MCAT Bio Biochem Flashcards
What are the two main componenets of the viral envelope.
Viral envelopes consist of phospholipids and glycoproteins that contribute to recognition and interaction with other cell receptors.
Name each type of inhibition and what they all affect?
Competitive inhibition–> Increases Km and Vmax unchanged.
Noncompetitive inhibition–> Vmax is decreased while Km is unchanged.
Uncompetitive inhibition–> Vmax and Km both decrease.
What is the term used to describe “catalytic efficiency”?
Kcat=Vmax/Km
What is the order of scope covered from largest to smallest with Coenzymes, Prosthetic groups, and Cofactors?
Cofactors>Coenzymes>Prosthetic groups
Where are action potentials summated?
Action potentials begin in the axon hillock before they move down the axon.
What is hyperpolarization?
Hyperpolarization happens when the membrane potentail changes to a negative membrane potential due to the loss of potassium ions in the cell.
Which neurotransmitter would cause muscle flacidity? 1) Acetylcholine 2) Glutamine 3) Epinephrine 4) GABA
Muscle flacidity is caused by a lack of acetylcholine released by somatic cells that causes muscles to not contract.
What muscles would be expected to be forcefully contracting if a patient is struggling to breathe?
Forceful exhalation is defined as a contraction of the internal intercostal muscles to force air out, which is abnormal.
What is pulmonary surfactant and how does it affect respiration?
Pulmonary surfacant in involved in the reduction of aveolar surface tension. Decreased amounts of surfactant can lead to less area for gas exchange causing difficulty breathing.
What is ADH, Aldosterone, and ANP? What are their functions?
Vasopressin (ADH) is involved with water retention. So, a vasopressin receptor antagonist will cause the receptors to NOT retatain water causing large amounts of urine to be excreted. Aldosterone and ANP are also involved in either secretion of water/sodium or the retention of such. All are invloved in kidney function and urine secretion.
How do you know the change in pressure between the Glomerular Capillaries and the Bowman Space? Hint: It is positive/negative depending on the direction of flow.
Pressure going into the Bowman Space (from the Glomerular) is positive and flowing into the Glomerular Capillaries is negative.
If the anterior pituitary malfunctioned, what would be the resulting affect on the Thyroid?
The anterior pituitary gland creates a hormone called TSH (Thyroid stimulating horome) that stimulates the Thyroid to create T3 and T4 hormones
What is the function of the Pineal gland? What Bodily cycle does it tie into?
The Pineal gland secretes Melatonin (Melatonin production is stimulated by darkness and inhibited by light).
What would happen to the body if the concentration of aldosterone increased? (hint: It affects Sodium, Water, and Potassium.)
As Aldosterone concentration increases, water and salt retention will also increase, while potassium will be secreted due to stimulation of the distal ducts on the kidney nephron.
What are the affects of LH on both men and women?
Increase in LH will stimulate the follicles on the ovary to undergo ovulation. However, for males, LH will bind to receptors to stimulate testosterone synthesis.
Where are phospholipids created?
Phospholipids are synthesized on th surface of the smooth ER then packaged into vesicles and sent to the membrane.
What are dyeins and what is their function?
dyneins–> are motor proteins that are structurally similar to kinesins, but carry cargo toward the minus end of the mircotubule, which is usually oriented toward the center of the cell. There are two other types that are found in a smaller scale that either help with cellular transport or function of filia or flagella.
What are Kinesins and what is their function?
Kinesins–> are motor proteins that use ATP to power movement across microtubules and usually go towards the periphery (outside of the cell). They are also made up of four distinct subunits.
What are Myosins and what is their function?
Myosins–> similar to kinesins/dyneins (need ATP) but are not involved in transport. They play a role in actin-based muscular contraction in muscle, as well as a winde rande of motility processes (including actin contraction in cleavage furrow of cell seperation). Use ATP to carry out power stroke.
What is the fuction of actin microfilaments?
Actin Microfilaments (smallest of the skeleton)–> play a role in motility, cell cleavage, endocytosis/exocytosis, and muscle contraction.
What is the function of Intermediate filaments?
Intermediate filaments (the middle sized in the cytoskeleton)–> provide stuctural support and other functions; major example = Keratin (findernails, etc.).
What is the function of Mircotubules?
Microtubules (largest in cytoskeleton)–> Hollow cylinders composed of poolymeric tubulin dimers (alpha and beta). Contribute to chormosome movement during division and intracellular division.
