“Biological Molecules,” the captivating entities that form the foundation of all living organisms. Unit No. 2 of your first-year biology journey will take us deep into the microscopic realm, where we’ll unravel the mysteries of carbohydrates, lipids, proteins, and nucleic acids—the cornerstones of life itself. From the intricate structures of these molecules to their indispensable roles in cellular processes, metabolism, and genetic information storage, this unit promises to provide you with a solid understanding of the molecular basis of life.
Chapter 2 Biology of 1st Year Short Answers Questions
What is Biochemistry and why is it important for understanding anatomy and physiology?
Biochemistry is a branch of Biology that studies the chemical components and processes in living organisms. It’s important for understanding anatomy and physiology because all organism structures have biochemical organization.
Name some of the major organic compounds found in living organisms.
The major organic compounds in living organisms include carbohydrates, proteins, lipids, and nucleic acids.
- 1st Year Biology Unit No.1 Introduction Notes
- 1st Year Biology Unit No. 3 Enzymes Notes
- 1st Year Biology Unit No. 4 The Cell Notes
- 1st Year Biology Unit No. 5 Variety of Life Notes
- 1st Year Biology Unit No. 6 Kingdom Prokaryotae Notes
Compare the chemical composition of a bacterial cell and a mammalian cell.
Bacterial cells have a higher percentage of water and RNA, while mammalian cells have higher percentages of proteins, carbohydrates, lipids, and DNA.
How does the survival of an organism relate to its ability to obtain and use chemicals from its environment?
An organism’s survival depends on its ability to take in substances from its environment and use them to build cellular materials and obtain energy.
What is metabolism and how is it divided into different processes?
Metabolism refers to all the chemical reactions within a cell. It’s divided into anabolic reactions (building complex substances with energy) and catabolic reactions (breaking down complex molecules for energy).
Provide an example of coordinated catabolic and anabolic activities in living cells.
The interconversions of carbohydrates, proteins, and lipids that occur in living cells are examples of coordinated catabolic and anabolic activities.
Why is carbon considered the central element in the skeleton of life?
Carbon’s unique properties and tetravalent nature allow it to form stable covalent bonds, enabling the synthesis of complex cellular structures.
How does the stability of carbon’s tetravalency impact cellular structures?
The stability associated with carbon’s tetravalency makes it favorable for creating intricate cellular structures, including stable chains, rings, and branched structures.
What is the significance of C-C bonds in organic molecules?
C-C bonds form the skeleton of organic molecules, providing the foundation for various complex compounds in biological systems.
What type of bond results from the sharing of electron pairs between atoms?
Covalent bonds result from the sharing of electron pairs between atoms, forming stable molecular connections.
How does carbon contribute to the diversity of organic compounds?
Carbon’s ability to combine with elements like hydrogen, oxygen, nitrogen, phosphorus, and sulfur leads to a wide variety of organic compounds with different structures and functions.
Why are macromolecules like cellulose, fats, and proteins important in cells?
Large organic molecules serve as building blocks of cell structures and provide storage for smaller molecules like glucose. They also play a role in cell function and energy storage.
What role do small molecules like glucose and amino acids play in cellular processes?
Small molecules function as sources of energy and building blocks for macromolecules. Some, like ATP, serve as immediate energy sources for cellular metabolism.
Why is water considered the medium of life?
Water is considered the medium of life due to its abundance in organisms and its involvement in various biochemical reactions, including those essential for cell function.
How does water contribute to biochemical reactions in cells?
Water takes part in numerous biochemical reactions, including hydrolysis and reactions during photosynthesis, providing a medium in which cellular processes can occur.
What role does water play in solvent properties?
Water’s polarity makes it an excellent solvent for polar substances and allows ions and molecules to move freely in solution, facilitating chemical reactions within cells.
How does water’s heat capacity benefit organisms?
Water’s high heat capacity allows it to absorb heat while maintaining a stable temperature, which in turn helps regulate the internal environment of organisms and protects against sudden temperature changes.
What is heat of vaporization and how is it expressed for water?
Heat of vaporization is the energy required to convert a unit mass of liquid to gas at a constant temperature. For water, it’s expressed as calories absorbed per gram vaporized.
How does the heat of vaporization of water impact living organisms?
The heat of vaporization (574 Kcal/kg) of water helps regulate heat during oxidation and provides cooling through transpiration in plants and perspiration in animals. Even a small amount of water evaporation can lower the temperature significantly.
