Bio/Biochem II Flashcards
If a lung is punctured, what effect will this likely have on breathing?
The punctured lung will be unable to inflate, affecting inhalation
What is a statement that can explain why lung volume never drops below 15 ml/kg?
The residual volume is such that the lungs are at their minimum volume under maximum intrapleural pressure
Which of the following best explains why a Robertsonian carrier may have no health problems due to his or her chromosome rearrangement?
Genes on the lost p arms can be found elsewhere in the genome
How many chromosomes are found in a liver cell of a Robertsonian translocation carrier?
45 (short arms of 2 fused chromosomes is usually lost)
The Km for a Michaelis-Menten plot is:
The SUBSTRATE concentration at half of Vmax
Histone deacetylation of lysine results in:
decreased gene expression
Histone acetylation of lysine results in:
increased gene expression
The N and C termini are:
N = positive, C = negative
Where are post-transcriptional modifications carried out?
Within the nucleus
If the DNA of a representative species from each of the major kingdoms was examined, the sequences for what would be similar?
DNA synthesis
What are some molecules that have an atom with sp2-type hybridization?
Carbon dioxide, carbonate, formaldehyde
If it says something lacks introns…
It has a bacterial origin
What are transmembrane proteins made of?
Glycoproteins
Which components of cells are physically connected by a gap junction?
The cytoskeleton of one to the cytoskeleton of the other
Cardiac disorders involving gap junction dysfunction would most likely manifest clinically through:
Arrhythmia
Why are chemical synapses slower than electrical synapses?
Chemical synapses require the movement of agents through intercellular space
What type of control does siRNA exert on an enzyme?
Post-transcriptional control (due to its structure, siRNA is only able to bind to other RNA strands, not to DNA or protein)
Meiosis I results in:
2 haploid cells with 23 chromosomes, each chromosome consisting of 2 sister chromatids (sister chromatids remain attached)
Given that delta G is negative for a particular reaction, what can be said about the equilibrium constant K?
K > 1
The concentration of intracellular signaling molecules fluctuates rapidly in dividing cells during the cell cycle. Which of the following experimental techniques would be best to elucidate the mechanism of regulation for these proteins?
Western blot and RT-PCR
For a reaction with a Keq, a change in temperature could:
Increase or decrease the rate of one molecule to another
ATP is not required for:
Spontaneous reactions
Which of the following molecules is/are most likely to have selective proteins in the BBB to facilitate its passage into the brain?
Amino acids
What are some functions of the blood-brain barrier?
Protection of brain from bodily hormones, maintenance of a stable chemical equilibrium for the brain, and allowing of more glucose to enter the btrain than any other tissue
If pharmacologists wished to convert morphine into a form available to brain tissue, which of the following changes could be made to its molecular structure to allow for the best chance to use the drug as a direct brain treatment?
Replace the alcoholic protons with acetyl groups
Folate is a common supplement given to pregnant women to prevent neural tube defects. The most likely reason is:
Folate plays a role in ectodermal induction
What is skeletal muscle?
Striated, always polynucleated, voluntary
What is smooth muscle?
Always uninucleated, innervated by the autonomic nervous system, exhibit myogenic activity
What is cardiac muscle?
Striated, innervated by the autonomic nervous system, exhibit myogenic activity, can be uninucleated or binucleated
Which zone or band in the sarcomere does NOT change its length during muscle contraction? Why?
A-band; it is the entire length of the myosin filament
What are the events that initiate muscle contraction, in order? Start with neurotransmitter release and trace the pathway to the point where myosin binds with actin.
Release of acetylcholine from motor neuron -> activation of acetylcholine receptors in sarcolemma -> depolarization of sarcolemma -> spreading of signal using T-tubules -> release of calcium from sarcoplasmic reticulum (SR) -> binding of calcium to troponin -> conformational shift in tropomyosin -> exposure of myosin-binding sites -> myosin binds to actin
What role does the binding of ATP to the myosin head place in the cross-bridge cycle? What about the dissociation of ADP and inorganic phosphate from the myosin head?
ATP binding allows the myosin filament to disconnect from actin, dissociation from ADP and inorganic phosphate causes the powerstroke (upon attachment of actin, the myosin head snaps back to a low energy position and moves the actin filament toward the center of the sarcomere)
What is tetanus?
The summation of multiple simple twitches that occur too quickly for the muscle to relax, leads to a stronger and more prolonged contraction of the muscle
What is the difference between compact and spongy bone?
Compact bone = dense, used for its strength; forms most of the outer layers of a bone, Spongy bone = has many spaces between bony spicules called trabeculae, is the site of marrow production; is found in the interior core of the bone, helps distribute forces or pressures on the bone
What are the three structural parts of a bone? Which part contributes most to linear growth?
Diaphysis, metaphysis, epiphysis (where growth plates are found, contribute to linear growth)
What chemical forms most of the inorganic component of bone?
Hydroxyapatite crystals
What are the functions of osteoblasts, osteoclasts, and chondrocytes?
Osteoblasts build bone, osteoclasts break down bone, chondrocytes form cartilage
What liquid provides the lubrication for movable joints? What tissue produces it?
