RVHS 1. Organelles and Cellular Structures

River Valley High School 1 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures River Valley High School 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures Name: ( ) Class: 25J__ Date: References Title Authors Campbell Biology (9th Edition) Reece, Urry, Cain, Wasserman, Minorsky, Jackson Molecular Biology of the Cell (5th edition) Alberts, Johnson, Lewis, Raff, Roberts and Walter Biological Science 1. Organisms, Energy and Environment (3rd Edition) Taylor, Green, Stout and Soper Advanced Biology: Principles and Applications (2nd edition) Clegg and Mackean H2 Biology Syllabus 9477 (2025) Candidates should be able to use the knowledge gained in the following section(s) in new situations or to solve related problems. Related Topics Genetics and Inheritance Concepts The Structure of Nucleic Acids and Gene Expression Organisation of Genomes The Cell Cycle Energy and Equilibrium Transformation of Energy between the Environment and Organisms Infectious Diseases Viral diseases (e.g. Influenza, HIV) Learning Outcomes 1A. Organelles and Cellular Structures a. Outline the cell theory with the understanding that cells are the smallest unit of life, all the cells come from pre-existing cells; and living organisms are composed of cells. b. interpret and recognise drawings, photomicrographs and electron micrographs of the cytoplasm (cytosol) and cellulose cell wall, and the following membrane systems and organelles: rough and smooth endoplasmic reticulum, Golgi body, mitochondria, ribosomes, lysosomes, chloroplasts, cell surface membrane, nuclear envelope, centrioles, nucleus and nucleolus (for practical assessment, candidates may be required to operate a light microscope, mount slides and use an eyepiece graticule and a stage micrometer) c. Outline the functions of the membrane systems and organelles listed in (b). d. Describe the structure of a typical bacterial cell (small and unicellular, peptidoglycan cell wall, circular DNA, 70S ribosomes and lack of membrane -bound organelles) (KIV: Organisation of Genomes – Prokaryotes)

River Valley High School 2 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures Lecture Outline I. Cells: The Fundamental Units of Life II. Techniques to Study Cell Structures A. Microscopy B. Cell Fractionation C. Autoradiography III. Prokaryotic and Eukaryotic Cells IV. Eukaryotic Cells A. Components of Eukaryotic Cells B. Cytosol C. Membranous Organelles D. Non-membranous Organelles E. Extracellular Structures F. Plant and Animal Cells Websites URL Description http://learn.genetics.utah.edu/ Select “Cells” for concise information, interactive animations and links to video resources on cell structure and function. https://www.youtube.com/watch?v=wJyUtbn0O5Y “The Inner Life of a Cell”. A 3D computer graphics animation on the various biological mechanisms occurring within a white blood cell. http://www.cellsalive.com/cells/bactcell_js.htm Interactive bacterial cell. Download the site here.

River Valley High School 3 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures I. Cells: The Fundamental Units of Life In the hierarchy of biological organisation, the cell is the simplest collection of matter that can live. There are diverse forms of life existing as unicellular organisms. More complex organisms are multicellular – their bodies are cooperatives of many kinds of specialised cells that are often arranged into higher levels of organisation (e.g. tissues, organs, organ systems), yet cells remain their basic units of structure and function. Source: Encyclopaedia Britannica, Inc. A cell (Latin: cella – “a small room”) is ⬧ the basic structural and functional unit of an organism ⬧ a membrane bound structure containing bio logical molecules ⬧ a self-contained and self-maintaining entity o take in nutrients, convert these nutrients into energy, carry out specialis ed functio ns, and reproduce as necessary. ⬧ stores its own set of instructions for carrying out each of these activities Source: Campbell Biology, pg141

River Valley High School 4 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures The cell was first described by Robert Hooke in 1665. Subsequent observations by other scientists led to the development of the modern cell theory, which states that: 1. The cell is the smallest unit of life. 2. All cells arise from pre-existing cells by dividing into two. 3. All known living things are made up of one or more cells. 4. Energy flow (metabolism and biochemistry) occurs within cells. 5. Cells contain hereditary information (DNA) which is passed from cell to cell during cell division. 6. All cells are basically the same in chemical composition in organisms of similar species. 7. Some organisms are made up of only one cell and are known as unicellular organisms. 8. Others are multicellular, composed of several cells. 9. The activity of an organism depends on the total activity of independent cells. II. Techniques to Study Cell Structures A. Microscopy Microscopes are the most important tools of cytology, the study of cell structure. Important parameters in microscopy ⬧ Magnification: ratio of an object’s image size to its actual size ⬧ Resolution: the minimum distance between two points at which they can be distinguished as two points Light Microscopy Light microscopy involves passing visible light through the specimen and then through glass lenses, which refract (bend) the light in a way such that the image of the specimen is magnified as it is projected into the eye, photographic film, or digital sensor. Source: http://www.tpub.com/ Source: http://teachers.saschina.org/ Electron Microscopy Electron microscopy involves focusing a beam of electrons i. through the specimen (Transmission Electron Microscopy) or ii. onto its surface (Scanning Electron Microscopy).

River Valley High School 5 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures Transmission Electron Microscopy (TEM) TEM is used to study the internal ultrastructure1 of cells. The TEM aims an electron beam through a very thin section of the specimen. Darker areas of the image represent regions of the specimen that is electron dense, where few electrons are transmitted. Lighter areas of the image represent regions of the specimen that is less electron dense where many electrons are transmitted. Patterns of transmitted electrons can also be passed onto a photographic film to capture a permanent record. This photograph that is taken is called an electron micrograph. Scanning Electron Microscopy (SEM) SEM is used for detailed study of the surface of a specimen . S pecimens need not be sectioned, can frequently be studied whole and intact. The electron beam scans the surface of the sample. SEM has great depth of field, resulting in a three-dimensional image. Exposed areas of the specimen is coated with gold so it is electron dense while sheltered areas remain uncoated, thus are less electron dense . Exposed areas of the specimen are lighter on the i mage while sheltered areas of the specimen are darker on the image. 1 Cellular anatomy revealed by an electron microscope. Source: Campbell Biology, pg142 Source: Encyclopaedia Britannica, Inc.

River Valley High School 6 2025 JC1 H2 Biology Lecture Topic 1: Organelles and Cellular Structures Advantages of Electron Microscopy ⬧ Much higher resolution (0.5 nm for TEM and 5 -20 nm for SEM) is ac hieved than by light microscopy (around 200 nm); ⬧ Much higher magnification of specimens (x250 000) than in light micros