What are the products of water ionization and their concentrations in pure water at 25°C?
Water ionizes into H+ and OH- ions. At 25°C, the concentration of each ion in pure water is about 10-7 mole/litre.
How do H+ and OH- ions impact cellular reactions?
H+ and OH- ions are involved in various reactions within cells and affect their biochemical processes.
How does water function as an effective lubricant and protective agent?
Water serves as a lubricant that protects against friction-related damage. It creates a cushion around organs, such as tears protecting the eyes and fluid cushion around other organs.
Define carbohydrates and provide examples of their sources.
Carbohydrates are compounds composed of carbon, hydrogen, and oxygen. They occur in organisms and play structural and functional roles. Examples include cellulose, starches, and sugars found in plants and micro-organisms.
What is the significance of the ratio of hydrogen and oxygen in carbohydrates?
The ratio of hydrogen to oxygen in carbohydrates is the same as in water. It is a key defining feature of these compounds.
How are glycoproteins and glycolipids formed, and what roles do they play?
Glycoproteins and glycolipids are compounds formed by combining carbohydrates with proteins and lipids, respectively. They have structural roles in the extracellular matrix and biological membranes.
What are carbohydrates also known as, and how are they classified?
Carbohydrates are also known as ‘saccharides’, derived from the Greek word ‘sakcharon’ meaning sugar. They are classified into three groups: (i) Monosaccharides, (ii) Oligosaccharides, and (iii) Polysaccharides.
What are monosaccharides and how are they chemically characterized?
Monosaccharides are simple sugars that are sweet in taste, soluble in water, and cannot be hydrolyzed into simpler sugars. They are characterized chemically as either polyhydroxy aldehydes or ketones, with most carbon atoms having hydroxyl groups except one, which is either part of an aldehyde or keto group.
What is the general formula for monosaccharides with 3 to 7 carbon atoms, and give an example of a hexose?
Monosaccharides with 3 to 7 carbon atoms have the general formula (CH2O)n, where n is a whole number from three to seven. An example of a hexose is glucose.
How do monosaccharides typically exist in solution?
Most monosaccharides form ring structures when in solution. For instance, ribose forms a five-cornered ring called ribofuranose, while glucose forms a six-cornered ring known as glucopyranose.
What is the significance of glucose in biological systems, and where is it commonly found?
Glucose is a crucial hexose in biological systems. It is present in free form in fruits and is abundant in grapes, figs, and dates. Glucose is also a component of many disaccharides and polysaccharides, and it can be obtained from starch, cellulose, and glycogen through hydrolysis.
What are oligosaccharides, and how many monosaccharides do they typically yield upon hydrolysis?
Oligosaccharides are carbohydrates that yield two to ten monosaccharides upon hydrolysis. Those yielding two monosaccharides are called disaccharides, those yielding three are trisaccharides, and so on.
Provide an example of a common disaccharide and its hydrolysis products.
Sucrose is a common disaccharide (cane sugar) that hydrolyzes into glucose and fructose upon hydrolysis. Both glucose and fructose are reducing sugars.
What are polysaccharides, and what is their main characteristic?
Polysaccharides are complex and abundant carbohydrates in nature. They are usually branched, tasteless, and have high molecular weights. They are composed of several monosaccharide units linked by glycosidic bonds.
Name two types of starch and briefly describe their structural differences.
Starches are of two types: amylose and amylopectin. Amylose has unbranched chains of glucose and is soluble in hot water, while amylopectin has branched chains and is insoluble in hot or cold water.
What is the main role of starch in the diet of animals, and where is it commonly found?
Starch serves as the primary source of carbohydrates for animals. It is found in fruits, grains, seeds, and tubers.
What is glycogen also known as?
Glycogen is also referred to as animal starch.
Where is glycogen primarily stored in the body?
Glycogen is mainly stored in the liver and muscles of animals.
What is the characteristic reaction of glycogen with iodine?
Glycogen gives a red color with iodine.
What is the result of hydrolysis of glycogen?
Hydrolysis of glycogen yields glucose.
What is cellulose’s primary role in plants?
Cellulose is the main constituent of cell walls in plants.
How does cellulose react with iodine?
Cellulose does not produce any color change with iodine.
What is the primary component of cotton?
