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Question 1
Incorrect
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You encounter a patient in the Emergency department who has been in a severe car accident. You need to insert a venous cannula for aggressive fluid resuscitation. Applying the Hagen-Poiseuille equation, you select a cannula with appropriate dimensions for maximum flow into the vein.
As per this law, which of the following statements is correct?Your Answer: Flow is proportional to the radius of the cannula squared
Correct Answer: Flow will be faster through a shorter cannula
Explanation:Poiseuille’s Equation and Fluid Flow in Cylinders
Poiseuille’s equation is used to describe the flow of non-pulsatile laminar fluids through a cylinder. The equation states that the flow rate is directly proportional to the pressure driving the fluid and the fourth power of the radius. Additionally, it is inversely proportional to the viscosity of the fluid and the length of the tube. This means that a short, wide cannula with pressure on the bag will deliver fluids more rapidly than a long, narrow one.
It is important to note that even small changes in the radius of a tube can greatly affect the flow rate. This is because the fourth power of the radius is used in the equation. Therefore, any changes in the radius will have a significant impact on the flow rate. Poiseuille’s equation is crucial in determining the optimal conditions for fluid delivery in medical settings.
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This question is part of the following fields:
- Basic Sciences
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Question 2
Incorrect
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At what stage of eukaryotic mitosis do the centromeres of chromosomes separate?
Your Answer: Telophase
Correct Answer: Anaphase
Explanation:Chromosome Division during Anaphase
Chromosomes are joined together in an X shape at the centromere. During anaphase, the centromeres break down and the chromosomes divide into two identical pairs called sister chromatids. These sister chromatids then move to opposite sides of the cell along a network of spindle fibres. When the cell divides during telophase, each daughter cell receives one sister chromatid from the parent cell. This ensures the accurate copying and propagation of genes. The process of chromosome division during anaphase is crucial for the proper distribution of genetic material in cells.
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This question is part of the following fields:
- Basic Sciences
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Question 3
Incorrect
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As part of your general practice placement, you have been tasked with conducting an audit on the duration of solid food introduction in the practice population. You review the data for the last six infants born within the practice:
6 months, 7 months, 8 months, 9 months, 10 months, 11 months.
What is the variance value for the duration of solid food introduction in the practice population?Your Answer: 17.6
Correct Answer: 74.9
Explanation:Variance and Standard Deviation in Breast Feeding Duration
Variance is a statistical measure that indicates how spread out a set of data is. In the case of breast feeding duration, variance can help us understand how much the duration varies from the mean. The formula for variance involves squaring the difference between each data point and the mean, then dividing the sum by n-1, where n is the total number of data points. In a sample population, n-1 is a better estimate of variance than n because it accounts for the variability within the sample.
For example, if the variance of breast feeding duration is 74.9 months, this indicates that the duration is widely distributed from the mean of 17.6 months. A smaller variance, such as 4.5 months, would indicate that the duration varies less and is closer to the mean. The standard deviation, which is the square root of the variance, is also important in the spread of data. In a normal distribution, 95% of observations will fall within two standard deviations of the mean.
In the case of breast feeding duration, the mean is 17.6 months, indicating that babies are breast fed for an average of 15 and a half months. The median, which is the middle number in the data set, is 15 months, meaning that half of the babies were breast fed for 15 months. variance and standard deviation can help us better understand the distribution of breast feeding duration and other medical measurements.
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This question is part of the following fields:
- Basic Sciences
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Question 4
Correct
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What is the final product of glycolysis besides ATP?
Your Answer: Pyruvate
Explanation:Glycolysis: The Energy-Producing Reaction
Glycolysis is a crucial energy-producing reaction that converts glucose into pyruvate while releasing energy to create ATP and NADH+. It is one of the three major carbohydrate reactions, along with the citric acid cycle and the electron transport chain. The reaction involves ten enzymatic steps that provide entry points to glycolysis, allowing for a variety of starting points. The most common starting point is glucose or glycogen, which produces glucose-6-phosphate.
Glycolysis occurs in two phases: the preparatory (or investment) phase and the pay-off phase. In the preparatory phase, ATP is consumed to start the reaction, while in the pay-off phase, ATP is produced. Glycolysis can be either aerobic or anaerobic, but it does not require nor consume oxygen.
Although other molecules are involved in glycolysis at some stage, none of them form its end product. Lactic acid is associated with anaerobic glycolysis. glycolysis is essential for how the body produces energy from carbohydrates.
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This question is part of the following fields:
- Basic Sciences
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Question 5
Correct
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What are the potential clinical consequences of a lack of vitamin E?
