Gen-Bio1-Day-2-Copy.pptx

General Biology I LESSON 2 Objectives: At the end of the lesson, learners should be able to… 1. Describe the structure and function of major and subcellular organelles. 1.1. Describe the structure and functions of major cell organelles. The modern principles of the Cell Theory include the follo...

General Biology I LESSON 2 Objectives: At the end of the lesson, learners should be able to… 1. Describe the structure and function of major and subcellular organelles. 1.1. Describe the structure and functions of major cell organelles. The modern principles of the Cell Theory include the following: 1. All known living things are made up of cells. 2. The cell is the structural and functional unit of all living things. 3. All cells come from pre-existing cells by division. (Spontaneous generation does not occur). 4. Cells contain hereditary information which is passed from cell to cell during cell division. 5. All cells are basically the same in chemical composition. 6. All energy flow (metabolism and biochemistry) of life occurs within cells. I have here names of the organelles, try to impersonate them, and you will win a prize! If organelles could talk/ Bardagulan, what do you think each organelle would say? CELL ORGANELLES are subcellular structure that has one or more specific jobs to perform in the cell, much like an organ does in the body. are specific structure within a cell, and there are many different types of organelles. All cells have four basic structures: 1.Cell membrane – the outer boundary of the cell. 2.Genes/ Genetic information 3.Cytoplasm – the material between the cell membrane and the nucleus. 4.Ribosomes 1. CELL MEMBRANE  Cell Membrane and Its Functions The cell membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. The cell membrane (plasma membrane) is a thin semi-permeable membrane that surrounds  A thin layer of lipid and protein molecules held by noncovalent bonds. Separates the cell contents from the surrounding medium or cellular environment. A typical cell membrane ranges from 5 to 10 nanometers (nm; 1nm = 10-9 m) Parts and The cell membrane is mainly structure composed of phospholipid molecules. Phospholipids are made of glycerol, two fatty acids and a phosphate group. Phospholipid molecules are amphiphatic, meaning the two ends have different properties in water. The phosphate head is hydrophilic (“water-loving”) or soluble in water. The tail end of the molecule is Parts and structure In 1972, S. J. Singer and Garth Nicolson proposed the fluid mosaic model of the membrane. According to this model, there are various protein molecule embedded in the phospholipid bilayer. Fluid-Mosaic Model of Cell Membrane Mosaic model -it is made up of a bunch of different molecules or a pattern of different types of molecules such as integral proteins, peripheral proteins, glycoproteins, phospholipids, glycolipids, and in some cases cholesterol, lipoproteins put together that are distributed across the membrane, also known as a mosaic. Membrane has a mosaic of protein molecules bobbing in a fluid of phospholipid bilayer: a. Integral or intrinsic proteins are protein molecules that penetrate deeply into the lipid bilayer. b. Peripheral or extrinsic proteins are protein molecules that remain on the surface of the membrane. Features of Fluid Mosaic Model: The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid, but more like a 'fluid'. The movement of the mosaic of molecules makes it a penetrable barrier. 3 main factors that influence cell membrane fluidity: 1.Temperature: The temperature will affect how the phospholipids move and how close together they are found. When it’s cold they are found closer together and when it’s hot they move farther apart. 2. Cholesterol The cholesterol molecules are randomly distributed across the phospholipid bilayer, helping the bilayer stay fluid in different environmental conditions. The cholesterol holds the phospholipids together so that they don’t separate too far, letting unwanted substances in, or compact too tightly, restricting movement across the membrane. 3. Saturated and unsaturated fatty acids Fatty acids are what make up the phospholipid tails. kinks of unsaturated hydrocarbon tails of phospholipids keeps membranes fluid Saturated fatty acids are chains of carbon atoms that have only single bonds between them. As a result, the chains are straight and easy to pack tightly. Unsaturated fats are chains of carbon atoms that have double bonds between some of the carbons. The double bonds create kinks in the chains, making it harder for the chains to pack tightly. Parts and Cholesterol, another lipid composed of four fused structure carbon rings, is found alongside phospholipids in the core of the membrane. Carbohydrate groups are present only on the outer surface of the plasma membrane and are attached to proteins, forming glycoproteins, or lipids, forming glycolipids. Functions of cell membrane they keep toxic substances out of the cell; they contain receptors and channels that allow specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular and extracellular activities to pass between organelles and between the cell and the outside environment; they separate vital but incompatible metabolic processes conducted within organelles.  Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell, while keeping other substances out. It also serves as a base of attachment for the cytoskeleton in some organisms and the cell wall in others. Cell membrane also serves to help support the cell and help maintain its shape. Another function of the membrane is to regulate cell growth through the balance of endocytosis and exocytosis. What organelle is this? The Nucleus WHAT IS NUCLEUS? It is the most noticeable organelle in all eukaryotic cells. The nucleus is a membrane bound structure that contains the cell’s hereditary information. The nucleus is also known as karyon and its study is known as karyology. It is the CEO of the cell directing all the functions for life and, in addition prepares the cell for growth and replication. Parts and Composition 1. Location and shape in animal cells: rounded and in the centre of the cell. 2. plant cells: lens shaped and pushed to the side of the cell by the vacuole. 2. Nuclear membrane or envelope – surrounds the nuclear contents and is a double membrane. 3. Nuclear pores – many and control the passage of molecules and structures into and out of the nucleus. 4. Nucleoplasm – the ‘cytoplasm’ of the nucleus. 5. Nucleolus – this is an extra dense area of DNA and protein where the ribosomes (rRNA is synthesized) are produced. 6. Chromatin – is made up of DNA (a nucleic acid) and proteins called histones. When the cell is about to divide the chromatin condenses into separate chromosomes which consists of DNA that comprises the hereditary information and instructions for cell growth, development, and reproduction. CELL NUCLEUS STRUCTURE Nucleopla sm FUNCTIONS: The nucleus is an organelle dubbed as the central government of the cell. It is because it contains the genetic material that codes for the vital functions of the cell. The nucleus is the organelle responsible in maintaining the integrity of DNA and in controlling cellular activities such as: a. metabolism, b. growth, and c. reproduction by regulating gene expression. Other functions of Nucleus 1. Nucleus contains all the genetic information in its chromatin. 2. Nucleus take part in transmission of genetic information from parent cell to its daughter cells and from one generations to the next. 3. Division of nucleus is pre-requisite to cell division. 4. Nucleus forms ribosomes on its nucleolus. 5. It maintains cellular metabolism through controlling synthesis of particular types of enzymes. 6. Differential functioning of genes result in cell differentiation and development of particular morphology. 8. Newly formed cells grow in size and become mature with the help of structural proteins and other substances IMPORTANT PROCESSES which involve NUCLEUS PROTEIN SYNTHESIS: The nucleus regulates the synthesis of proteins in the cytoplasm through the use of messenger RNA (mRNA). mRNA is a transcribed DNA segment that serves as a template for protein production. It is produced in the nucleus and travels to the cytoplasm through the nuclear pores of the nuclear envelope. The Nucleolus Functions The nucleolus is the nuclear subdomain that assembles ribosomal subunits in eukaryotic cells or rewrite ribosomal RNA (rRNA) and combine it with proteins. This results in the formation of incomplete ribosomes (Small and large subunits) Nucleolus’ main function is the production of subunits which then together form ribosomes. IMPORTANT PROCESSES The site of rRNA transcription and processing, and of ribosome assembly. The more proteins a cell needs to make, the more ribosomes it needs, and therefore, the larger the nucleolus. CYTOPLASM Cell materials excluding nucleus: the complex of chemical compounds and structures within a plant or animal cell excluding the nucleus. Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. Cytoplasm contains the cytosol, organelles, vesicles, and cytoskeleton. Microsoft® Encarta® 2009. © 1993-2008 Microsoft Corporation. All rights reserved Cytosol Cytosol is a mixture of water, salt, cytoskeleton and protein filaments, soluble proteins, and vaults proteins, among other organic molecules (glucose and other simple sugars, polysaccharides, amino acids, nucleic acids, and fatty acids). Ions of sodium, potassium, calcium, and other elements are also found in the cytosol.. Cytoplasmic Inclusions These are non-living elements that lack membranes and metabolic functions, which exist inside the cytosol. The most common inclusions are lipid droplets, crystals, pigments, and glycogen Functions Most of the important activities of the cell occur in the cytoplasm. Cytoplasm contains molecules such as enzymes which are responsible for breaking down waste and also aid in metabolic activity. Cytoplasm is responsible for giving a cell its shape. It helps to fill out the cell and keeps organelles in their place. Without cytoplasm, the cell would be deflated and materials would not be able to pass easily from one organelle to another. Processes and Activities that occur in Cytoplasm 1.Metabolic Pathways Glycolysis This process occurs in cytoplasm of the cell and does not necessarily require the presence of oxygen, that is why it is a common process in both aerobic respiration and the anaerobic pathway. 2.Cellular Processes/ Cytokinesis  Cell Division 3. Cytoplasmic Streaming In plants cells, a process known as cytoplasmic streaming takes place where there is movements of the cytoplasm around the vacuole. The motion transports nutrients, proteins and organelles within the cells. Protein builder/ factory of the cell The ribosome is made up of two parts, called subunits. The larger of the two subunits is where the amino acids get added to the growing protein chain. The small subunit is where the mRNA binds and is decoded. Each of the subunits is made up of both protein and ribonucleic acid (RNA) components. Fig. 7.10 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings  Ribosomes are the protein builders or the protein synthesizers of the cell. They are like construction guys who connect one amino acid at a time and build long chains. Ribosomes are special because they are found in both prokaryotes and eukaryotes.  Cell types that synthesize large quantities of proteins (e.g., pancreas) have large numbers of ribosomes and prominent nuclei. Types of Ribosome Free ribosomes, are suspended in the cytosol and synthesize proteins that function within the cytosol. Bound ribosomes, are attached to the surface of the endoplasmic reticulum and synthesize proteins that are either included into membranes or for export from the cell. Both types of ribosomes are structurally similar but differ in their location and the types of proteins they produce. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings WHAT IS A mitochondrion? (The word mitochondrion is derived from the Greek words míto(s) which means “thread”, and chóndrion means “small grain“.) They are minute sausage-shaped, well- defined cytoplasmic organelles/structures found in the hyaloplasm (clear cytoplasm) of the cell which take part in a variety of cellular metabolic functions. The mitochondrion (plural mitochondria) is a double membrane-bound organelle found in all eukaryotic organisms. can also be referred to as the “power house” of the cell PARTS AND STRUCTURE OF THE MITOCHONDRION Outer membrane - It is smooth and is composed of equal amounts of phospholipids and proteins. Inner membrane - The inner membrane of mitochondria is more complex in structure. It is folded into a number of folds many times and is known as the cristae. This folding help to increase the surface areas inside the organelle. Cristae – this is where the third stage of cellular respiration, oxidative phosphorylation (ETC and chemiosmosis), occurs, producing a large amount of ATP (ATP synthesis). Matrix – this is where the second stage of cellular respiration, Krebs cycle, occur. The matrix is a complex mixture of proteins and enzymes. These enzymes are important for the synthesis of ATP molecules, mitochondrial ribosomes, tRNAs and mitochondrial Functions of Mitochondrion The chief function of the mitochondria is to create energy(responsible for energy production) for cellular activity by the process of aerobic respiration. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved. Mitochondria contain enzymes that help convert food material like glucose into adenosine triphosphate (ATP), which can be used directly by the cell as an energy source.  Mitochondria tend to be concentrated near cellular structures that require large inputs of energy, such as the flagellum, which is responsible for movement in sperm cells and single-celled plants and animals. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Mitochondria are unusual organelles in that they contain: 1. Deoxyribonucleic acid (DNA), 2. Ribosomes, the protein-producing organelles abundant in the cytoplasm. Within the mitochondria, the DNA directs the ribosomes to produce proteins, many of which function as enzymes, or biological catalysts, in ATP production. The number of mitochondria in a cell depends on the cell's function. Cells with particularly heavy energy demands, such as muscle cells, have more mitochondria than other cells. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved. Mitochondria are quite dynamic: moving, changing shape, and dividing. PROCESSES IN THE MITOCHONDRION CELLULAR RESPIRATION is the process of creating energy for the cell wherein most of the chemical reactions concerned with this process happen in the mitochondria. Mitochondrial Inheritance Like nucleus, mitochondrion also holds a chromosome. The DNA on this chromosome is referred to as mitochondrial DNA or MtDNA. mitochondrial DNA is inherited only from the mother—a type of inheritance known as maternal inheritance. The study of mitochondrial DNA has been employed to study human evolution. Mutations in mitochondrial DNA have been implicated in a number of genetic diseases, which include diabetes mellitus, deafness, heart disease, Alzheimer’s disease, Parkinson disease, and Leber’s hereditary optic neuropathy, a condition of complete or partial blindness resulting from degeneration of the optic nerve. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved. CHLOROPLAST CHLOROPLAST The chloroplast is one of several members of a generalized class of plant structures called plastids. Amyloplasts store starch in roots and tubers. Chromoplasts store pigments for fruits and flowers. The chloroplast produces sugar via photosynthesis Chloroplasts gain their color from high levels of the green pigment chlorophyll. Chloroplasts measure about 2 microns x 5 microns and are found in leaves and other green structures of plants and in eukaryotic algae. PARTS  The thylakoids, flattened sacs, are stacked into grana and are critical for converting light to chemical energy. Thylakoid membrane- is rich in chlorophyll, thus it is where light-dependent reaction of photosynthesis occurs. Stroma- is where the light-independent reaction, or the Calvin cycle takes place. Peroxisomes are small, membrane-bound organelles that contain enzymes for various metabolic reactions, including the breakdown of fatty acids and the detoxification of hydrogen peroxide. Peroxisomes are self-replicating and their proteins are imported directly from the cytosol. An intermediate product of the transfer of hydrogen from various substrates to oxygen by the peroxisomes is hydrogen peroxide (H2O2), a poison. But the peroxisome contains enzyme catalase, which converts hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen (O₂), protecting the cell from oxidative damage caused by hydrogen peroxide.  Some peroxisomes break fatty acids down, and are transported to mitochondria for fuel. Others detoxify alcohol and other harmful compounds. Specialized peroxisomes, glyoxysomes, convert the fatty acids in seeds to sugars, an easier energy and carbon source to transport. Peroxisomes are present in a wide variety of eukaryotic cells, including those in animals, plants, and fungi. CYTOSKELETON It is a network of protein fibers that provides structural support, cell shape, and facilitates cell movement and intracellular transport. The cytoskeleton organizes the structures and activities of the cell.  The cytoskeleton provides mechanical support and maintains shape of the cell. The cytoskeleton provides anchorage for many organelles and cytosolic enzymes. The cytoskeleton is dynamic, dismantling in one part and reassembling in another to change cell shape. TYPES: 1. Microtubules, the thickest fibers, are hollow rods. They move chromosomes during cell division (Spindle fibers). Another function is as tracks that guide motor proteins carrying organelles to their destination. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring. During cell division the centrioles replicate. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings  Microtubules are the central structural supports in cilia and flagella. Fig. 7.2 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 2. Microfilaments, the thinnest class of the cytoskeletal fibers, are solid rods of the globular protein actin. Microfilaments are designed to resist tension. With other proteins, they form a three- dimensional network just inside the plasma membrane.  The shape of the microvilli in this intestinal cell are supported by microfilaments, anchored to a network of intermediate filaments. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 3. Intermediate filaments, are specialized for bearing tension. Intermediate filaments are built from a diverse class of subunits from a family of proteins called keratins. Intermediate filaments are more permanent fixtures of the cytoskeleton than are the other two classes. They reinforce cell shape and fix organelle location. https://www.khanacademy.org/test-prep/mcat/cells/cell- membrane-overview/a/fluid-mosaic-model-cell-membranes- article