Cotton is primarily composed of pure cellulose.
Why can’t humans digest cellulose?
Humans lack the necessary enzyme, cellulase, to digest cellulose.
How is cellulose digested in herbivores?
Micro-organisms like bacteria, yeasts, and protozoa in the digestive tract of herbivores secrete cellulase to digest cellulose.
What is the major product of hydrolysis of cellulose?
Hydrolysis of cellulose also yields glucose molecules.
What are lipids and how do they interact with water and organic solvents?
Lipids are a diverse group of compounds related to fatty acids. They are insoluble in water but soluble in organic solvents like ether, alcohol, chloroform, and benzene.
How do lipids store energy compared to carbohydrates?
Lipids store double the amount of energy compared to the same quantity of carbohydrates. This is due to the higher proportion of C-H bonds and low proportion of oxygen in lipids.
Apart from energy storage, what other functions do lipids serve?
Lipids are components of cellular membranes due to their hydrophobic nature. Some lipids provide insulation against heat and cold, and act as waterproof material.
Give examples of protective structures made from lipids.
Waxes in the exoskeleton of insects and cutin in the plant cuticle (leaves, fruits, seeds) are examples.
How are lipids classified and what are some examples of lipid classes?
Lipids are classified as acylglycerols, waxes, phospholipids, sphingolipids, glycolipids, and terpenoid lipids. Terpenoid lipids include carotenoids and steroids.
What are acylglycerols composed of, and what’s the most common type?
Acylglycerols are composed of glycerol and fatty acids. Triacylglycerol (triglyceride) is the most widespread type of acylglycerol.
Explain the structure of fatty acids and their variations.
Fatty acids have even numbers of carbon atoms in a straight chain. They can be saturated (no double bonds) or unsaturated (up to 6 double bonds). Fatty acids in animals are straight chains, while in plants they can be branched or ringed.
How do fats containing unsaturated fatty acids differ from those containing saturated fatty acids?
Fats with unsaturated fatty acids are liquid at room temperature and are called oils. Fats with saturated fatty acids are solid at room temperature. Plant fats are usually liquid, while animal fats are solid.
What are waxes chemically composed of, and what purpose do they serve in organisms?
Waxes are mixtures of long-chain alkanes, alcohols, ketones, and esters of long-chain fatty acids. They provide protective coatings for fruits, leaves, and some insects, preventing water loss and damage.
How do fats and oils compare in terms of specific gravity and crystallinity?
Fats and oils have a specific gravity of about 0.8 and are lighter than water. While they are not crystalline, some can crystallize under specific conditions.
What are phospholipids composed of?
Phospholipids are composed of glycerol, fatty acids, and phosphoric acid. They also contain nitrogenous bases such as choline, ethanolamine, and serine.
Where are phospholipids commonly found?
Phospholipids are widespread in bacteria, animal, and plant cells. They are frequently associated with cellular membranes.
How is phosphatidic acid structured?
Phosphatidic acid consists of glycerol, two fatty acids attached to carbons 1 and 2, and a phosphoric acid group attached to carbon 3 of glycerol. In phospholipids, a nitrogenous base (e.g., choline) is linked to the phosphoric acid group in phosphatidic acid.
What is the role of phospholipids in cells?
Phospholipids are crucial components of cell membranes. They contribute to membrane structure, fluidity, and selective permeability. They also play a role in cell signaling and compartmentalization.
What is the significance of terpenoids?
Terpenoids are a diverse group of compounds made up of repeating isoprenoid units. They give rise to various important compounds like rubber, carotenoids, steroids, and terpenes.
How do lipids contribute to cellular functions?
Lipids serve as a major energy source for cells. They also play a vital role in forming the structure of cell membranes and organelles. Additionally, lipids provide insulation, mechanical protection, and help prevent water loss and damage from abrasion.
What is the significance of proteins in cells?
Proteins comprise over 50% of the total dry weight of cells and are present throughout the cell. They perform various functions such as building cell structures, regulating metabolism, acting as enzymes, hormones, carriers, and antibodies.
How do proteins control cell metabolism?
Enzymes, which are proteins, play a crucial role in controlling cell metabolism by catalyzing biochemical reactions.
How do proteins contribute to defense mechanisms?
Antibodies, a type of protein, defend the body against pathogens, while blood clotting proteins prevent blood loss after injuries.
What is the basic composition of amino acids?
