Bio/Biochem II

Question 1

anterior pituitary hormones

Answer 1

FSH, LH, TSH, STH, ACTH, GH, and prolactin Anterior Pituitary Hormones”FLAGTOP” F: Follicle Stimulating Hormone L: Luteinizing Hormone A: ACTH G: Growth Hormone T: Thyroid Stimulating Hormone O: MSH - melanOcyte stimulating hormone P: Prolactin

Question 2

posterior pituitary hormones

Answer 2

ADH (vasopressin) and oxytocin

Question 3

only parathyroid hormone is: parathyroid hormone

Answer 3

A hormone of the parathyroid gland that regulates the metabolism of calcium and phosphorus in the body.

Question 4

thyroid hormones

Answer 4

T3, T4, calcitonin

Question 5

adrenal cortex hormones

Answer 5

aldosterone and cortisol

Question 6

adrenal medulla hormones

Answer 6

catecholamines (epinephrine and norepinephrine)

Question 7

Pancreas hormones

Answer 7

insulin, glucagon, somatostatin (inhibits digestive hormones, slows digestion)

Question 8

reproductive organ hormones

Answer 8

estrogen, testosterone, progesterone, human chorionic gonadotropin (hCG)-Human chorionic gonadotropin (hCG) is a hormone produced by the placenta after implantation.

Question 9

keratin is

Answer 9

an intermediate filament

Question 10

actin and ______ are the same thing

Answer 10

microfilaments

Question 11

negatively charged forms of asparagine and glutamine

Answer 11

asparatate and glutamate

Question 12

a mother’s breastmilk transfers this immune protection to the infant:

Answer 12

igG antibodies

Question 13

Gastrulation

Answer 13

the process in which a gastrula develops from a blastula by the inward migration of cells aka the process whereby the inner cell mass is converted into the trilaminar embryonic disk comprised of the three primary germ layers (ectoderm, mesoderm, and endoderm)

Question 14

Ectoderm

Answer 14

outermost germ layer; produces sense organs, nerves, and outer layer of skin

Question 15

Endoderm

Answer 15

innermost germ layer; develops into the linings of the digestive tract and much of the respiratory system

Question 16

Mesoderm

Answer 16

middle germ layer; develops into muscles, and much of the circulatory, reproductive, and excretory systems

Question 17

the normal maturation pathway of ova is…

Answer 17

oogonia (2n)->Primary oocyte (occurs via mitosis, 2n) ->secondary oocyte (completion of meiosis 1, n) -> mature ovum (completion of meiosis 2, this process requires sperm (n)) each month one primary oocyte comes out of its arrest (in prophase 1) and develops into a secondary oocyte, which ruptures from the follicle and is released into the fallopian tube

Question 18

mullerian ducts->differentiate to form

Answer 18

fallopian tubes, uterus, uterine cervix, and the superior aspect of the vagina

Question 19

mneumonic for the path taken by spermatozoa is SEVEN UP

Answer 19

Seminiferous tubules Epididymis Vas deferens Ejaculatory ducts nothing (placeholder for N to make mneumonic work) Urethra Penis

Question 20

Where do sperm mature after spermatids are generated?

Answer 20

epididymis

Question 21

trophoblast

Answer 21

outer cells of the blastocyst that secrete enzymes that allow implantation, eventually grow to generate the placenta

Question 22

Morula

Answer 22

A solid ball of cells that makes up an embryo; in humans, this stage occurs within four days of fertilization.

Question 23

Blastocyst

Answer 23

A fluid-filled sphere formed about 5 days after fertilization of an ovum that is made up of an outer ring of cells and inner cell mass. This is the structure that implants in the endometrium of the uterus.

Question 24

in males the ______ duct develops into the male reproductive organs

Answer 24

Wolffian

Question 25

the ___ gene on the _____ chromosome causes the development of testes

Answer 25

SRY, Y

Question 26

During labor, the hormone _____ is released to initiate contractions. The contractions that occur stimulate the release of more oxytocin which relaxes the cervix and allows the baby’s head to descend. This response is an example of:

Answer 26

oxytocin, positive feedback

Question 27

In SDS-PAGE, SDS (i.e. lauryl sulfate) is an anionic detergent, meaning that when dissolved its molecules have a net negative charge. SDS denatures and coats proteins to give them a uniform negative charge, causing them to migrate towards the _________

Answer 27

positively-charged anode in the gel

Question 28

Pepsin

Answer 28

an enzyme released in the stomach that catabolizes proteins to smaller peptides and amino acids

Question 29

Amylase

Answer 29

an enzyme that catalyzes the hydrolysis of starches to sugars and is produced by the salivary glands and pancreas

Question 30

Hexokinase

Answer 30

an enzyme that catalyzes the phosphorylation of sugars

Question 31

Lactase

Answer 31

an enzyme that catalyzes the hydrolysis of lactose to glucose and galactose

Question 32

ejaculatory pathway

Answer 32

vas deferens, ejaculatory duct, urethra. Glands along this pathway produce semen. Seminal vesicles, prostate gland and bulbourethral gland. Testicular activity is controled by two anterior pituitary hormones. FSH regulates sperm production (ICSH-Interstitial cell stim horm.) LH stimulates the interstitial cells to produce testosterone.

Question 33

females are born with large numbers of primary oocytes arrested in prophase one, but after puberty ovulation begins to occur where one primary oocyte completes _______ to become ________

Answer 33

meiosis 1, a secondary oocyte -primary oocytes are diploid while secondary oocytes are haploid since homologous chromosomes separate during anaphase of meiosis 1

Question 34

the menstrual cycle is variable because the _______ phase is variable while the ______ phase is relatively constant

Answer 34

variable= follicular/proliferative phase constant= leuteal/secretory

Question 35

menopause

Answer 35

the progressive loss of ovarian follicle units known as atresia, results in a decrease in ovarian production of estrogen, this reduces the negative feedback to the anterior pituitary, ultimately increasing levels of LH and FSH

Question 36

The most common function of proteins in the body is

Answer 36

not enzymatic, but structural. Structural proteins are fibrous proteins that have an elongated shape and provide structural support for cells and organ tissues. The first type of fibrous proteins are keratins, which form the skin, hair, and nails. not enzymatic, but structural. Structural proteins are fibrous proteins that have an elongated shape and provide structural support for cells and organ tissues. The first type of fibrous proteins are keratins, which form the skin, hair, and nails. A third type of structural protein you should know for test day is collagen, which is found in tendons, forms connective ligaments within the body, and gives extra support to the skin.

Question 37

Keratin

Answer 37

The first type of fibrous proteins are keratins, which form the skin, hair, and nails. Keratins are classified as soft or hard according to their sulfur content (i.e. the relative number of cysteine residues in their polypeptide chains). The low-sulfur keratins of the skin are much more flexible than the high-S, hard keratins.

