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Alisha's MCAT Flashcards > Bio > Flashcards

Bio Flashcards

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1
Q

What is the other function of the mitrochondria besides ATP production?

A

The mitrochondria can also induce apoptosis through the release of enzymes from the ETC.

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2
Q

What is the function of the smooth endoplasmic reticulum?

A

The smooth endoplasmic reticulum functions in lipid synthesis, detoxification, and the transport of proteins from RER to the golgi apparatus.

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3
Q

What is the function of the hydrolytic enzymes within peroxisomes?

A

The function of the hydrolytic enzymes is to break down long-chain fatty acids through β-oxidation.

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4
Q

What is the cytoskeleton composed of?

A

Microfilaments, microtubules, and intermediate filaments.

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5
Q

What is the structure and function of microfilaments?

A

Microfilaments are composed of solid rods of actin, and they are resistant to compression and fracture which allows them to aid in the formation of the cleavage furrow, and interact with myosin for muscle contraction.

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6
Q

What is the structure and function of microtubules?

A

Microtubules are composed of hollow polymers of tubulin, and they function to provide pathways through which motor proteins can carry vesicles.

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7
Q

What are cilia and flagella composed of?

A

Microtubules

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8
Q

What is 9+2 structure?

A

Seen in eukaryotic organelles of motility; Nine pairs of microtubules forming an outer ring with two microtubules in the center.

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9
Q

What is the structure and function of centrioles?

A

Centrioles are found in the centrosome, and are composed of nine triplets of microtubules (hollow center) and they function to organize microtubules during the mitotic spindle.

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10
Q

What is the structure and function of intermediate filaments?

A

Intermediate filaments are composed of a diverse group of filamentous proteins (ie. keratin, desmin) that function in cell-cell adhesion and maintaining the overall structure of the cell.

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11
Q

What is are other purposes of epithelial tissue besides covering and lining body cavities?

A

Absorption, secretion, and sensation. Epithelial cells often constitute the parenchyma (functional parts) of organs.

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12
Q

How are archaea similar to eukaryotes?

A

Both archaea and eukaryotes contain histones, similar RNA polymerases, and they both begin translation with methionine.

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13
Q

How are archaea similar to prokaryotes?

A

Both archaea and prokaryotes contain a single, circular chromosome, and divide either by binary fission or budding.

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14
Q

What are three common bacterial shapes?

A
  1. ) Cocci → Spherical
  2. ) Bacilli → Rod-like
  3. ) Spirilli → Spiral-shaped
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15
Q

What differences between gram postive and gram negative bacteria cause gram postive bacteria to be suseptible to penicillin?

A

Gram positive bacteria have a thick cell wall composed of peptidoglycan. While gram negative bacteria have a thin cell wall that is also composed of peptidoglycan an an outer membrane. Penicillin targets an enzyme that catalyzes the cross-linkage of peptidoglycan. Therefore, the cell wall is weakened leading to the suseptibility of these bacterium to osmotic damage and lyses.

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16
Q

What is the composition of prokaryotic flagella?

A

Prokaryotic flagella are composed of a basal body, a hook, and a filament. The basal body anchors the flagella to the bacterium and rotates, the hook attaches the basal body and the filament, and the filament spins due to the rotations from the basal body in order to propel the bacterium.

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17
Q

Describe the three processes of bacterial genetic recombination.

A
  1. Transformation → The host genome integrates the genome of a nearby, lysed bacteria.
  2. Conjugation → F+ cell transfers some of its genetic material to an F- cell via a sex pilus. The F- cell becomes an F+ cell, and can now be referred to as Hfr.
  3. Transduction → Takes places through a vector. A bacteriophage attaches itself to and inserts its genome into a bacterial cell. This leads to the breakdown of the host cells genome. During the viral reproduction, some of the host cells genome may become incorporated onto the bacteriophage. When the virus infects another cell, the host cells genome may be transferred and integrated into the new cell’s genome.
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18
Q

Identify and decribes the four phases of bacterial growth.

A
  1. Lag Phase → Bacteria adjust to their new environment
  2. Exponential/Log Phase → After adjusting, bacteria begin to reproduce
  3. Stationary Phase → As resources deplete, reproduction slows
  4. Death Phase → As there are more bacteria than resources, bacteria begin dying
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19
Q

What is an enveloped virus?

A

An enveloped virus is one that has an outer layer of phospholipids with an inner capsid.

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20
Q

Describe the pathway of retroviral nucleic acids from infection to viral progeny.

A
  1. Viral genome (single-stranded RNA) enters cell
  2. Reverse transcriptase transcribes this genome into double-stranded DNA
  3. This DNA is translated by the host cell’s machinery
  4. Viral progeny are produced and released
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21
Q

Describe the differences between the lytic and lysogenic cycles.

A

During the lytic cycle the viral genome is translated into viral progeny, and relased via host cell lysis. During the lysogenic cycle, the viral genome is integrated into the host cell’s genome, and may indefinitely remain there or enter the lytic cycle due to environmental factors.

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22
Q

How do prions cause disease?

A

Prions are infectious proteins, that cause protein misfolding (alpha helixes → beta-pleated sheets). This misfolding decreases the solubility of the protein, causing problems with protein degredation. This can lead to protein aggregates forming.

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23
Q

Name the amino acids with nonpolar, nonaromatic side chains (7).

A

Glycine (smallest H atom R-group), alanine & valine & leucine & isoleucine (alkyl side chains), methionine (sulfur w/ methyl), proline (cyclic with amino group attached to R group).

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24
Q

Name the amino acids with aromatic side chains (4).

A

Tryptophan (double ring w/ N atom), phenylalanine (nonpolar, benzene), tyrosine (benzene w/ hydroxyl groups makes it polar), histidine (two N atoms in ring, + charge)

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25
Q

Name the amino acids with polar side chains (5).

A

Serine & threonine (contain -OH), asparagine & glutamine (contain amide), and cysteine (contains thiol -SH).

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26
Q

Name the amino acids with negatively charged (acidic) side chains (2).