Synovial fluid, produced by the synovium, lubricates movable joints
With which of the following molecules does Ca2+ bind after its release from the sarcoplasmic reticulum to regulate muscle contraction?
Troponin
When the knee moves back and forth during walking, what prevents the surfaces of the leg bones from rubbing against each other?
Articular cartilage
What are some true statements about the periosteum?
Serves as a site of attachment of bone to muscle, cells of the periosteum may differentiate into osteoblasts, and the periosteum is a fibrous sheath that surrounds long bones
To facilitate the process of birth, an infant’s head is somewhat flexible. This flexibility is due in part to the two fontanelles, which are soft spots of connective tissue in the infan’t skull. With time, the fontanelles will close through a process known as:
Intramembranous ossification
What does it mean for an allele to be dominant? Recessive?
Requires only one copy for expression; requires two copies for expression
What does it mean for a genotype to be homozygous? Heterozygous? Hemizygous?
Homozygous = 2 alleles are the same, heterozygous = 2 alleles are different, hemizygous = only 1 allele is present for a given gene
What is the difference between complete dominance, codominance, and incomplete dominance?
Complete dominance = one allele masks the expression of the other, codominance = a gene has more than 1 dominant allele, incomplete dominance = a gene has no expressed alleles, heterozygotes have phenotypes that are intermediate between homozygotes
What is the difference between penetrance and expressivity?
Penetrance = the proportion of the population that expresses a phenotype, given a particular genotype; Expressivity = the differences in expression of a phenotype in individuals
With which phase of meiosis does each of Mendel’s laws most closely correlate?
Mendel’s first law (Law of Segregation) = Anaphase I; Mendel’s second law (Law of Independent Assortment) = Prophase I
Why would genetic leakage in animals be rare prior to the last century?
Genetic leakage requires the formation of a hybrid organism that can then mate historically, so fertile hybrids were certainly rare before a more modern understanding of genetics
Why is genetic drift more common in small populations? What relationship does this have to the founder effect?
Genetic drift occurs due to chance, so its effects will be more pronounced with a smaller sample size; the founder effect occurs when a small group is reproductively isolated from the larger population, allowing certain alleles to take on a higher prevalence in the group than in the rest of the population
All five criteria of the Hardy-Weinberg principle are required to imply what characteristic of the study population?
The criteria for the Hardy-Weinberg principle all imply that the study population is not undergoing evolution; thus, the allele frequencies will remain stable over time
What is natural selection?
Certain traits that arise from chance are more favorable for reproductive success in a given environment, and that those traits will be passed on to future generations
What is the modern synthesis model?
Natural selection is for specific alleles, which are passed on to future generations through formation of gametes; the alleles for these favorable traits arise from mutations
What is inclusive fitness?
The reproductive success of an organism is not only due to the number of offspring it creates, but also the ability to care for young (explains changes based on survival of hte species)
What is punctuated equilibrium?
For some species, little evolution occurs for a long period, which is interrupted by rapid bursts of evolutionary change
If a male with hemophilia (XhY) is crossed with a female carrier of both color blindness and hemophilia (XcXh), what is the probability that a female child will be phenotypically normal?
0.5
What are some true statements based on Darwin’s theory of evolution?
Natural selection is the driving force for evolution, natural selection can drive organisms living in groups to ultimately become distinct species, and fitness is measured by reproductive success
What are some necessary conditions for Hardy-Weinberg equilibrium?
(1) No change in the DNA sequence, (2) No migration, (3) A very large population size, (4) Random mating, and (5) No natural selection
What is DNA methyltransferase?
An enzyme responsible for catalyzing the methylation (and therefore silencing) of DNA
If a disease is an X-linked recessive disorder:
A woman must have a mutated copy of the gene on both of her X chromosomes in order to express the trait
In the ETC, are electron carriers mobile and hydrophobic?
No
What is observed in a patient experiencing hyperventilation?
Net exhalation of CO2, increased blood pH, increased hemoglobin O2 affinity
Between folic acid, carbonic acid, ascorbic acid, and citric acid, which is not an organic acid?
Carbonic acid (because no covalent bond between carbon and hydrogen)
Conn’s syndrome, also known as primary hyperaldosteronism, is most likely to cause which symptom?
Low blood potassium (Aldosterone = increases Na+ reabsorption and K+ secretion)
What are some post-transcriptional modifications that are involved in the life cycle of a virus?
Splicing and polyadenylation
Viruses are directly involved in which of the following processes in bacteria?
Transduction (foreign DNA is introduced into the cell by a viral vector)
What interaction would exist between 2 intra-subunit molecules?
Ion-dipole interactions
In an adult, which of the following cell types is LEAST likely to enter a programmed G0 phase of the cell cycle?
Epithelial cells
Viruses are distinct from most biological organisms in that they:
Are pathogenic entities which have been described as not being “living”
A disruption in the regulation of which cellular process is probably responsible for keloids?
Mitosis
Malonyl-CoA is an intermediate in cytosolic fatty acid biosynthesis. Its inhibition of the B-oxidation of long-chain fatty acids:
Prevents the degradation of newly synthesized fatty acids
For methylation and deamination:
a pyrimidine cannot be converted to a purine and vice versa
Which base is heavier: thymine or uracil?