Question 38

actin and myosin

Answer 38

The second type of fibrous proteins you must know are the actin and myosin proteins of muscle tissue. Actin and myosin interact to form cross-linkages that allow the sliding of the filaments over each other in muscle contraction, which takes place through the contraction and relaxation of the sarcomere, the fundamental unit of all muscle fibers. When muscle contracts, the actin and myosin filaments slide over each other and the H-zone (myosin-only region), Z-lines (sarcomere boundaries), and I-band (actin-only region) all shrink, while the A-band (the entire myosin region) remains the same size. The opposite occurs upon muscle relaxation.

Question 39

collagen

Answer 39

A third type of structural protein you should know for test day is collagen, which is found in tendons, forms connective ligaments within the body, and gives extra support to the skin. Collagen is a triple helix formed by three proteins that wrap around one another. Many collagen molecules are cross-linked together in the extracellular space to form collagen fibrils to provide structural support for the cell. Elastin polypeptide chains are cross-linked together to form flexible, elastic fibers that give stretched tissues flexibility and the ability to recoil spontaneously as soon as the stretching force is relaxed.

Question 40

Where are endorphins released from?

Answer 40

Endorphins are produced in the anterior pituitary gland, along with other hormones such as luteinizing hormone (LH), follicle stimulating hormone (FSH), and growth hormone (GH).

Question 41

What are depressants?

Answer 41

Depressants cause relaxation by reducing nervous system activity. Alcohol is the most commonly used depressant. It works by stimulating the production of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter associated with reduced anxiety, and dopamine, which promotes euphoria. Alcohol slows the activity of the frontal lobe, reducing judgment and lowering inhibitions. While drinking, people can become unable to recognize the consequences of their actions, and their speech may be slurred and motor skills diminished.

Question 42

WHat are opiates?

Answer 42

Opiates are derived from the poppy plant and include such drugs as morphine and codeine. Opiates cause a sense of euphoria and a decreased reaction to pain by binding to opioid receptors in the nervous system. Opiate overdose can cause death when the brain stops sending signals for respiration. After prolonged use, these drugs can cause the brain to entirely stop producing endorphins, meaning that withdrawal is very painful.

Question 43

What are stimulants?

Answer 43

Stimulants increase arousal in the nervous system, often through the release and inhibition of the reuptake of dopamine, norepinephrine, and serotonin. This effectively increases arousal, increasing heart rate and blood pressure, and creating effects of anxiety, delusions of grandeur, euphoria, hypervigilance, and decreased appetite.

Question 44

What are hallucinogens?

Answer 44

Hallucinogens, such as lysergic acid diethylamide (LSD) and ketamine, distort perception, enhance sensory experiences, and cause introspection, all while increasing heart rate and blood pressure, increasing body temperature, and dilating the pupils.

Question 45

Is marijuana a stimulant, depressant, or hallucinogen?

Answer 45

marijuana has qualities of a stimulant, depressant, and hallucinogen. Marijuana, which is the name used for the leaves and flowers of the plants Cannabis sativa and Cannabis indica, has an active chemical called tetrahydrocannabinol (THC) which affects certain receptors in the brain. Additionally, THC increases the production of GABA and dopamine. Physiologically, THC can cause an increase in appetite, dry mouth, fatigue, eye redness, lowered blood pressure, and increased heart rate.

Question 46

What is the most common excitatory neurostransmitter and what is the most common inhibitory neurotransmitter?

Answer 46

Glutamate is an excitatory neurotransmitter and is the most common, as 90% of brain cells are responsive to glutamate. In contrast, GABA is the main inhibitory neurotransmitter of the CNS, and it hyperpolarizes cells to reduce action potential firing. Alcohol binds and activates GABA receptors (in other words, alcohol is a GABA agonist), so the effects of GABA are associated with alcohol intoxication. Glycine is another inhibitory neurotransmitter found in the spinal cord and brainstem that can work in conjunction with GABA.

Question 47

limbic system

Answer 47

neural system located below the cerebral hemispheres; associated with emotions and drives

Question 48

What is innate immunity?

Answer 48

Nonspecific protection against foreign substances indiscriminantly. All cells but lymphocytes. Cells include: Eosinophils are granulocytes, or cells that contain small particles termed granules in their cytoplasm. Other granulocytes include basophils and neutrophils, both of which also are involved in innate immunity. non-cellular component of the innate immune system includes anatomical barriers and signaling molecules such as cytokines and complement proteins, while the cellular component includes a range of white blood cell types (leukocytes) that play various roles in responding to threats. White blood cells include neutrophils, lymphocytes, monocytes (which differentiate into macrophages or dendritic cells), eosinophils, basophils, and mast cells. The various components of the innate immune system can act independently or be coordinated in the process of inflammation.

Question 49

What is passive immunity?

Answer 49

the short-term immunity that results from the introduction of antibodies from another person or animal.

Question 50

What is the adaptive immune system?

Answer 50

The adaptive immune system includes B cells and T cells, both of which are lymphocytes that are produced in the bone marrow and mature in the lymphatic system. B cells recognize antigens and secrete large amounts of antibodies in response. The human body utilizes five classes of antibodies: immunoglobulin (Ig) A, IgD, IgE, IgG, and IgM, which differ in the details of their heavy chains. This response is known as humoral immunity. In contrast, T cells correspond to the cell-mediated branch of the adaptive immune system. T cells, which mature in the thymus, recognize cells that were originally self, but have been damaged by viral infections or have malfunctioned in ways likely to turn them into cancer cells. Then, various subgroups of T cells either directly attack compromised/foreign cells or mobilize responses to them based on antigen fragments that are presented by major histocompatibility complex (MHC) class I and II.

Question 51

In eukaryotes which residues are most prone to phosphorylation?

Answer 51

In eukaryotes, the residues most prone to phosphorylation are serine (S), tyrosine (Y), and threonine (T).

Question 52

What is the difference between kinases, phoshatases, and phosphorylases?

Answer 52

A kinase functions to add a phosphate group to its substrate. The opposite of this activity is the removal of phosphate from a substrate, a function which is performed by phosphatase enzymes. Phosphorylase enzymes also add phosphate groups to their substrates, so the “general effect” of a phosphorylase on its substrate is similar to that of a kinase. Specifically, kinases transfer phosphate groups from a high-energy source (usually ATP) to their substrates, while phosphorylases transfer phosphate from an inorganic phosphate source.

Question 53

What are Lyases

Answer 53

group elimination to form double bonds

Question 54

What are Ligases

Answer 54

catalyze the formation of bonds with the input of ATP and the removal of water

Question 55

What are the two hormones used for fluid regulation?

Answer 55

Two major hormones respond to low fluid levels by increasing fluid retention: aldosterone (the main example of a class of steroid hormones known as mineralocorticoids) and anti-diuretic hormone (ADH), a peptide hormone that is also known as vasopressin. However, these two hormones have different mechanisms. Aldosterone works by increasing sodium absorption in the distal convoluted tubule and collecting duct of the nephron, which drives water absorption. Aldosterone also increases excretion of potassium and hydrogen ions in the urine. In contrast, ADH increases the permeability of the collecting duct to water, thereby increasing water absorption. Thus, ADH acts to reduce the osmolarity of blood by increasing the amount of water present without changing the solute levels, whereas aldosterone does not affect osmolarity because sodium reabsorption drives water absorption.