Your Answer: Ataxia
Explanation:Vitamin E Deficiency
Vitamin E deficiency is a rare condition that is more likely to occur in individuals with problems affecting the absorption of dietary fats. This includes those with a history of bowel surgery, pancreatic insufficiency, and cystic fibrosis. Premature infants are also at a higher risk of developing this deficiency as vitamin E does not easily cross the placenta. However, supplementation with vitamin E can reverse the damage in some cases.
The effects of vitamin E deficiency can be severe and can cause spinocerebellar degeneration, which includes limb ataxia, loss of joint position sense, loss of sensation of vibration, and loss of deep tendon reflexes. Additionally, it can cause degeneration of retinal pigments, leading to blindness. In premature infants, it can cause haemolytic anaemia, thrombocytosis, and oedema.
Overall, vitamin E deficiency is crucial in preventing and treating its effects. It is important to identify individuals who are at a higher risk of developing this deficiency and provide them with appropriate supplementation to prevent any long-term damage.
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This question is part of the following fields:
- Basic Sciences
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Question 6
Correct
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During which stage of the cell cycle does the replication of DNA occur?
Your Answer: S phase
Explanation:The Five Phases of the Cell Cycle
The cell cycle is a complex process that is divided into five main phases, each with its unique cellular events. The first phase is the G0 phase, which is a resting phase where the cell has stopped dividing and is out of the cell cycle. The second phase is the G1 phase, also known as interphase Gap 1, where cells increase in size, and a checkpoint control mechanism prepares the cell for DNA synthesis.
The third phase is the S phase, where DNA replication occurs. The fourth phase is the G2 phase, also known as Gap 2, which is a gap between DNA synthesis and the onset of mitosis. During this phase, the cell continues to grow until it is ready to enter mitosis. Finally, the fifth phase is the M phase, also known as mitosis, where cell growth stops, and the cell focuses its energy to divide into two daughter cells.
A checkpoint in the middle of mitosis, known as the metaphase checkpoint, ensures that the cell is prepared to complete division. the five phases of the cell cycle is crucial in how cells divide and grow.
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This question is part of the following fields:
- Basic Sciences
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Question 7
Correct
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In which part of the cell are the electron transport chain carriers situated?
Your Answer: Mitochondrial cristae
Explanation:The Electron Transport Chain in Mitochondria
The electron transport chain (ETC) is a crucial process in cellular aerobic respiration that occurs in the mitochondrial cristae. These are folded membranes inside the organelle. During respiration, NADH and FADH produced from other parts of the process, such as glycolysis, transfer electrons from electron donors to electron acceptors through redox reactions. This electron transfer is coupled with proton transfer across the mitochondrial membrane, creating an electrochemical proton gradient. This gradient induces the production of ATP, which is used as an energy currency by the cell.
ATP is produced through a mechanism called chemiosmotic phosphorylation. The structure of the mitochondrion is essential for this process to occur. The cristae provide a large surface area for the ETC to take place, and the mitochondrial membrane is impermeable to protons, allowing for the creation of the proton gradient. The inner membrane also contains ATP synthase, the enzyme responsible for producing ATP through chemiosmotic phosphorylation.
In summary, the electron transport chain in mitochondria is a complex process that involves the transfer of electrons and protons across the mitochondrial membrane to create a proton gradient. This gradient is then used to produce ATP through chemiosmotic phosphorylation. The structure of the mitochondrion is crucial for this process to occur efficiently.
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This question is part of the following fields:
- Basic Sciences
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Question 8
Correct
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What is the primary role of the nucleus in a eukaryotic cell?
Your Answer: To regulate gene transcription and translation
Explanation:The Nucleus: Control Centre of the Cell
The nucleus is the control centre of the cell, responsible for regulating gene transcription from DNA into mRNA and from mRNA into peptide/protein synthesis. Eukaryotic cells have a membrane-enclosed organised nucleus, while prokaryotic cells lack this structure. The nuclear structure consists of an outer and inner nuclear membrane that form the nuclear envelope, which has nuclear pores allowing the movement of water-soluble molecules. Inside the nucleus is the nucleoplasm containing the nuclear lamina, a dense fibrillar network that acts as a skeleton and regulates DNA replication and cell division. The nucleus also contains nucleoli, structures involved in the formation of ribosomes responsible for mRNA translation.
Although the incorrect answer options above describe processes in which the nucleus is involved, none of them constitutes its main function within the cell.
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This question is part of the following fields:
- Basic Sciences
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Question 9
Incorrect
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To what type of cell can mesenchymal stem cells transform?