Thymine
What are a few examples of aprotic solvents?
Acetone, DMSO
What are a few examples of protic solvents?
Water, methanol
What is the function of ligase during S-phase?
Binds together pieces of the lagging strand
What is passive immunity?
The transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another
What is natural immunity?
Immunity that is present in the individual at birth, prior to exposure to a pathogen or antigen (skin, salivary enzymes, neutrophils, natural killer cells, complement)
What is cell-mediated immunity?
An immune response that does not involve antibodies, but involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen
What is innate (non-specific) immunity?
Includes anatomical barriers, secretory molecules, and cellular components
If splicing took place in a virus…
It is a DNA virus
What is a structure found in the blood-brain barrier?
Tight junctions
What would be useful in cellular movement?
Flagella, cilia, actin polymerization
What are the four fundamental tenets of the cell theory?
All living things are made of cells, the cell is the basic functional unit of life, all cells arise from other cells, and genetic information is carried in the form of DNA and is passed from parent to daughter cell
What is the function of the nucleus?
Stores genetic information and is the site of transcription
What is the function of the mitochondria?
Involved in ATP production and apoptosis
What is the function of the lysosome?
Break down cellular waste products and molecules ingested through endocytosis, and is involved in apoptosis
What is the function of the rough ER?
Synthesizes proteins destined for secretions
What is the function of the smooth ER?
Lipid synthesis and detoxification
What is the function of the Golgi apparatus?
Packages, modifies, and distributes cellular products, transport of lipids, creation of lysosomes
What is the function of the peroxisome?
Break down very long chain fatty acids, synthesize lipids, and contribute to the pentose phosphate pathway
What would be the outcome of a deficiency in the production of hydrogen peroxide?
An inability to digest very long chain fatty acids
What are microfilaments composed of?
Actin
What are microtubules composed of?
Tubulin
What are intermediate filaments composed of?
Keratin
How do the cytoskeletal structures of centrioles and flagella differ?
Centrioles = 9 triplets of microtubules around a hollow center, flagella = 9 doublets on the outside, with two microtubules on the inside
How is Archaea similar to bacteria/eukaryotes?
Archaea’s similarities to bacteria: single-celled organisms that lack a nucleus or membrane-bound organelles, contain a single circular chromosome, divide by binary fission or budding; Archaea’s similarities to eukaryotes: start translation with methionine, contain similar RNA polymerases, contain DNA associated with histones
How do the structures of eukaryotic and prokaryotic flagella differ?
Eukaryotic flagella = microtubules composed of tubulin, organized in a 9+2 arrangement ; bacterial flagella = made of flagellin and consist of a filament, basal body, and hook
What is transformation?
The acquisition of exogenous genetic material that can be integrated into the bacterial genome
What is conjugation?
The transfer of genetic material from one bacterium to another across a conjugation bridge, from F+ to F- cells, or a portion from an Hfr cell to a recipient
What is transduction?
The transfer of genetic material from one bacterium to another by a bacteriophage
What are the four phases of the bacterial gorwth curve and the features of each phase?
Lag phase, exponential phase, stationary phase, death phase
What does an enveloped, single-stranded positive-sense RNA virus mean?
The virus contains an outer layer of phospholipids with an inner capsid. Within the capsid, there is single-stranded RNA that can be immediately translated to protein by the ribosomes of the host cell
Describe the pathway of retroviral nucleic acids from infection of a host cell to release of viral progeny.
Enters as single-stranded RNA, undergoes reverse transcription to form double-stranded DNA, DNA enters the host genome and replicates with the host cell, DNA transcribed to mRNA to be used to make structural proteins, mRNA doubles as viral genome for new virions, once new virions are assembled they can be released to infect other cells
What is the difference between the lytic and lysogenic cycles?
Lytic cycle = bacteriophages replicate in the host cell in extremely high numbers until the host cell lyses and releases the virions; lysogenic cycle = the bacteriophage genome enters the host genome and replicates with the host cell as a provirus
What are some examples of connective tissues?
Cartilage, ligaments, adipose tissue, blood
What types of nucleic acids could form the genome of a virus?
Single-stranded RNA, double-stranded DNA, single-stranded DNA
What occurs in the Golgi apparatus?
Modification and distribution of proteins
What is a statement that correctly describes HSV?
Herpes simplex virus adds its genetic information to the genetic information of the cell
What can account for a bacterium’s ability to increase its genetic variability and thus adapt itself to resist different antibiotics?
Conjugation and transduction
After infectoin of a cell, a viral particle must transport itself to the nucleus in order to produce viral proteins. What is the likely genomic content of the virus?
Double-stranded DNA
What occurs during G1 phase?
Cell grows and performs its normal functions. DNA is examined and repaired.
What occurs during S phase?
DNA is replicated.
What occurs during G2 phase?
Cell continues to grow and replicates organelles in preparation for mitosis. Cell continues to perform its normal functions.
What occurs during M phase?
Mitosis (cell division) occurs.
What occurs during G0 phase?
The cell performs its normal functions and is not preparing to divide.
