TBL Revision

Question 1

Which of the following karyotypes represents an example of a monosomy?

45, X

46, XX

46, XY

47, XXX

69, XYY

Answer 1

45, X

The human karyotype is composed of 22 autosomal chromosomes and two sex chromosomes equalling a total of 46 chromosomes. Any loss in a chromosome from a pair is termed monosomy. In the above example “45, X” is monosomy since there is a loss of a sex chromosome (either X or Y). Conversely, “47,XXX” represents trisomy since there is an extra X chromosome.

Question 2

Negative feedback loops mostly function to allow the body to..?

Amplify physiological signals

Counteract positive feedback loops

Generate an alternative negative pathway

Link the central nervous system to the endocrine system

Maintain a variable at a particular set point

Answer 2

Maintain a variable at a particular set point

Negative feedback loops are utilised in order to maintain equilibrium and homeostasis. Most systems in the body function by way of negative feedback loops. This is best observed via an example - Regulation of CO2: An increase in [CO2] in the extracellular fluid increases breathing. This results in reduced [CO2] in the extracellular fluid. So, the high amount of CO2 initiates events (breathing in this case) that return the CO2 concentrations to a normal baseline. This is a negative feedback loop.

Question 3

If an active drug is administered together with an inducer of metabolism, what happens to its therapeutic effect?

Decreases due to faster metabolism

Decreases due to slower metabolism

Increases due to faster metabolism

Increase due to slower metabolism

Remains the same

Answer 3

Decreases due to faster metabolism

If metabolism is induced, then that means more enzymes / more efficient enzymes are around – more active drug gets broken down into the metabolite. If the active drug gets broken down quicker, then less is available to at in the target and produce the desired effect. So the therapeutic effect is decreased.

Question 4

Both α 1 - and α 2 -adrenoceptor antagonists can be used to lower blood pressure.

True or False?

Answer 4

False

Antagonism of α1-adrenoceptors on peripheral resistance vessels causes relaxation and lowers blood pressure, but presynaptic α2-adrenoceptors reduce noradrenaline release. Blockage of these autoreceptors would increase noradrenaline release and tend to raise vascular resistance.

Question 5

Fibrotic tissue regains full functionality.

True or False?

Answer 5

False

Fibrotic tissue is rich in fibroblasts and collagen fibers and cannot regain full functionality.

Question 6

A partial agonist is one that, even at its highest dose, cannot achieve the same maximal response as a full agonist at the same receptor.

True or False?

Answer 6

True

That is the definition of a partial agonist.

Question 7

The development of liver cirrhosis (liver disease) is due to?

Lack of proliferation capacity for liver cells.

Destruction of the liver architecture.

Answer 7

Destruction of the liver architecture

Hepatocytes (liver cells) can proliferate after injury but in the event of prolonged stress (injury) the architecture of the organ can get damaged and is replaced by fibrotic (scar) tissue. The architecture cannot be fully restored and this leads to loss of organ function.

Question 8

Hyperplasia involves…?

Cell growth

Cell proliferation

Answer 8

Cell proliferation

Hyperplasia describes cell proliferation.

Hypertrophy describes cell growth.

Question 9

Chiasmata form between which of the following structures?

Any two chromatids

Maternal chromosomes

Non-sister chromatids

Paternal chromosomes

Sister chromosomes

Answer 9

Non-sister chromatids

Chiasmata are where the non-sister chromatids are physically joined during the process of recombination during meiosis (prophase I). This crossing over event generates a new arrangement of the alleles on the chromosome (the recombinant).

Question 10

What is the function of Fibroblasts?

Answer 10

Repair

Question 11

Acetylcholine is metabolised by cholinesterases in the cytoplasm.

True or False?

Answer 11

False

Within the synaptic cleft, acetylcholine is mainly broken down by acetylcholinesterase.

Question 12

Metaplasia is …?

Labile cells in the intestinal epithelium becoming reprogrammed.

Intestinal epithelium cells changing morphology

Answer 12

Labile cells in the intestinal epithelium becoming reprogrammed.

In metaplasia cells that make up a tissue change to another cell type, eg squamous epithelium in the place of columnar epithelium or the other way around in response to a stressor. This is caused by stem or progenitor cells reprogramming to differentiate to another cell type and not due to existing cells changing morphology and function.

Question 13

In the Autonomic Nervous system, the communication between pre and postganglionic neuron is done via..?

Acetylcholine

Adrenaline

Dopamine

Noradrenaline

Serotonin

Answer 13

Acetylcholine

In both sympathetic and parasympathetic pathways, the communication between pre and post ganglionic is done via the release of acetylcholine (pre) to act in nicotinic receptors (in the post). Remember, this needs to be a stimulatory/positive pathway, so nicotinic are fast (ligand-gated ion channels) and allow Na+ to get in – depolarisation.

Question 14

Which of the following is one of the main driving forces of protein folding?