Question 56

What is ANP/ANF?

Answer 56

Two major hormones respond to low fluid levels by increasing fluid retention: aldosterone (the main example of a class of steroid hormones known as mineralocorticoids) and anti-diuretic hormone (ADH), a peptide hormone that is also known as vasopressin. However, these two hormones have different mechanisms. Aldosterone works by increasing sodium absorption in the distal convoluted tubule and collecting duct of the nephron, which drives water absorption. Aldosterone also increases excretion of potassium and hydrogen ions in the urine. In contrast, ADH increases the permeability of the collecting duct to water, thereby increasing water absorption. Thus, ADH acts to reduce the osmolarity of blood by increasing the amount of water present without changing the solute levels, whereas aldosterone does not affect osmolarity because sodium reabsorption drives water absorption.

Question 57

What are the steps of fertilization?

Answer 57

Fertilization takes place in the Fallopian tube, when a sperm cell encounters a secondary oocyte. The sperm cell passes through the corona radiata, a layer of follicular cells surrounding the oocyte, and the zona pellucida, a layer of glycoproteins between the corona radiata and the oocyte. This triggers the acrosome reaction, in which digestive enzymes are released that allow the nucleus of the sperm cell to enter the egg. The secondary oocyte completes meiosis II, creating a second polar body and a mature ovum. Then, the haploid nuclei of the sperm cell and the ovum merge, creating a diploid one-cell zygote. As the zygote travels to the uterus, it undergoes a series of mitotic cell divisions known as cleavage. Once the zygote has cleaved into a mass of 16 cells by three to four days after fertilization, it is known as the morula. By three to five days after fertilization, the morula develops some degree of internal structure and becomes a blastocyst, with a fluid-filled cavity in the middle known as the blastocoel. The blastocyst implants in the uterine endometrium and further differentiates into the gastrula. The gastrula has three layers: the ectoderm, the mesoderm, and the endoderm. These layers eventually go on to form specific organs and components in the body.

Question 58

What are the steps of mitosis?

Answer 58

In eukaryotes, the process of asexual cell division is known as mitosis. Mitosis takes place in four phases: prophase, metaphase, anaphase, and telophase. Prophase prepares the cell for mitosis: the DNA condenses such that distinct chromosomes become visible, as sister chromatids (or copies of a given chromosome) join at a region known as the centromere. The kinetochore assembles on the centromere, and is the site where microtubule fibers that extend from the centrosome and form the mitotic spindle attach to pull the sister chromatids apart in later stages of mitosis. Other microtubules known as asters extend from the centrosome to anchor it to the cell membrane. Additionally, the nuclear envelope and the nucleolus disappear, and the mitotic spindle forms. In metaphase, the chromosomes line up at the middle of the cell along an imaginary line that is known as the metaphase plate. In anaphase, the sister chromatids are separated and pulled to opposite sides of the cell by shortening of the microtubules attached to the kinetochores. Telophase can be thought of as the opposite of prophase, as a new nuclear envelope appears around each set of chromosomes and a nucleolus reappears within each of those nuclei. The process of mitosis is completed by cytokinesis.

Question 59

What is crossing over?

Answer 59

In prophase I of meiosis, homologous chromosomes (i.e., the maternal and paternal copies of a given chromosome) pair up with each other in a process known as synapsis, forming tetrads. While paired up, homologous chromosomes may exchange genetic information in a process known as crossing over. The crossing-over points are known as chiasmata. This process results in recombinant DNA that is another source of variation in sexual reproduction, in addition to the variability inherent to the process. In metaphase I, homologous pairs, which take the form of tetrads, line up at the metaphase plate. The orientation of the homologous pairs is random in terms of which side of the metaphase plate the maternal or paternal copy of a given chromosome in a homologous pair winds up. In anaphase I, the homologous pairs are separated, and one member of each pair is pulled to each side of the cell. In meiosis II, which operates similarly to mitosis, the sister chromatids are split up into two haploid daughter cells.

Question 60

single v double crossover

Answer 60

-Single-crossover events affect only the ends of chromosome arms, while double-crossover events can affect segments in the middle of chromosome arms. -A double-crossover event is one in which chromosomal arms of homologous chromosomes cross over in two different places along the arm. This results in a section in the middle of each chromosome being exchanged. A simplified schematic of a single- vs. a double-crossover event is shown below.

Question 61

What are myocytes?

Answer 61

Myocytes are skeletal muscle cells that have multiple nuclei on the periphery of the cell and they are formed via the fusion of multiple precursor cells.

Question 62

What are the two types of fibers in skeletal muscles?

Answer 62

There are two different types of fibers within skeletal muscles: red fibers (slow-twitch fibers) and white fibers (fast-twitch fibers). Red fibers obtain their color from the presence of abundant reserves of myoglobin, and are also rich in mitochondria. This means that they prefer oxidative metabolism, and therefore are present in large quantities in muscles that specialize in performing less intense actions over a longer period of time. White fibers, in contrast, lack those elements, and tend to mobilize glycogen for quick bursts of intense action followed by fatigue.

Question 63

What are intercalated disks?

Answer 63

A unique feature of cardiac muscle is that its cells are connected by structures known as intercalated discs, which connect the cytoplasm of adjacent cardiac muscle cells, allowing ions to pass from cell to cell. These connections are known as gap junctions, and they allow action potentials to pass rapidly from one cardiac muscle cell to another.

Question 64

esterification of fatty acids is synonymous with

Answer 64

the formation of glycogen from glucose; it packs the fatty acids into molecules for storage rather than using them immediately. This would occur if glucose were already abundant in the body.

Question 65

The mitotic spindle is composed of what?

Answer 65

microtubules

Question 66

What are analogous structures?

Answer 66

-structures that perform a similar function but are not similar in origin -Analogous structures are those structures that evolved independently to carry out the same function. Thus, the wing of a bee and the wing of a bird are analogous structures.

Question 67

What are homologous structures?

Answer 67

homologous structures are similar in origin but not function (whale flippers /human arms) Homologous structures are those that have a similar evolutionary history, arising from the same source, even if they now have different functions. The forelimbs of mammals (human arm, walrus flipper, bat wing) would all be homologous despite their different functions.

Question 68

What is an agonist?

Answer 68

a molecule that, by binding to a receptor site, stimulates a response

Question 69

What are lacteals?

Answer 69

are structures in the intestines associated with absorbing fat into the lymphatic system.

Question 70

acetylation of histones

Answer 70

opens chromatin, allowing transcription

Question 71

What are the eicosanoid signaling molecules?

Answer 71

prostaglandins, thromboxanes, and leukotrienes signaling molecules made from the oxidation of fatty acids \ Eicosanoids may also act as endocrine agents to control the function of distant cells.