Your Answer: White blood cells
Correct Answer: Osteoblasts
Explanation:Mesenchymal Cells: The Stem Cells of the Human Skeleton
Mesenchymal cells are the primary stem cells of the human skeleton. These multipotent cells originate in the bone marrow and have the ability to differentiate into various cell types. Osteoblasts, responsible for bone formation, chondrocytes, which give rise to cartilage, and adipocytes, specialized in storing energy as fat, are some of the cells that mesenchymal cells can produce. Muscle cells, or myocytes, arise from muscle satellite cells, while skin cells come from epithelial stem cells. Neurons mostly arise from neural stem cells, although some may come from astrocytes. White blood cells, on the other hand, come from hematopoietic stem cells. Mesenchymal cells play a crucial role in the maintenance and repair of the human skeleton, making them an essential area of study in regenerative medicine.
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This question is part of the following fields:
- Basic Sciences
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Question 10
Correct
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What function does vitamin E serve in the body?
Your Answer: Antioxidant
Explanation:Vitamin E and its Functions
Several substances are classified as vitamin E, with alpha-tocopherol being the most common, accounting for 90% of human vitamin E. Alpha-tocopherol is composed of two carbon rings and a long saturated hydrocarbon chain, making it hydrophobic. It has an aromatic ring with an OH- group attached to it. Other substances with vitamin E activity include other tocopherols and tocotrienols, all of which act as antioxidants. Alpha-tocopherol is particularly important in cell membranes, preventing the peroxidation of unsaturated fatty acids by free radicals. It also has other functions, such as regulating gene transcription, inhibiting clotting formation, reducing proliferation of vascular smooth muscle, and playing a role in immunity.
Despite claims that taking vitamin E can reduce the risk of heart disease, cancer, and enhance sexual performance, there is currently no strong evidence to support these claims.
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This question is part of the following fields:
- Basic Sciences
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Question 11
Incorrect
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Of which cellular structure is the fibrillar centre a component?
Your Answer: The chromosomes
Correct Answer: The nucleolus
Explanation:The Fibrillar Centre in the Nucleolus
The fibrillar centre is a crucial component of the nucleolus, which is found in most metazoan nucleoli, particularly in higher eukaryotes. Along with the dense fibrillar components and the granular component, it forms the three major components of the nucleolus. During the end of mitosis, the fibrillar centre serves as a storage point for nucleolar ribosomal chromatin and associated ribonucleoprotein transcripts. As the nucleolus becomes active, the ribosomal chromatin and ribonucleoprotein transcripts begin to form the dense fibrillar components, which are more peripherally located and surround the fibrillar centres. The transcription zone for multiple copies of the pre-rRNA genes is the border between these two structures. It is important to note that the fibrillar centre is not a component of any of the cell structures mentioned in the incorrect answer options.
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This question is part of the following fields:
- Basic Sciences
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Question 12
Incorrect
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What is the primary reason for malnutrition?
Your Answer: Inadequate intake of multiple vitamins
Correct Answer: Inadequate intake of calories in any form
Explanation:Malnutrition
Malnutrition refers to a state where the dietary intake is insufficient to maintain a healthy state and stable weight. It can be caused by over- or under-nutrition, but it is commonly used to describe under-nutrition. Malnutrition can be defined as a state of nutrition where a deficiency, excess, or imbalance of energy, protein, and other nutrients causes measurable adverse effects on tissue, function, and clinical outcome. Protein malnutrition is the most severe form of malnutrition, causing significant mortality and clinical effects such as kwashiorkor. Carbohydrate malnutrition is less common as carbohydrate sources are widely grown and cheap. Fat malnutrition rarely results in problems if there is adequate dietary protein and carbohydrate. Deficiencies of fat-soluble vitamins can result in various clinical effects. Body size can give some indication of nutritional status, but many obese patients may have nutritional deficiencies due to their faddy diets.
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This question is part of the following fields:
- Basic Sciences
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Question 13
Incorrect
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Which process occurs mainly in the smooth endoplasmic reticulum?
Your Answer: Translation
Correct Answer: Steroid synthesis
Explanation:The Functions of Endoplasmic Reticulum and Lysosomes
The endoplasmic reticulum (ER) is a complex network of membranes that is divided into two types: rough and smooth. The rough ER is characterized by the presence of ribosomes on its cytosolic side, which makes it an important site for protein production, modification, and transport. On the other hand, the smooth ER is involved in cholesterol and steroid handling, as well as calcium storage in some cells. This type of ER is particularly prominent in cells that produce large amounts of steroid hormones, such as those found in the adrenal cortex.