What are the three types of junctions and their functions?
Anchoring junctions–> involve cadherins; help keep cell/tissue in place. Gap junctions–> formed by connexin proteins, connects cells so that diffusion/communication can take place. Tight junctions–> invlove several types of proteins, are found in epithelial cells, and prevent solutes from being able to move freely between tissues (i.e. blood-brain barrier).
In oogenesis, when does the primary occytes turn into the secondary occyte (it’s either before birth or at puberty)? When are they diploid and haploid?
When women are born, they are born with primary oocytes arrested in Meiosis I. When puberty occurs, those primary occytes complete meisis I and become secondary occytes that are haploid (while primary occytes are diploid).
What hormone is released when the egg attaches to the uterine lining and what mechanism does it stimulate?
Directly after the egg implants in the uterine lining, it releases cHG, that mimics LH, to maintain the Corpus Luteum, thus maintaining estrogen and progesterone levels to signal to the body that pregnancy is occuring.
What are Osteoblasts/Osteoclasts and their function?
Osteoblasts –>use hydroxyapatite to create the bone matrix. Osteoclast–> Break down the bone matrix to inject calcium and phospate into serum levels if they’re low.
What is the difference between ligaments and tendons?
Ligaments: Are used to connect bone to bone. Tendons are used to connect muscle to bone.
How would you go about finding what estradiol looks like when given four different steriods to choose from?
Estradiol (a steriod and a form of estrogen) is going to have the common 4-ring that steriods normally have. Also, the -diol refers to OH (hydroxy) groups attached to the steriod. Di means two. So, it should be relatively easy to reason through.
What is the difference between multipotent, pluripotent, and totipotent stem cells?
Multipotent stem cells–> in various types of tissue and can develop onto various forms, unlike other types. Pluripotent stem cells–> are similar to multipotent cells but are NOT found in adults.
Totipotent stem cells–> Can give rise to embryos or placental tissue but cannot form anything else and are NOT found in adults.
What are sutures (related to the body) and where are they found?
Sutures are a fibrous connective tissue that are found in the skull–and only in the skull–are used to connect pieces of the skull together.
What is a use of vitamin D in the body?
Vitamin D is useful in the body as it allows an uptake of calcium and phosphate from the intestines.
What is SDS-PAGE used for?
SDS-PAGE is used to disrupt secondary and tertiary structures in proteins while also applying a negative charge across the gel–as well as the protein–to separate protein by mass or size.
If we had an SDS-PAGE experiment with a protein composed of 3 small subunits and 1 large one, what would the lines in the gel display?
SDS-PAGE–> separates proteins and their subunits by size or mass. Therefore, smaller subunits will travel farther through the gel, while larger subunits will travel shorter. So, if we had three small subunits and one large, one very dark long line would show up for the three small subunits, but a faded shorter line would show up for the larger subunit because it did not move as far through the gel.
What creates collagens in the skin?
Fibroblasts are the most internal structure of skin and are used to synthesize collagen.
What is the name of the fiber that connects the epithelial layer of the skin with the endothelium of capallaries?
The Epithelial layer of tissue is connected to the endothelium of the capillaries via a fiber called Fibronectin.
What are the general roles of the Sympathetic and Parasympathetic nervous systems?
Sympathetic NS EXCITES the body while the Parasympathetic NS CALMS the body
If someone had the nerves in the front of their spine severed (while the lateral and dorsal were intact) what symptoms would this person be experiencing?
Sensory (afferent) nerves are on the dorsal side of the spine–in the rear. Motor nerves are located in the ventral and lateral sides of the spine.
Where is Myelin produced?
Oligodendrocytes produce myelin sheathing in the CNS. However, Shwann cells produce myelin sheathing in the PNS
What type of neurons are found in the CNS/cerebrum? Hint: “polarity”
Multipolar neurons are dominate in the Frontal lobe/CNS/cerebrum because they allow quick and complicated neural responses.
What is more likely to cause a neuron to fire? 1) one EPSP 2) one IPSP or 3) Multiple EPSPs or 4) Multiple IPSPs ?
Rapid EPSPs (excitatory post-synaptic potentials) will cause a neoron to fire whereas IPSP (Inhibitory post-synaptic potentials) will hyperpolarize a neuron or inhibit its firing. Also, Myelination has nothing to do with neuron excitability.
