Unit 1_RB PDF - Introduction to Cell

Parul Institute of Technology Biotechnology Department Course: B. Tech Subject Name: Remedial Biology Subject Code: 303144102 Unit I TOPIC: Introduction to Cell © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) © Dr. Sanni...

Parul Institute of Technology Biotechnology Department Course: B. Tech Subject Name: Remedial Biology Subject Code: 303144102 Unit I TOPIC: Introduction to Cell © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) © Dr. Sanni Kumar, Ph.D., Postdoc (IITH)  CELL: THE UNIT OF LIFE When you look around, you see both living and non-living things. You must have wondered and asked yourself – ‘what is it that makes an organism living, or what is it that an inanimate thing does not have that a living thing has’…? The answer to this is… the presence of the basic unit of life – the cell in all living organisms. ❑ All organisms are composed of cells. ❑ Some are composed of a single cell and are called unicellular organisms, while others, like us, are composed of many cells and are called multicellular organisms. © Dr. Sanni Kumar, Ph.D., Postdoc (IITH)  DEFINITION A cell is the smallest biological unit that is capable of performing life functions. KEY POINTS ❑ The cell is the basic structural and functional unit of all forms of life. ❑ Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. ❑ The term comes from the Latin word cellula meaning 'small room'. ❑ Most cells are only visible under a microscope. ❑ Cells emerged on Earth about 4 billion years ago. ❑ All cells are capable of replication, protein synthesis, and motility. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) © Dr. Sanni Kumar, Ph.D., Postdoc (IITH) CELL THEORY ❑ In 1838, Matthias Schleiden, a German botanist, examined a large number of plants and observed that all plants are composed of different kinds of cells that form the tissues of the plant. ❑ At about the same time, Theodore Schwann (1839), a British Zoologist, studied different types of animal cells and reported that cells had a thin outer layer, which is today known as the ‘plasma membrane’. He also concluded, based on his studies on plant tissues, that the presence of a cell wall is a unique character of the plant cells. ❑ On the basis of this, Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and products of cells. Schleiden and Schwann together formulated the cell theory. This theory, however, did not explain how new cells were formed. ❑ Rudolf Virchow (1855) first explained that cells divide and new cells are formed from pre-existing cells (Omnis cellula-e cellula). He modified the hypothesis of Schleiden and Schwann to give the cell theory a final shape. ❑ Cell theory as understood today is: (i) all living organisms are composed of cells and products of cells. (ii) all cells arise from pre-existing cells. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CELL TYPES © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) PROKARYOTIC ❑ Prokaryotic cells are single-celled microorganisms known to be the earliest on earth. ❑ Prokaryotes include Bacteria and Archaea. The photosynthetic prokaryotes include cyanobacteria that perform photosynthesis. ❑ A prokaryotic cell consists of a single membrane and therefore, all the reactions occur within the cytoplasm. They can be free-living or parasites. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) EUKARYOTIC ❑ Eukaryotic cells have a nucleus enclosed within the nuclear membrane and form large and complex organisms. Protozoa, fungi, plants, and animals all are eukaryotic cells. ❑ They are classified under the kingdom Eukaryota. ❑ They can maintain different environments in a single cell that allows them to carry out various metabolic reactions. ❑ This helps them grow many times larger than the prokaryotic cells. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) PROKARYOTIC AND EUKARYOTIC CELLS © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CONSTITUENTS ❑ Different substances that make a cell are collectively called Protoplasm. ❑ Protoplasm is composed of:- 1. Water - 70-80% Water is present in the cell. 2. Carbohydrates 3. Lipids 4. Proteins 5. Electrolyte - Sodium (Na+), Potassium (K+), Magnesium (Mg2+), Calcium (Ca2+), Phosphat , Chloride (Cl-), and Bicarbonate (HC03 - ). © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) STRUCTURE ❑ Major Structures Present in a cell are:- 1. Cell Wall 2. Cell Membrane 3. Cytoplasm and its Organelles 4. Nucleus © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CELL ORGANELLES ❑ The cellular components are called cell organelles. ❑ These cell organelles include both membrane and non-membrane-bound organelles present within the cells and are distinct in their structures and functions. ❑ They coordinate and function efficiently for the normal functioning of the cell. ❑ A few of them function by providing shape and support, whereas some are involved in the locomotion and reproduction of a cell. ❑ There are various organelles present within the celll, and they are classified into three categories based on the presence or absence of a membrane. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CELL ORGANELLES ❑ Organelles without membrane: The Cell wall, Ribosomes, and Cytoskeleton are non- membrane-bound cell organelles. They are present both in the prokaryotic cell and the eukaryotic cell. ❑ Single membrane-bound organelles: Vacuole, Lysosome, Golgi Apparatus, and Endoplasmic Reticulum are single membrane-bound organelles present only in a eukaryotic cell. ❑ Double membrane-bound organelles: Nucleus, mitochondria and chloroplast are double membrane-bound organelles present only in a eukaryotic cell. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CELL WALL ❑ The cell wall is the outermost covering of plant cells. ❑ The cell wall is present only in plants and in some fungi, bacteria, and algae. ❑ It is present outside the cell membrane and is tough, flexible, and sometimes rigid in its texture. ❑ It is mainly composed of cellulose, long fibers of carbohydrates including hemicellulose, lignin, and pectin. ❑ The main functions of the cell wall are: 1. Protecting the cell against physical damage and invading pathogens. 2. The cell wall controls and regulates the direction of cell growth. 3. Providing the strength, structural support and maintaining the shape of the cell. 4. Functions as a storage unit by storing carbohydrates for use in plant growth, especially in seeds. 5. It allows entry of smaller molecules through it freely. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CELL MEMBRANE ❑ The cell membrane is also known as the plasma membrane. ❑ It is the outermost covering of animal cells. It is a semi-permeable membrane composed of lipids and proteins. ❑ The plasma membrane forms the boundary between the outer environment and living systems. ❑ The plasma membrane controls both the entry and exit of both solute and solvent between the cell and the environment. ❑ With regards to permeability characteristics, a plasma membrane can be semi-permeable, impermeable, permeable and selectively permeable in nature. ❑ The main functions of the plasma membrane or cell membrane include: 1. Protecting the integrity of the interior cell. 2. Providing support and maintaining the shape of the cell. 3. Helps in regulating cell growth through the balance of endocytosis and exocytosis. 4. The cell membrane also plays an important role in cell signalling and communication. 5. It acts as a selectively permeable membrane by allowing the entry of only selected substances into the cell. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH)  CYTOPLASM ❑ The functions of cytoplasm are as follows: 1. One of the major functions of cytoplasm is to enable cells to maintain their turgidity, which enables the cells to hold their shape. 2. The jelly-like semifluid complex of cytoplasm is called cytosol or cytoplasmic matrix or intracellular fluid. 3. It encompasses the cytosol with filaments, ions, proteins, macromolecular structures and also other organelles suspended in the cytosol. 4. The jelly-like fluid of the cytoplasm is composed of salt and water and is present within the membrane of the cells and embeds all of the parts of the cells and organelles. 5. The cytoplasm is home to many activities of the cell as it contains molecules and enzymes that are crucial in the breakdown of waste. 6. The cytoplasm also assists in metabolic activities. 7. Cytoplasm provides shape to the cell. It fills up the cells thus enabling the organelles to remain in their position. The cells, without cytoplasm, would deflate , and substances would not permeate easily from one to another organelle. 8. A part of the cytoplasm, the cytosol has no organelles. Instead, the cytosol is enclosed by matrix boundaries that fill up the cell section which does not hold the organelles. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) NUCLEUS ❑ The nucleus is a double-membraned organelle found in all eukaryotic cells. ❑ It is the largest organelle, which functions as the control centre of the cellular activities and is the storehouse of the cell’s DNA. ❑ By structure, the nucleus is dark, round, surrounded by a nuclear membrane. ❑ It is a porous membrane (like cell membrane) and forms a wall between cytoplasm and nucleus. ❑ Within the nucleus, there are tiny spherical bodies called nucleolus. ❑ It also carries an essential structure called chromosomes. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) MITOCHONDRIA ❑ Mitochondria are called the powerhouses of the cell as they produce energy-rich molecules for the cell. ❑ The mitochondrial genome is inherited maternally in several organisms. ❑ It is a double membrane-bound, sausage-shaped organelle found in almost all eukaryotic cells. ❑ The double membranes divide its lumen into two distinct aqueous compartments. ❑ The inner compartment is called a ‘matrix’, which is folded into cristae, whereas the outer membrane forms a continuous boundary with the cytoplasm. ❑ They usually vary in their size and are found either round or oval in shape. ❑ Mitochondria are the sites of aerobic respiration in the cell, produce energy in the form of ATP, and helps in the transformation of the molecules. For instance, glucose is converted into adenosine triphosphate – ATP. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH)  CELL STRUCTURE ❑ Close your eyes and picture a brick wall. What is the basic building block of that wall? A single brick, of course. ❑ Like a brick wall, your body is composed of basic building blocks, and the building blocks of your body are cells. Your body has many kinds of cells, each specialized for a specific purpose. Just as a home is made from a variety of building materials, the human body is constructed from many cell types. ❑ For example, epithelial cells protect the surface of the body and cover the organs and body cavities within. Bone cells help to support and protect the body. Cells of the immune system fight invading bacteria. ❑ Additionally, blood and blood cells carry nutrients and oxygen throughout the body while removing carbon dioxide. ❑ Each of these cell types plays a vital role during the growth, development, and day-to-day maintenance of the body. In spite of their enormous variety, however, cells from all organisms—even ones as diverse as bacteria, onion, and human—share certain fundamental characteristics © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) CELL STRUCTURE © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) © DR. SANNI KUMAR, PH.D., POSTDOC (IITH)  STUDYING CELLS ❑ Cells vary in size. With few exceptions, individual cells cannot be seen with the naked eye, so scientists use microscopes (micro- = “small”; -scope = “to look at”) to study them. ❑ A microscope is an instrument that magnifies an object. Most photographs of cells are taken with a microscope, and these images can also be called micrographs. ❑ The optics of a microscope’s lenses change the orientation of the image that the user sees. A specimen that is right- side up and facing right on the microscope slide will appear upside-down and facing left when viewed through a microscope, and vice versa. ❑ Similarly, if the slide is moved left while looking through the microscope, it will appear to move right, and if moved down, it will seem to move up. This occurs because microscopes use two sets of lenses to magnify the image. Because of the manner by which light travels through the lenses, this system of two lenses produces an inverted image binocular or dissecting microscopes work in a similar manner, but include an additional magnification system that makes the final image appear to be upright). © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) LIGHT MICROSCOPES ❑ Most student microscopes are classified as light microscopes. Visible light passes and is bent through the lens system to enable the user to see the specimen. ❑ Light microscopes are advantageous for viewing living organisms, but since individual cells are generally transparent, their components are not distinguishable unless they are colored with special stains. ❑ Staining, however, usually kills the cells. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) LIGHT MICROSCOPES ❑ Light microscopes commonly used in the undergraduate college laboratory magnify up to approximately 400 times. Two parameters that are important in microscopy are magnification and resolving power. Magnification is the process of enlarging an object in appearance. ❑ Resolving power is the ability of a microscope to distinguish two adjacent structures as separate: the higher the resolution, the better the clarity and detail of the image. ❑ When oil immersion lenses are used for the study of small objects, magnification is usually increased to 1,000 times. In order to gain a better understanding of cellular structure and function, scientists typically use electron microscopes. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) ELECTRON MICROSCOPES ❑ In contrast to light microscopes, electron microscopes use a beam of electrons instead of a beam of light. ❑ Not only does this allow for higher magnification and, thus, more detail (Figure ), it also provides higher resolving power. ❑ The method used to prepare the specimen for viewing with an electron microscope kills the specimen. ❑ Electrons have short wavelengths (shorter than photons) that move best in a vacuum, so living cells cannot be viewed with an electron microscope. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) ELECTRON MICROSCOPES ❑ In a scanning electron microscope, a beam of electrons moves back and forth across a cell’s surface, creating details of cell surface characteristics. ❑ In a transmission electron microscope, the electron beam penetrates the cell and provides details of a cell’s internal structures. ❑ As you might imagine, electron microscopes are significantly more bulky and expensive than light microscopes. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) MICROSCOPIC IMAGE © DR. SANNI KUMAR, PH.D., POSTDOC (IITH)  BIOMOLECULES ❑ Biomolecules are defined as any organic molecule present in a living cell that is essential for body functions and manufactured within the body. ❑ They can vary in nature, type, and structure where. Some may be straight chains; some may be cyclic rings, or both. ❑ Also, they can vary in physical properties such as water solubility and melting points. TYPES OF BIOMOLECULES MACRO MOLECULES MICRO MOLECULES © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) © DR. SANNI KUMAR, PH.D., POSTDOC (IITH)  MICRO MOLECULES ❑ The word micromolecule refers to a small molecule of low molecular weight and is often referred to as a monomer. ❑ Monomers are combined through different biochemical reactions to form a macromolecule, which is known as a polymer. ❑ Cells are composed of various micromolecules. The interaction between different types of molecules maintains the cell's proper structure and function. ❑ Molecules in the cell participate in various biochemical processes inside the cell to maintain the cell. ❑ The most essential micromolecules in cells are nucleotides, amino acids, monosaccharides, fatty acids, and glycerol. These molecules can also join together to form complex compounds known as macromolecules. ❑ The most important examples of macromolecules in a cell are nucleic acids, proteins, carbohydrates, and lipids. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) SUGARS ❑ Sugars are combined together forming carbohydrates. Sugars contain only carbon, oxygen, and hydrogen. ❑ Glucose is one of the most important micromolecules that form carbohydrates. It may be found in the form of a ring (cyclic glucose) or an open-chain (acyclic glucose). In plants, glucose micromolecule is produced during photosynthesis where carbon dioxide and water produce glucose and oxygen in a biochemical reaction. ❑ Glucose micromolecules are a major source of energy for plants, and also for other organisms and animals that feed on plants. ❑ It plays a vital role in the cellular respiration reaction that takes place in living organisms. During the reaction, oxygen and glucose react in a reaction producing water, carbon dioxide, and adenosine triphosphate (ATP). ❑ ATP is used by all cells to get energy since it is the main source of energy for living cells. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) AMINO ACIDS ❑ Amino acid is a monomer that makes up proteins. There are 20 amino acids micromolecules. ❑ Amino acids are organic molecules containing an amino group, a hydroxyl group, and a carbon side chain. ❑ All amino acids share the same basic structure; however, they differ in their carbon side chain. ❑ Amino acids micromolecules vary in terms of polarity, charge, molecular weight, and functions. ❑ Amino acids are either non-essential or essentia , whereas non- essential amino acids are synthesized inside the human body from glucose mainly, y so it is not essential to get them from the diet. Whereas essential amino acids are not synthesized inside the body so they must be obtained from the diet. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) FATTY ACIDS ❑ Fatty acids provide energy to the body, protect internal organs, form cellular membranes, control blood pressure and cholesterol, and help in the absorption of fat-soluble minerals such as vitamins A, K, E, and D. ❑ Fatty acids are micromolecules that form fats when combined together. There are two types of fats, saturated and unsaturated fats. ❑ Saturated fats are bad fats found in processed and baked foods such as desserts, cookies, and pizza. It is also found in animal products such as dairy products, pork, and beef. Saturated fats are unhealthy and should be taken in small amounts. ❑ On the other hand, unsaturated fats are healthier. Saturated fats are usually found in hazelnuts, peanut butter, almonds, pumpkin seeds, sunflower seeds, and avocados. It is also found in oils extracted from plants like peanut oil, sesame oil, and olive oil. ❑ Fatty acids influence cholesterol levels in the blood; therefore, we should limit the consumption of saturated fats and increase the consumption of unsaturated fats since saturated fats found in processed and baked foods increase the risk of strokes, cardiovascular diseases, and obesity. While unsaturated fats keep our brain healthy and decrease the risk of developing Alzheimer’s disease. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) WATER ❑ Water is an inorganic micromolecule. It is found in its free form. ❑ Water contains two hydrogen atoms and one oxygen atom only. Water is essential for every living organism since most of the bodyweight is made up of water. Also, water has various important functions such as removing waste from the body, controlling the temperature of the body, and improving the function of the brain. ❑ Water is being consumed either directly by drinking water or indirectly by eating foods that contain large amounts of water like fruits and vegetables. ❑ Water helps in the production of saliva, it acts as a lubricant that protects joints, spinal cord, and tissues from friction as well as inflammation. ❑ Water can also help in digestion and absorption of various nutrients, it helps in weight loss, improves the blood circulation, decreases illness and infections, improves cognitive functions, boosts energy and improves mood. ❑ Drinking water prevents dehydration, thus it brightens the skin. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH) MINERALS ❑ Minerals are essential micromolecules that maintain the health of the body. Minerals keep the muscles, heart, bones, and brain functioning properly. ❑ Moreover, they are important for synthesizing hormones and enzymes. Also, they are important for activating some enzymes for biochemical reactions. ❑ Minerals are needed in certain amounts, whereas some minerals such as phosphorus, sulfur, chloride, calcium, potassium, and sodium are required in large amounts. ❑ Whereas trace minerals like copper, iron, zinc, selenium, iodine, cobalt, and fluoride are needed in small amounts only, and taking them in large amounts might harm the body. ❑ Minerals are found in various foods or as supplements. © DR. SANNI KUMAR, PH.D., POSTDOC (IITH)  THANK YOU Suggestions for improvement regarding educational material and content are welcomed and appreciated. Please send feedback to [email protected] © Dr. Sanni Kumar, Ph.D., Postdoc (IITH)