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Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Biochemistry · 200 Level
This is the complete lecture note for BCH 202 General Biochemistry 2, prepared for Biochemistry students at 200 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS • Course Code: BCH 202 • Course Title: General Biochemistry II • Course Credit Load: 2 Units • List of Series: Foundations of Cell Theory and Diversity Structures and Functions of Cellular Organelles Chemical Composition and Fractionation of Cells Water and Electrolyte Balance in Cellular Systems Acidity, Alkalinity, and pH in Cellular Activities Suggested Outline for Series 1: Foundations of Cell Theory and Diversity Part 1: Origins and Principles of Cell Theory Historical background of cell theory Core principles of cell theory Modern extensions of cell theory Part 2: Types and Characteristics of Cells Prokaryotic cell structure and features Eukaryotic cell structure and features Constancy and diversity among cell types Part 3: Comparative Overview of Plant and Animal Cells Unique features of plant cells Unique features of animal cells Key similarities and differences Part 4: Interrelationships of Cellular Components Functional integration of organelles Cellular organisation and communication Introduction Cells are often described as the fundamental units of life, and every living organism is built upon their structure and function. The development of cell theory marked a turning point in biological sciences, providing a framework that explains how organisms are organised and how they sustain life. By studying the foundations of cell theory and the diversity of cell types, learners gain insight into the principles that underpin biochemistry and the broader field of life sciences. This Series is therefore crucial, as it sets the stage for understanding the organisation of cells and their variations across different organisms.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The aim of this Series is to equip you with the knowledge to explain the origins and principles of cell theory, to analyse the types and characteristics of cells, and to evaluate the similarities and differences between plant and animal cells, while also appreciating the interrelationships among cellular components. We shall commence this Series by exploring the historical background and core principles of cell theory, followed by its modern extensions. Next, we will examine the types and characteristics of cells, beginning with prokaryotic cells and then moving on to eukaryotic cells, highlighting their constancy and diversity. Subsequently, we will compare plant and animal cells, identifying their unique features as well as their similarities. Finally, we will wrap up by considering how cellular components interact and integrate to maintain organisation and communication within the cell. Series Learning Outcomes Upon completing this Series, you should be able to: SLO 1.1 define the historical background and core principles of cell theory, SLO 1.2 explain the modern extensions of cell theory and their relevance to biochemistry, SLO 1.3 describe the structural features of prokaryotic cells, SLO 1.4 analyse the structural features of eukaryotic cells, SLO 1.5 evaluate the constancy and diversity among different cell types, SLO 1.6 identify the unique features of plant cells, SLO 1.7 identify the unique features of animal cells, SLO 1.8 compare the similarities and differences between plant and animal cells, and SLO 1.9 explain how cellular components interact to maintain organisation and communication within the cell. 1.1 Origins And Principles Of Cell Theory 1.1.1 historical background of cell theory The cell theory is a fundamental concept in biology which states that all living organisms are composed of cells. A cell is defined as the smallest structural and functional unit of life, capable of carrying out essential processes such as metabolism, growth, and reproduction. The origins of cell theory can be traced back to early observations made using primitive microscopes. In 1665, Robert Hooke examined thin slices of cork and described the tiny compartments he observed as “cells”. Later, Antonie van Leeuwenhoek improved the design of microscopes and was able to observe living microorganisms, which he referred to as “animalcules”. These discoveries laid the foundation for the idea that cells are the basic building blocks of life. Over time, further studies by scientists such as Matthias Schleiden and Theodor Schwann in the 1830s established that plants and animals are both composed of cells. Rudolf Virchow later contributed by stating that all cells arise from pre-existing cells, reinforcing the continuity of life. Fill in the blank: The scientist who first described cells while examining cork was __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing early microscopes and Hooke’s cork cell observations Figure 1.1 Early observations of cells using primitive microscopes Search string: “Robert Hooke cork cells diagram OER” 1.1.2 core principles of cell theory The core principles of cell theory are threefold. First, all living organisms are composed of one or more cells. Second, the cell is the basic unit of structure and function in living organisms. Third, all cells arise from pre-existing cells through division. These principles highlight the universality of cellular organisation across diverse forms of life. The recognition of these principles unified biology by providing a common framework for studying organisms. Whether examining bacteria, plants, or animals, the same cellular foundation applies. This universality is what makes cell theory a cornerstone of biochemistry and life sciences. Fill in the blank: One of the core principles of cell theory is that all cells arise from __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Box 1.1 Core principles of cell theory All living organisms are composed of one or more cells The cell is the basic unit of structure and function in living organisms All cells arise from pre-existing cells Search string: “cell theory principles infographic OER” 1.1.3 modern extensions of cell theory As scientific knowledge advanced, modern extensions of cell theory were introduced. These include the understanding that cells contain hereditary information in the form of DNA, which is passed from one generation to the next. Another extension is that energy flow occurs within cells, involving processes such as respiration and metabolism. Additionally, the activity of an organism depends on the collective activity of its cells, meaning that cellular processes directly influence the health and function of the whole organism. Modern cell theory also acknowledges the role of specialised structures within cells, known as organelles, which carry out distinct functions. For example, mitochondria are responsible for energy production, while the nucleus stores genetic material. These insights have expanded the scope of cell theory beyond its original principles, making it more comprehensive and applicable to modern biochemistry. Fill in the blank: The hereditary material contained within cells is __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing modern extensions of cell theory, including DNA, energy flow, and organelles Figure 1.2 Modern extensions of cell theory” Search string: “modern cell theory diagram OER” Pilot questions 1.1 Who first observed and named “cells” while studying cork? State one contribution of Antonie van Leeuwenhoek to cell theory. List the three core principles of cell theory. What hereditary material is recognised in modern extensions of cell theory? Which organelle is responsible for energy production in cells? 1.2 Types And Characteristics Of Cells 1.2.1 prokaryotic cell structure and features Prokaryotic cells are cells that lack a membrane-bound nucleus and other membrane-bound organelles. The term “prokaryote” comes from Greek, meaning “before nucleus”. These cells are generally smaller and simpler in structure compared to eukaryotic cells. They include organisms such as bacteria and archaea. Prokaryotic cells typically contain a cell wall, which provides shape and protection, a plasma membrane, which regulates the movement of substances in and out of the cell, and cytoplasm, which houses the genetic material and ribosomes. The genetic material is usually a single circular DNA molecule located in a region called the nucleoid. Ribosomes are present for protein synthesis, but they are smaller than those found in eukaryotic cells. Fill in the blank: The region in a prokaryotic cell where DNA is located is called the __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing the structure of a typical prokaryotic cell Figure 1.3 Structure of a prokaryotic cell Search string: “prokaryotic cell diagram OER” 1.2.2 eukaryotic cell structure and features Eukaryotic cells are cells that contain a membrane-bound nucleus and other specialised organelles. The term “eukaryote” means “true nucleus”. These cells are generally larger and more complex than prokaryotic cells, and they make up organisms such as plants, animals, fungi, and protists. The nucleus houses the cell’s DNA and controls cellular activities. Other organelles include mitochondria, which generate energy, endoplasmic reticulum, which synthesises proteins and lipids, and the Golgi apparatus, which modifies and packages proteins. Plant eukaryotic cells also contain chloroplasts, which are responsible for photosynthesis. Fill in the blank: The organelle responsible for energy production in eukaryotic cells is the __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing the structure of a typical eukaryotic cell Figure 1.4 Structure of a eukaryotic cell Search string: “eukaryotic cell diagram OER” 1.2.3 constancy and diversity among cell types Cells exhibit both
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