A

Aspartic acid (anion is aspartate) & glutamic acid (anion is glutamate), both contain carboxyl groups.

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27
Q

Name the amino acids with postively charged (basic) side chains (3).

A

Arginine (three N atoms in side chain), Lysine (terminal, primary amino group), histidine (aromatic ring w/ two N atoms)

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28
Q

Name the hydrophobic amino acids (5).

A

alanine, isoleucine, leucine, valine, and phenylalanine (long alkyl side chains, nonpolar).

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29
Q

Name the hydrophillic amino acids (5).

A

histidine & arginine & lysine (+ charged), and glutamate (glutamic acid) and aspartate (aspartic acid) (- charged).

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30
Q

At pH=1 what is the predominant form for a generic amino acid?

A

Positively charged

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31
Q

At pH=7 what is the predominant form for a generic amino acid?

A

Zwitterion

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32
Q

At pH=11 what is the predominant form for a generic amino acid?

A

Negatively charged

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33
Q

What is the formula for calculating the isoelectric point of a neutal amino acid?

A

pI = [pKa(amino group) + pKa(carboxyl group)]/2

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34
Q

What is the formula for calculating the isoelectric point of an acidic amino acid?

A

pI = [pKa(R group) + pKa(carboxyl group)]/2

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35
Q

What is the formula for calculating the isoelectric point of a basic amino acid?

A

pI = [pKa(amino group) + pKa(R group)]/2

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36
Q

How many amino acid residues does an oligopeptide contain?

A

Contains less than 20 amino acid residues.

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37
Q

What is the role of proline in secondary structure?

A

Due to the rigidness of its cyclic structure proline creates kinks and turns in ɑ-helices and β-pleated sheets, respectively.

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38
Q

What are the stablizing bonds for tertiary protein structure?

A

Van der Waals forces, H-bonds, Ionic bonds, Covalent bonds.

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39
Q

What are the stablizing bonds in quarternary structure?

A

Van der Waals forces, H-bonds, Ionic bonds, Covalent bonds.

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40
Q

Why do hydrophobic amino acids move to the interior of proteins?

A

Water cannot form H-bonds with hydrophobic amino acids → water molecules must rearrage themselves to maximize H-bonding → decrease in entropy → unfavorable → more favorable for hydrophillic amino acids to be on the exterior

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41
Q

What is a protein with a nucleic acid prosthetic group called?

A

Nucleoprotein

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42
Q

What are the five phases of the cell cycle and what are their key functions?

A
  1. G1 → Cell grows and performs normal functions, DNA is examined and repaired
  2. S → DNA replication
  3. G2 → Cell continues to grow and carry out normal functions, organelles begin to replicate
  4. M → Cell divides
  5. G0 → Cell carries out normal functions, and is not preparing to divide
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43
Q

What are the four mitotic phases, and what are their key features?

A
  1. Prophase → DNA begins condensing, nuclear membrane begins to dissolve, nucleoli disappears, and centrioles migrate to opposite sides of the cell and begin to form mitotic spindle
  2. Metaphase → chromosomes line up at the metaphase plate under the guidance of the spindle apparatus
  3. Anaphase → sister chromatids separate, and are pulled to opposite sides of the cell
  4. Telophase/Cytokinesis → Chromosomes decondense, spindle apparatus breaks down, nuclear membrane begins reforming, cell divides into two identical daughter cells
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44
Q

Describe the process of meiosis.

A
  1. Diploid cell; 46 chromosomes, 46 sister chromatids, 23 pairs of homologous chromosomes
  2. After DNA rep. → 46 chromosomes, 92 sister chromotids, 23 pairs of homologs
  3. After Meiosis 1 → 23 chromosomes, 46 sister chromostids, 0 pairs of homologs → 2 daughter cells
  4. After Meiosis 2 → 23 chromosomes, 23 sister chromatids, 0 pairs of homologs → 4 gametes
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45
Q

For each meiotic phase, what are the differences between the corresponding mitotic phase?

A
  1. Prophase 1 → Homologous chromosomes come together as tetrads, crossing over
  2. Metaphase 1 → Tetrads line up at metaphase plate
  3. Anaphase 1 → Homologous chromosomes separate, centromeres do not break
  4. Telophase 1 → chromatin may/may not condense, interkinesis (rest period) occurs as cell prepares for meiosis 2
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46
Q

What are the interstitial cells of leydig responsible for?

A

Secrete testosterone, and other male androgens that are key for sexual differentiation in a fetus w/ XY genotype

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47
Q

What are the sertoli cells responsible for?

A

Nourishing sperm during their development

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48
Q

What are the semineferous tubules responsible for?

A

Sites of sperm production

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49
Q

What is the scrotum?

A

The scrotum is the external pouch that hangs below the penis, contains testes, cooler (2-4 °C) than body

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50
Q

What is the pathway of sperm through the male reproductive system?

A
  1. Semineferous tubules
  2. Epididymis → sperm flagella gain motility, and stored here
  3. Vas deferens
  4. Ejaculatory duct
  5. Urethra
  6. Penis
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51
Q

What is the purpose of the prostate gland?

A

Along w/ the seminal vesicles, the prostate gland give the sperm and seminal fluid mildly alkaline properties so the sperm can survive in the relatively acidic environment of the female reproductive tract

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52
Q

What is the acrosome?

A

The acrosome is located on the head of the sperm, and contains enzymes that are capable of penetrating the coron radiata and zona pellucida of the ovum, permitting fertilization

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53
Q

What are the female reproductive organs?

A
  1. ovaries → produce estrogen and testosterone → containing thousands of follicles which contain, nourish, and protect immature ova
  2. once a month, an egg is ovulated into the peritoneal sac
  3. then it is drawn into the fallopian tube (oviduct) which is connected to the urterus (site of fetal dev.)
  4. lower end of cervix (connected to vaginal canal)
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54
Q

What stage of meiosis are primary and second oocytes arrested in?

