primary active transport | active transport in which the energy source is ATP directly (Na/K pump) |
| Secondary active transport | active transport in which the energy source or diving factor is an ionic gradient (Na/glucose transport) |
| Endocytosis | invagination of a portion of the membrane in which the vesicle travels into the cell |
| Endosomes | vesicles resulting from endocytosis |
| Pinocytosis | endocytosis of liquids |
| Phagocytosis | endocytosis of larger particulate matter |
| Exocytosis | the export of molecules or liquid via vesicles |
| Nucleoplasm | the mixture of chromatin and the aqueous phase of the nucleus |
| Nucleolus | a highly organized region within the nucleus centered around certain chromosomes that are involved in ribosomal RNA synthesis |
| Signal peptide | a short segment of a polypeptide indicating that a ribosome’s destination is to be on the ER |
| Smooth ER functions | synthesis of the majority of cell’s membrane lipids, hydroxylation of toxins, catabolism of glycogen, regulate calcium concentrations |
| Rough ER functions | post-translational modification of polypeptides |
| Signal sequence | a sequence of amino acids at the N-terminus of a polypeptide which binds to an SRP |
| Signal recognition particle | located in the cytoplasm, these direct the ribosome to the ER, and bind to to signal sequence receptors |
| Signal sequence receptors | embedded in the ER membrane, which allow for docking of the SRP, which allows the ribosome to be anchored |
| Signal peptidase | in the ER lumen, and degrades the signal sequence |
| Golgi apparatus | a complex of flattened membraneous sacs called cisternae that are involved in chemical modification of a maturing protein |
| Glycosylation | addition of carbohydrates |
| Sulfation | addition of inorganic sulfates |
| Proteolysis | reducing the size of the protein |
| Lysosomes | vesicles originating from the membrane of the Golgi which contain hydrolytic enzymes to degrade polymers into monomeric subunits |
| Cocci bacteria | spherical-cell bacteria |
| Bacillus | rod-shaped-cell bacteria |
| Sprilla | rigidly-twisted-cell bacteria |
| Spirochete | flexible-twisted-cell bacteria |
| Inclusion bodies | aggregates of organic molecules that facilitate in the prokaryotic cell’s functions (akin to organelles) |
| Glycolayx | bacterial capsule, a polysaccharide layer |
| Capsid | virus with protein shell without nucleic acid inside |
| Nucleocapsid | virus with protein shell with nucleic acid inside |
| Viral matrix proteins | proteins that attach the membrane to the enveloped virus |
| Hershey and Chase experiment | infected E.coli with radiolabelled phosphorus and sulfur. |
| Anfinsen experiment | experiment involving denaturing a ribonuclease with beta-mercapoethanol and 8M, which cleaves disulfide bonds. Enzymatic activity restore after refold. Structure fluctuates but stabilized by other structures. |
Created by:
ruiyuwu1998
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