What occurs during prophase?
Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite poles and begin forming the spindle apparatus
What occurs during metaphase?
Chromosomes gather along the metaphase plate in the center of the cell under the guidance of the spindle apparatus
What occurs during anaphase?
Sister chromatids separate, and a copy of each chromosome migrates to opposite poles
What occurs during telophase?
Chromosome decondense, nuclear membrane reforms, nucleoli reappear, spindle apparatus breaks down, cell divides into two identical daughter cells
What is the ploidy of the daughter cells produced from meiosis I? From meiosis II?
After meiosis I = two haploid daughter cells; after meiosis II = up to four haploid gametes
What is the difference between between homologous chromosomes and sister chromatids?
Homologous chromosomes = related chromosomes of opposite parental origin; Sister chromatids = identical copies of the same DNA that are held together at the centromere
What are the functions of interstitial cells of Leydig and Sertoli cells?
Interstitial cells of Leydig = secrete testosterone and other male sex hormones (androgens); Sertoli cells = nourish sperm during their development
During which phase of meiosis is a primary oocyte arrested? During which phase of meiosis is a secondary oocyte arrested?
A primary oocyte is arrested in prophase I; a secondary oocyte is arrested in metaphase II
What is an acrosome and what organelle forms from it?
Acrosome (modified Golgi apparatus) = contains enzymes that are capable of penetrating the corona radiata and zona pellucida of the ovum, permitting fertilization to occur
Which hormones are key to sexual differentiation in a fetus with XY genotype? Describe the expected phenotype if receptors to these hormones are absent?
Androgens lead to male sexual differentiation (absence of androgen receptors leads to an XY genotype)
Which of the following is the correct sequence of the development of a mature sperm cell?
Spermatogium -> primary spermatocyte -> secondary spermatocyte -> spermatid -> spermatozoan
In patients with Alzheimer’s disease, there is a defect in the way the sprindle apparatus attaches to the kinetochore fibers. At which stage of mitotic division would one first expect to be able to visualize this problem?
Prophase (spindle apparatus interacts with kinetochore at end of prophase)
A physician who diagnoses a granulosa cell tumor (excessive estrogen) should look for a secondary cancer in which of the following parts of the reproductive tract?
Endometrium (estrogen thickens endometrial lining)
Upon ovulation, the oocyte is released into the:
Abdominal cavity
At which points in the cell cycle would chemotherapy prevent cell division?
S stage, prophase, or metaphase
What contributes to genetic variability?
Random fertilization of an egg by a sperm, random segregation of homologous chromosomes, crossing over between homologous chromosomes during meiosis
What is a key difference between mitosis and meiosis?
During metaphase of mitosis, centromeres are present directly on the metaphase plate; during metaphase of meiosis I, there are no centromeres on the metaphase plate
What is a component of prophase?
The nucleoli disappear
An individual who is phenotypically female is found to have only one copy of a disease-carrying recessive allele on the X chromosome, yet she demonstrates all of the classic symptoms of the disease. Geneticists determine she has a genotype that likely arose from nondisjunction of one of her parents. What is the likely genotype of this individual?
45,X (one copy of recessive allele = no dominant allele)
During which phase of the menstrual cycle does progesterone concentration peak?
Luteal phase
What would be seen during pregnancy?
High levels of hCG in the first trimester, high levels of progesterone throughout the pregnancy, low levels of FSH in the first trimester
What is the difference between determinate and indeterminate cleavage?
Determinate cleavage = cell division that results in cells having definitive lineages (at least one daughter cell is programmed to differentiate into a particular cell type); indeterminate cleavage = cell division that results in cells that can differentiate into any cell type (or a whole organism)
From zygote to gastrula, what are the various stages of development?
Zygote -> 2-, 4-, 8-, and 16-cell embryo -> morula -> blastula (blastocyst) -> gastrula
During which stage of development does implantation occur?
The blastula (blastocyst) stage
What are the primary germ layers, and what organs are formed from each?
Ectoderm (epidermis, hair, nails, epithelia of nose, mouth, anal canal), lens of eye, nervous system, adrenal medulla, inner ear; Mesoderm (musculoskeletal system, circulatory system, excretory system, gonads, muscular and connective tissue layers of digestive and respiratory systems, adrenal cortex); Endoderm (epithelial linings of digestive and respiratory tracts, parts of liver, pancreas, thyroid, bladder, distal urinary and reproductive tracts)
What is induction and how does it influence development?
The process by which nearby cells influence the differentiation of adjacent cells, ensures proper spatial location and orientation of cells that share a function or have complementary functions
What tissues do neural crest cells develop into?
Peripheral nervous system
What is the difference between determination and differentiation?
Determination = the commitment of a cell to a particular lineage; differentiation = the actual changes that occur in order for the cell to assume the structure and function of the determined cell type
What are the three types of potency? What lineages can a cell of each type differentiate into?
Totipotency = any cell type in the developing embryo or in extraembryonic tissues; pluripotency = any cell type in the developing embryo; multipotency = any cell type within a particular lineage
What are the four types of cell-cell communication?
