AAMC Bio Flashcards
What is the ratio of the results of a cross between two heterozygotes?
If we call the recessive gene r and its dominant allele R, then a cross between two heterozygote strains Rr will produce the genotypes RR:Rr:rr in a ration of 1:2:1.
What is the relationship between mRNA degradation and cell differentiation/protein production?
If oligonucleotides, such as mRNA, were not degraded rapidly by intracellular agents. The destruction of mRNA prevents continuous protein production, allowing the cell to change its protein expression over time. (basically allows for protein gradients that let tissue differentiation occur, think the protein gradients leading to things like anterior pituitary development) The coordination of cell differentiation during development is extremely sensitive to the timing of mRNA turnover.
Which structures control heart rate, muscle coordination, and appetite respectively?
Brain stem, cerebellum, and hypothalamus
What is an antisense gene? How does a sense strand differ from an antisense strand? How does its regulation relate to the regulation of sense genes?
Antisense is the non-coding DNA strand of a gene. A cell uses antisense DNA strand as a template for producing messenger RNA (mRNA) that directs the synthesis of a protein. Antisense can also refer to a method for silencing genes. The sense strand is the strand of DNA that has the same sequence as the mRNA, which takes the antisense strand as its template during transcription, and eventually undergoes (typically, not always) translation into a protein. Sense strand is in the 3’ to 5’ direction and it is not transcribed into mRNA. Antisense strand is directed in the 5’ to 3’ direction and it is transcribed into mRNA. antisense gene would need to be regulated in a manner similar to the manner in which the target gene is regulated so that the antisense RNA is produced at the same time that the sense mRNA is produced.
Describe the pain perception pathway? How does this pathway differ for reflexes?
The pain system involves a set of ascending pathways that convey nociceptive information from peripheral nociceptors via the neuronal tracts of the spinal cord to the higher levels of the CNS. When free nerve endings are excited, their membrane potential changes (transduction) and is converted into an action potential (transformation). Descending pain pathway is the suppression pathway
Afferent (i.e. ascending) A-delta and C fibres of the periphery transmit the pain stimulus via action potentials to the dorsal horn of the spinal cord. The transmission of nociceptive information from the first to the second neuron takes place at the synapsis by means of excitatory neurotransmitters. The neurotransmitters bind post-synaptically to specific receptors and produce an action potential, which is transmitted to the brain.
Reflex pain is a complex condition that occurs when the body’s pain withdrawal reflex fails to disappear long after the triggering event. The neurological phenomenon, known as the withdrawal reflex, occurs when the body executes a chain of reactions to remove an affected body part from painful stimuli. The sensory neuron then synapses with interneurons (neurons found in the spinal cord that relay signals between (afferent) sensory neurons and (efferent) motor neurons) that connect to motor neurons
What are the differences between eukaryotic and prokeryotic cells?
Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not. genetic material in prokaryotes is not membrane-bound.
The most fundamental difference is that eukaryotes do have “true” nuclei containing their DNA, whereas the genetic material in prokaryotes is not membrane-bound.
In eukaryotes, the mitochondria and chloroplasts perform various metabolic processes and are believed to have been derived from endosymbiotic bacteria. In prokaryotes similar processes occur across the cell membrane; endosymbionts are extremely rare.
The cell walls of prokaryotes are generally formed of a different molecule (peptidoglycan) to those of eukaryotes (many eukaryotes do not have a cell wall at all).
Prokaryotes are usually much smaller than eukaryotic cells.
Prokaryotes also differ from eukaryotes in that they contain only a single loop of stable chromosomal DNA stored in an area named the nucleoid, while eukaryote DNA is found on tightly bound and organised chromosomes. Although some eukaryotes have satellite DNA structures called plasmids, these are generally regarded as a prokaryote feature and many important genes in prokaryotes are stored on plasmids.
Genes
Prokaryotes also differ from eukaryotes in the structure, packing, density, and arrangement of their genes on the chromosome. Prokaryotes have incredibly compact genomes compared to eukaryotes, mostly because prokaryote genes lack introns and large non-coding regions between each gene.
Whereas nearly 95% of the human genome does not code for proteins or RNA or includes a gene promoter, nearly all of the prokaryote genome codes or controls something.
although similar, is distinct enough that several types of antibiotics are able to preferentially target prokaryotic ribosomes over eukaryotic ribosomes. Of human and bacterial cells, only bacterial cells have cell walls (C), and most bacterial chromosomes are circular whereas human chromosomes are linear
What are the key differences between mitosis and meiosis?
