Nikolay's Genetics Lessons

Glutamine plays a crucial role in the biosynthesis of purines, which are vital components of nucleic acids (DNA and RNA). It acts as a nitrogen donor in the synthesis of the nucleotide bases adenine and guanine. This process is essential for the production of ATP, GTP, and other nucleotides that are fundamental for cellular energy, protein synthesis, and cell division. Without glutamine's contribution to purine synthesis, the body would struggle to maintain adequate levels of these critical nucleotide bases, impacting a wide range of biological processes. Which amino acid is essential for purine synthesis, acting as a precursor for the nucleotide bases adenine and guanine? A) Histidine B) Glutamine C) Arginine D) Leucine https://www.youtube.com/watch?v=wJYfYLf2jsM

Cystic fibrosis is a disorder that damages your lungs, digestive tract and other organs. It's an inherited disease caused by a defective gene that can be passed from generation to generation. Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. The ΔF508 mutation is a deletion of three nucleotides that results in the loss of the phenylalanine at the 508th position in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein. This mutation leads to the production of a CFTR protein that is misfolded. As a result, the protein is not properly transported to the cell surface, where it is needed to help control the movement of salt and water in and out of cells. This leads to the thick and sticky mucus characteristic of cystic fibrosis. The ΔF508 mutation is the most common cause of cystic fibrosis worldwide, accounting for about 70% of CFTR mutations in patients globally. Other mutations listed, such as G551D, R117H, and N1303K, are also found in the CFTR gene of cystic fibrosis patients but are much less common compared to ΔF508. Problem: Which CFTR mutation is the most prevalent among patients with Cystic Fibrosis? A) G551D B) R117H C) ΔF508 D) N1303K https://www.youtube.com/watch?v=05EsDlewlGE

The amino acid tryptophan can act as a precursor for which of the following neurotransmitters? A) Dopamine B) Serotonin C) Acetylcholine D) GABA In the structure of proteins, which amino acid interrupts α-helix formation due to its rigid cyclic structure? A) Proline B) Glycine C) Alanine D) Leucine https://www.youtube.com/watch?v=57gOLWiT_V0

Which structure describes the specific sequence of amino acids in a protein? A) Primary structure B) Secondary structure C) Tertiary structure D) Quaternary structure Which of the following is not a type of secondary structure found in proteins? A) Alpha helix B) Beta sheet C) Beta turn D) Gamma loop https://www.youtube.com/watch?v=uwmYewpOXfY

Chaperones and enzymes are both crucial proteins that play distinct roles in cellular function and protein metabolism, but their functions and mechanisms of action differ significantly. Chaperones: Function: Chaperones assist in the correct folding of nascent (newly synthesized) and misfolded proteins. They help proteins attain their native, functional conformation and prevent the aggregation of unfolded or partially folded proteins. Chaperones do not form part of the final structure of the protein they assist. Mechanism: Chaperones work by temporarily binding to hydrophobic (water-repelling) regions of a protein that are normally hidden in the folded state. This binding prevents these regions from sticking together and forming aggregates. Some chaperones also facilitate the refolding of denatured proteins. The ATP-driven cycle of binding and release of substrate proteins is common in the action of many chaperones, which provides the energy required for their function. Types: There are several types of chaperones, including heat shock proteins (Hsps), which are named based on their discovery as proteins upregulated in response to heat stress. Each type has specific roles and mechanisms, such as Hsp70, Hsp90, and chaperonins. Enzymes: Function: Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. They are crucial for virtually all biochemical reactions in living organisms, including digestion, energy production, and synthesis of biomolecules. Mechanism: Enzymes lower the activation energy required for reactions to occur, thereby increasing the rate of those reactions. They typically have an active site, a specific region where substrate molecules bind. The enzyme-substrate complex then undergoes a reaction to form product(s), after which the products are released, and the enzyme is free to catalyze another reaction. Specificity: Enzymes are highly specific to their substrates due to the precise shape and chemical properties of their active sites. This specificity ensures that enzymes catalyze only specific reactions. In summary, the primary role of chaperones is to assist in protein folding and prevent aggregation, ensuring proteins achieve and maintain their functional three-dimensional structures. Enzymes, on the other hand, are catalysts that increase the rate of biochemical reactions. Both are essential for life, but they operate through fundamentally different mechanisms and serve distinct functions within the cell. Problem: What is the term for a small protein or peptide that assists in the folding of other proteins but is not part of the final structure? A) Enzyme B) Substrate C) Chaperone D) Coenzyme https://www.youtube.com/watch?v=3KJpQzX8930