Autocrine (signal acts on same cell that secreted it); paracrine (signal acts on local cells); juxtracrine (cell triggers adjacent cells through direct receptor stimulations); endocrine (signal travels via the bloodstream to act on cells at distant sites)
What is the difference between apoptosis and necrosis?
Apoptosis = programmed cell death and results in contained blebs of the dead cell that can be picked up and digested by other cells ; necrosis = cell death due to injury and results in spilling of cytoplasmic contents
What is the oxygenation status of the blood in the umbilical arteries/umbilical vein?
Umbilical arteries carry deoxygenated blood, umbilical vein carries oxygenated blood
What are the three fetal shunts? What vessels or heart chambers do they connect? What organ does each shunt bypass?
1) Foramen ovale (connects right atrium to left atrium, bypasses lungs); 2) Ductus arteriosus (connects pulmonary artery to aorta, bypasses lungs); 3) Ductus venosus (connectus umbilical vein to inferior vena cava, bypasses the lungs)
What are some of the key developmental features of each trimester?
1st trimester: organogenesis (development of heart, eyes, gonads, limbs, liver, brain); 2nd trimester: tremendous growth occurs, movement beings, face becomes distinctly human, the digits elongate; 3rd trimester: rapid growth and brain development continue, there is transfer of antibodies to the fetus
What occurs in each of the three phases of birth?
1st phase: cervix thins out and amniotic sac ruptures; 2nd phase: uterine contractions, coordinated by prostaglandins and oxytocin, result in birth of fetus; 3rd phase: placenta and umbilical cord expelled
Which of the following developmental stages has the greatest nuclear-to-cytoplasmic ratio?
Blastula
Which of the following is likely to be found in maternal blood during pregnancy?
Progesterone produced by placental cells
A cancer cell is removed from a patient and cultured. The cells in this culture seem to be able to divide indefinitely with no cellular senescence. Which protein is likely activated in these cells that accounts for this characteristic?
Telomerase (synthesizes telomeres, which counteracts shortening during replication)
What is true about adult stem cells?
Less controversial than embryonic stem cells, require treatment with various transcription factors, reduced risk of rejection if the patient’s own stem cells are used
A child is born with an imperforate anus, in which the anal canal fails to form correctly and the rectum is not connected to the outside world. This pathology is:
Apoptosis
Following a myocardial infarction, the heart often heals by the creation of a scar by fibroblasts. This is an example of:
Incomplete regeneration
Which of the following shows the correct order of early developmental milestones during embryogenesis?
Morula -> blastula -> gastrula
A pregnant woman is accidentally given a single dose of a teratogenic drug late in the third trimester. The baby is born three days later. Which of the following is the most likely outcome?
Respiratory distress at birth, but no long-term effects (disturb embryo/fetus)
What are some true statements about fetal circulation?
More arteries than veins in the umbilical cord, foramen ovule is the only shunt that connects the two chambers of the heart, ductus venosus is the only shunt that bypasses the liver
What is an axon?
Transmits an electrical signal (the action potential) from the soma to the synaptic knob
What is an axon hillock?
Integrates excitatory and inhibitory signals from the dendrites and fires an action potential if the excitatory signals are strong enough to reach threshold
What is a dendrite?
Receive incoming signals and carry them to the soma
What is a myelin sheath?
Acts as insulation around the axon and speeds conduction
What is a soma?
The cell body and contains the nucleus, endoplasmic reticulum, and ribosomes
What is a synaptic bouton?
Lies at the end of the axon and releases neurotransmitter
What is a collection of cell bodies in the CNS?
Nucleus
What is a collection of cell bodies in the PNS?
Ganglion
Which two types of glial cells, if not properly functioning, will make an individual most susceptible to a CNS infection?
Astrocytes (nourish neurons, form blood-brain barrier, helps protect brain from foreign pathogens gaining entrance), microglia ingest and break down waste products and pathogens
Guillain-Barre syndrome (GBS) is an autoimmune disease that causes demyelination in the peripheral nervous system. What type of glial cell is being targeted in GBS?
Schwann cells
What neural structure initiates the action potential?
Axon hillock
What entity maintains the resting membrane potential? What is the approximate voltage of the resting membrane potential?
Is -70 mV, maintained by K+Na+ ATP-ase
What is the difference between temporal and spatial summation?
Temporal summation = integration of muliple signals close to each other in time; spatial summation = integration of multiple signals close to each other in space
During the action potential, which ion channel opens first? How is this ion channel regulated? What effect does the opening of this channel have on the polarization of the cell?
Na+ channel opens first (around -50 mV), regulated by inactivation which occurs around +35 mV (can only be reversed by repolarizing the cell), opening of Na+ channel causes depolarization
During the action potential, which ion channel opens second? How is this ion channel regulated? What effect does the opening of this channel have on the polarization of the cell?
K+ channel opens second (around +35 mV), regulated by closing at low potentials around -70 mV, opening of K+ channels causes repolarization, and eventually hyperpolarization
What is the difference between the absolute and relative refractory period?
Absolute refractory period = the cell is unable to fire an action potential regardless of the intensity of the stimulus; relative refractory period = the cell can fire an action potential only with a stimulus that is stronger than normal
What ion is primarily responsible for the fusion of neurotransmitter-containing vesicles with the nerve terminal membrane?