One of the key differences between mitosis and meiosis occurs during their respective anaphases. During anaphase of mitosis, sister chromatids are pulled apart at the centromeres, each becoming an independent chromosome in the two diploid daughter cells. During anaphase I of meiosis I, homologous pairs of chromosomes are separated into the two daughter cells. However, each chromosome still consists of two sister chromatids joined to each other at the centromere. It is not until anaphase II of meiosis II that the centromere is split and the sister chromatids separate. Mitosis and meiosis are both processes which describe the production of new cells. Mitosis produces 2 daughter cells which are genetically identical to the parent cell. Each daughter cell is diploid (contains the normal number of chromosomes). This is the result of DNA replication and 1 cell division. Mitosis is used in growth and asexual reproduction. Meiosis produces 4 daughter cells, each of which are unidentical to the parent cell and to one another. Each daughter cell is haploid (contains half the number of normal chromosomes). This is the result of DNA replication, followed by crossing over of homologous chromosomes and separation of chromosomes. There are two cell divisions: the parent cell divides once and then each cell produced by this first division divides once. Meiosis is used to produce gametes (sperm and egg cells), the cells of sexual reproduction. Two gametes fuse to form a zygote, a diploid cell with the full number of chromosomes.
What is plasma clearance?
Plasma clearance refers to the capacity of the kidney to remove a substance from the plasma
What is the glomerulus? How does it function within the kidney?
a cluster of nerve endings, spores, or small blood vessels, in particular a cluster of capillaries around the end of a kidney tubule, where waste products are filtered from the blood.
Glomerular filtration is the first step in making urine. It is the process that your kidneys use to filter excess fluid and waste products out of the blood into the urine collecting tubules of the kidney, so they may be eliminated from your body.
What does Tm have to do with flow through the kidneys? What is the relevance of this term and how is it affected by filtration rate?
Tm is a characteristic of the individual substances in the tubule system and a measure of how efficiently each substance can be reabsorbed. (e.g. the transport maximum of glucose). High Tm = high capacity to be reabsorbed in the kidney tubules. If you increase the glomerular filtration rate eventually the rate of flow would reach a point at which it exceeds the rate at which the tubule cells could reabsorb the substance. The fluid would be flowing too rapidly through the tubule for the cells to reabsorb all the substance. The rate of flow through the tubule at which the substance begins to be observed in the urine is Tm. At that point the rate of flow of fluid through the tubule begins to exceed the capacity of the kidney tubule cells to reabsorb the substance.
What affect does increased blood pressure have on the glomerular filtration rate?
Increasing blood pressure should increase flow of fluid through the kidney (think vasconstriction which occurs with increased bp) system and decrease, rather than increase, water reabsorption because at some point the flow rate through the tubule will exceed the kidney tubule cells capacity to reabsorb water.
What is albumin? What happens if you have extra albumin in the blood? What disorder is caused by a decrease in plasma albumin?
albumin, one of the major plasma proteins. Albumin is a protein made by your liver. Albumin helps keep fluid in your bloodstream so it doesn’t leak into other tissues. Plasma proteins are big and cannot cross membrane walls but water can (they raw in water to blood vessels/promote reabsorption/ they are promoters of an increase in osmotic pressure). An increase in plasma albumin will upset the osmotic balance because the blood will become hypertonic with respect to the tissue. Water will have to flow into the bloodstream to reestablish equilibrium. One of the causes of edema, increased fluid in body tissues, is a decrease in the plasma protein level. Water builds up in interstitial fluid because not enough albumin to promote reabsorption. This occurs, for instance, in starvation when the body is forced to use its albumin as an energy source. An increase in the plasma protein level would have the opposite effect: fluid would enter the bloodstream
What is aldosterone? Where is it released from and what does it do?
Aldosterone, which is produced by the adrenal cortex, causes Na+ reabsorption by kidney tubules. Such a mechanism decreases Na+ levels in the urine. Physiologically normal kidneys respond to aldosterone by increasing the reabsorption of both sodium and water. This leads to an increase in blood volume and therefore blood pressure.
What is a common characteristic of bacteria (prokaryotic) and eukaryotic cells?
the ability to produce ATP via ATP synthase is common to both bacterial and human cells. Both types of cells possess a membrane-embedded electron transport chain capable of generating a H+ gradient, which drives synthesis of ATP via ATP synthase. This ATP synthesis takes place on the plasma membrane of bacteria and on the inner mitochondrial membrane in human cells.
What is the parathyroid hormone? What does it secrete? What would happen to the body if it did not have it?
Removal of the parathyroid gland would lead to hypocalcemia, a condition of low blood calcium, resulting from the lack of parathyroid hormone. This would cause increased neuromuscular excitability because of the change in membrane potential, which under normal physiological conditions, is partially kept in balance with extracellular calcium. Parathyroid hormone leads to increased levels of calcium in the body by promoting osteoclast differentiation and calcitriol formation. It is activated and inhibited by the calcium sensing receptors on the parathyroid hormone and calcitriol also inhibits
Which tissues arise from the mesoderm?
THE ECTODERM gives rise to the central nervous system (the brain and spinal cord); the peripheral nervous system; the sensory epithelia of the eye, ear, and nose; the epidermis and its appendages (the nails and hair); the mammary glands; the hypophysis; the subcutaneous glands; and the enamel of the teeth
Ectodermal development is called neurulation in regard to nervous tissue
THE MESODERM gives rise to connective tissue, cartilage, and bone; striated and smooth muscles; the heart walls, blood and lymph vessels and cells; the kidneys; the gonads (ovaries and testes) and genital ducts; the serous membranes lining the body cavities; the spleen; and the suprarenal (adrenal) cortices
THE ENDODERM gives rise to the epithelial lining of the gastrointestinal and respiratory tracts; the parenchyma of the tonsils, the liver, the thymus, the thyroid, the parathyroids, and the pancreas; the epithelial lining of the urinary bladder and urethra; and the epithelial lining of the tympanic cavity, tympanic antrum, and auditory tube
What is ectopic pregnancy?