A

Primary oocytes are arrested in Prophase 1, and secondary oocytes are arrested in Metaphase 2 → complete meiosis when fertilizating occurs

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55
Q

What are the 4 phases of the menstrual cycle and characteristics?

A
  1. Follicular phase: the egg develops, and endometrial lining becomes vascularized and glandularized (FSH ↑, LH =, estrogen ↓ then ↑, progesterone ↓)
  2. Ovulation: the egg is released from the follicle into the peritoneal sac (FSH ↑, LH ↑↑, estrogen ↑, progesterone ↓)
  3. Luteal phase: corpus luteum produces progesterone to maintain endometrium (FSH ↓, LH =, estrogen ↑, progesterone ↑)
  4. Menses: shedding of the endometrial lining (FSH ↓, LH ↓, estrogen ↓, progesterone ↓)
  • hormone concentrations depend on feedback loops
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56
Q

What is the function of oxidoreductases?

A

Oxidoreductases function to catalyze oxidation/reduction reactions.

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57
Q

What is the function of transferases?

A

Catalyze the transfer of functional groups from one molecule to another (ie. kinases transfer phosphate groups).

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58
Q

What is the function of hydrolases?

A

Catalyze the breaking of a compound into two molecules through the addition of water.

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59
Q

What is the function of lysases?

A

Catalyze the cleavage of a molecule into two products.

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60
Q

What is the function of isomerases?

A

Catalyze the rearragement of bonds within a molecule.

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61
Q

What is the function of ligases?

A

Catalyze addition/synthesis reactions.

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62
Q

What is the function of cofactors and coenzymes, and what is the difference between them?

A

Cofactors and coenzymes bind to the active site of the enzyme and participate in the catalysis of the reaction, usually through ionization, protonation, or deprotonation.

Cofactors are inorganic, and coenzymes are generally organic.

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63
Q

What is the Michaelis-Menton equation?

A

v = vmax[S] / Km + [S]

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64
Q

What does vmax represent?

A

vmax represents the rate at which the enzyme is working at max velocity.

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65
Q

What does Km represent?

A

Km is the michaelis constant, and it represents the substrate concentration at which half of the enzyme’s active sites are full. It is often used to represent the affinity of an enzyme for its substrate. A higher Km represents a lower affinity, because a greater substrate concentration is necessary for half saturation of the enzyme.

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66
Q

At half of vmax, how are Km and [S] related?

A

Km = [S]

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67
Q

What does Kcat measure?

A

The number of substrate molecules converted to product.

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68
Q

What is the catalytic efficiency of the enzyme?

A

Kcat/Km

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69
Q

What is the effect of increasing [S] and [E] on vmax?

A

When [S] is low, increasing it will increase enzyme activity, but once vmax is reached there is no effect on enzyme activity. Increasing [E] will always increase vmax.

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70
Q

How do Michaelis-Menton and Lineweaver-burk plots differ?

A

The axis are different: MM plots v vs [S], while LWB plots 1/v vs 1/[S]

MM is a hyperbolic graph, and LWB is a straight line.

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71
Q

What does a michaelis menton plot look like?

A
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72
Q

What does a lineweaver burk plot look like, and what do the x and y intercepts represent?

A

X-intercept: 1/[Km]

Y-intercept: 1/vmax

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73
Q

What is enzyme cooperativity?

A

Enzyme cooperativity when binding a substrate encourages the transition of other subunits from a low-affinity tense state (T) to a high affinity relaxed state (R).

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74
Q

What is the ideal temperature for an enzyme in the human body?

A

37 °C = 98.6 °F = 311 K

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75
Q

What is the ideal pH for most enzymes?

A

7.4

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76
Q

What is the ideal pH for a gastric enzyme?

A

2

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77
Q

What is the ideal pH for a pancreatic enzyme?

A

8.5

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78
Q

Where do competitive inhibitors bind, and what are their effects on the Km and vmax?

A

Competitive inhibitors binds to the active site, the increase the Km and don’t impact the vmax.

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79
Q

Where do noncompetitive inhibitors bind, and what are their effects on the Km and vmax?

A

Noncompetitive inhibitors bind to the allosteric site, and don’t impact the Km, and decrease the vmax.

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80
Q

Where do mixed inhibitors bind, and what are their effects on the Km and vmax?

A

Mixed inihibitors bind to the allosteric site of either the enzyme or the enzyme-substrate complex. They can either increase (enzyme) or decrease (enzyme-substrate complex) and they decrease the vmax.

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81
Q

Where do uncompetitive inhibitors bind, and what are their effects on the Km and vmax?

A

Uncompetitive inhibitors bind to the allosteric site, and they decrease Km and decrease vmax.

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82
Q

What are examples of transient modifications on enzymes?

A

Allosteric activation and inactivation are examples of transient modifications. An activator will cause a conformational shift in the protein making the active site more available for binding to the substrate. An inactivator does the opposite.

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83
Q

What are examples of covalent modifications on enzymes?

A

Covalent modifications include phosphorylation and glycoslation (covalent attachment of sugar molecules that can tag the enzyme for transport or can modify protein activity and selectivity).

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84
Q

What are zymogens?

A

Zymogens are precursors of active sites. They contain a catalytic (active) domain and a regulatory domain. They exist because some enzymes cannot exist actively outside of where their catalytic activity is necessary (trypsin, if released outside of the pancreas, would digest the organ itself).

85
Q

What is the difference between determinate and indeterminate cleavage?

A

Determinate cleavage produces cells that differentiate into a certain type of cell, and indeterminate cleavage produces cells that can still develop into complete organisms (monozygotic twins).

86
Q

What the various stages of development, from zygote to gastrula?

A
  1. Cleavage: Zygote undergoes rapid mitotic cell divisions, ends with the formation of a morula (solid mass of cells)
  2. Blastulation: Morula develops into blastula, which is a hollow ball of cells w/ a fluid-filled inner cavity
  3. Implantation: The blastula moves through the fallopian tube to the uterus, where is burrows into the endometrium
  4. Gastrulation: Once the blastula implants, it can begin developing the three distinct germ layers, which is then known as the gastrula
87
Q

What are the three germ layers and what organs does each layer give rise to?