Amino acids contain carbon, nitrogen, oxygen, and hydrogen. They have an amino group and a carboxyl group attached to an alpha carbon, and they vary mainly due to the nature of the R group.
How are amino acids linked to form proteins?
Amino acids are linked together through peptide bonds. The amino group of one amino acid reacts with the carboxyl group of another, releasing a water molecule in the process.
What is the result of peptide bond formation between amino acids?
Peptide bonds form between the carboxyl group of one amino acid and the amino group of another amino acid. This creates a bond known as a peptide bond and leads to the formation of dipeptides, tripeptides, and longer polypeptide chains.
How many different types of amino acids are constituents of proteins?
There are about 20 different types of amino acids that are constituents of proteins, out of the approximately 170 types of amino acids found in cells and tissues.
What is the primary structure of a protein?
The primary structure of a protein refers to the specific sequence of amino acids in the protein molecule. It determines the order of amino acids along the chain.
Who determined the sequence of amino acids in a protein molecule for the first time?
F. Sanger was the first scientist to determine the sequence of amino acids in a protein molecule. He worked on insulin and found it to be composed of two chains with a total of 51 amino acids.
How are the alpha and beta chains arranged in hemoglobin?
Hemoglobin is composed of four chains, two alpha and two beta chains. Each alpha chain has 141 amino acids, while each beta chain contains 146 amino acids.
How is the size of a protein molecule determined?
The size of a protein molecule is determined by the type and number of amino acids it comprises.
What determines the sequence of amino acids in a protein?
The sequence of amino acids in a protein is determined by the order of nucleotides in the DNA.
Why is the specific arrangement of amino acids important in a protein?
The specific arrangement of amino acids in a protein is crucial for its proper functioning. If any amino acid is out of place, the protein may fail to carry out its normal function.
Give an example of a protein with a critical amino acid substitution.
Sickle cell hemoglobin in human beings is an example where a single amino acid substitution in each beta chain leads to improper oxygen transport, causing severe health issues.
What are the two common secondary structures in proteins?
The two common secondary structures in proteins are the α-helix and the β-pleated sheet.
How many amino acids are typically present in each turn of an α-helix?
There are 3.6 amino acids in each turn of an α-helix.
What type of bonds maintain the tertiary structure of proteins?
The tertiary structure of proteins is maintained by ionic bonds, hydrogen bonds, and disulfide bonds (-S-S-).
What is the main distinction between fibrous and globular proteins?
Fibrous proteins have a structural role, consisting of one or more polypeptide chains forming fibrils, while globular proteins have a spherical or ellipsoidal shape due to multiple folding of polypeptide chains and are involved in various functions.
What holds together the quaternary structure of complex proteins?
The quaternary structure of complex proteins is held together by hydrophobic interactions, hydrogen bonds, and ionic bonds among the aggregated polypeptide chains.
Give an example of a protein that exhibits quaternary structure.
Hemoglobin, the oxygen-carrying protein in red blood cells, exhibits a quaternary structure.
What is the main difference between the tertiary structures of fibrous and globular proteins?
Fibrous proteins have a dominant secondary structure and are insoluble, while globular proteins have a dominant tertiary structure and are soluble in aqueous media.
How are hydrophobic and hydrophilic amino acids arranged in the most stable tertiary conformation of a protein in an aqueous environment?
Hydrophobic amino acids are buried inside the protein molecule, while hydrophilic amino acids are located on the surface.
Name a protein with a structural role and a fibrous nature.
Keratin, found in nails and hair, is an example of a fibrous protein with a structural role.
What type of bonds contribute to the stability of the α-helix structure?
The stability of the α-helix structure is maintained by hydrogen bonds formed among amino acid molecules in successive turns of the helix.
What are nucleic acids, and why were they named as such?
Nucleic acids are complex molecules consisting of nucleotide units. They were named “nucleic acids” due to their isolation from cell nuclei and their acidic nature.
How many types of nucleic acids are there, and what are they called?
There are two types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Where is DNA primarily found within a cell?
DNA is primarily found in chromosomes, cell nuclei, and to a lesser extent in mitochondria and chloroplasts.
What are the components of a nucleotide?
A nucleotide consists of three subunits: a 5-carbon sugar (pentose sugar), a nitrogen-containing base, and a phosphoric acid.
Differentiate between ribose and deoxyribose sugars in nucleotides.
