Steps of PCR in sequence are?
Atherosclerosis is associated with:
Intellectual disability is seen in?
Essential fatty acid:
Energy reserve of the body is:
FMGE 2018 - Biochemistry FMGE Practice Questions and MCQs
Question 11: Steps of PCR in sequence are?
- A. Denature DNA, Extend DNA, Anneal Primers
- B. Anneal Primers, Extend DNA, Denature DNA
- C. Extend DNA, Anneal Primers, Denature DNA
- D. Denature DNA, Anneal Primers, Extend DNA (Correct Answer)
Explanation: ***Denature DNA, Anneal Primers, Extend DNA*** - This sequence represents the three fundamental steps of each PCR cycle, ensuring accurate and efficient **DNA amplification**. - **Denaturation** separates the double-stranded DNA template, **annealing** allows primers to bind to specific sequences, and **extension** synthesizes new DNA strands. *Denature DNA, Extend DNA, Anneal Primers* - This order is incorrect because **primer annealing** must occur before DNA extension can begin. - Primers provide the necessary starting points for the **DNA polymerase** to synthesize the new strands. *Anneal Primers, Extend DNA, Denature DNA* - This sequence is incorrect as the **template DNA** must first be denatured to separate the strands before primers can anneal to them. - If the DNA is not denatured, the primers cannot access their target sequences. *Extend DNA, Anneal Primers, Denature DNA* - This order is incorrect because **DNA extension** is the final step, occurring only after denaturation and primer annealing. - The polymerase requires both a denatured template and bound primers to initiate synthesis.
Question 12: Atherosclerosis is associated with:
- A. Histidine
- B. Lysine
- C. Homocysteine (Correct Answer)
- D. Leucine
Explanation: ***Homocysteine*** - Elevated plasma levels of **homocysteine**, known as hyperhomocysteinemia, are an independent **risk factor for atherosclerosis** and cardiovascular disease. - While the precise mechanism is complex, homocysteine is thought to promote endothelial damage, oxidative stress, and lipid peroxidation, contributing to **plaque formation**. *Histidine* - **Histidine** is an essential amino acid involved in various metabolic processes, including the synthesis of **histamine** and carnosine. - It is not directly associated with the pathogenesis or risk factors for atherosclerosis. *Lysine* - **Lysine** is an essential amino acid important for **protein synthesis** and many bodily functions. - There is no established direct link between lysine levels and the development or progression of atherosclerosis. *Leucine* - **Leucine** is a branched-chain amino acid (BCAA) crucial for **muscle protein synthesis** and energy metabolism. - While some studies hint at associations between BCAAs and metabolic health, leucine itself is not a known direct risk factor or etiologic agent for atherosclerosis.
Question 13: Intellectual disability is seen in?
- A. Von Gierke disease
- B. Alkaptonuria
- C. Albinism
- D. Phenylketonuria (Correct Answer)
Explanation: ***Phenylketonuria*** - **Phenylketonuria (PKU)** is an inherited metabolic disorder where the body cannot process the amino acid **phenylalanine**, leading to its accumulation in the blood and brain. - Untreated PKU results in severe neurological problems, including **intellectual disability**, seizures, and developmental delays. *Von Gierke disease* - **Von Gierke disease** is a type of glycogen storage disease primarily affecting the liver and kidneys, causing **hypoglycemia** and **lactic acidosis**. - It does not typically involve intellectual disability; cognitive development is usually normal if metabolic complications are managed. *Alkaptonuria* - **Alkaptonuria** is an inherited disorder characterized by the accumulation of **homogentisic acid**, leading to dark urine, ochronosis (bluish-black discoloration of cartilage and connective tissue), and arthritis. - It does not cause intellectual disability. *Albinism* - **Albinism** is a group of inherited disorders characterized by a reduced or complete lack of **melanin pigment** in the skin, hair, and eyes. - While it causes vision problems, such as photosensitivity and nystagmus, it is not associated with intellectual disability.
Question 14: Essential fatty acid:
- A. Citric acid
- B. Palmitic acid
- C. Linoleic acid (Correct Answer)
- D. Stearic acid
Explanation: ***Linoleic acid*** - **Linoleic acid** is an **omega-6 fatty acid** that is considered essential because the human body cannot synthesize it and must obtain it through diet. - It is a precursor for other important fatty acids like **arachidonic acid**, which are involved in inflammation and blood clotting. *Citric acid* - **Citric acid** is an organic acid found in citrus fruits and is a key intermediate in the **Krebs cycle** (citric acid cycle), a central metabolic pathway, but it is not a fatty acid. - It is readily synthesized by the body and is therefore not considered an essential nutrient. *Palmitic acid* - **Palmitic acid** is a **saturated fatty acid** with 16 carbon atoms, which is the most common fatty acid in animals and plants. - It can be synthesized by the human body from excess carbohydrates and proteins, hence it is not an essential fatty acid. *Stearic acid* - **Stearic acid** is another common **saturated fatty acid** with 18 carbon atoms, found in various animal and plant fats. - Like palmitic acid, it can be endogenously synthesized by the body and is not considered essential.
Question 15: Energy reserve of the body is:
- A. Fibres
- B. Triglyceride (Correct Answer)
- C. Carbohydrate
- D. Proteins
Explanation: ***Triglyceride*** - **Triglycerides** are the primary form of **energy storage** in the body, stored predominantly in **adipose tissue**. - They provide a highly concentrated and long-term energy reserve, crucial for periods of fasting or increased energy demand. *Fibres* - **Dietary fibers** are indigestible plant-derived carbohydrates that contribute to digestive health but do not serve as a direct energy reserve for the body. - They are important for maintaining gut motility and regulating blood sugar, but are not metabolized for energy. *Carbohydrate* - **Carbohydrates** (primarily **glycogen**) serve as the **body's most immediate energy source**, stored in the liver and muscles. - However, glycogen stores are limited and are depleted much faster than triglyceride stores during prolonged energy needs. *Proteins* - **Proteins** have numerous structural and functional roles in the body, but are typically used for energy only in cases of **prolonged starvation** when carbohydrate and fat reserves are severely depleted. - Their primary function is not energy storage, and their breakdown for energy can lead to **muscle wasting** and compromise essential body functions.