Question 72

What are catecholamines?

Answer 72

dopamine, norepinephrine, epinephrine (all derived from tyrosine)

Question 73

Lysozyme

Answer 73

enzyme that kills bacteria

Question 74

Bacterial genes do not have

Answer 74

introns

Question 75

Meiosis I results in

Answer 75

homologous chromosomes being separated, generating haploid daughter cells Meiosis I results in 2 haploid cells, each with 23 chromosomes consisting of 2 sister chromatids per chromosome. In the male, the sister chromatids are split into 4 gametes during meiosis II. For females, meiosis I results in a secondary oocyte (a gamete) and a polar body. Penetration of the secondary oocyte by a sperm brings on anaphase II. Telophase II produces a zygote and a second polar body. Remember for the MCAT: mitosis results in diploid daughter cells, while meiosis results in haploid cells to produce gametes.

Question 76

Rt-PCR gives us info on?

Answer 76

the amount of RNA expressed.

Question 77

What is an apoenzyme?

Answer 77

an inactive enzyme that lacks a necessary cofactor.

Question 78

What is a coenzyme?

Answer 78

Coenzymes are small organic molecules that bind (or donate functional groups) to coenzyme-dependent enzymes.

Question 79

What is a cofactor?

Answer 79

a substance (other than the substrate) whose presence is essential for the activity of an enzyme.

Question 80

What is the purpose of the pulmonary surfacant?

Answer 80

Its adsorption to the water-alveolar interface decreases surface tension, decreasing the pressure difference required to inflate the airway. Pulmonary surfactant adsorbs to the air-water-alveoli interface, reducing surface tension and the total force resisting expansion. This increases pulmonary compliance—a measure of lung volume change at a given pressure of inspired air—and decreases the work required to expand the lungs at a given atmospheric pressure. In general, surfactant molecules are amphipathic, meaning that they contain both hydrophobic and hydrophilic regions. The diagram below shows surfactant molecules surrounding a micelle of oil. The hydrophobic tails of the surfactant molecules mix well with the hydrophobic oil, while the hydrophilic heads point away from the oil droplet.

Question 81

what amino acid does acetylation happen to?

Answer 81

Lysine-Acetylation promotes transcription by attaching acetyl groups to lysine residues on histones, making them less positively-charged and causing a looser wrapping pattern that allows transcription factors to access the genome more easily.

Question 82

Uncompetitive v noncompetitive inhibition

Answer 82

In noncompetitive inhibition, the inhibitor can combine with either the enzyme or the enzyme-substrate complex. In pure noncompetitive inhibition, the value of Vmax is decreased. Since these inhibitors do not compete with the substrate, their activity is unaffected by substrate concentration. Since the inhibitor always affects a consistent proportion of the available enzyme, Vmax is reduced. However, Km remains the same since if Vmax, is reduced, Vmax/2 is reduced proportionally, and the amount of substrate required to reach this new, reduced Vmax/2 is the same as the original Km. Uncompetitive inhibition is when the inhibitor binds to only the enzyme-substrate complex, and inactivates it. This causes the number of active enzyme-substrate complexes to decrease, thereby decreasing Vmax. Km also decreases to exactly the same degree as Vmax. Since both kinetic factors decrease to the same extent, the slope of the Lineweaver-Burk plot of enzyme activity will be the same as for the uninhibited enzyme.

Question 83

phosphatase v phosphorylase

Answer 83

phosphorylase- adds P group phosphatase- removed P group

Question 84

carbonic acid

Answer 84

Compound that results from the combination of carbon dioxide and water H2CO3

Question 85

Aldosterone

Answer 85

salt-retaining hormone which promotes the retention of Na+ by the kidneys. na+ retention promotes water retention, which promotes a higher blood volume and pressure, also exchanges K+ ions for Na+ ions, so it excretes K+ while reabsorbing Na+

Question 86

transduction v transformation v conjugation (genetic material)

Answer 86

Transduction is a form of horizontal gene transfer in bacteria in which bacteriophages (viruses that infect bacteria) transmit genomic material. Transformation involves direct uptake of genetic material from the environment and is not mediated by viruses. Conjugation is a horizontal gene transfer process in bacteria in which plasmid DNA is transferred from one bacterium to another through a pilus. Viruses are not involved. *there is also transduction where sensory neurons receive stimuli then turn them into electrical waves

Question 87

What is the order of the reaction in terms of the substrate when represented with a michaelis menten graph?

Answer 87

at the beging it is linear making it first order then once satururated it becomes zero order because vmax is reached

Question 88

acyl coA v acetyl co A

Answer 88

acyl has a R- chain coming off the carbonyl carbon while acetyl has a methyl group ttached

Question 89

nucleic acid bases

Answer 89

Nitrogen-containing aromatic compounds that make up the coding portion of nucleic acids

Question 90

What is a protic solvent?

Answer 90

solvents that will readily donate H+ to reagents, such as a hydrogen bonded to a nitrogen or oxygen a protic solvent is a solvent that has a hydrogen atom bound to an oxygen (as in a hydroxyl group), a nitrogen (as in an amine group) or a fluorine (as in hydrogen fluoride)

Question 91

toluene

Answer 91

methylbenzene

Question 92

common examples of polar aprotic solvents

Answer 92

acetone or DMSO

Question 93

cell-mediated immunity

Answer 93

type of immunity produced by T cells that attack infected or abnormal body cells Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.

Question 94

nonspecific immunity

Answer 94

The innate (non-specific) immune system includes anatomical barriers, secretory molecules, and cellular components. Among the mechanical anatomical barriers are the skin and internal epithelial layers, the movement of the intestines, and the oscillation of bronchopulmonary cilia.

Question 95

Cytokines

Answer 95

Hormone-like chemicals facilitating communication between brain and immune system.

Question 96

what types of cells comprise the adaptive immune system?

Answer 96

The adaptive immune system includes B cells and T cells, both of which are lymphocytes that are produced in the bone marrow and mature in the lymphatic system. B cells recognize antigens and secrete large amounts of antibodies in response. The human body utilizes five classes of antibodies: immunoglobulin (Ig) A, IgD, IgE, IgG, and IgM, which differ in the details of their heavy chains. This response is known as humoral immunity. In contrast, T cells correspond to the cell-mediated branch of the adaptive immune system. T cells, which mature in the thymus, recognize cells that were originally self, but have been damaged by viral infections or have malfunctioned in ways likely to turn them into cancer cells. Then, various subgroups of T cells either directly attack compromised/foreign cells or mobilize responses to them based on antigen fragments that are presented by major histocompatibility complex (MHC) class I and I

Question 97

In the lysogenic cycle, bacteriophages can integrate themselves into the host genome, at which point they are referred to as a

Answer 97

prophage or a provirus.