Ribonucleotides contain ribose sugar, while deoxyribonucleotides have deoxyribose sugar (with one oxygen removed from the OH group at carbon 2).
Name the two categories of nitrogenous bases and provide examples for each.
Nitrogenous bases are categorized into single-ringed pyrimidines (cytosine, thymine, uracil) and double-ringed purines (adenine, guanine).
How do nucleosides and nucleotides differ?
A nucleoside is formed by combining a base with a pentose sugar, while a nucleotide is formed by adding a phosphoric acid to a nucleoside.
What is the significance of ATP in cells?
ATP (adenosine triphosphate) is a crucial nucleotide used as an energy currency within cells.
What is the role of DNA in a cell?
DNA serves as hereditary material and controls cell properties and activities.
How are nucleotides connected to form DNA chains?
Nucleotides are connected through phosphodiester linkages in a specific sequence to create polynucleotide chains.
Can you give an example of a dinucleotide and its importance?
Nicotinamide adenine dinucleotide (NAD) is an example of a dinucleotide that plays a vital role as a coenzyme in cellular oxidation-reduction reactions.
What did Erwin Chargaff’s data in 1951 suggest about the ratios of bases in DNA?
The data suggested that adenine and thymine have equal ratios, as do guanine and cytosine.
How did Maurice Wilkins and Rosalind Franklin determine the structure of DNA?
They used X-ray diffraction to determine the structure of DNA.
What did James D. Watson and Francis Crick do simultaneously with Wilkins and Franklin’s work?
They built a scale model of DNA.
How are the two polynucleotide strands in DNA coiled around each other?
They are coiled in the form of a double helix.
What type of bonds hold the two DNA strands together?
Weak hydrogen bonds hold the two strands together.
How are base pairs arranged in DNA?
Adenine (A) always pairs with thymine (T), and guanine (G) pairs with cytosine (C).
How many hydrogen bonds are between an A-T base pair? How about a G-C base pair?
There are two hydrogen bonds between A and T, and three hydrogen bonds between G and C.
How many base pairs are there in each turn of the DNA double helix?
There are 10 base pairs in each turn, which is about 34 Angstrom units.
What is the relationship between the amount of DNA and the number of chromosomes?
The amount of DNA is fixed for a species and depends on the number of chromosomes.
How does the amount of DNA in germ cells compare to somatic cells?
The amount of DNA in germ cells (sperms and ova) is half that of somatic cells.
What are the types of RNA and their respective functions?
Answer: The three main types of RNA are messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). mRNA carries genetic information from the nucleus to ribosomes for protein synthesis. tRNA transfers amino acids to the site of protein synthesis. rRNA forms a significant part of the ribosome and aids in protein synthesis.
What is the function of messenger RNA (mRNA) and how does its length vary?
Answer: Messenger RNA (mRNA) carries genetic information from DNA to ribosomes for protein synthesis. Its length varies depending on the size of the gene and the protein it codes for. For instance, a protein with 1,000 amino acids would require an mRNA of around 3,000 nucleotides.
What is the role of transfer RNA (tRNA) and how many types of tRNA are found in a cell?
Answer: Transfer RNA (tRNA) transfers amino acids to the site of protein synthesis and is responsible for linking them together. Each amino acid corresponds to a specific tRNA molecule. Therefore, a cell typically contains at least 20 different types of tRNA molecules.
What is ribosomal RNA (rRNA) and how does it contribute to protein synthesis?
Answer: Ribosomal RNA (rRNA) is a major component of cellular RNA, often comprising up to 80% of the total RNA. It plays a key role in protein synthesis by being a vital component of ribosomes. Ribosomes facilitate the translation of genetic information from mRNA into specific protein molecules.
What are conjugated molecules and how do carbohydrates combine with other molecules?
Answer: Conjugated molecules are formed when two different molecules from distinct categories combine. Carbohydrates can combine with proteins to form glycoproteins or with lipids to form glycolipids. These conjugated molecules, such as glycoproteins and glycolipids, are integral to the structure of plasma membranes and have functional significance.
How are nucleic acids combined with proteins and what are their roles?
Answer: Nucleic acids and basic proteins combine to form nucleoproteins. Nucleohistones, a type of nucleoprotein, are present in chromosomes and have both structural and functional importance. These conjugated proteins play a crucial role in regulating gene expression.
