CJC Organelles & Cellular Structures Lecture Notes

1 CATHOLIC JUNIOR COLLEGE 9744 H2 Biology CORE IDEA: 1] THE CELL AND BIOMOLECULES OF LIFE 1.1 ORGANELLES AND CELLULAR STRUCTURES Narrative: Cellular structures provide the means to drive cellular processes Knowing how cellular structures facilitate specific cellular processes is fundamental to explaining how life ‘works’. The cell theory states that the cell is the smallest and most basic unit of life and th at cells grow only from existing cells. Understanding the role of cellular organelles (such as nucleus, ribosome, chloroplast and mitochondrion) and cellular structures (for example, the cytoskeleton) is crucial to understanding how organisms and life at large work . One key concept often explored in this chapter is “how are the structures of the organelles adapted for their functions?” There are significant differences between cells of prokaryotes and eukaryotes. Using bacteria as a model, the nucleoid is not enclosed by any membrane. Plasmid may be present as extra -chromosomal DNA. Membrane-bound organelles, such as mitochondria and endoplasmic reticulum, are absent. Prokaryotic ribosomes are different from eukaryotic ribosomes. Some bacterial cells have cell walls that comprise peptidoglycan rather than cellulose. Within the eukarya domain, the cell model of plants is also different from that of animals. Unlike unicellular organisms which merely undergo cellular division, cells of multicellular organisms undergo both division and differentiation to allow them to carry out their specific functions. Guiding Questions: ● Why is a cell the basic unit of life and how does it promote continuity of life? ● How is the basic unit crucial in understanding what constitutes life? ● What are the differences between cells of prokaryotes and eukaryotes, between cells of plants and animals, and between cells of unicellular and multicellular organisms? ● In what ways do viruses not fit the cell model? LEARNING OUTCOMES Candidates should be able to: Subtopic Learning Outcomes Pg. Cell Theory (a) Outline the cell theory with the understanding that cells are the smallest unit of life, all cells come from pre-existing cells; and living organisms are composed of cells. 3 Eukaryotes (b) Interpret and recognise drawings, photomicrographs and electronmicrographs of the following membrane systems and organelles: rough and smooth endoplasmic reticulum, Golgi body, mitochondria, ribosomes, lysosomes, chloroplasts, cell surface membrane, nucle ar envelope, centrioles, nucleus and nucleolus. (c) Outline the functions of the membrane systems and organelles listed in (b). 3-22 Prokaryotes (Bacteria) (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). 23-27 Viruses (e) Describe the structural components of viruses, including enveloped viruses and bacteriophages, and interpret draw