In ectopic pregnancy, implantation occurs in a site other than the endometrial lining of the uterine cavity—in the fallopian tube, uterine cornua, cervix, ovary, or abdominal or pelvic cavity. Ectopic pregnancies cannot be carried to term and eventually rupture or involute. The main reason for the occurrence of ectopic pregnancies is the failure of the fertilized egg to be transported from the oviducts to the uterus. When the transport system fails, the embryo implants in the oviduct, rather than in the uterus.
What roles do lutenizing hormone, progesterone, and estrogen play in the ovulatory cycle?
GnRH stimulates the pituitary gland to produce follicle stimulating hormone (FSH), the hormone responsible for starting follicle (egg) development and causing the level of estrogen, the primary female hormone, to rise. Leutinizing hormone (LH), the other reproductive pituitary hormone, aids in egg maturation and provides the hormonal trigger to cause ovulation and the release of eggs from the ovary. Luteinizing hormone and follicle-stimulating hormone, which are produced by the pituitary gland, promote ovulation and stimulate the ovaries to produce estrogen and progesterone. Estrogen and progesterone stimulate the uterus and breasts to prepare for possible fertilization. Estrogen and progesterone are not directly involved in triggering ovulation
What are the spin numbers on H NMR?
Dont kyl be kyne be kene Alkyl 0-3 Alkyne 2-3 Alkene 4.6-6 Aromatic 6-8.5 Aldehyde 9-10 Carboxylic acid 10.2-12
What is the equation for magnification? What happens to magnification when you shift one of the terms by either increasing or decreasing the value?
Using equations, recall that 1 / o + 1 / i = 1 / f, where f is positive for a concave mirror and remains constant. If o decreases, the (1 / o) term must increase, which means the (1 / i) term must decrease to compensate. Since i is negative for virtual images, decreasing the (1 / i) term means becoming less negative, which means that the magnitude of i decreases, which corresponds to the image moving closer to the mirror. As far as magnification goes, if we solve the above equation for i, we get i = of / (o – f). Magnification = –i / o = f / (f – o). Since o < f, then decreasing o would increase the denominator (f – o), and thus decrease the magnification.
How is fluid homeostasis obtained?
fluid homeostasis, which is obtained by balancing hydrostatic and osmotic pressures. Whereas hydrostatic pressure forces fluid out of the capillary, osmotic pressure draws fluid back in. Osmotic pressure is determined by osmotic concentration gradients, that is, the difference in the solute-to-water concentrations in the blood and tissue fluid.
How would hydrostatic pressure and the body be affected by a blod clot on the venous side of the capillary bed?
To answer this, it is necessary to know that blood flows from arteries to capillaries and then to veins. If flow is blocked at the venous side, blood would accumulate in the capillaries. Thus, hydrostatic pressure would build up in the capillaries, causing a net increase in fluid flow into the interstitial spaces.
What actions occur during inspiration?
The diaphragm contracts and pulls downward, causing air to enter the lungs.Elevation of the rib cage increases the volume inside the chest cavity, reduction of pressure inside the pleural cavity causes air to move into the lungs, and contraction of the external intercostal rib muscles helps the chest expand. active phase of ventilation because it is the result of muscle contraction. During inspiration, the diaphragm contracts and the thoracic cavity increases in volume. This decreases the intraalveolar pressure so that air flows into the lungs.
What does it mean for a virus to be olbligate?
An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. They need the host cells metabolic machinery to reproduce so if you attempt to grow them on sterilized noncellular growth media it would not work because they do not have access to the host cell. Virus structure cannot be visualized with a light microscope and a bacteriophage is a virus in bacteria.
What is hybridization and how can it occur?
Hybridization is the process of combining two complementary single-stranded DNA or RNA molecules and allowing them to form a single double-stranded molecule through base pairing. In a reversal of this process, a double-stranded DNA (or RNA, or DNA/RNA) molecule can be heated to break the base pairing and separate the two strands. (lab technique) Hybridization requires base pairing between complementary nucleic acid sequences
What is the tidal volume? How can the value for tidal volume be used to ascertain the air that enters the alveoli on each inspiration?
The tidal volume is the amount of air that moves into the lungs during each inspiration. Some of this air does not reach the alveoli so it is not available for gas exchange with the circulatory system. The volume of such gas in the air passageways, (trachea, bronchi and bronchioles) is called the respiratory dead space. Subtracting the dead space of 150 mL from the tidal volume of 800 mL gives 650 mL, the quantity of air that enters the alveoli on each inspiration. Over ten breaths then, 6,500 mL will flow into the alveoli for gas exchange