Chaperone proteins

Disulphide bonds

Entropic interactions

Hydrogen bonding

Hydrophobic interactions

Answer 14

Hydrophobic interactions

Protein folding is initiated and guided by the movement of hydrophobic amino acids away from the hydrophilic environment of water. This hydrophobic core is then surrounded by hydrophilic amino acids that interact with the solvent (water) and other solutes such as ions. This is an entropic process but the answer “hydrophobic interactions” is more precise since it relates directly to the formation of this core.

Question 15

A 35 year old is prescribed an antidepressant for manage their depression. The doctor warns they will unfortunately feel their mouth very dry due to the new drug and gives some solutions to this.
How would you classify this effect?

Adverse

Desired

Placebo

Side

Toxic

Answer 15

Adverse

The stem describes an undesired effect at normal doses (as warned by the doctor when prescribing). However, this is harmful to the patient (dry mouth can be a really difficult effect to cope with), so the best answer is adverse effect.

Question 16

tRNA is required during which cellular process?

mRNA processing

Transcription

Transcription and translation

Transcription, translation, mRNA processing

Translation

Answer 16

Translation

tRNA carries one of the twenty amino acids used by cells and is utilised only during protein synthesis and therefore translation.

Question 17

Sympathetic nervous stimulation to the gut inhibits gut motility and sphincter tone.

True or False?

Answer 17

False

Sympathetic nervous stimulation releases noradrenaline and inhibits gut motility but increases the tone of the sphincters.

Question 18

In which phase of meiosis does recombination occur?

Anaphase I

Metaphase I

Metaphase II

Prophase I

Prophase II

Answer 18

Prophase I

In prophase I the chromosomes condense into the tetrad (where each pair of sister chromatids is aligned). A structure known as the chiasmata then forms between non-sister (non-homologous) chromosomes. Recombination occurs and there is a reciprocal transfer of genetic information generating recombinants.

Question 19

A competitive antagonist shifts the log dose–response curve of an agonist to the right, without affecting the maximal response.

True or False?

Answer 19

True

This because by increasing the agonist concentration, then the agonist will be able to compete (and win) with the antagonist and reach maximum response.

Question 20

There are two subtypes of β-adrenoceptors.

True or False?

Answer 20

False

A third type, the β 3 -adrenoceptor, is found in adipocytes, the heart, colon, bladder and some other tissues, but is less widespread than the β 1 - and β 2 -adrenoceptors.

Question 21

The parasympathetic and sympathetic nervous systems have opposite effects in every organ.

True or False?

Answer 21

False

While the two autonomic systems have broadly opposing actions on many organs, other organs may be controlled by only one system. The kinetics of the two systems also vary, with the PNS fine-tuning organ activity at rest, while the SNS produces rapid coordinated responses of many organs in a physiological emergency.

Question 22

Which type of inflammation is histologically characterised by an increased number of lymphocytes?

Chronic inflammation

Acute inflammation

Answer 22

Acute Inflammation

Acute inflammation is characterised by an increased number of neutrophils, while chronic inflammation is characterised by an increased number of lymphocytes.

Question 23

Irreversible drug-receptor antagonism

Answer 23

Irreversible antagonists will bind permanently to the target receptor and as a result no matter how much the agonist concentration is raised there will be no observable effect.

Question 24

A receptor antagonist is defined as a drug with zero affinity for the receptor.

True or False?

Answer 24

False

An antagonist needs to bind to the receptor as the agonist. So it needs to have affinity. Then once is bound, leads to no effect, so has no efficacy.

Question 25

In the action potential represented below which ion (efflux) is responsible for phase B? (Repolarisation)

Ca2+

Cl-

H+

K+

Na+

Answer 25

K+

Phase B represents the repolarisation of the membrane by the opening of voltage-gated K+ channels. The efflux K+ ions lowers the membrane potential eventually leading to hyper-polarisation and the induction of the refractory period (3-4.5ms on the chart above) where none of the Na+ voltage-gated channels can be activated.

Question 26

Which of the following best describes a sarcomere?

Composed primarily of actin, myosin and albumin

Linked by intercalated disks

Made up of many individual myocytes

The basic repeating units of striated muscle

Titan molecules and Z-disks

Answer 26

The basic repeating units of striated muscle

Each sarcomere is made up from actin and myosin in repeating units and this is the basic unit of muscle contraction. The motion of the sarcomere can be described by the sliding filament theory and the interaction of cross bridges in the presence of Ca2+ ions.

Question 27

Apoptosis can cause inflammation.

True or false?

Answer 27

False

Apoptosis is programmed cell death that is regulated. The cell breaks down into smaller entities called apoptotic bodies that are removed by phagocytosis. This event does not cause inflammation.

–Necrosis causes inflammation because some components of the dying cell that are capable of triggering inflammation come into contact with healthy cells nearby

Question 28

A full agonist achieves a maximal response when all its receptors are occupied

True or False?

Answer 28

False

Maximal response can be achieved by the full agonist occupying only a fraction of receptoras available.

Question 29

What characterises an enzyme linked receptor?

Fastest response of all types of receptors

Ligand binding activates extracellular enzyme

Ligand binding activates a G-protein coupled receptor

Ligand binding activates intracellular receptor

Ligand binding activates intracellular enzyme

Answer 29

Ligand binding activates intracellular enzyme

Enzyme linked receptors are characterised by: 1. a transmembrane domain (often a single helix), 2. an extracellular ligand binding site/domain, 3. an intracellular catalytic domain (enzyme).