Calcium
What are the three main methods by which a neurotransmitter’s action can be stopped?
Enzymatic degradation, reuptake, or diffusion
What parts of the nervous system are in the CNS? PNS?
CNS = brain and spinal cord; PNS = cranial and spinal nerves, sensory nerves
What do afferent/efferent neurons do?
Afferent (sensory) neurons bring signals from a sensor to the CNS; efferent (motor) neurons bring signals from the CNS to an effector
What functions are accomplished by the somatic/autonomic nervous system?
Somatic nervous system = voluntary action, especially moving muscles; autonomic nervous system = involuntary actions
What are the effects of the sympathetic/parasympathetic nervous system?
Sympathetic = “fight-or-flight”, increased heart rate, bronchial dilation, redistribution of blood to locomotor muscles, dilation of pupils, slowing of digestive and urinary function; parasympathetic = “rest-and-digest”, slowing heart rate and constricting the bronchi, redistributing blood to the gut, promoting exocrine secretions, constricting pupils, promoting peristalsis and urinary function
What is the pathway of neural impulses in a monosynaptic reflex? In a polysynaptic reflex?
Monosynaptic reflex = a sensory (afferent, presynaptic) neuron dires directly onto a motor (efferent, postsynaptic) neuron; polysynaptic reflex = sensory neuron may fire directly onto a motor neuron, but interneurons are used as well (the interneurons fire onto other motor neurons)
What is a true statement about action potentials?
Once an action potential is triggered, an impulse of a given magnitude and speed is produced
What is a difference between nerves and tracts?
Nerves may carry more than one type of information; tracts can only carry one type of information
A surgeon accidentally clips a dorsal root ganglion during a spinal surgery. What is a likely consequence of this error?
Loss of sensation at that level
When lipids leave the stomach, what stages of digestion have been accomplished? What enzymes are added to accomplish the next phase?
Physical digestion = in mouth and stomach, reducing particle size; chemical digestion = pancreatic lipase, colipase, cholesterol esterase, bile (in small intestine); absorption occurs in more distal portion of small intestine
True or False: All lipids enter the circulation through the lymphatic system.
False (small free fatty acids enter the circulation directly)
Describe the structure of a micelle.
Collections of lipids with their hydrophobic ends oriented toward the center and their charged ends oriented toward the aqueous environment (collect lipids within their hydrophobic centers)
A diabetic patient begins insulin injections for management of blood glucose levels. What is the expected impact on the patient’s weight?
Increase in insulin levels -> increase lipid storage and decrease lipid mobilization from adipocytes -> weight gain
What is the ratio of free fatty acids to glycerol produced through lipid mobilization?
3:1
What is the primary method of transporting free fatty acids in the blood?
Free fatty acids remain in the blood, bonded to albumin and other carrier proteins
Order the lipoproteins from greatest percentage of protein to least percentage of protein. Which molecules are primarily involved in triaglycerol transport?
HDL (good cholesterol) > LDL > IDL > VLDL > chylomicrons
Lipoproteins are synthesized primarily by which two organs?
Intestine and liver
When physicians order a lipid panel to evaluate a patient, which value do they prefer to see over a minimum threshold rather than below a minimum?
HDL is considered “good” cholesterol because it picks up excess cholesterol from blood vessels for excretion (HDL would be checked for being over a minimum value)
Under what conditions is HMG-CoA reductase most active? In what cellular region does it exist?
HMG-CoA reductase is most active in the absence of cholesterol and when stimulated by insulin; cholesterol reduces the activity of HMG-CoA reductase, which is located in the smooth endoplasmic reticulum (HMG-COA = RATE LIMITING STEP IN CHOLESTEROL + KETONE SYNTHESIS)
What proteins are specific to the formation and transmission of cholesteryl esters, and what are their functions?
LCAT catalyzes the esterification of cholesterol to form cholesteryl esters; CETP promotes the transfer of cholesteryl esters from HDL to IDL, forming LDL
What are the five steps in the addition of acetyl-CoA to a growing fatty acid chain?
Attachment to acyl carrier protein, bond formation between molecules, reduction of a carbonyl group, dehydration, and reduction of a double bond
How does B-oxidation of unsaturated fatty acids differ from that of saturated fatty acids?
There is an additional isomerase and reductase for the B-oxidation of unsaturated fatty acids, which provide the stereochemistry necessary for further oxidation
True or False: Fatty acids are synthesized in the cytoplasm and modified by enzymes in the smooth endoplasmic reticulum.
TRUE
Why are fatty acids used to create ketone bodies instead of creating glucose?
Fatty acid degradation results in large amounts of acetyl-CoA which cannot enter the gluconeogenic pathway to produce glucose ; energy is packaged into ketone bodies for consumption by the brain and muscles
What conditions and tissues favor ketogenesis and ketolysis?
Ketogenesis: prolonged fast, occurs in the liver, increasing concentrations of acetyl-CoA; ketolysis: prolonged fast, low-energy state in muscle and brain, does not occur in the liver
True or False: Bodily proteins will commonly be broken down to provide acetyl-CoA for lipid synthesis.