Question 98

Anchoring junctions include adherens junctions, which are associated with

Answer 98

cadherins

Question 99

The essential idea behind anchoring junctions is that they

Answer 99

connect cytoskeletal components of the cell with other cells and/or the extracellular matrix, thereby contributing to the overall structural stability of tissues. Adherens junctions involve cadherin-mediated connections between actin filaments and other cells and the extracellular matrix. Desmosomes also involve cadherin, but in this case cadherin connects intermediate filaments to other cells. Hemidesmosomes are junctions in which integrins connect the intermediate filaments of cells to the extracellular matrix.

Question 100

Gap junctions are formed by connexin proteins, which connect cells in a way such that __________ can take place between them, enabling communication, without involving direct contact between the cytoplasmic fluids of each cell.

Answer 100

diffusion Gap junctions are relatively less common, but they play certain crucial roles within the body. The most important example for the MCAT is in cardiac muscle, where gap junctions allow cells to contract at the same time.

Question 101

tight junctions are found in _______ cells.

Answer 101

epithelial As the name suggests, the cells in tight junctions are linked very closely to each other, preventing solutes from being able to move freely from one tissue into another. A classic example is the blood-brain barrier, where the epithelial cells in blood vessels in the brain form very tight junctions that allow the close regulation of which substances from the bloodstream can enter the central nervous system. Some types of epithelial tissue have relatively few tight junctions; these are known as leaky epithelia. Examples include some parts of the kidney.

Question 102

What is the difference between GLUT4 and GLUT2 transporters?

Answer 102

both glucose transporters but GLUT2-hepatocites and pancreatic cells GLUT4-adipose tissue and muscle

Question 103

If you are given a few molecules how do you know which one is most likely to undergo positive beta decay?

Answer 103

Positive beta decay, also known as positron emission, occurs when the proton-to-neutron ratio is too high. Thus, we are looking for the answer choice with the highest proton-to-neutron ratio.

Question 104

What is the process called that creates genetic diversity in bacteria (bacteria’s equivalent of sexual reproduction-but not actually sexual reproduction)?

Answer 104

Conjugation=In bacteria, the direct transfer of DNA between two cells that are temporarily joined. (creates genetic diversity in bacteria) Conjugation involves the transfer of a plasmid through a bridge that is created when a sex pilus on one bacterium (often known as F+, which refers to the presence of the fertility factor, or as male) attaches to another bacterium (generally known as F−). During this process, the fertility factor itself is duplicated and transferred, converting the F− cell into an F+ cell.

Question 105

What is made in the nucleolus?

Answer 105

ribosomes/rRNA

Question 106

What is the difference between monocistronic and polycistronic mRNAs?

Answer 106

mRNA molecules are said to be monocistronic when they contain coding sequences for a single polypeptide. This is the case for most eukaryotic mRNAs. Polycistronic mRNA carries several open reading frames (ORFs), each of which is translated into a polypeptide. These polypeptides usually have a related function (they often are the subunits composing a final complex protein), and their coding sequence are grouped and regulated together in a regulatory region, containing a promoter and an operator. Most of the mRNA found in bacteria are polycistronic.

Question 107

What are integrins?

Answer 107

Integrins are transmembrane receptors that modulate cell-to-extracellular matrix interactions. Specifically, these proteins often attach the cell to collagen and fibronectin fibers.

Question 108

What are cadherins?

Answer 108

Cadherins are transmembrane proteins which play a primary role in cell-to-cell adhesion (remember that C stands for cell-to-cell), forming adherens junctions to bind cells within tissues together.

Question 109

Keratins are classified as soft or hard according to their?

Answer 109

sulfur content (i.e. the relative number of cysteine residues in their polypeptide chains). The low-sulfur keratins of the skin are much more flexible than the high-S, hard keratins.

Question 110

Immunoglobulins are

Answer 110

antibodies secreted by plasma cells

Question 111

antibodies let the body know when it needs to

Answer 111

mobilize an immune response by recognizing substances (antigens) that need to be eliminated and by being recognized by other components of the immune system

Question 112

Antibodies have a Y-shaped structure consisting of two heavy chains and two light chains that are linked by ________ bonds.

Answer 112

disulfide

Question 113

The specific site on an antigen that is recognized by an antibody is known as the?

Answer 113

epitope Extensive random recombination of the antigen-recognizing area of the antibody (also known as the paratope) allows the generation of antibodies that recognize potentially infinitely many types of antigens. Antibodies are used in the adaptive immune system, most notably by B cells. Antigen-antibody interactions are also used in many biotechnology-related applications, most notably western blotting, in which antibodies are used to visualize proteins of interest after gel electrophoresis

Question 114

Calcitonin ________ plasma concentrations of Ca2+

Answer 114

decreases

Question 115

One key example is that calcitonin stimulates bone formation by increasing osteoblast activity and decreasing osteoclast activity. what are osteoblasts and osteoclasts?

Answer 115

Osteoblasts are responsible for the formation of bone whereas the osteoclasts are responsible for the breakdown of the bones.

Question 116

The antagonist hormone to calcitonin is?

Answer 116

parathyroid hormone (PTH), which acts to increase plasma Ca2+ concentrations by (among other things) decreasing bone formation by osteoblasts and increasing bone degradation by osteoclasts.

Question 117

What are the weights of eukaryotic and prokaryotic ribosomes?

Answer 117

prokaryotic: 70s eukaryotic: 80s

Question 118

Steps of muscle contraction

Answer 118

1.ACh released from synaptic vesicles 2.Binding of ACh to motor end plate 3.Generation of electrical impulse in sarcolemma (depolarization) 4.Conduction of impulse along T-tubules 5.Release of Calcium ions by SR 6.Calcium binds to troponin 7. Exposure of myosin binding sites on actin 8. Cross-bridge formation and contraction ACh is released from presynaptic axon terminals in the neuromuscular junction, and bind to Acetylcholine receptors (AChRs). This opens ligand-gated Na+ channels that allow sodium to influx into the post-synaptic cell. This influx of sodium causes depolarization in the muscle cell, and the AP is able to get into the interior of the muscle cell using T-tubules, which carry the AP (action potential) to the sarcoplasmic reticulum (SR). THIS is when Ca2+ ions come into play. Calcium ions efflux from the SR into the muscle fiber’s cytoplasm and bind to troponin, creating a troponin-Ca complex. This causes a conformational change in the tropomyosin that the troponin is bound to, pulling the whole structure away from myosin binding sites on the actin. Now, myosin. Myosin has ADP bound to it when it is not bound to the actin site. Once it binds, ADP comes off, and initiates the power stroke, whereby myosin ratchets along the actin, pulling it closer together and shortening the sarcomere. Now, to detach, it requires ATP, which when bound allows the myosin to let go. The myosin now is in a bent form that’s useless unless it can get back to its “cocked” form. This is done by ATP hydrolysis, which gets the myosin ready to bind to the actin again. Now, with ADP bound all over again, it can bind the actin, and repeats the whole process over!

