Module 5 (Introduction to Cell Structures and Functions...)

• Bacteria are single-celled organisms that lack nucleus or any membrane-bound organelle.
• Like plants, bacteria have cell wall, but the difference is that plant cell wall is made up of cellulose while bacterial cell wall is composed of peptidoglycan-a protein-sugar (polysaccharide) molecule.
• The main function of the cell wall is it helps in providing support, mechanical strength and rigidity to cell. It also protects cell from bursting in hypotonic medium.
• Capsule is a protective covering of bacteria made up of polysaccharide, its role is to keep the bacterium from drying out and protect it from phagocytosis (engulfing) by larger microorganisms.
• Capsule has a slime layer which covers the outside part of the cell wall. It works also as a food reserve and sticks the cells together.
• Like eukaryotic organisms, bacteria have also cytoplasm. The function of cytoplasm is for cellular growth, metabolism and replication of genetic material of bacterial cell.
• Cytoplasm is also called the store house of all the chemicals and components that are used to sustain the life of a bacteria.
• Plasma membrane is also called the cytoplasmic membrane, a semi-permeable membrane which allows only selected materials to move inside and outside of the cell. It is composed of phospholipids, proteins and carbohydrates, forming a fluid-mosaic.
• Plasma membrane helps in transportation of substances including removal of wastes from the body and providing a mechanical barrier to the cell.
• Bacterial ribosome functions for protein synthesis.
• Proteins are molecules that perform all the functions of cells and living organisms.
• The main difference between bacterial ribosomes and eukaryotic ribosomes is that some antibiotics will inhibit the function of bacterial ribosomes, but in the case of eukaryotes.
• The function of ribosomes aside from protein synthesis, is that it helps in transferring the genetic material of bacterial cells.
• Flagella is a cellular component that can only be found mostly in prokaryotes like bacteria.
• Flagella is a hair like structure that provides a means of locomotion.
• Flagella helps the bacterial cell to move in clockwise and counter-clockwise, forward and helps the cell to spin.
• Flagella can be found either on both ends of a bacterium or all over its surface.
• Pili is the small hair like projections emerging from outside of the cell surface.
• Pili assist the bacteria in attaching or adhering on a surface or sometimes to host.
• Pili is also involved in gene transfer mechanism called sex pili or fertility pili.
• The gene is transferred through pilus from donor to recipient cell, this process is called conjugation.
• Without pili, many disease causing bacteria lose their ability to infect because they are unable to attach to host tissue.
• Plasmid are small circular DNA.
• The function of plasmid is to exchange DNA between bacterial cells.
• Nucleiod region is the irregularly-shaped section of the prokaruyotic cell where DNA is housed.
• Plasmid housed lacks the membrane found in the nucleus of eukaryotic cells.
• The nucleoid also contains RNA, proteins and enzymes used for cellular processes.