TMJC Cells Notes

Page 1 of 54 TMJC Biology unit Tampines Meridian Junior College JC1 H2/9744 Biology 2023 Core Idea 1A 1. Cell – The Basic Unit of Life SYLLABUS OVERVIEW No. Overarching Idea Topics 1 Core Idea 1 The Cell and Biomolecules of Life Cell – The Basic Unit of Life 2 Biomolecules of Life and Cellular Transport 3 Core Idea 3 Energy and Equilibrium Transformation of Energy – Photosynthesis and Cellular Respiration 4 Core Idea 2 Genetics and Inheritance Genetics and Inheritance (I) – The Cell Cycle 5 Genetics and Inheritance (II) – DNA Replication and Gene Expression 6 Genetics and Inheritance (III) – DNA Mutations and their Consequences 7 Genetics and Inheritance (IV) – Molecular Techniques in DNA Analysis 8 Genetics and Inheritance (V) – Organization of Genome & Control of Gene Expression in Eukaryotes [Includes Core Idea 1D: Stem Cells] 9 Genetics and Inheritance (VI) – Organization and Inheritance of Viral Genomes 10 Genetics and Inheritance (VII) – Organization of Genome & Control of Gene Expression in Prokaryotes 11 Genetics and Inheritance (VIII) - Inheritance 12 Core Idea 3 Energy and Equilibrium Communication and Equilibrium in Multicellular Organisms 13 Core Idea 4 Biological Evolution Biological Evolution 14 Extension Topic A Infectious Diseases Immunity and Infectious Diseases 15 Extension Topic B Impact of Climate Change on Animals & Plants Climate Change – Causes and Impacts on Animals and Plants *Note: complete pre- lecture activity on pg 10 before lecture

Page 2 of 54 TMJC Biology unit TOPIC SYNOPSIS Core Idea 1 – The Cell and Biomolecules of Life – entails the study of cells, which are the basic units of life. The following questions should help you frame your learning: • 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 life? • How are the structures of biomolecules related to their functions? • How do cells regulate the movement of substances into and out of themselves, and what a re the implications of such movements? • 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? Sub-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 that cells grow from existing cells. Understanding the role of cellular organelles (such as the nucleus, ribosome, chloroplast and mitochondrion) and cellular structures (for example, the cytoskeleton) will help in understanding the conc ept of how structure relates to function. There are significant differences between cells of prokaryotes and eukaryotes. Using bacteria as a model, the nucleoid is not enclosed by any membrane. Plasmids 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 division and differentiation to allow them to carry out their specific functions. Biomolecules make up cells and cells regulate many cellular processes, including the movement of substances into and out of themselves, through membranes The different classes of biomolecules (sugars, lipids, proteins and nucleic acids) function as molecular building blocks for macromolecules to be assembled. Nucleic acids, which include DNA and RNA, are made from monomers known as nucleotides. Phospholipids, cholesterol, carbohydrates and proteins are important components in biological membranes. Cells need to regulate the movement of substances into and out of themselves. Substances such as water, oxygen, glucose and minerals are important in the synthesis of new molecules and impor tant cellular processes. According to the fluid mosaic model, cell membranes are selectively permeable due to the nature of the phospholipids and proteins from which they are made. The movement of different molecules depends on the nature of the substances through transport processes such as osmosis, diffusion and active transport. Membranes allow cells to create and maintain internal environments that are different from external environments. Eukaryotic cells also contain internal membrane structures that partition the cell into specialised compartments so that cellular processes can occur with optimal activity e.g. chloroplasts and mitochondria. The endomembrane system, consisting of rough and smooth endoplasmic reticulum and Golgi apparatus, is responsible for protein processing and vesicular transport within the cell. Prokaryotes generally lack such membrane -bound organelles and endomembrane systems; yet they survive and reproduce. In the endosymbiotic theory, organelles like mitochondria and chloroplasts represent formerly free-living prokaryotes that were taken inside another cell, and this could explain the link between the two domains in the tree of life. In contrast to eukaryotic and prokaryotic cells, viruses lack several of those cellul ar structures. They rely on eukaryotes and prokaryotes to reproduce. In this regard, viruses are considered obligate parasites and there is debate as to whether viruses are living or non-living organisms.

Page 3 of 54 TMJC Biology unit LEARNING OUTCOMES Core Idea 1A: Organelles and Cellular Structures This concept discusses the typical cell model of prokaryotes and eukaryotes, including plants and animals. A strong understanding of the structure of the following organelles and cellular structures in relation to their function is necessary: rough and smooth endoplasmic reticulum, Golgi body, mitochondria, ribosomes, lysosomes, chloroplasts, cell surface membrane, nuclear envelope, centrioles, nucleus and nucleolus. Candidates should be able to: 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. b) Interpret and recognize 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, nuclear envelope, centrioles, nucleus and nucleolus. (For practical assessment, students may be required to operate a light mic roscope, mount slides and use an eyepiece graticule and a stage micrometer) c) Outline the functions of the membrane systems and organelles listed in LO1A(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). e) Describe the structural components of viruses , including enveloped viruses and bacteriophages, and interpret drawings and photographs of them. f) Discuss how viruses challenge the cell theory and concepts of what is considered living.

Page 4 of 54 TMJC Biology unit LECTURE OUTLINE 1 Overview of Cells 1.1 The Cell Theory 1.2 Cell fractionation 2 Eukaryotic Cells 2.1 What are the organelles and structures that eukaryotic cells possess? 2.1.1 Cell Surface Membrane 2.1.2 Nucleus 2.1.3 Ribosomes 2.1.4 Endoplasmic Reticulum 2.1.5 Golgi Apparatus/ Golgi Body 2.1.6 Lysosomes 2.1.7 Mitochondria 2.1.8 Chloroplasts [Endosymbioti