Name the carbohydrates suitable as food for man.
Answer: Carbohydrates suitable for food in humans include:
Monosaccharides like glucose and fructose.
Disaccharides like sucrose (table sugar) and lactose (found in milk).
Polysaccharides like starch (found in grains, potatoes, etc.) and glycogen (stored in the liver and muscles).
Why are fats considered as high energy compounds?
Answer: Fats are considered high-energy compounds because they have a high caloric content compared to other macronutrients like carbohydrates and proteins. Fats have a higher number of carbon-hydrogen (C-H) bonds, and when these bonds are oxidized through metabolic processes such as beta-oxidation, a significant amount of energy is released. This energy is captured in the form of ATP (adenosine triphosphate), a molecule that carries energy for various cellular processes.
What is the function of mRNA?
Answer: mRNA stands for messenger RNA. Its primary function is to convey genetic information from DNA to the ribosomes, which are the cellular machinery responsible for protein synthesis. DNA contains the instructions for building proteins, but it cannot directly participate in protein synthesis. So, when a particular protein is needed, the DNA’s genetic code for that protein is transcribed into mRNA in a process called transcription. The mRNA molecule then moves from the cell nucleus to the ribosomes in the cytoplasm, where it serves as a template for protein synthesis.
What is the general formula for amino acids?
Answer: The general formula for amino acids is NH2CHRCOOH, where NH2 represents an amino group, CHRCOOH represents the carboxyl group, and the R is the side chain specific to each amino acid. This side chain, also known as the radical group, gives each amino acid its unique properties.
What is the percentage of water in brain cells of man?
Answer: The brain is composed of a relatively high percentage of water. It’s estimated that the brain tissue is about 75% water. However, different regions of the brain and individual variations can lead to slight differences in the exact percentage. Water is crucial for various biochemical and physiological processes in the brain and is involved in the transportation of nutrients, removal of waste products, maintenance of structural integrity, and support of neurotransmitter functions.
Unit 2 Biology 1st Year Long Questions
Question: Describe the importance of water for life.
Answer: Water is essential for all forms of life on Earth, and its importance cannot be overstated. It plays a crucial role in various biological processes, making it a fundamental molecule for sustaining life. Here are some of the key reasons why water is important for life:
Solvent for Biochemical Reactions: Water’s unique properties as a solvent enable it to dissolve a wide range of substances, both ionic and non-ionic. This property allows chemical reactions necessary for life, such as metabolism and cellular processes, to take place within a liquid environment.
Medium for Biological Processes: Most biochemical reactions in cells occur in an aqueous environment. Water’s presence facilitates the transport of molecules within cells, allows enzymes to function properly, and provides a medium for the exchange of nutrients, gases, and waste products.
Temperature Regulation: Water has a high specific heat capacity, meaning it can absorb and release a significant amount of heat without undergoing significant temperature changes itself. This property helps regulate temperature in organisms and environments, preventing abrupt fluctuations that could be harmful to life.
Heat of Vaporization: The heat of vaporization of water is high, meaning that a substantial amount of heat is required to convert water from a liquid to a gas. This property is essential for cooling mechanisms in organisms, such as sweating in humans and transpiration in plants.
Cohesion and Adhesion: Water exhibits strong cohesion (water molecules sticking to each other) and adhesion (water molecules sticking to other surfaces). These properties are critical for capillary action in plants, helping water move against gravity through their vascular systems.
Solvent for Nutrients: Water dissolves and transports nutrients and minerals necessary for growth and metabolic processes in organisms.
Biological Structures: Water contributes to the structure of cells and biological molecules. It is a major component of cells and bodily fluids, providing support and maintaining the shape of cells.
Photosynthesis: Water is a raw material for photosynthesis in plants. During photosynthesis, plants use sunlight to convert water and carbon dioxide into oxygen and glucose, releasing energy for growth and maintenance.
Hydrolysis and Digestion: Water is involved in hydrolysis reactions, where large molecules are broken down into smaller ones by the addition of water molecules. This is essential for digestion and nutrient absorption in organisms.
Lubrication and Protection: Water’s lubricating properties help reduce friction between body surfaces and organs, such as joints and membranes. It also provides protection against physical trauma by acting as a cushion.