A
  1. Ectoderm: Develops into the integument (epidermis, hair, skin, nails) and also the nervous system
  2. Mesoderm: Develops into the musculoskeletal circulatory, and most of the excretory system
  3. Endoderm: Develops into the epithelial linings of the disgestive and respiratory tracts
88
Q

What is induction and how does it influence development?

A

Induction is the ability of one group of cells to influence the fate of nearby cells ensuring the proper spatial location and orientation of cells that share a common function.

89
Q

What is the process of neuralation?

A
  1. First the notochord forms along the axis of the organism
  2. Neural groove and neural folds form on both sides
  3. Neural folds form neural tube, which develops into the CNS
  4. Neural crest cells at the tip of each neural fold form the PNS
90
Q

What is the difference between determination and differentiation?

A

Determination is the committment to a particular cell lineage, while differentiation is the process of undergoing the actual changes that occur in order for a cell to assume the structure and function of the determined cell type.

91
Q

What are the three types of potency?

A
  1. Totipotent: Embryonic stem cells → can differentiate into any cell type
  2. Pluripotent: Differentiate into any cell type except for the ones found in placental structures
  3. Multipotent: Differentiate into multiple cell types within a particular group
92
Q

What are the 4 types of cell-cell communication?

A
  1. Autocrine signals: Act on the same cell that secreted the signal
  2. Paracrine: Act on cells in the neighboring area
  3. Juxtacrine: Act on adjacent cells
  4. Endocrine: Secreted hormones that travel through the bloodstream to act on target tissue
93
Q

What is the difference between apoptosis and necrosis?

A

Apoptosis is programmed cell death, while necrosis is cell death caused by tissue damage as a result of injury.

94
Q

What is the oxygen status in the umbilical arteries and umbilical vein?

A

Umbilical arteries carry deoxygenated blood from the fetus to the placenta, while the umbilical vein carries oxygenated blood from the placenta to the fetus.

95
Q

What are the three fetal shunts, what do they each connect, and what do the each bypass?

A
  1. Foramen ovale: Connects the left and right atrium, and bypasses the lungs
  2. Ductus arteriosus: Connects the pulmonary artery and aorta, and bypasses the lungs
  3. Ductus veriosus: Connects the umbilical vein and inferior vena cava, and bypasses the liver
96
Q

What are the key developments in each trimester?

A
  1. First trimester: Major organs form, and brain is almost fully developed
  2. Second trimester: Fetus begins to grow in size and begins to move
  3. Third trimester: Antibodies are transported from the mother to the fetus, and the brain develops further
97
Q

What are the key phases of birth (3)?

A
  1. First, cervix thins out and amniotic sac ruptures
  2. Strong uterine contractions result in the birth of the fetus
  3. Afterbirth: placenta and umbilical cord are expelled
98
Q

How do cytoskeletal and motor proteins differ?

A

Cytoskeletal proteins tend to be fibrous with repeating domains (ie. collagen, elastin, keratins, actin, tubulin), while motor proteins tend to have ATPase activity & binding heads (myosin, kinesins, dyneins) → both function in cellular motility

99
Q

What are the three types of cell adhesion molecules (CAMs), and what are their functions?

A
  1. Cadherins → group of glycoproteins that mediate calcium-dependent cell adhesion
  2. Integrins → group of proteins that have two membrane-spanning chains called α and β, aid in communication with the ECM
  3. Selectins → Bind to carbohydrate molecules that project from other cell surfaces
100
Q

When an antibody binds to an antigen, what are the three outcomes?

A
  1. Neutralize antigen
  2. Opsonization: marking antigen for destruction by WBCs
  3. Agglutinating the antibody-antigen complex in order to be phagocytized by macrophages
101
Q

What are enzyme-linked receptors?

A

Enzyme linked receptors may display catalytic activity in response to ligand binding. They have three primary protein domains: a membrane-spanning domain which anchors the receptor in the cell membrane, a ligand-binding domain which is stimulated by the appropriate ligand and induces a conformational change which activates the catalytic domain. This often results in the initiation of a second messenger cascade.

102
Q

What is a notable example of an enzyme-linked receptor?

A

An example of an enzyme-linked receptor is receptor tyrosine kinase (RTK). RTKs are composed of a monomer that dimerizes upon ligand binding, the dimer is the active form that phosphorylates additional cellular enzymes (including itself → autophosphorylation).

103
Q

What are G protein coupled receptors (GPCR)?

A

GPCRs are a large family of integral membrane proteins involved in signal transduction, and they are characterized by their seven membrane-spanning α-helices. The receptors differ in the specificity of the ligand-binding area found on the extracellular surface of the cell. The binding of a ligand, increases the affinity of the receptor for a G protein, and the binding of a G protein represents a switch to the active site, once GDP is replaced w/ GTP, the α subunit is able to dissociate from the β and γ subunits.

104
Q

What type of ion channel is active at all times?

A

Ungated channels are active at all times.

105
Q

How do transport kinetics differ from enzyme kinetics?

A

Transport kinetics display both vmax and km values, and they can also exhibit cooperativity.

106
Q

What is electrophoresis, and what are three of the most common methods?

A

Electrophoresis is the process of separating proteins, by subjecting them to an electric field, which moves them according to their net charge and size. The three most common methods are:

  1. Native PAGE: analyzing proteins in their native states; limited by varying mass-to-charge and mass-to-size ratios; protein can be recovered from the gel
  2. SDS PAGE: separates protein based on relative molecular mass; protein is denatured
  3. Isoelectric focusing: separates based on isoelectric point (pI) → Anode is (+) and acidic
107
Q

What is chromatography and what are the four most common methods?

A

Chromatography is a process that is used to separate and identify compounds from a complex mixture.

