BFD105 - Biological Foundations

Part A- Carbohydrates

• 1)Describe the key functions of carbohydrates.

Carbohydrates help break down protein molecules, eliminate dehydration and eliminate ketosis, among many other processes. They act as the main source of energy. They provide energy. They aid in blood sugar control. They provide some non-essential amino acids along with the carbon skeleton by synthesis (Drula et al., 2022).

• 2)Name the functional groups present in a glucose molecule and the link to water solubility of glucose. Where in nature can glucose be found?

The simplest sugar is glucose, with the chemical formula C₆H₁₂O₆. It is composed of six carbon units, or hexose, and has one aldehyde group (-CHO) and five hydroxyl groups (-OH) (Hantzidiamantis & Lappin, 2019). These functional groups can form hydrogen bonds with water molecules. In nature, glucose can be found in both coupled and free forms, found in honey and delicious fruits (Liang et al., 2022).

• 3)Explain the role of carbohydrates in energy storage in the human body.

Carbohydrates are essential for providing energy to every cell in the body. Excess glucose is converted into fat and stored in the body's fat cells or converted into glycogen, a form of carbohydrate storage (Chandel, 2021).

• 4)Discuss the structure of starch and its biological roles in plants and animals.Describe two major structural differences between cellulose and starch.

Long chains of linked sugar molecules make up starch. Plants use starch mainly to store energy. Starch is a source of sugar in animal feed. Animals use the enzyme amylase, which is found in saliva and the pancreas and breaks down starch for energy, breaking down starch (Apriyanto et al., 2022). The connections between glucose molecules and the structure of the molecule constitute two structural differences between starch and cellulose. While cellulose uses beta 1,4 bonds and has a stiff, elongated structure, starch uses alpha 1,4 and 1,6 bonds and has a branched structure.

• 5)Investigate the enzymatic reactions involved in the digestion and utilization of two disaccharides in the human body.

Maltose is converted into glucose by maltase. Lactase and sucrase in turn break down lactose and sucrose, two other disaccharides. The enzymes lactase and sucrase convert lactose into glucose and galactose and sucrose into glucose and fructose, respectively (Maske et al., 2021).

Part B- Lipids and Transport across the membrane

• 1)What is the difference between saturated and unsaturated fatty acids? Give an example for each type of fatty acid.

The unbranched linear chain of CH₂groups with a terminal carboxylic acid is called a saturated fatty acid. These chains are connected by carbon-carbon single bonds. There is no double bond between them (Adeva-Andany et al., 2019). For example, stearic acid. In contrast, unsaturated fatty acids are complex fatty acids that have a terminal carboxylic acid group and a bent hydrocarbon chain linked together by a carbon-carbon double bond. They contain one or more double bonds between carbon atoms (Coniglio et al., 2023). For example, oleic acid.

• 2)Define lipids and explain their roles as essential biomolecules in living organisms.

Fats called lipids perform a number of functions in your body. They help regulate what goes in and out of your cells and are a component of cell membranes. They aid in hormone production, vitamin absorption, movement, and energy storage (Feingold, 2024).

• 3)What is the definition of an essential fatty acid? Name two essential fatty acids.

The term essential fatty acids refers to polyunsaturated fatty acids that the body cannot produce on its own, but are important for good health. Omega-3 and omega-6 are two essential fatty acids (Patel et al., 2020).

• 4)Explain the process of lipid (Triacylglycerol) digestion in the human digestive system, including the roles of bile salt and pancreatic lipase.

Triglycerides are broken down in the mouth by lingual lipase, which is secreted by glands in the tongue and activates lipid digestion. Lingual and gastric enzymes contribute to the digestive process that takes place in the stomach. Lipid emulsions of a crude nature pass through the duodenum as small lipid droplets, where they combine with pancreatic juice and bile to undergo significant changes in chemical and physical form. Pancreatic lipase, bile salts and colipase are produced by bile and pancreatic juice and work together to ensure effective lipid breakdown and absorption (Salhi et al., 2021).

• 5)What are phospholipids, and how do they contribute to the structure and function of cell membrane?What are the major functions of proteins in the cell membrane?