In summary, water’s unique properties make it an essential component for the survival and function of all known forms of life. Its ability to facilitate biochemical reactions, regulate temperature, transport nutrients, and contribute to the structure of biological molecules underscores its importance for the existence of life on Earth.
Question: Describe what do you know about polysaccharides.
Answer: Polysaccharides are complex carbohydrates composed of repeating units of simple sugars (monosaccharides) linked together by glycosidic bonds. They play important roles in various biological processes and structures. Here are the key points about polysaccharides based on the provided text:
Definition and Composition: Polysaccharides are large molecules composed of numerous monosaccharide units joined together. They are made up of carbon, hydrogen, and oxygen atoms, with the general formula (CxH2yOy).
Functions
Structural Role: Polysaccharides contribute to the structural integrity of cells and organisms. They can form rigid structures, such as the cell walls of plants, providing support and protection.
Energy Storage: Some polysaccharides, like glycogen in animals and starch in plants, serve as energy storage molecules. Glucose molecules are stored in these polysaccharides and can be broken down when energy is needed.
Cellular Recognition: Certain polysaccharides on cell surfaces are involved in cell recognition and communication. They play a role in interactions between cells and their environment.
Types of Polysaccharides:
Starch: Found in plants, starch serves as a storage form of glucose. It is composed of two main types: amylose (unbranched) and amylopectin (branched).
Glycogen: Found in animals, glycogen is the primary storage form of glucose in the liver and muscles. It is highly branched for efficient energy release.
Cellulose: Found in plant cell walls, cellulose forms a strong and rigid structure. Unlike starch and glycogen, cellulose is composed of β-glucose units and is not digestible by most animals.
Chitin: Found in the exoskeleton of arthropods and the cell walls of fungi, chitin provides structural support and protection.
Hyaluronic Acid: Present in connective tissues, hyaluronic acid contributes to lubrication and shock absorption in joints.
Formation and Breakdown: Polysaccharides are synthesized through condensation reactions that link monosaccharide units together, releasing water molecules. Hydrolysis reactions break down polysaccharides into their constituent monosaccharides.
Diverse Functions: Polysaccharides have diverse roles based on their structure and location. For example, they can form gels, absorb water, provide mechanical strength, and facilitate adhesion between cells.
Importance in Cellular Functions: The stability and versatility of polysaccharides contribute to cellular processes, energy storage, and maintaining the structural integrity of organisms.
In summary, polysaccharides are complex carbohydrates with crucial roles in structural support, energy storage, cellular recognition, and other biological processes. They are diverse in structure and function, contributing to the overall functionality and organization of living organisms.
Question: Write a short note on amino acids.
Answer: Amino acids are organic compounds composed of carbon, hydrogen, oxygen, and nitrogen. They are the building blocks of proteins, which are essential molecules for the structure and functioning of cells and organisms. The importance of amino acids in cellular processes and biological systems is closely tied to the properties of carbon and its unique role in organic compounds.
Carbon, as the basic element of organic compounds, holds a central position in the molecules of life. Its tetravalent nature allows it to form covalent bonds with various other elements, creating stable configurations that are crucial for the synthesis of complex cellular structures. Carbon atoms can bond with other carbon atoms, forming stable chains or rings, which contributes to the vast diversity of organic compounds. The bonds formed by carbon atoms provide the backbone for organic molecules.
Amino acids, which contain both an amino group (-NH2) and a carboxyl group (-COOH), are the fundamental components that make up proteins. About 20 types of amino acids are commonly found in proteins, each distinguished by its side chain or R-group. Amino acids are linked together through peptide bonds, forming polypeptide chains. These chains fold and interact to create the intricate three-dimensional structures of proteins, ultimately determining their functions.
Proteins have four levels of structural organization: primary, secondary, tertiary, and quaternary. The primary structure refers to the sequence of amino acids in a protein, which is determined by the genetic code. The secondary structure involves regular folding patterns such as alpha-helices and beta-pleated sheets, stabilized by hydrogen bonding. The tertiary structure encompasses the overall 3D arrangement of the polypeptide chain, influenced by various bonds and interactions. In some proteins, multiple polypeptide chains come together in the quaternary structure, forming functional protein complexes.
Proteins serve diverse roles in living organisms. They act as enzymes, catalyzing biochemical reactions; as structural components, providing support and organization to cells and tissues; as antibodies, defending against pathogens; as carriers, transporting molecules; and as hormones, regulating various physiological processes.