Question 30

The termination of action of synaptic noradrenaline is mainly done by metabolism (MAO and COMT).

True or False?

Answer 30

False

The actions of noradrenaline are ended mainly by reuptake into the presynaptic neuron by its respective transporter.

Question 31

The synaptic uptake of noradrenaline can be inhibited selectively.

True or False?

Answer 31

True

The uptake transporter can be inhibited by antidepressant drugs (is one example).

Question 32

What are the functions of microtubules?

Cytoskeletal structures involved in cell division, motility and vesicular transport

Cytoskeletal structures involved in cell division, muscle contraction and vesicular transport

Cytoskeletal structures involved in muscle contraction

Cytoskeletal structures involved in nuclear stability

Cytoskeletal structures involved in plasma membrane structural stability

Answer 32

Cytoskeletal structures involved in cell division, motility and vesicular transport

Microtubules are principally utilised in cellular motility (flagella of a sperm cell, cilia of a epithelia cells), transport (the motion of vesicles around the cell), and in cell division the spindle apparatus that connects to the chromosomes and pulls them apart is composed chiefly of microtubules.

Question 33

Phagocytosis removes infectious pathogens only.

True or False?

Answer 33

False

Phagocytosis removes infectious pathogens and dead (apoptotic cells).

Question 34

1.Choose two cations and one anion that are most important in the functioning of the cell.

a. Na+
b. Mg2+
c. K+
d. Ca2+
e. H+
f. OH-
g. Cl

Answer 34

Na+, K+and Cl-

-ions are critical in the ionic maintenance across the cell membrane. The physics of this is complex but in essence the balance of these three ions: 1. osmotically stabilises the cell and makes room for incoming molecules: the [Cl-] is lowered because of the internally generated negative membrane voltage2. this negative membrane voltage is generated by the movement of Na+ and K+ions across the membrane(action of the Na-K ATP pump).

Question 35

2.What is the structure of the plasma membrane and why can’t ions pass through?

Answer 35

The plasma membrane is made up of a phospholipid bilayer. This consists of hydrophilic phosphate heads that orientate into and out of the cell as well as hydrophobic lipid tails that orientate towards each other. The plasma membrane also comprises of transmembrane transporter proteins as well as surface proteins,antigens and proteins,that play a role in numerous aspects of cell signalling. Integrated into the plasma membrane are also other molecules such as carbohydrates as well as cholesterol. Ions cannot pass across the membrane because of their highly charged nature-since this is chemically unfavourable in the vicinity of the hydrophobic lipid tails.

Question 36

What types of transporters are used to transport chloride ions into/out of the cell?

Answer 36

Channels –open and close to let a specific ion move across the membrane down a concentration gradient(facilitated diffusion)

• Transporters –move two ions at once, at least one down a concentration gradient(symporter)
• Exchangers –two ions move in opposition to one another(antiporter)
• ABC-class (ATP-binding-cassette) channel –use ATP across the membrane-for example the CFTR ATP-gated anion channel.

Question 37

A mutation of the CFTR protein means that the transporter is either faulty or breaks down very shortly after production and never makes it to the plasma membrane. This leads to an accumulation of chloride ions in the cell. What might the effect of this be on other ions in the cell?

Answer 37

With an accumulation of chloride ions inside the cell, this results in an increased negative charge within the cell. To balance this,K+ is retained inside the cell to achieve balanceof electrical charge across the membrane.

Question 38

What effect might this ion balance have when thinking about cells in the lungs and homeostasis of water? (High concentration of chloride ions in the cell)

Answer 38

A high concentration of chloride ions inside the cells leads to retention of water intracellularly. This means water is dragged from the mucus that lines the lung airways, resulting in drier, stickier mucus that is harder to move and is therefore leaves patients more susceptible to infection.

Question 39

CF is caused by a mutation of the CFTR protein, a transporter that regulates chloride ion transport across the membrane. How does knowing this allow us to better treat patients with CF?

Answer 39

Earlier diagnosis
Potential for genetherapy
Allows us to predict where the disease will affect
More targeted therapy for patients
Life prolongation

Question 40

Organise the following statements to most accurately describe the process of transcription:

a) RNA polymerase recognises a promotor region
b) The DNA is read in a 3’ to 5’ direction, providing a template for mRNA
c) RNA polymerase attaches to the DNA molecule
d) The mRNA molecule continues to be synthesised until a stop sequence is encountered
e) The DNA molecule unwinds and separates

Answer 40

A,C,E,B,D

Question 41

Genetic material of coronaviruses Exists as double-stranded helices, comprised of the bases G, A, T, C

True or False?

Answer 41

False, is single-stranded RNA, and has uracil instead of thymine

Question 42

Genetic material of coronaviruses exists as negatively charged single-strands, comprised of the bases: G, A, U, C

True or false?

Answer 42

True

Question 43

Name some methods of protein denaturation. Choose one to explain.

Answer 43

Heat, changing pH, changing salinity, oxidation, changing solvent