False (proteins are more valuable to the cell than lipids)
Where does the bulk of protein digestion occur?
Small intestine
During protein processing, what is the eventual fate of each of the following components: carbon skeleton, amino group, side chains?
Carbon skeleton: transported to the liver for processing into glucose or ketone bodies; amino group: feed into urea cycle for excretion; basic side chains end up like amino group, acidic side chains end up like carbon skeleton
What are enzymes used for lipid digestion in the digestive tract?
Pancreatic lipase, cholesterol esterase, colipase (colipase required for optimal activity of pancreatic lipase)
What is the fate of long-chain fatty acids that are contained within molecules?
Transport into chylomicrons released into the lymphatic system
During fatty acid mobilization, which of the following occurs?
HSL is activated, free fatty acids are released
How do chylomicrons and VLDL differ?
Chylomicrons are synthesized in the intestine, VLDL are synthesized in the liver
What could result from an absence of apolipoproteins?
An inability to secrete lipid transport lipoproteins, an inability to endocytose lipoproteins, a decreased ability to remove excess cholesterol from blood vessels
Statin drugs inhibit HMG-CoA reductase. As such, they are likely prescribed for:
Hypercholesterolemia (high cholesterol)
Which fatty acid can be synthesized by humans?
16:0 (palmitic acid -> 16 carbons)
The majority of triacylglycerols stored in adipocytes originate from:
Synthesis in the liver
2,4-Dienoyl-CoA reductase is used in the oxidation of:
Polyunsaturated fatty acids
What is true regarding ketolysis?
Ketolysis generates acetyl-CoA (breakdown of ketone bodies to make acetyl-CoA for energy, occurs in muscle tissue/brain)
What is LEAST likely to result from protein degradation and processing by the liver?
Fatty acids (prolonged starvation state -> gluconeogenesis won’t produce fatty acids)
Why can heat be used as a measure of internal energy in living systems?
Delta U = Q - W , W = 0 -> Delta U = Q
How does coupling with ATP hydrolysis alter the energetics of a reaction?
Yields about 30 kJ/mol of energy, can be harnessed to drive other reactions forward
Explain why ATP is an inefficient molecule for long-term energy storage
ATP is an intermediate energy-storage molecule and is not energetically dense
Name electron carriers and their relevant metabolic pathways in the cell.
NADH (glycolysis, fermentation, citric acid cycle, ETC); NADPH (PPP, lipid biosynthesis, bleach formation, oxidative stress, photosynthesis); CoQ: ETC; cytochromes: ETC ; glutathione: oxidative stress
Provide an example of disequilibrium that is maintained at the expense of cellular energy.
Sodium-potassium pump
What tissue is least able to change its fuel source in periods of prolonged starvation?
Cells that rely solely on anaerobic respiration
During which stage is there the greatest decrease in the circulating concentration of insulin?
Postabsorptive state
Describe insulin.
Promotes glucose uptake by adipose tissue in muscle, glucose utilization in muscle cells, and macromolecule storage
Describe glucagon.
Increases blood glucose levels by promoting glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis
Describe cortisol.
Increases lipolysis and amino acid mobilization, while decreasing glucose uptake in certain tissues (increasing glucose levels) and enhancing the activity of other counterregulatory hormones
Describe catecholamines.
Increase glycogenolysis/gluconeogenesis (stop glycogen synthesis) in muscle and liver and lipolysis in adipose tissue
Describe thyroid hormones.
Increase basic metabolic rate and potentiate the activity of other hormones, produces calcitonin (thyroid hormones: T3 (3 iodines) and T4 (4 iodines))
What vital sign abnormalities might be expected in a patient with thyroid storm?
Hyperthermia, tachycardia, hypertension, tachypnea (high respiratory rate)
What is the preferred fuel for cells in the well-fed state?
Glucose (exception = cardiac muscle, which prefers fatty acids)
What are the major metabolic functions of the liver?
Maintaning a steady-state concentration of glucose in the blood through glucose uptake and storage, glycogenolysis, gluconeogenesis; participates in cholesterol and fat metabolism, urea cycle, bile synthesis, detoxification of foreign substances
How is the respiratory quotient expected to change when a person transitions from resting to brief exercise?
Will cause the respiratory quotient to approach 1 (RQ = CO2 produced / O2 consumed)
What is true about the hydrolysis of ATP?
The free energy of hydrolysis of ATP is nearly the same as for ADP
How do hormonal controls of glycogen metabolism differ from allosteric controls?
Hormonal control is systemic and covalent
What tissue is most dependent on insulin?
Resting skeletal muscle
In the absence of oxygen, which tissue would experience damage most rapidly?
Brain
A respiratory quotient approaching 0.7 indicates metabolism primarily of which macromolecule?
Lipids
What side effect would be anticipated for someone taking leptin to promote weight loss?
Drowsiness
How many times are ATP stores turned over per day?
1000
Which process is expected to begin earliest in a prolonged fast?