  1. Column Chromatography: Column is filled with silica or alumina beads; both size and polarity have a role in determining how quickly the compound moves through
  2. Ion-Exchange Chromatography: Beads are coated with charged substances, so they attract or bind compounds that have an opposite charge → opposite charge = higher retention time
  3. Size-Exclusion Chromatography: Beads contain tiny pores → smaller molecule = longer retention time
  4. Affinity Chromatography: a column can be customized to have a high affinity for a certain proteins → drawbacks: the protein may not elute because affinity may be too high
108
Q

What are two methods used to determine protein structure?

A

X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy.

109
Q

What is a protein analysis method that can be used to determine amino acid composition?

A

Edman degradation: uses cleavage to sequence proteins of up to 50 to 70 amino acids → selectively removes the N-terminal amino acid of the protein

110
Q

What method can be used to determine protein concentration?

A

Bradford protein assay: mixes a protein with a green-brown dye, when mixed with protein it turns blue → larger protein concentration = larger blue dye concentration.

111
Q

What is the function of the axon?

A

Axons transmit action potential from soma to synaptic knob.

112
Q

What is the function of the axon hillock?

A

The axon hillock integrates excitatory & inhibitory signals from dendrites, and if result is excitatory an AP will be initiated.

113
Q

What is the function of dendrites?

A

Dendrites receive incoming messages from other cells.

114
Q

What is the function of myelin sheath?

A

Myelin sheath acts as insulation around the axon, and speeds up conduction.

115
Q

What is the function of soma?

A

Somas are the cell bodies, and they contain the nucleus.

116
Q

What is the function of the synaptic button?

A

The synaptic button functions as the nerve terminal, and ensures the proper release of neurotransmitters.

117
Q

What are collection of cell bodies in the CNS and PNS referred to?

A

A collection of cell bodies in the CNS is called the nucleus, and a collection of cell bodies in the PNS are called ganglion.

118
Q

What is the function of astrocytes?

A

Astrocytes function to nourish neurons, and form the blood-brain barrier.

119
Q

What is the function of microglia?

A

Microglia are phagocytic cells that ingest and break down waste products and pathogens in the CNS.

120
Q

What is the difference between Schwann cells and oligodendrocytes?

A

Schwann cells function to myelinate axons in the PNS, and oligodendrocytes function to myelinate axons in the CNS.

121
Q

What is the function of ependedymal cells?

A

Ependedymal cells function to line ventricles in the brain and produce CSF.

122
Q

What neuronal structure initiates the AP?

A

Axon hillock.

123
Q

What ions maintain the membrane potential?

A

Na+ and K+ maintain the resting membrane potential (-70 mV).

124
Q

What is the difference between temporal and spatial summation?

A

Temporal summation is the integration of multiple signals close to eachother in time, and spatial summation is the integration of multiple signals close to eachother in time.

125
Q

Describe AP propagation.

A
  1. Na+ ions channels open at around -55 mV
  2. This causes depolarization (+), and Na+ channels become inactivated at around 35 mV
  3. Positive potential increase inside of the cell causes voltage-gated potassium channels to open
  4. Efflux of potassium causes repolarization and hyperpolarization
126
Q

What is the difference between absolute and relative refractory period?

A

Absolute refractory period is when the cell is unable to fire an AP, and relative refractory period is when the cell is able to fire an AP, but only with greater than avg. stimulus.

127
Q

What happens when the AP reaches the nerve terminal?

A

Voltage-gated Ca+2 channels open causing a calcium ion influx, leading to neurotransmitter containing vesicles to fuse with the cell membrane at the synapse.

128
Q

What are the three methods of neurotransmitter regulation?

A
  1. Neurotransmitters can be broken down by enzymatic reactions
  2. Neurotrasmitters can be brought back into the presynaptic neuron using reuptake carriers
  3. Neurotransmitters may diffuse out of the synaptic cleft
129
Q

What is the PNS composed of?

A

Sensory and motor neurons, as well as 31 pairs of spinal nerves, and 10/12 pairs of cranial nerves.

130
Q

What is the difference between afferent and efferent neurons?

A

Afferent neurons are sensory neurons, and efferent neurons are motor neurons.

131
Q

What is the difference between a monosynaptic response and a polysynaptic response?

A

A monosynaptic response is when there is a single synapse between the sensory and motor neuron (knee-jerk), while a polysynaptic response is when there is at least one interneuron between the sensory and motor neuron (withdrawal reflex but other leg is needed for balance).

132
Q

How are carbohydrates containing a ketone/aldehyde named?

A

Aldehyde → aldose → (ie. six carbon sugar would be an aldohexose)

Ketone → ketose → (ie. five carbon sugar would be ketopentose)

133
Q

What are stereoisomers?

A

Stereoisomers are compounds that have the same chemical formula but differ in terms of the spatial arrangement of their component atoms.

134
Q

What are epimers and what are some examples for glucose?

A

Epimers differ in configuration at exactly one chiral carbon, and some examples of epimers of glucose would be D-allose, D-mannose and D-galactose.

135
Q

What are enantiomers, and what are some examples of enantiomers of glucose?

A

Enantiomers are non-superimposable mirror images, and examples are D-glucose and L-glucose.

136
Q

During ring formation, what happens to the carbonyl carbon?

A

The carbonyl carbon becomes chiral, and is referred to as the anomeric carbon, the orientation of the -OH substituent determines whether the sugar molecule is the α or β anomer.

137
Q

What is mutarotation?

A

Exposting hemiacetal rings to water will cause them to spontaneously cycle between the open and closed form, either the α or β anomer can be formed.

138
Q

Which anomer is favored, α or β, and why?

A

The β anomer is favored in solution, because the hydroxyl group of the anomeric carbon is equatorial, allowing there to be less steric strain than the axial position (α anomer).

139
Q

What is esterification?

A

Esterification is a reaction through which a hydroxyl group reacts with either a carboxylic acid/deriv. to form an ester.

140
Q

What is glycoside formation?

A

Glycoside formation refers to the reaction between an alcohol and a hemiacetal (or hemiketal) group on a sugar to yield an alkoxy group.