Amino acids can be categorized based on the properties of their side chains (R-groups). These properties include whether they are nonpolar, polar uncharged, polar positively charged (basic), or polar negatively charged (acidic) at physiological pH (~7.4). Leucine is a nonpolar, hydrophobic amino acid. Its side chain does not ionize and cannot form ionic bonds at physiological pH. Aspartate has a side chain that contains a carboxyl group (-COOH). At physiological pH, this group loses a hydrogen ion (H⁺), becoming negatively charged (-COO⁻). This negative charge allows aspartate to form ionic bonds with positively charged entities, including the side chains of basic (positively charged) amino acids like lysine, arginine, and histidine. Proline has a unique cyclic structure that locks its nitrogen in a ring, making it rigid. It is nonpolar and does not form ionic bonds at physiological pH. Glycine, the simplest amino acid, has a hydrogen atom as its side chain. It is nonpolar and does not have a chargeable side group capable of forming ionic bonds at physiological pH. Thus, aspartate, with its ability to carry a negative charge at physiological pH due to its carboxylate side chain, is capable of forming ionic bonds, making it the correct choice among the options given. Problem: Which amino acid has a side chain that can form an ionic bond at physiological pH? A) Leucine B) Aspartate C) Proline D) Glycine https://www.youtube.com/watch?v=FCcjT9K8v1U

Aspartate and aspartic acid refer to different forms of the same amino acid, distinguished by their protonation state, which depends on the pH of their environment: Aspartic Acid: This is the name given to the molecule when it is in its protonated form. Aspartic acid has a carboxylic acid group (-COOH) in its side chain, along with an amino group (-NH2) as part of its main structure, like all amino acids. When the carboxyl group on the side chain is protonated, it means it holds onto an extra hydrogen ion (H+), giving it the formula -COOH. This form is generally prevalent under acidic conditions (low pH). Aspartate: This term refers to the deprotonated form of aspartic acid. In physiological or slightly basic conditions (pH around 7.4 or higher), the carboxylic acid group (-COOH) on the side chain loses a hydrogen ion (H+), becoming negatively charged (-COO-). This form is often involved in protein structure and function, participating in ionic interactions with other molecules or metal ion coordination in enzymes. The transition between aspartic acid and aspartate is a common example of an acid-base equilibrium, where the molecule can donate or accept a hydrogen ion depending on the pH of its surroundings. This adaptability is crucial for the roles of aspartic acid/aspartate in biological systems, such as enzyme catalysis, ion transport, and the transmission of nerve signals. https://www.youtube.com/watch?v=HeIGR85J4K8

Polypeptides are linear chains of amino acids linked by peptide bonds. A polypeptide becomes a protein when it folds into a specific three-dimensional structure that is biologically active, meaning it can perform its specific function in the cell. Proteins are functional biological molecules that often consist of one or more polypeptides that have folded into a unique, functional three-dimensional structure. Proteins can be made of a single polypeptide chain or multiple polypeptide subunits. The complexity, folding, and post-translational modifications of these chains contribute to the functional diversity of proteins. Therefore, while all proteins are essentially polypeptides because they are made from amino acid chains, not all polypeptides qualify as proteins. Some polypeptides might act as hormones, toxins, or signaling molecules without adopting the complex structures or functions typically associated with proteins. Problem: Which of the following statements is true regarding polypeptides and proteins? A) All polypeptides are proteins, but not all proteins are polypeptides. B) All proteins are polypeptides, but not all polypeptides are proteins. C) Proteins and polypeptides are exactly the same. D) Proteins are made of nucleotides, while polypeptides are made of amino acids. https://www.youtube.com/watch?v=sg1pLSE-fwY

African Sri Lankans, mainly the Sri Lanka Kaffirs, are a very small Ethnic group in Sri Lanka who are descendants of African mercenaries, musicians, and laborers taken to what is now Sri Lanka by Portuguese colonists during the period of Portuguese colonial rule on the island. There are currently around 10,000 African Sri Lankans. They live in pockets of communities along the island's coastal regions of Trincomalee, Batticaloa, and Negombo. The Portuguese colonists used them to fight the Ceylonese Kings. The main African Sri Lankans are known as Kaffirs. This term is not used as a racial pejorative as in other parts of the world. Some were originally Muslims, while others practiced African religions, but many have now converted to Catholicism and Buddhism. They speak a lyrical creole language with a mix of native Sinhalese and Tamil. https://www.youtube.com/watch?v=PJnN2ftrIDI

Proline is unique among the standard amino acids because it has a secondary amine group, where the nitrogen atom is part of a ring structure. This ring is formed by the side chain bonding back to the nitrogen atom of the amino acid, creating a rigid structure. This ring structure significantly influences the folding and stability of proteins by creating kinks in the polypeptide chain and limiting the rotation around the N-C bond. This property makes proline distinct and critical in the formation of turns and loops in the secondary structure of proteins, thus affecting the overall three-dimensional structure and function of the protein. Unlike the other options, which either do not have a ring in their side chain or have different types of side chains, proline's ring directly involves the backbone's nitrogen, making it integral to its structure. Problem: Which amino acid has a ring structure in its side chain? A) Proline B) Arginine C) Alanine D) Lysine https://www.youtube.com/watch?v=TBcIMUny1bg