Enzyme phosphorylation and dephosphorylation
The toxic cyanide anion (CN-) binds to cytochrome c oxidase and prevents electron transfer. Dosing of BP-CML cells with cyanide would result in:
Reduced intracellular ATP and apoptosis or necrosis (would slow down ETC)
If oxygen consumption is reduced, what should happen to NADH levels?
NADH levels would increase (ETC would not be functioning properly, so NADH would not be oxidized to NAD+ and H+)
If a compound is already inhibiting the ETC, adding a compound that decouples the proton gradient across the inner mitochondrial membrane would:
Not have a strong effect on the cells
Why would hyperventilation lead to a decreased blood CO2 concentration?
The rate of CO2 exhalation exceeds the rate of CO2 production in the cells (main source of CO2 = production in krebs cycle)
In red blood cells, bicarbonate can be exchanged for chloride in the plasma. Why do red blood cells in venous circulation have a higher concentration of chloride ions?
Higher concentrations of CO2 in venous erythrocytes produce bicarbonate and drive the exchange of Cl- from the plasma into the cell
If blood pH goes down, it could be shown by:
Anaerobic respiration leading to lactic acid buildup, hypoventilation, and underproduction of bicarbonate
What are integrins?
Transmembrane receptors that modulate cell-to-extracellular matrix interactions
What are cadherins?
Transmembrane proteins which play a primary role in cell-to-cell adhesion
What is dynein?
A motor protein that moves cellular “cargo” along microtubule “train tracks”
What is a promoter?
Upstream DNA sequences in the eukaryotic genome that bind with transcription factors
What is an operator?
Structures in operons, which are involved in prokaryotic gene expression
What is the G-ratio?
The ratio of the diameter of the myelinated region surrounding the axon to the diameter of the axon itself (G-ratio = 1 if no myelination)
What would explain the failure of doxycycline to inhibit human protein synthesis?
Eukaryotic ribosomes lack a binding site for the drug
If a ribosome can bind aminoacyl-tRNA for binding to the A site of the 30s ribosome subunit even though the drug is not bound:
The drug is not able to stop protein synthesis
Increased protein solubility in aqueous solution will most likely result from:
More S, T, N, or Q residues on the outside of the protein
During rat embryogenesis, researchers noticed the development of a fluid-filled cavity in cells that had previously undergone morulation. That cavity was most likely a:
Blastocoel
During the isoelectric focusing procedure, cytokine Z migrated closer to the cathode than the control protein. This is most likely because Cytokine Z has a higher concentration of which amino acid?
Lysine (positively charged amino acid)
Which of the following changes would most likely be found in patients with mitochondrial myopathy?
Muscle aches due to lactic acid buildup
What makes an alcohol primary, secondary, or tertiary?
The number of carbons that surround the alcohol
Which of the following is most likely true of the 5’-UTR region?
It is transcribed, but is typically not translated or is only partially translated
What does a mature mRNA consist of?
A 5’-cap, the 5’ UTR, coding regions, the 3’ UTR, and a poly(A) tail
According to the passage, what total length of DNA is found in the average human cell before it is condensed for mitosis?
(6 x 10^9 bp)(0.3 x 10^-9 m/bp) = 1.8 m
Arrange the following in increasing order of compactness: nucleosome, heterochromatin, euchromatin, DNA helix.
DNA helix < euchromatin < heterochromatin < nucleosome
Defects in which of the following proteins would most likely lead to loss of structural integrity in skin epithelial cells?
Intermediate filaments (microtubules are also for structural integrity, but NOT in skin)
The frequency of the allele for colorblindness is 8%. Which of the following is the frequency of colorblind women and colorblind men in the population, respectively?
Frequency of gene = 0.08 -> odds of being homozygous = 0.0064 = 0.64%, since men only need a single copy of the gene, their odds would be 8%
What is the difference between transformation, transduction, and conjugation?
Transduction = DNA is transferred from one bacteria to another by a virus; transformation = genetic alteration of cell from direct uptake and incorporation of exogenous material; conjugation = transfer of genetic material, ordinarily in the form of a plasmid
It was proposed that nucleic acids were composed of a single tetramer of four nitrogenous bases linked by a circular, sugar-phosphate backbone. What apparent weakness exists in applying this model of nucleic acid structure to the experimenters’ conclusion regarding the source of genetic information?
The model does not contain sufficient structural complexity to explain genetic variation
What would challenge the researchers’ conclusions regarding the identity of the genetic material involved in the experiment?
Protein which happened not to pick up the 35S label entered the cell from the phage
What disease does angiogenesis play a role in?
Cancer
The researchers later used SDS-PAGE and size-exclusion chromatography to separate different mixtures containing both CP8 (a 76-kDa protein) and Zp_127 (a 40-kDa protein). CP8 would be expected to:
Travel a smaller distance during SDS-PAGE and elute more quickly during size-exclusion chromatography
Women over 35 years of age have an increased risk of nondisjunction due to errors in what phase of meiosis?
Anaphase II
Which of the following factors would be most likely to cause acetic acid to completely dissociate in aqueous solution?
Continuous removal of protons from the solution
How do Kd and the Hill coefficient relate to cooperativity/binding affinity?
Kd = lower the Kd, more binding affinity; a Hill coefficient around 1 means positive cooperativity