141
Q

What is the purpose of Tollens’ reagent and Benedict’s reagent?

A

They are used to detect the presense of reducing reagents. Tollens’ reagent produces a silvery mirror when acetals are present and Benedict’s reagent produces a reddish precipitate of Cu2O.

142
Q

What is cellulose linked by?

A

Cellulose is a chain of β-D-glucose molecules linked by β-1,4 glycosidic bonds. It is the main structural component of plants, and undigestible by humans.

143
Q

What are starches linked by?

A

Starches are linked by α-D-glucose monomers, they are digestible by humans.

144
Q
A
145
Q

What is the difference between amylose and amylopectin, and which is more soluble in solution?

A

Amylose is a linear glucose polymer lined via α-1,4 glycosidic bonds, while amylopectin has the same linkage as amylose, but also contains branches via α-1,6 glycosidic bonds. Amylopectin is more soluble due to its branched structure.

146
Q

Should amylopectin or glycogen experience more effects from branch-cleaving enzymes?

A

Glycogen has more branching than amylopectin, so it will experience a higher rate of enzymatic branch cleavage.

147
Q

What are peptide hormones composed of, how do they travel through the bloodstream, where do they bind, what do they do once they bind, and how quick and long are the effects they produce?

A

Peptide hormones are composed of amino acids. They are water-soluble, and therefore can travel freely in the bloodstream. They are polar, and therefore cannot pass through the plasma membrane. They bind to extracellular receptors, where they trigger the transmission of a second messenger (signal cascade). Peptide hormones exert effects that are rapid, but short-lived.

148
Q

What are steroid hormones composed of, how do they travel through the bloodstream, where do they bind, what do they do once they bind, and how quick and long are the effects they produce?

A

Steroid hormones are derived from cholesterol. They are lipid-soluble, and therefore cannot travel freely through the bloodstream and must be carried by specific proteins. They are minimally polar, and can pass through the plasma membrane, allowing them to bind to and produce a conformational change in cytosolic or intranucleus receptors. The effects that these hormones produce are slow but they are long-lived.

149
Q

What is the purpose of a signal cascade?

A

A signal cascade can induce amplification of the signal.

150
Q

What are amino-acid derivative hormones, and what are some examples?

A

Amino-acid derivative hormones are modified amino acids. Some examples are epinephrine, norepinephrine, triidothyronine, and thyroxine.

151
Q

What is the difference between direct and tropic hormones?

A

Direct hormones have major effects on non-endocrine tissues, while tropic hormones have major effects on other endocrine tissues.

152
Q

How are the hypothalamus and the anterior pituitary connected?

A

The hypothalamus stimulates the anterior pituitary through the release of hormones into the hypophyseal portal system.

153
Q

What are the five hypothalamic tropic hormones that are released and stimulate the anterior pituitary?

A
  1. Gonadotropin-releasing hormone (GnRH) → Promotes the release of FSH and LH from anterior pituitary
  2. Growth hormone-releasing hormone (GHRH) → Promotes the release of growth hormone
  3. Thyroid-releasing hormone (TRH) → Promotes the release of thyroid stimulating hormone (TSH)
  4. Corticotropin-releasing factor (CRF) → Promotes the release of adrenocorticotropic hormone (ACTH)
  5. Prolactin-inhibiting factor (PIF or dopamine) → inhibits the release of prolactin
154
Q

How do the hypothalamus and the posterior pituitary interact?

A

Interactions occur through nerve projections from the hypothalamus to the PP. Antidiuretic hormone (ADH or vasopressin) and oxytocin are synthesized in the hypothalamus and then travel down these axons to the PP, where they are released into the bloodstream.

155
Q

What hormones does the anterior pituitary release in response to stimulation from the hypothalamus?

A
  1. Follicle-stimulating hormone (FSH): promotes the release of ovarian follicles in females and spermatogenesis in males
  2. Lutenizing hormone (LH): promotes ovulation in females and testosterone production in males
  3. Adrenocorticotropic hormone (ACTH): promotes the synthesis and release of glucocorticoids from the adrenal cortex
  4. Thyroid-stimulating hormone (TSH): promotes the synthesis and release of triiodothyronine and thyroxine from the thyroid
  5. Prolactin: promotes milk production
  6. Endorphins: decrease the perception of pain and can produce euphoria
  7. Growth hormone: Promotes growth of bone and muscle and shunts glucose to these tissues → raises blood glucose concentrations
156
Q

What hormones does the posterior pituitary release?

A

The posterior pituitary releases two hormones that are produced in the hypthalamus. ADH, which is secreted in response to low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron. Oxytocin, which is secreted during childbirth, and promotes uterine contraction and milk ejection (positive feedback loop).

157
Q

What hormones does the thyroid produce?

A
  1. Triiodothyronine (T3) and Thyroxine (T4): are produced by follicular cells and contain iodine → increase basal metabolic rate and alter the utilization of glucose and fatty acids → required for proper neurological and physical development in children
  2. Calcitonin: produced by parafollicular (C) cells → decreases plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absoption in the gut, and promoting calcium storage in the bone
158
Q

What hormone do the parathyroid glands release?

A

The parathyroid glands release PTH, whihc increases blood calcium concentration. PTH decreases excretion of calcium by the kidneys and increase bone resorption directly to increase blood calcium concentrations. It also activates vitamin D, which is necessary for calcium and phosphate absorption from the gut.

159
Q

What does the adrenal cortex produce?

A

The adrenal cortex produces three classes of steroid hormones.

  1. Glucocorticoids: cortisol and cortisone
  2. Mineralocorticoids: aldosterone
  3. Cortical Sex Hormones: androgens
160
Q

What is the function of glucocorticoids?

A

Glucocorticoids (including cortisol and cortisone) increase blood glucose concentration, reduce protein synthesis, inhibit the immune system, and participate in the stress response. Glucocorticoid release is stimulated by ACTH.

161
Q

What is the function of mineralocorticoids?