What is the charge of a cell that’s depolarized?
A normal cell sits at -70mV and when depolarized will move to -45mV
Do sodium channels close or deactivate (there is a difference) when a neuron fires? Also, this keeps them from firing again.
During the absolute refractory period of a neuron, sodium channels deactivate (not just close), which causes the neuron to be unable to fire again until it has returned to baseline.
What is the function of GABA and Glutamate in the neural system?
GABA is the standard inhibitory neurotransmitter. Howevere, Glutamate is the classic example of an excitatory neurotransmitter!
What is cell-mediated immunity?
Cell-mediated Immunity has to do with specific T cells that offer a respose that does NOT include antibodies, but uses phagocytosis, cytokines, and the release of specific lymphocytes.
What is DNA polymerase I?
DNA Polymerase I—> Helps connect Okazaki fragments together and remove the RNA primer.
What is DNA Polymerase II?
DNA Polymerase II—> Primarily involved in DNA repair
What is DNA Polymerase III?
DNA Polymerase III—> Is involved in the main process of DNA synthesis.
What is DNA Ligase?
DNA Ligase—> Joins normal DNA strand together, but can also join Okazaki fragments together
What is the function of Primase?
DNA Primase—> Creates an RNA primer for the lagging strand.
What are the three enzymes that are involved with the unwinding and stablization of DNA during replication?
The enzymes involved in the unwinding and stablization of DNA are 1) Topoisomerase (uncoils the DNA so it can be broken apart for replication) 2) Single Stranded Binding Proteins (inhibit the single strand of DNA from rebinding) and 3) Helicase (unzips the DNA for replification).
What does the term ‘Anhedonia’ mean?
Anhedonia—> The lack of feeling of pleasure.
If someone was sicked by a virus, recovered completely, then was sicked by a different strain of the same pathogen, what would be the immune response to the pathogen?
Resistance to a particular strain of pathogens does not confer resistance to other strains (even if they are similar). A person likely would NOT have any increased response to a new strain of a similar pathogen. (think if the general flu and something like Swine Flu).
What is the process of a phagosome as it ingests a foreign object?
The primary function of phagosomes is to ingest the possible pathogen and immediately kill it (due to very high acidity via proton pumps) so that the bacteria will die before it can replicate and lyse the phagosome.
What are restricing enzymes called and what is there function within DNA?
Endonucleases are restricting enzymes. They cleave WITHIN a nucleaic sequence where Exonucleases cleave on the ends of sequences.
In gel electrophoresis, is DNA postive or negatively charged and is it moving towards the anode or cathode?
Gel Electrophoresis negatively charges DNA so that it may move it towards the anode (yes, the anode)
What does the term Incomplete Penetrance mean?
Incomplete Penetrance—> Clinical symptomes (phenotype) may not always be expressed even though someone may have a disease causing mutation (genotype).
In miRNA gene silencing, a small RNA binds to a mRNA to begin degradation. This prevents translation of the mRNA. What is this called?
Hybridization. That process is describing of complementatry nucleotides
What part of the nervous system–specifically–causes your pupils to dialate?
The PNS, but specifically the sympathetic motor neurons.
If a student conducts an experiment involving harmful bacteria, what is the proper lab method to dispose of this harmful bacteria?
The proper–and best way–is to place the sample in an autoclave where the temperature exceeds 120C and 2atm, which is enough to kill almost anything.
Where do single and double crossovers occur on a chromosome?
Single crossovers occur on the end of chromosomal arms while double crossovers occur in segments in the middle of the chromosome.
When cancer cells are present, what can we expect of lactate levels? Low or High and why? What would glycolysis be doing in this case?
In cancer cells, we would expect high levels of lactate via fermentation due to lack of O2 and inhibited glycolysis.
How does mismatch repair occur?
Say two amino acids are connected that should not be (Like T and G), mismatch repair will cut one of those out, and replace it, most likely with a Cytoseine to match the G.
If a new cancer drug is being developed, what stage of the cell cycle would NOT be used for possible treatment?
G knot (Go) is the general stage of cellular arrest (it does this on its own). So, it would not be beneficial to target that phase since it’s arresting the cell already.
What is southern blotting?
Southern blotting is used to determine the concentration of DNA in a cell. Uses gel electrophoresis too.
What is northern blotting?