Question 119

tetany

Answer 119

constant muscle contraction

Question 120

Thick muscle fibers

Answer 120

myosin

Question 121

thin muscle fibers

Answer 121

actin

Question 122

unit of contraction in a muscle cell

Answer 122

sarcomere

Question 123

in muscle contraction ATP binds to?

Answer 123

the myosin head, causing a conformational change releasing it from actin

Question 124

muscle contraction: when the action potential reaches the sarcoplasmic reticulum, Ca2+ is released and binds to….

Answer 124

troponin which allows contraction to take place

Question 125

What type of hormones have faster response times, steroid or peptide, and why?

Answer 125

peptide hormones have faster response times and have short-term effects steroid hormones have a slow response time because they affect transcription, their effects are also long lasting and potentially even permanent

Question 126

In the Krebs cycle, malate is reversibly oxidized by the microsomal enzyme malate dehydrogenase, producing?

Answer 126

NADH and oxaloacetate (its the step where oxaloacetate is regenerated)

Question 127

In eukaryotes, the citric acid cycle takes place in the _______, while in aerobic prokaryotes it is carried out in the _______.

Answer 127

In eukaryotes, the citric acid cycle takes place in the mitochondrial matrix, while in aerobic prokaryotes it is carried out in the cytosol.

Question 128

The basic logic of the citric acid cycle is that the two-carbon molecule acetyl-CoA joins with the four-carbon molecule oxaloacetate to form a six-carbon molecule known as citrate. Citrate then undergoes a series of redox and decarboxylation reactions to generate the products of the citric acid cycle. The final product is the four-carbon compound oxaloacetate, which joins with acetyl-CoA to start the process again. Each turn of the citric acid cycle generates?

Answer 128

1 GTP (which you can think of as functionally equivalent to ATP), 3 NADH, 1 FADH2, and 2 CO2. NADH and FADH2 are electron transporters that ultimately produce energy through the electron transport chain.

Question 129

Does the Citric Acid Cycle require O2?

Answer 129

Even though oxygen is not a reactant or a product, the citric acid cycle requires oxygen indirectly, because it is dependent on the aerobic electron transport chain to regenerate NAD+ and FAD for the process to continue.

Question 130

oxygen tension (partial pressure)

Answer 130

measures the partial pressure of oxygen (pressure exerted by oxygen as part of a mixture of gases)

Question 131

. A good way to remember the development of the zygote is the mnemonic “More blasting gas, I’m nervous,” which outlines the process of…

Answer 131

morula to blastula to gastrula to neurulation. The blastocoel is a fluid-filled central region present in the blastocyst during mammalian embryogenesis. The blastocyst consists of an inner cell mass (ICM), along with an outer cell layer called the trophoblast, which surrounds both the ICM and blastocoel.

Question 132

Gastrulation is the stage in embryonic development in which?

Answer 132

the single-layered blastula becomes the three-layered gastrula, the three germ layers of which are the ectoderm, endoderm, and mesoderm

Question 133

The inner cell mass is the mass of cells within the?

Answer 133

blastocyst that will eventually give rise to the fetus.

Question 134

Gastrulation is the stage in embryonic development in which the single-layered blastula becomes the?

Answer 134

three-layered gastrula, the three germ layers of which are the ectoderm, endoderm, and mesoderm.

Question 135

Where does the beta-oxidation of fatty acids occur and how do the fatty acids get there?

Answer 135

mitochondria, carnitine shuttle that brings fatty acids into the mitochondria and helps transport acetyl-coA out

Question 136

In chemistry, a protic solvent is a solvent that has a hydrogen atom bound to an?

Answer 136

oxygen (as in a hydroxyl group), a nitrogen (as in an amine group) or a fluorine (as in hydrogen fluoride)

Question 137

a molecule with n chiral centers will have ____stereoisomers (excluding meso compounds, which are molecules with multiple stereocenters that have an internal plane of symmetry that allows their mirror images to be superimposable)

Answer 137

2^n

Question 138

Amino acids are chiral, and the ______ comprise the overwhelming majority of amino acids that occur in nature.

Answer 138

L-stereoisomers

Question 139

isomers of carbohydrates occur in nature

Answer 139

D-isomers

Question 140

Where does transcription take place?

Answer 140

nucleus of eukaryotic cells

Question 141

The 5’-untranslated region (5′-UTR) is the region of mRNA that is directly upstream from the initiation codon. This region is important for the regulation of ________ of a transcript

Answer 141

translation

Question 142

the 5’-UTR region-is it transcribed and translated?

Answer 142

This region is important for the regulation of translation of a transcript; from this information alone, we know that the 5’-UTR must be transcribed. However, as it is the “untranslated” region, we can conclude that this region is not translated or only partially translated into a protein.

Question 143

With PCR the amplification of DNA is exponential and can be calculated using the formula:

Answer 143

2^n copies would be produced after n cycles

Question 144

What is the difference between nucleosomes and chromatin?

Answer 144

nucleosome refers to the DNA wrapped around the histone while chromatin is many nucleosomes condensed together

Question 145

Intermediate filaments such as keratin are directly responsible for?

Answer 145

structural integrity in skin

Question 146

microtubules are not involved in structural integrity, but in?

Answer 146

mitosis, meiosis, cell trafficking of vessels, and ciliar/flagellar motion.

Question 147

Titin is a component of?

Answer 147

muscle

Question 148

Myosin is a _______ protein necessary for the actin mediated movement

Answer 148

motor

Question 149

Voluntary muscles may contract involuntarily due to a?

Answer 149

reflex arc The classic example is the patellar tendon reflex, in which sudden stretching of the patellar tendon leads to an involuntary contraction of the quadriceps. Such contraction occurs before the signal has even reached the brain. This arc contains a sensory neuron, which carries sensory information from peripheral receptors toward the spinal cord, and a motor neuron, which carries a signal from the spinal cord to an effector muscle. This particular reflex arc also contains an interneuron, which is a neuron within the spinal cord that synapses on both the sensory and motor neurons, connecting them.

Question 150

Depolarization of the muscle is triggered by sodium ______

Answer 150

influx

Question 151

Huntington’s disease is a fatal condition characterized by involuntary movements and dementia. It is caused by?

Answer 151

an expanded CAG repeat in the gene that encodes the huntingtin protein on chromosome 4; this causes the progressive atrophy of brain structures. This disease has autosomal dominant inheritance.

Question 152

Parkinson’s is caused by

Answer 152

loss of dopamine-producing cells

Question 153

MS is an autoimmune disease caused by the immune system attacking and damaging the?

Answer 153

myelin sheath in the nervous system. The loss of myelin impairs nervous signal conduction. The exact symptoms of MS depend on which nerve fibers are damaged.

Question 154

absolute v relative refractory period

Answer 154

Absolute-impossible to generate another AP Relative- difficult but not impossible with enough stimulus

Question 155

difference between alpha and beta sugars

Answer 155

On the C1 carbon (the one attached to two oxygens): The β-anomer has the hydroxyl is the equatorial position, while the α-anomer has the hydroxyl in the axial position.