A

Mineralcorticoids, including aldosterone, promote sodium reabsorption in the distal convoluted tubule and collecting duct, increasing water reabsorption. Aldosterone also increases potassium and hydrogen ion excretion. Aldosterone activity is regulated by the renin-angiotensin aldosterone system.

162
Q

What is the renin-angiotensin-aldosterone system?

A
  1. Decreased blood pressure causes the juxtaglomerular cells of the kidney to secrete renin
  2. Renin cleaves an inactive plasma protein, angiotensin, to its active form angiotensin I
  3. Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs
  4. Angiotensin II stimulates the adrenal cortex to secrete aldosterone
163
Q

What are examples of the cortical sex hormones?

A

Cortical sex hormones include androgens like testosterone, and estrogens in both males and females.

164
Q

What is the adrenal medulla, and what hormones does it secrete?

A

The adrenal medulla is derived from the nervous systems, and secretes catecholamines into the bloodstream. Catecholeamines include epinephrine and norepinephrine, which are involved in the sympathetic response. These hormones promote glycogenolysis, increase the basal metabolic rate, increase heart rate, dilate the bronchi, and alter blood flow.

165
Q

What is the function of the pancreas, and what hormones does it produce?

A

The pancreas produce hormones that regulate glucose homeostasis.

  1. Glucagon is produced by the α-cells of the pancreas, and raises blood glucose levels
  2. Insulin is produced by β-cells and lowers blood glucose levels
  3. Somatostatin is produced by δ-cells (delta) and inhibits insulin and glucagon secretion
166
Q

What hormones do the gonads secrete and what is their function?

A

The testes secrete testosterone, and the ovaries secrete estrogen and progesterone. They are involved in the development and maintainance of the reproductive systems and secondary sex characteristics.

167
Q

What is hormone does the pineal gland release and what is its function?

A

The pineal gland releases melatonin, which is responsible for regulating circadian rhythms.

168
Q

What hormone do the kidneys secrete?

A

The kidneys secrete erythropoietin, which stimulates the bone marrow to produce erythrocytes, in response to low blood oygen levels.

169
Q

What hormone do the atria of the heart secrete?

A

The atria of the heart secrete atrial natriuretic peptide (ANP), which promotes excretion of salt and water in the kidneys in response to stretching of the atria (high blood volume).

170
Q

What hormone does the thymus secrete?

A

The thymus secretes thymosin, which is important for proper T-cell development and differentiation.

171
Q

What is the movement of air through the respiratory system?

A

Air…

  1. Enters the nares of the nose
  2. Passes through nasal cavity and is filtered by mucous membranes and nasal hairs (vibrissae)
  3. Passes through pharynx & larynx
  4. Moves into cartilaginous trachea
  5. Moves into 1/2 mainstream bronchi
  6. Continue into bronchioles
  7. Air exchange occurs in the alveoli (covered in
172
Q

Where is the diaphragm located, and is it under somatic or autonomic control?

A

The diaphragm divides the thoracic cavity from the abdominal cavity, and it is under somatic control.

173
Q

What is the process for inhalation?

A
  1. The diaphragm (flattens) and the external intercostal muscles are actively used to expand the thoracic cavity
  2. The intrapleural space volume increases, decreasing the pressure
  3. The lungs will expand into the intrapleural space, causing a pressure drop in the lungs
  4. Air will then be sucked inside the lungs due to the external higher-pressure environment
174
Q

What is the process for exhalation?

A

Exhalation is a passive relaxation of the external intercostal muscles and the diaphragm. This process can be sped up by using the internal intercostal muscles and abdominal muscles to pull the rib cage down.

175
Q

What are the lung capacities and volumes (6)?

A
  1. Total Lung Capacity (TLC): The maximum volume of iar in the lungs when one inhales completely; usually around 6 to 7 liters
  2. Residual Volume (RV): The volume of air remaining in the lungs when one exhales completely
  3. Vital Capacity (VC): The difference between the minimum and maximum volume of air in the lungs (TLC-RV)
  4. Tidal Volume (TV): The volume of air inhaled or exhaled in a normal breath
  5. Expiratory Reserve Volume (ERV): The volume of additional air that can be forcibly exhaled after a normal exhalation
  6. Inspiratory Reserve Volume (IRV): The volume of additional air that can be forcibly inhaled after a normal inhalation
176
Q

How do you calculated vital capacity?

A

VC = IRV + ERV + TV

177
Q

How is breathing regulated?

A

Breathing is primarily regulated by a collection of neurons in the medulla oblongata called the ventilation center. These neurons contain certain chemoreceptors that are sensitive to CO2 concentration. As the CO2 concentration increases, the respiratory rate will increase so that more carbon dioxide will be exhaled and levels drop.

178
Q

What type of blood do pulmonary arteries and pulmonary veins carry?

A

Pulmonary arteries carry deoxygenated blood, and pulmonary veins carry oxygenated blood.

179
Q

What is the driving force for gas exchange at the capillary level?

A

The driving force for gas exchange is the pressure differential for distinct gases.

180
Q

How can the highly vascular respiratory tract be used for thermoregulation?

A

The large surface area of interaction between the alveoli and capillaries allows the respiratory system to assist in thermoregulation through vasodilation and vasoconstriction.

181
Q

What are some immune functions of the respiratory system?

A
  1. Vibrissae, mucous membrane, and mucociliary escalator help filter the incoming air and trap particulate matter
  2. Lysozyme in the nasal cavity and saliva attacks the peptidoglycan cell walls of gram-positive bacteria
  3. Macrophages engulf and digest pathogens –> notify other cells that there is an invader
  4. Mucosal surfaces are covered with IgA antibodies
  5. Mast cells have antibodies on their surface, that when triggered, can promote the release of inflammatory chemicals –> often involved in allergic reactions
182
Q

What is the equation for the bicarbonate buffer system?

A

CO2 (g) + H2O (l) ⇔ H2CO3 (aq) ⇔ H+ (aq) + HCO3- (aq)

183
Q

When the pH of the blood is lower (acidemia) what occurs to the respiration rate?