Lysosomes, on the other hand, are organelles that are responsible for breaking down and recycling cellular waste. They are formed by the Golgi apparatus, which is another complex network of membranes found in eukaryotic cells. Lysosomes contain a variety of enzymes that are capable of breaking down different types of molecules, including proteins, lipids, and carbohydrates.
In summary, the ER and lysosomes are two important organelles in eukaryotic cells that play different roles in cellular metabolism. While the ER is involved in protein production, modification, and transport, the lysosomes are responsible for breaking down and recycling cellular waste.
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This question is part of the following fields:
- Basic Sciences
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Question 14
Correct
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A premature baby is born and the anaesthetists are struggling to ventilate the lungs because of insufficient surfactant. How does Laplace's law explain the force pushing inwards on the walls of the alveolus caused by surface tension between two static fluids, such as air and water in the alveolus?
Your Answer: Inversely proportional to the radius of the alveolus
Explanation:The Relationship between Alveolar Size and Surface Tension in Respiratory Physiology
In respiratory physiology, the alveolus is often represented as a perfect sphere to apply Laplace’s law. According to this law, there is an inverse relationship between the size of the alveolus and the surface tension. This means that smaller alveoli experience greater force than larger alveoli for a given surface tension, causing them to collapse first. This phenomenon is similar to what happens when two balloons of different sizes are attached together, with the smaller balloon emptying into the larger one.
In the lungs, this collapse of smaller alveoli can lead to atelectasis and collapse if surfactant is not present. Surfactant is a substance that reduces surface tension, making it easier to expand the alveoli and preventing smaller alveoli from collapsing. this relationship between alveolar size and surface tension is crucial in respiratory physiology, as it helps explain the importance of surfactant in maintaining proper lung function.
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This question is part of the following fields:
- Basic Sciences
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Question 15
Correct
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What are the primary constituents of the cytoskeleton in eukaryotic cells?
Your Answer: Microfilaments, intermediate filaments and microtubules
Explanation:The Eukaryotic Cytoskeleton: A Structural Support System
The eukaryotic cytoskeleton is a network of structures that provide structural support to the cell. It helps the cell maintain its shape, protects it from external pressure, and performs intracellular transport. The cytoskeleton is made up of three major structures: microfilaments, intermediate filaments, and microtubules. Microfilaments are thin double helices made up of actin and are involved in pressure resistance and cell motility. Intermediate filaments have a more complex structure and maintain cell shape while bearing tension. Microtubules are hollow cylinders made up of alpha and beta tubulin proteins and are involved in intracellular transport, cell movement, and form the mitotic spindle during cytokinesis.
Cilia, flagella, and lamellipodia are structures that are not part of the cell’s cytoskeleton but are made up of components of it and perform unique functions such as cell movement and extracellular sensing. Kinesin and dynein are motor proteins that support microtubule function. Microfilaments and alpha/beta microtubules are incorrect because they leave out intermediate filaments. Tubulin and actin are proteins of microtubules and microfilaments, respectively, but myosin is a motility protein involved in muscle contraction. The eukaryotic cytoskeleton is an essential component of the cell that provides structural support and enables various cellular functions.
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This question is part of the following fields:
- Basic Sciences
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Question 16
Correct
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The arrangement of amphipathic phospholipids in the mammalian cell membrane, what is it like?
Your Answer: A lipid bilayer with hydrophilic heads facing out and hydrophobic tails facing in
Explanation:The Function and Structure of the Mammalian Cell Membrane
The mammalian cell membrane serves as a protective barrier that separates the cytoplasm from the extracellular environment. It also acts as a filter for molecules that move across it. Unlike plant and prokaryotic cells, mammalian cells do not have a cell wall. The main component of the cell membrane is a bilayer of amphipathic lipids, which have a hydrophilic head and a hydrophobic tail. The phospholipids in the bilayer are oriented with their hydrophilic heads facing outward and their hydrophobic tails facing inward. This arrangement allows for the separation of the watery extracellular environment from the watery intracellular compartment.
It is important to note that the cell membrane is not a monolayer and the phospholipids are not linked head-to-tail. This is in contrast to DNA, which has a helical chain formation. Overall, the structure and function of the mammalian cell membrane are crucial for maintaining the integrity and proper functioning of the cell.
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This question is part of the following fields:
- Basic Sciences
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Question 17
Correct
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What is the primary factor that increases the risk of thiamine (vitamin B1) deficiency?