Tryptophan exhibits anomalous behavior in terms of absorbance at 280 nm primarily due to its unique aromatic side chain, which contains an indole ring. This indole ring structure allows tryptophan to absorb ultraviolet light more effectively than other amino acids. In protein concentration determination, this property of tryptophan, along with tyrosine and to a lesser extent phenylalanine, is exploited to estimate the protein content by measuring absorbance at 280 nm. Tryptophan's strong absorbance at this wavelength, due to its larger and more complex aromatic structure, makes it a key contributor to the overall absorbance of proteins at 280 nm, thus playing a crucial role in spectrophotometric protein assays. Problem: The anomalous behavior of which amino acid's absorbance at 280 nm is primarily due to its unique aromatic side chain, useful in protein concentration determination? A) Tyrosine B) Tryptophan C) Phenylalanine D) Histidine https://www.youtube.com/watch?v=3ZU2sKAfEPg

Do you know who are aboriginal people of Sri Lanka? The Veddas - it i small tribal community in Sri Lanka, the island (formerly called Ceylon) that lies in the Indian Ocean off the southern tip of India. Physically, the Veddas are of Proto-Australoid stock, associated with the earliest strata of population identifiable in South Asia. Genetic studies suggest they are related to the tribes of Malaysia. Modern Veddas are believed to be descended from the island's earliest aboriginal inhabitants, though clearly they have been exposed to genetic mixing with later groups. The name "Vedda" is a Dravidian word meaning "one who uses bows and arrows," and Veddas traditionally lived by hunting and gathering in the forests of Sri Lanka. However, the Veddas call themselves Vanniyalato or "people of the forest." The Vedda minority in Sri Lanka may become completely assimilated. The Vedda language is becoming extinct, even if some elders still speak it, especially in Dambana, which is to some extent the "Vedda capital" of the island. https://www.youtube.com/watch?v=wbSmT0b4w4E

Sri Lankan women are known for their beauty. This video is going to be about genetic secrets of beauty of Shi Lankian women. On this map you can see to whom Sri Lankans are mostly related. Majority of the modern day Sri Lankan population identify as Sinhalese, and their ancestry is primarily from Bengal and Gujarat and another major group is tamils originally from Indian province Tamil Nadu. Bengali women are also known for their beauty, because of their caucasoid/mongoloid mixture. Since most Sri Lankan’s are descendants of Bengalis, this may explain why so many Sri Lankan women are so beautiful (especially in the central highland parts of the country). Tamil women too have their beauty. And as a geneticist I have to say that another reason might be because Sri Lankan’s are so mixed, with Indian, European, Arab, East Asian, and even Vedda and Africans, thus creating beautiful people. As you know the inbreeding is bad and outbreeding is good for the health which we percive as beaty. https://www.youtube.com/watch?v=LNQt5C4VV8s

Branched-chain amino acids (BCAAs), comprising leucine, isoleucine, and valine, are essential nutrients found in proteins of various food sources, such as meat, dairy products, and legumes. These amino acids are unique due to their aliphatic side chains with a branch, a structure that plays a pivotal role in human health and metabolism. BCAAs are critically involved in muscle protein synthesis, energy production, and the regulation of blood sugar levels. Their ability to stimulate muscle recovery and growth, while also potentially reducing exercise-induced fatigue, makes them particularly valuable for athletes and individuals engaged in regular physical training. Moreover, BCAAs are not only important for physical health but are also involved in maintaining mental health by influencing brain function and mood regulation, highlighting their comprehensive impact on overall well-being. Problem: Which amino acid is classified as a branched-chain amino acid (BCAA)? A) Glutamine B) Tyrosine C) Valine D) Asparagine https://www.youtube.com/watch?v=yyWCKcV_Fxk

The isoelectric point (pI) of an amino acid is the pH at which the amino acid exists in its zwitterionic form and carries no net electric charge. At this pH, the amino group is protonated, and the carboxyl group is deprotonated, leading to a molecule that has both positive and negative charges but whose overall net charge is zero. This unique state means that the amino acid is electrically neutral, which significantly affects its solubility and migration in an electric field. The isoelectric point is a critical property for the separation of amino acids and proteins in techniques such as isoelectric focusing. The isoelectric point (pI) of an amino acid is: A) The pH at which the amino acid exists predominantly as a zwitterion B) The pH at which the amino acid carries no net electric charge С) Both A and B are correct D) The pH at which the amino acid is most soluble in water https://www.youtube.com/watch?v=tkVcqux8I7o