Northern blotting is used to find cellular concentration of RNA (NOT DNA). It uses the same mechanism of southern blotting–gel electrophoresis.
Say you had 4 amino acids, how would you determine the amount of configurations that they could form?
Whatever the number of amino acids there are–say there are four–it would be that number (n) factorial. (example 4! which would be 4x3x2x1 = 24
If an organ has low circulating levels of a hormone, what will be the body’s reaction to a low amount of hormone circulation in the blood?
The body will stimulate the organ to produce more of the hormone(s) in hopes to raise the levels of it present circulating in the blood.
In a negative inducible operon, if the repressor is already bound, what could you add to restore active trascription?
NOT an activator but an INDUCER! This would block the repressor from binding.
What is Western blotting?
Western blotting is accomplished through another mechanism NOT invloving gel electrophoresis. In Western blotting, we are looking for specific proteins (not amino acids or mRNA like the others).
What contributes–in the largest context–to DNA helix stability?
The hydrophobic effect is what contributes in the largest extent. Decreases the hydrophobic effect will only weaken the DNA helix.
What does Pluripotent mean?
Pluripotent cells, usually embryonic cells, are cells that can essentially become any type of cell needed. Adults do not have this cells.
What end–positive or negative–does polymerization in actin happen at, and why?
The rate of polymerization or depolymerization depends on how much actin is present. The positive (+) end is attatched to ATP while the negative (-) end is attatched to ADP. Polymerization occurs faster at the positive (+) end.
What does the term ‘allosteric inhibition’ mean?
Allosteric inhibition describes inhibition that occurs anywhere other than the active site.
If substrate and allosteric activators are increased in a solution, will the Vmax and Kcat change or stay the same? Why?
Vmax is not effected by substrate concentration (only addition of enzymes), but increase of activators will increase the reaction rate.
What is the difference between post-transcriptional modification and post-translational modification?
Post-transcriptional modifcation occurs before entering the cytoplasm. This happens when mRNA is created. Post-translational modification is after the actual protein or structure is created when something else is added like a phosphate or a glucose.
What is bacterial transformation?
Bacterial transformation is where a bacteria just takes up foreign genetic material from its’ environment and inserts it into its DNA sequence.
What is bacterial transduction?
Bacterial transduction is where new DNA is injected into the bacteria by a virus where it inserts itself into the DNA sequence.
What is the difference between osmotic and hydorstatic pressure?
Hydrostatic pressure is the ‘pushing’ pressure exerted on a container. Osmotic pressure is the ‘pulling’ pressure due to the presense of solutes in solution (usually, in blood).
What would the effect be on ATP production if the proton gradient was disipated (in addition to lack of function of the ETC)?
The disassociation of the proton gradient would be redundunt in this context. If the ETC was already severvely hindered, the dispersion of the proton gradient wouldn’t make any greater noticeable difference than what is already happening.
What would be the affects on the body if someone was given a Calcitonin antagonist?
Calcitonin decreases plasma Ca2+ concentration. So, decrease in Calcitonin would increase osteoclast activity, which would stimulate bone breakdown to add Ca2+ to blood plasma.
What is a useful way to know the developemental stages after the morula?
The mnemonic “More Blasting Gas, I’m Nervous.”, which outlines the process: Morula, Blastula, Gastrula, and to Neurulation. That’s going from smallest to largest portions of the embryo
What is the synaptoemal complex?
It is a protein based linkage that appears during meiosis and connects homologous chromosomes. Helps with crossing over and any issues would hinder crossing over from occuring or at least occuring properly.
What is angiogenesis and what disease will propagate under misregulation?
Angiogenesis is the creation of blood vessels and vascular pathways and is often seen in Cancer do to the large demands of tumor growth.
When comparing unicellular eukaryotes, like algea, to human cells, what is a large characteristical difference that will be observed?
That nearly 95% of the human genome does NOT code for protein or RNA, whereas, algea almost exclusively encodes for proteins.
What is the name of the cell that nourishes developing sperm in the testes?
They’re called Leydig cells. They’re activated by FSH.
If the synaponemal complex is severed in a cell, destroying the protein-DNA linkage, what bridge between the two bodies is affected?
Homologous chromosomes in prophase I will be hindered where the interactions occur and could possibly affect recombination, as well.
What parts of the body consist of ectoderm?
Ectoderm gives rise to skin, hair, body cavities, nervous tissue, etc.