Compound lipids called phospholipids are made up of fatty acids, nitrogenous bases, alcohols, and phosphoric acid (Colin & Jaillais, 2020). These complex lipids give membranes their fluid quality and are important components of cell membranes. These phospholipids make up the inner portion of the cell membrane's bilayer, with the hydrophilic head and hydrophobic tail forming the outer portion. Membrane proteins function as receptors, enzymes, cytoskeletal proteins, and transient binding sites that help direct cell migration and other cell-cell interactions (White et al., 2021).

• 6)Briefly explain the following three ways of transport across the cell membrane: simple diffusion, facilitated diffusion and active transport.

Molecules are transferred across cell membranes through three main mechanisms. The simplest mechanism, called simple diffusion, requires no energy input and direct movement of small uncharged molecules, such as carbon dioxide and oxygen, across the phospholipid bilayer along a gradient concentration (from high concentration to low concentration) (Hoogeboom et al., 2023). Passive diffusion, follows a concentration gradient but is controlled a bit more by using protein channels or transporters to move certain molecules across the membrane (Pei, 2022). For substances to move from low to high concentrations or for cells to maintain certain internal conditions, active transport requires energy (ATP) to pump the molecules against their concentration gradient (Maeda, 2022).

Part C- Proteins

• 1)Describe four major roles of proteins in the human body with an example for each.

Roles of proteins in the human body (Sharma et al., 2021):

• a)They protect against infection and help remove foreign bodies. These proteins are called antibodies.
• b)Enzymes are proteins that catalyze or accelerate biological processes. For example, the digestive enzyme pepsin helps break down protein in meals.
• c)Contractile proteins are proteins that play a role in muscle contraction and movement. For example, myosin and actin.
• d)Structural proteins are proteins that provide structural support for the body and are found, among other things, in connective tissues. For example: collagen.

• 2)What is protein denaturation? Identify and briefly explain four factors that can induce protein denaturation.

The process of breaking the connections or strong bonds that make up protein molecules is called protein denaturation (Zhang & Ertbjerg, 2019). After denaturation, the bonds and connections of protein molecules are degraded and converted to a more amorphous or loose form, the majority of which is insoluble.

Four factors that can induce protein denaturation are:

• a)The fragile bonds that hold the protein's shape are broken by high temperatures.
• b)The electrical charges that maintain the structure of proteins are disrupted by strong acids or bases.
• c)Protein interactions may be altered and hydrogen bonds broken by high salt concentrations.
• d)Proteins can be solubilized by certain solvents, which alter the environment and lead to their unfolding.

• 3)What is the function of an enzyme? Describe the concept of irreversible enzyme inhibition. Explain the mechanisms behind irreversible enzyme inhibition.

The body's ability to function and maintain overall health depends on enzymes (Jamova et al., 2022). In the human body, they help speed up chemical processes. They are essential for a number of processes, including respiration, food digestion, nerve and muscle function, and more. Irreversible enzyme inhibition occurs when an inhibitor molecule permanently attaches to an enzyme, thereby "paralyzing" it. A covalent bond, a strong chemical bond, is often created during this binding process between the inhibitor and the active site amino acid side chain of the enzyme. These persistent bonds prevent the enzyme from properly binding to its substrate, stopping the catalytic process, unlike reversible inhibitors which can dissociate. Examples include neurotoxins, which permanently inhibit enzymes essential for nerve function, and penicillin, which interferes with bacterial cell formation.

• 4)How are proteins classified based on their shape and structure? Provide examples.

There are two types of proteins: globular proteins and fibrous proteins. Fibrous proteins are proteins with polypeptide chains arranged in a parallel configuration and linked together by hydrogen and disulfide bonds to resemble fibers (He et al., 2020). Examples include keratin (found in hair, wool, nails and skin) and myosin (found in muscle). In contrast, globular proteins are proteins that have intramolecular hydrogen bonds and are folded to form a sphere (Titus et al., 2022). Examples include albumin in eggs, hemoglobin in the blood, and insulin in the pancreas.

• 5)Differentiate between essential and non-essential amino acids, give examples and discuss the significance of essential amino acids in the diet.

20 separate amino acids are used by our bodies to make proteins. 9 are considered essential because our bodies cannot produce them on their own and can only rely on food consumption. Histidine and lysine are examples of essential amino acids required for growth, tissue repair, and various metabolic functions. The body can convert available amino acids into the remaining 11 non-essential amino acids.

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