Question 156

transformation v transduction

Answer 156

A prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment in a process called transformation Transduction is the movement of genes between bacteria by bacteriophages (viruses that infect bacteria)

Question 157

catabolism v anabolism

Answer 157

anabolism is the creation of complex molecules

catabolism is the breakdown of complex molecules

Question 158

actin is a type of

Answer 158

microfilament

Question 159

Cholecystokinin (CCK) acts in the

Answer 159

small intestine upon the entry of food into the duodenum from the stomach. This peptide hormone functions to aid a series of processes involved in digestion. Among these are stimulating pancreatic acinar cells to release digestive enzymes, stimulating feelings of satiety (fullness) to suppress hunger, inhibiting stomach emptying, and lowering gastric acid secretion

Question 160

Somatostatin, (aka growth hormone inhibiting hormone) inhibits the release of ____

Answer 160

Cholecystokinin (CCK)

Question 161

When does hyperpolarizagtion occur?

Answer 161

potassium is pushed by both electrical potential In the first phase of the action potential, depolarization, the sodium voltage-gated channels open and Na+ ions rush into the cell. The sudden influx of positive charges continues until the cell membrane reaches full depolarization at +40 mV, at which point the sodium channels close and potassium voltage-gated channels open. Now that the interior of the cell is positive, the potassium is pushed by both electrical potential and its own concentration gradient to rush out, causing repolarization. Repolarization continues until the cell overshoots the −70 mV level, making the cell temporarily hyperpolarized, during what is called the refractory period. Then, the sodium-potassium pumps get back to work to re-establish the resting state of the cell.

Question 162

Does mature mRNA contain promoters?

Answer 162

no

Question 163

pentose phosphate pathway converts NADP+ into _____ and converts glucose 6-phosphate into ____.

Answer 163

NADPH, ribose 5-phosphate (Ribose 5-phosphate is used in nucleotide synthesis)

Question 164

What are the two main functions of NADPH?

Answer 164

1. Its a reducing agent needed for the synthesis of lipids and nucleic acids
2. helps protect against the damage from reactive oxygen species by regenerating the antioxidant glutathione from its oxidized form

Question 165

What are the two stages of the pentose phosphate pathway, and which is the limiting step?

Answer 165

the oxidative phase and the non-oxidative phase

There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 5-carbon sugars.

In the oxidative phase, glucose 6-phosphate is first converted to 6-phosphoglucono-δ-lactone by glucose 6-phosphate dehydrogenase. This step produces 1 NADPH and is the rate-limiting step of the process

The non-oxidative phase allows cells that do not specifically need ribulose 5-phosphate, which can easily be converted into ribose 5-phosphate, to process it in a way that feeds back into the glycolysis pathway and allows the oxidative phase to continue. More specifically, it involves multiple steps, through which the carbon skeleton of ribose 5-phosphate is rearranged, resulting in a net conversion of six five-carbon sugars (ribose 5-phosphate) to five six-carbon sugars (fructose 6-phosphate). Fructose 6-phosphate can be easily converted back into glucose 6-phosphate, which can re-enter glycolysis; additionally, glyceraldehyde 3-phosphate, which is another product of the non-oxidative phase, can also be shunted back into glycolysis.

Question 166

Northern blotting is best used for detecting and identifying?

Answer 166

mRNA and RNA sequences

Question 167

RT-PCR techniques are best used to detect?

Answer 167

RNA expression

Question 168

The conversion of fumarate to malate is a key step in the?

Answer 168

citric acid cycle, which occurs in the mitochondrial matrix of the cell

Question 169

What is the difference between a holoenzyme and a apoenzyme?

Answer 169

A holoenzyme is an enzyme attached to its cofactor.

An apoenzyme is an inactive enzyme without its cofactor.

Question 170

____is produced only in the oxidative phase of the pentose phosphate pathway

Answer 170

NADPH

Question 171

Pentose phosphate pathway: Remember that the 1.____ phase is irreversible, while the 2._____ phase is reversible.

Answer 171

1. oxidative

2. non-oxidative

Question 172

In the pentose phosphate pathway Ribulose 5-phosphate is a product of the oxidative or non oxidative phase?

Answer 172

Ribulose 5-phosphate, a product of both the oxidative and non-oxidative pathways, can be converted to ribose 5-phosphate, which in turn can be used to make nucleotides. Therefore, both the oxidative and non-oxidative phases could be utilized for nucleotide production.

Question 173

A CO2 moledule is released in which phase of the pentose phosphate pathway?

Answer 173

In the oxidative phase, a carbon dioxide molecule is lost when converting the six-carbon glucose 6-phosphate to the five-carbon ribulose 5-phosphate. However, no carbon dioxide is lost in the non-oxidative phase. Thus, the non-oxidative phase yields more moles of ribulose 5-phosphate per mole of glucose 6-phosphate than the oxidative phase.

Question 174

The outer layer of skin is made up of ?

Answer 174

keratin accumulated in dead cells. Keratin is an intermediate filament that has great strength

Question 175

These cytoskeletal components are largely used to give the cell motility and to transport substances inside the cell

Answer 175

microfilamenta and micro tubuoles, they do not provide a large amount of strength or rigidity

Question 176

What types of blotting are associated with what type of molecules?

Answer 176

N: RNA
W: Protein
S: DNA
E: post-translational modification

Question 177

For enzymes with a single active site, kcat is referred to as the catalytic constant[1]. It can be calculated from the maximum reaction rate {\displaystyle V_{\max }}V_{\max } and catalyst site concentration {\displaystyle [E_{T}]}{\displaystyle [E_{T}]} as follows:

Answer 177

Kcat=Vmax/[E]

a measure of how many substrates one (1) enzyme can convert into a product per second.

Question 178

The higher the bond order, the stronger the bond and the ______ the vibrational stretching frequency in the IR spectrum

Answer 178

higher

ex. double bonds should have higher stretching frequencies than single bonds

Question 179

Somatostatin

Answer 179

is a peptide hormone secreted by delta cells of the pancreas. It inhibits both insulin and glucagon and its release is triggered by high glucose and amino acid levels.

Question 180

Gastrin

Answer 180

is a peptide hormone that stimulates secretion of HCl by the parietal cells of the stomach.

Question 181

Epinephrine

Answer 181

which is involved in the fight-or-flight response, provides the body more access to glucose. Specifically, epinephrine activates a G protein-coupled signal transduction pathway that activates glycogen phosphorylase (the enzyme involved in glycogen degradation) and inactivates glycogen synthase (the enzyme involved in glycogen synthesis).