A

As the H+ ion concentration increases, the bicarbonate buffer equation will shift left, generating additional carbon dioxide. The respiratory centers in the medulla oblongata are sensitive to the increasing partial pressure of carbon dioxide, and will also promote an increase in respiratory rate.

184
Q

What type of blood do pulmonary arteries carry?

A

Pulmonary arteries carry deoxygenated blood from the heart to the lungs.

185
Q

What type of blood do pulmonary veins carry?

A

Pulmonary veins carry oxygenated blood from the lungs to the heart.

186
Q

What are the two pumps of the heart?

A

The first pump is pulmonary circulation (where the right side of the heart accepts deoxygenated blood returning from the body and moves it to the lungs by way of the pulmonary arteries) and the second pump is systemic circulation (where the left side of the heart recieves oxygenated blood from the lungs by way of the pulmonary veins and forces it out to the body through the aorta).

187
Q

What structures does the atria recieve blood from?

A

The atria receives blood from either venae cavae (deoxygenated blood) or the pulmonary veins (oxygenated blood).

188
Q

What are the atrioventricular valves and where are they located?

A

The atrioventricular values are the tricuspid and bicuspid (mitral) valves. The tricuspid valve is located between the right atrium and the right ventricle, and the bicuspid or mitral valve is located between the left atrium and the left ventricle.

189
Q

What are the semilunar valves and where are they located?

A

The semilunar valves are the pulmonary valve and the aortic valve. The pulmonary valve is located between the right ventricle and pulmonary circulation, and the aortic valve is located between the left ventricle and the aorta.

190
Q

What are the steps for electrical conduction in the heart?

A
  1. Impulse initiation occurs at the SA node (located in the walls of the right atrium)
  2. The 2 atria contract simultaneously (atrial systole)
  3. The signal reaches the AV node –> signal is delayed here to allow the ventricles to completely fill before they contract
  4. The signal then travels to the bundle of His and its branches, which are embedded in the interventricular septum
  5. From there, the signal goes to the Purkinje fibers, which distribute the electrical signal to the ventricular muscle
191
Q

What is the intrinsic rhythm of the SA node?

A

The SA node has an intinsic rhythm of 60-100 signals/minute.

192
Q

How do sympathetic and parasympathetic signals affect heart rate?

A

Sympathetic signals speed up the heart rate and increase the contractility of heart muscle, while parasympathetic signals, provided by the vagus nerve, slow down the heart rate.

193
Q

What occurs during systole?

A

During systole, the ventricles contract and the closure of the AV valves occurs and blood is pumped out of the ventricles. Pressure increases.

194
Q

What occurs during diastole?

A

During diastole, the ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles. Pressure decreases.

195
Q

What is cardiac output, and how is it calculated? What is the average cardiact output for humans?

A

Cardiac output is the total blood volume pumped by a ventricle in a minute. Cardiac output (CO) is the product of heart rate (HR) and stroke volume (SV). The average cardiac output for humans is 5 liters/minute.

196
Q

What are the only two arteries that contain deoxygenated blood?

A

The only two arteries that carry deoxygenated blood are the pulmonary arteries and umbilical arteries.

197
Q

How do veins force blood up against gravity?

A

Most veins are surrounded by skeletal muscles which squeeze the veins as the muscles contract, forcing the blood up against gravity.

198
Q

What are the three portal systems and what are their functions?

A

The three portal systems are…

  1. Hepatic Portal System: blood leaving capillary beds in the walls of the gut passes through hepatic portal vein before reaching capillary beds in the liver
  2. Hypophyseal Portal System: blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituatary to allows for secretion of hormones
  3. Renal Portal System: blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta
199
Q

What happens to the interpleural space during normal inspiration?

A

As the external intercostal muscles expand the chest cavity, the interpleural space’s volume increases, causing the pressure to drop, and therefore causing the lungs to expand into the intrapleural space.

200
Q

Upregulation of what enzyme helps improve oxygen release into tissues?

A

Bisphosphoglycerate mutase converts 1,3-bisphosphoglycerate to 2,3-bisphosphoglycerate, which allosterically regulate hemoglobin by decreasing hemoglobin’s affinity for oxygen.

201
Q

What could cause a right-shift in the oxygen-dissociation curve?

A

Acidic byproducts (lactic acid) produced during exercise could cause a right-shift in the hemoglobin oxygen dissociation curve –> this phenomenon is known as the Bohr effect and allows muscles to recieve more oxygen from the blood during physical activity.

202
Q

What is blood composed of?

A

Blood is composed of plasma (aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins), and cells (erythrocytes, leukocytes, and platelets).

203
Q

Where do all blood cells originate?

A

All blood cells are formed from hematopoietic stem cells (originating in the bone marrow).

204
Q

What is the function of erythrocytes?

A

Erythrocytes (RBC’s) contain hemoglobin, which can bind to molecules of oxygen.

205
Q

What are the effects of histone acetylation and histone deacetylation?

A

Histones associate with DNA through forming salt bridges between positively charged amino acid residues and negatively charged phosphate groups. The acetylation of histones involves the transfer of acetyl groups to positively charged amino groups on lysine or arginine residues, reducing the positive charge on histones and disrupting the salt bridges. Histone deacetylation makes DNA less accessible (heterochromatin).

206
Q

What is the function of Complex II (or succinate-ubiquinone reductase)?

A

Complex II faciliates the transport of electrons from succinate in the citric acid cycle to Complex III. This occurs through the process of three steps:

  1. Electrons are transferred from FAD to produce FADH2, as succinate it oxidized to fumarate
  2. FADH2 is reoxidized to FAD when electrons are shuttled into the iron-sulfur centers in Complex II
  3. Ubiquinone, or coenzyme Q, accepts electrons from the iron-sulfur centers and transfers them to Complex III
207
Q
A
208
Q

What is the main process of chemiosmosis?

A

Chemiosmosis functions by establishing a proton gradient that can then be used to generate ATP using an ATPase.

Alisha's MCAT Flashcards (4 decks)

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