Your Answer: Chronic alcohol excess
Explanation:Thiamine: Its Roles, Sources, Deficiency States, and Manifestations
Thiamine is a vital nutrient that plays several roles in the body. It acts as a cofactor to enzymes involved in energy production, metabolism of branched chain amino acids, and regulation of nerve and muscle action potentials. It is found in many foods, including wheat, oats, and yeast-containing products. However, deficiency states can occur in chronic alcohol dependence, renal dialysis, and cultures that mainly consume white rice. The deficiency can manifest as ‘dry’ beriberi, which causes peripheral neuropathy, muscle weakness, fatigue, and reduced concentration, or ‘wet’ beriberi, which also involves heart failure and edema. In severe cases, Wernicke-Korsakoff syndrome can develop, which is an emergency requiring urgent IV replacement of thiamine. If left untreated, it can lead to irreversible amnesia, confabulation, and dementia. Therefore, all patients with alcohol-related admissions should be considered for Pabrinex, a B vitamin infusion.
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This question is part of the following fields:
- Basic Sciences
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Question 18
Correct
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What occurs in eukaryotic prophase?
Your Answer: Chromatin condenses into chromosomes
Explanation:The Stages of Prophase in Eukaryotic Mitosis
Prophase is the first stage of eukaryotic mitosis, except for plant cells which have a preprophase stage. During prophase, the cell’s chromatin, which is made up of DNA and associated proteins, condenses into double rod-shaped structures called chromosomes. This process is facilitated by the condensin protein I and/or II complexes. As the chromosomes form, the nuclear membrane and nucleoli disintegrate and disappear, making the chromatin visible.
Before prophase, the cell’s DNA is replicated during interphase, resulting in identical pairs of chromosomes called chromatids. These chromatids attach to each other at a DNA element called the centromere. DNA and centrosome duplication occur during interphase, while chromosome alignment takes place during metaphase. The nuclear membrane and nucleoli re-form during telophase, and the sister chromatids separate during anaphase.
In summary, prophase is the initial stage of eukaryotic mitosis where chromatin condenses into chromosomes, and the nuclear membrane and nucleoli disappear. Chromosome alignment, DNA and centrosome duplication, and re-formation of the nuclear membrane and nucleoli occur in subsequent stages.
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This question is part of the following fields:
- Basic Sciences
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Question 19
Incorrect
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A 10-year-old patient presents with recurrent skin cancer and is diagnosed with xeroderma pigmentosum. What is the defective biochemical mechanism in this disease?
Your Answer: Nucleotide transition
Correct Answer: DNA excision repair
Explanation:Xeroderma Pigmentosum and DNA Repair
Deoxyribonucleic acid (DNA) found in the skin cells can absorb ultraviolet (UV) light, which can cause the formation of pyrimidine dimers. These dimers are removed through a process called excision repair, where the damaged DNA is cut out and replaced with new DNA. However, if this process fails, it can lead to mutations in genes that suppress tumors or promote their growth, potentially leading to cancer.
Xeroderma pigmentosum is a genetic disorder that is inherited in an autosomal recessive pattern. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disorder. Generally, disorders that affect metabolism or DNA replication on a cellular or genetic level are inherited in an autosomal recessive pattern. On the other hand, genetic disorders that affect larger structural components are usually inherited in an autosomal dominant pattern. While there are exceptions to these rules, they can serve as a helpful guide for exam preparation.
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This question is part of the following fields:
- Basic Sciences
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Question 20
Correct
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What role does the nucleolus play in eukaryotic cells?
Your Answer: To transcribe ribosomal RNA and assemble ribosomes
Explanation:The Nucleolus: Structure and Function
The nucleolus is a non-membrane-bound structure that takes up about a quarter of the nuclear volume. It is composed mainly of proteins and nucleic acids and is responsible for transcribing ribosomal RNA (rRNA) and assembling ribosomes in the cell. Nucleoli are formed in nucleolar organizing regions (NORs), which are also the regions of the genes for three of the four eukaryotic rRNAs.
During ribosome assembly, ribosomal proteins enter the nucleolus from the cytoplasm and begin to assemble on an rRNA precursor. As the pre-rRNA is cleaved to produce 5.8S, 18S, and 28S rRNAs, additional ribosomal proteins and the 5S rRNA (which is synthesized elsewhere in the nucleus) assemble to form preribosomal subunits. These subunits then exit the nucleolus into the cytoplasm and combine to produce the final 40S and 60S ribosomal subunits.
Overall, the nucleolus plays a crucial role in protein synthesis by producing the components necessary for ribosome assembly. Its unique structure and function make it an essential component of the cell’s machinery.
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This question is part of the following fields:
- Basic Sciences
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