Question 182

cardiac output

Answer 182

= heart rate x stroke volume

Question 183

The renin-angiotensin-aldosterone system (RAAS)

Answer 183

The renin-angiotensin-aldosterone system (RAAS) is a signaling pathway responsible for regulating the body’s blood pressure. Stimulated by low blood pressure or certain nerve impulses (e.g. in stressful situations), the kidneys

The secretion of renin is stimulated by the following three factors: When a fall in arterial blood pressure is detected by pressure sensitive receptors (baroreceptors) in the arterial vessels. When a decrease in sodium chloride (salt) is detected in the kidney by the macula densa in the juxtaglomerular apparatusrelease an enzyme called renin

Question 184

bilirubin

Answer 184

Bilirubin is a brownish yellow substance found in bile. It is produced when the liver breaks down old red blood cells. Bilirubin is then removed from the body through the stool

Question 185

what is made in the liver?

Answer 185

hepatic cholesterol and clotting factor synthesis as well as bilirubin (the breakdown product of heme) conjugation and excretion occurs in the liver. No digestive enzymes are synthesized in the liver.

Question 186

No digestive enzymes are synthesized in the liver. Bile, which is synthesized in the liver and is involved in lipid digestion, is not a digestive enzyme but an ?

Answer 186

emulsifier (also bile salts are basic)

Question 187

Geometric isomers

Answer 187

are molecules that are locked into their spatial positions with respect to one another due to a double bond or a ring structure.

Question 188

Glucokinase

Answer 188

an enzyme that facilitates phosphorylation of glucose to glucose-6-phosphate in glycolysis

Question 189

Pyruvate Kinase

Answer 189

is an enzyme that is involved in glycolysis. Pyruvate kinase’s function is to catalyze the last step of glycolysis; thereby, generating the second ATP of glycolysis and pyruvate. It is able to catalyze this step by transferring the phosphate group from phosphoenolpyruvate (PEP) to ADP.

Question 190

Phosphofructokinase-1 (PFK-1)

Answer 190

is a glycolytic enzyme that catalyzes the transfer of a phosphoryl group from ATP to fructose-6-phosphate (F6P) to yield ADP and fructose-1,6-bisphosphate (FBP).

Question 191

Phosphoenolpyruvate carboxykinase (PEPCK)

Answer 191

is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide. It is found in two forms, cytosolic and mitochondrial.

Question 192

lysate

Answer 192

a preparation containing the products of lysis of cells

Question 193

transposable element

Answer 193

is a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell’s genetic identity and genome size. Transposition often results in duplication of the same genetic material.

Question 194

What is the main carrier of free fatty acids in the blood?

Answer 194

Albumin

Question 195

hnRNA

Answer 195

https://docs.google.com/document/d/1nRiCVht46vJ12bQqVq-gS847UrHpOi6Ck4q0iFNKVrs/edit?usp=sharing

Pre-mRNA

Question 196

In both males and females, follicle-stimulating hormone (FSH) directly stimulates?

Answer 196

the maturation of germ cells. In females, it does so by stimulating the recruitment and growth of the immature ovarian follicle. In males, FSH stimulates primary spermatocytes to proceed through meiosis.

Question 197

In males, LH stimulates production of

Answer 197

testosterone by Leydig cells.

Question 198

Secondary sex characteristics contribute to sexual dimorphism

Answer 198

or the presence of noticeable morphological differences between the sexes within a species.

Question 199

Vitamin C

Answer 199

acts as a cofactor in collagen synthesis. It is required for the hydroxylation of the collagen precursor, procollagen, a step needed for the later formation of the collagen triple helix structure. A deficiency of Vitamin C can result in impaired collagen synthesis and the development of the disease known as scurvy.

Question 200

Vitamin A

Answer 200

refers to a group of unsaturated compounds including retinal, retinol, retinoic acid, and beta-carotene. It is involved in proper immune function, normal growth and development (especially of epithelial cells), and vision.

Question 201

Vitamin B1

Answer 201

otherwise known as thiamine, is one of the B complex vitamins. Its phosphate derivatives, including thiamine pyrophosphate (TPP), act as coenzymes in the catabolism of sugars and amino acids. Its deficiency can lead to memory dysfunction (Korsakoff syndrome), visual disturbance (optic neuropathy), and cardiovascular and/or neurological problems (beriberi).

Question 202

Vitamin D

Answer 202

refers to a group of fat-soluble steroid hormones responsible for enhancing intestinal absorption of calcium and phosphate. Synthesis of vitamin D (specifically cholecalciferol) in the skin is the principal natural source of this vitamin and depends on exposure to UVB radiation, most typically from sun exposure. Dietary or dermally-synthesized vitamin D must be converted to its active form, calcitriol, by sequential hydroxylation in the liver and kidneys. Deficiency results in impaired bone mineralization and bone damage.

Question 203

Vitamin E is an

Answer 203

antioxidant

Question 204

Vitamin K promotes

Answer 204

coagulation

Question 205

WHat are the reciprocally regulated steps of glycolysis and gluconeogenesis

Answer 205

Certain enzymes are different between the two processes https://www.google.com/search?q=glycolysis+v+gluconeogenesis&rlz=1C1CHBF_enUS887&sxsrf=ACYBGNSd3JqMBMQas0KEuUzbAYWAuwlGDw:1581002346489&tbm=isch&source=iu&ictx=1&fir=2VSIvMseEzaIwM%253A%252CROHJAAY6GjSQ7M%252C_&vet=1&usg=AI4_-kQRd-nWcTd3XJe3YMF1j-3JB4S5kQ&sa=X&ved=2ahUKEwjshoHanL3nAhXij3IEHVXaD4EQ9QEwAHoECAYQAw#imgrc=2VSIvMseEzaIwM:

Question 206

With regard to actin, the critical concentration is….

Answer 206

the point at which no net polymerization or depolymerization occurs.

Question 207

All microtubules originate from

Answer 207

microtubule-organizing centers, or MTOCs. These structures anchor the minus end of the microtubule to prevent its depolymerization. They also form the origin of the spindle apparatus during cell division.

Question 208

What is the pH in the stomach v the pH in the small intestine and in which are pepsin and chymotripsin released?

Answer 208

The stomach is a highly acidic environment, where HCl causes the pH to drop below 2. Any enzymes that operate here, including pepsin, must be able to function efficiently in such conditions. In contrast, chymotrypsin operates within the small intestine, where the pH is higher due to the secretion of bicarbonate ion.

Question 209

WHat is the difference between a cofactor and a coenzyme?

Answer 209

“cofactor” is a broad category that encompasses both coenzymes and inorganic species, Coenzymes are a subset of cofactors that tend to bind loosely to their associated enzymes. This type of molecule is also known for transferring functional groups between species. NAD serves this function by donating its hydrogen to Complex I, which is one of the four protein complexes responsible for generating the proton gradient during aerobic cellular respiration.

Question 210

The ______ is responsible for sound localization

Answer 210

superior olive

Question 211

The _______ plays a key role in the processing of all sensation except for smell. (Those stimuli, known as olfactory sensations, are processed directly by the limbic system.)

Answer 211

thalamus

Question 212

Meissner’s corpuscles transmit sensory impulses associated with

Answer 212

light touch

Question 213

Free nerve endings respond mainly to

Answer 213

pain and temperature

Question 214

Merkel’s discs sense

Answer 214

deep pressure and texture