The resemblance between Greeks and North Indians can be traced back to historical interactions, notably during the era of the Indo-Greek Kingdoms that emerged following Alexander the Great's expedition into the Indian subcontinent around the 4th century BCE. This period marked the beginning of a profound cultural and genetic exchange between the Greeks and the local populations of what is now modern-day Afghanistan, Pakistan, and North India. The Indo-Greek Kingdoms served as a melting pot for Hellenistic and South Asian cultures, not only facilitating the exchange of artistic, philosophical, and scientific ideas but also intermarriages between the Greeks and the indigenous peoples. These interactions likely contributed to a genetic blend, which might explain the observed physical similarities between modern Greeks and North Indians. https://www.youtube.com/watch?v=eInQOhuya-4

In the secondary structure of proteins, specifically in the α-helix, the hydrogen bonds form between the carbonyl oxygen atom of one amino acid residue and the amino hydrogen of another residue that is four positions away in the primary sequence. This pattern of hydrogen bonding creates a helical structure that is both stable and common in many proteins. The α-helix is stabilized by these hydrogen bonds, which occur along the backbone of the polypeptide chain, not involving the side chains of the amino acids. This distinction helps differentiate the correct answer from the other options, which either refer to interactions involving side chains, positions that don't match the pattern seen in α-helices, or α-carbons, which are not directly involved in the hydrogen bonding that stabilizes the α-helix structure. Problem: In protein secondary structure, the α-helix is stabilized by hydrogen bonds. Between which parts of the amino acid residues do these hydrogen bonds form? A) Between the amino group of one residue and the carboxyl group of another residue, four positions away B) Between the side chains of amino acid residues that are three positions apart C) Between the side chain of one residue and the main chain carbonyl of another residue D) Between the α-carbons of adjacent amino acid residues https://www.youtube.com/watch?v=xmciORbc2Ig

Arginine is classified as a conditionally essential amino acid in humans. While it is generally considered non-essential because the body can usually synthesize it in sufficient quantities, there are circumstances under which the body's demand for arginine increases beyond its capacity to produce it. These circumstances include periods of rapid growth, illness, and physical trauma or stress. During such times, arginine becomes essential in the diet to meet the body's increased needs. Arginine plays vital roles in protein synthesis, wound healing, immune function, and the production of nitric oxide, a critical molecule for blood vessel dilation and blood flow. Thus, during periods of stress or illness, dietary intake of arginine becomes crucial for supporting these physiological processes. Problem: Which amino acid is classified as conditionally essential in humans, primarily during periods of illness and stress? A) Glycine B) Arginine C) Leucine D) Tyrosine https://www.youtube.com/watch?v=9-q-uGW2_TI

Selenocysteine is known as the 21st amino acid because of its unique presence and role in some proteins, despite not being coded directly by the DNA in the traditional sense. It is incorporated into proteins via a special mechanism that involves the recoding of the UGA stop codon, typically signaling the end of protein synthesis. This recoding requires a specific selenocysteine insertion sequence (SECIS) element in the mRNA. Selenocysteine is crucial for the catalytic activity of several enzymes, including thioredoxin reductase. Thioredoxin reductase is a selenium-containing enzyme that plays a vital role in cellular redox homeostasis by reducing thioredoxin, thereby contributing to the regulation of cell growth and protecting against oxidative stress. This function is essential for maintaining the balance of reactive oxygen species within cells and supports various critical biological processes. Problem: The rare amino acid selenocysteine is recognized as the 21st amino acid. It is incorporated into proteins by a specific tRNA recognizing the UGA codon, usually a stop signal. This amino acid is essential for the function of which of the following enzymes? A) Alcohol dehydrogenase B) Glucokinase C) Thioredoxin reductase D) Hexokinase https://www.youtube.com/watch?v=dUj0MKJtkHE

Glycine is unique among the standard amino acids because it has a hydrogen atom as its side chain (R group). The central carbon atom (α-carbon) of glycine is bonded to two hydrogen atoms, a carboxyl group (-COOH), and an amino group (-NH2). This symmetry around the α-carbon means that glycine does not have a chiral center, making it the only standard amino acid that is not optically active. Therefore, glycine does not exist in L or D configurations, unlike all other standard amino acids which have a chiral center and can exist as mirror-image forms (enantiomers) due to the presence of four different groups attached to the α-carbon. Problem: Give an answer to this question and explain: Which amino acid is not chiral and thus does not have an L or D configuration? A) Alanine B) Glycine C) Serine D) Isoleucine https://www.youtube.com/watch?v=r8IdPIRpckk