Chapter 3 Cell Structure and Function

Cell Structure and FunctionsNameInstitutional AffiliationDate CELL STRUCTURE AND FUNCTIONS Question 3.1: Cellular Level of Organization 1. The cell is referred to as the basic unit of life since it is where different metabolic processes that keep the organism arrive occur. 2. The basic principles of cell theory are: * The cell is the basic structural unit of life. * All organisms are composed of one or more cells. * New cells are formed by a process of cell division * New cells come from pre-existing cells. * All cells are from a common origin hence have almost similar chemical structure. 3. As cells increases, its surface area to volume ratio decreases. Small cells have large surface area to volume ratio as compared to large cells. This is because as a cell grows, its internal volume increases and cell membrane expands. However, volume increases rapidly than the surface area hence amount of surface area available to pass substances to a unit volume decreases steadily. Question 3.2: Prokaryotic cells 1. Are cells whose organelles are not membrane-bound e.g. bacterial. Its components include: The cell envelope which is the outer covering of protoplasm of a bacterial cell. It is composed of; * Glycocalyx- Outermost layer of the cell envelope consisting of polysaccharides. It gives the cell a sticky nature and prevents desiccation. * Cell wall- It is rigid covering that provides structural support and shape to the cell. It lies beneath the glycocalyx * Plasma membrane. It is a semi-permeable layer forming the innermost component of the envelope. It is made of phospholipid bilayer with protein. The cytoplasm is also part of the bacterial cell. It forms the protoplasm and its organelles are not membrane-bound. It consists of; * Menosome- Consists of vesicles, tubules and lamellae. It is of two types; septal mesosme that connects nucleoid with plasma membrane, septum formation and lateral mesosme which contains respiratory enzymes. * Ribosomes- Occur in helical groups called polysomes and helps in protein synthesis. Nucleoid- It is the genetic material. Plasmids-Are self-replicating segments, double-stranded chromosomes that gives bacteria unique phenotype character. Inclusion bodies- Are nonliving structures found in the cytoplasm. Composed of: * Gas vacuoles; Gas storing vacuoles that protect bacteria from harmful radiations. * Inorganic inclusions; Granules of several types that helps the bacteria to position themselves along geomagnetic lines. Flagella- It is unistranded and helps in forward movement. 2. Bacteria and archaea have got different ribosomal RNA. Just like the eukaryotes, archea have three RNAs while bacteria have got only one. The cell membrane of archaea contains ether linkages and the cell wall lacks peptidoglycan. In bacteria, the cell membrane has got ester bonds and the cell wall contains peptidoglycan. Question 3.3: Eukary...