bio.docx

**MODULE 5: INTRODUCTION TO CELL STRUCTURES AND FUNCTIONS OF A BACTERIUM** Bacteria are one of the most harmful microorganisms that cause diseases specifically infections to many living things. **BACTERIA** - single-celled organisms that lack nucleus or any membrane-bound organelle. \- classified...

**MODULE 5: INTRODUCTION TO CELL STRUCTURES AND FUNCTIONS OF A BACTERIUM** Bacteria are one of the most harmful microorganisms that cause diseases specifically infections to many living things. **BACTERIA** - single-celled organisms that lack nucleus or any membrane-bound organelle. \- classified as Prokaryotic Cell **Note:** Like plants and animals bacteria have also cellular components as well as unique names. \- most names of bacteria came from their **SHAPE** They have a simple cell structure. Their DNA is not enclosed in a nucleus; instead, it floats freely in the cell. They are usually smaller than eukaryotic cells. **Prokaryotic Cells**: Definition: These are simple, single-celled organisms without a nucleus. **Structure**: They have a simple cell structure. Their DNA is not enclosed in a nucleus; instead, it floats freely in the cell. **Size:** They are usually smaller than eukaryotic cells. **Eukaryotic Cells:** Definition: These cells can be single-celled or multicellular organisms with a nucleus. **Structure**: They have a more complex structure. Their DNA is enclosed within a nucleus. **Size**: They are generally larger than prokaryotic cells. **NOTE**: - Like plants and animals, bacteria have also cellular components as well as unique names. - Most names of bacteria came from their shape. **Bacterial cell -**is composed of different components that make them. It also has organelles that can also be found in both animal and plant cells. 1\. **CELL WALL -** 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. **Functions:** - helps in providing support, mechanical strength and rigidity to cell. \- also protects cell from bursting in hypotonic medium **CELLULOSE**: - Found in plant cell walls. \- Composed of glucose molecules linked by β-1,4-glycosidic bonds. \- Provides structural support and rigidity to plant cells. **PEPTIDOGLYCAN:** - Found in bacterial cell walls. \- Composed of sugar chains cross-linked by short peptides. \- Provides strength and rigidity to bacterial cells. 2\. **CAPSULE** - A protective covering of bacteria made up of polysaccharide **Function**: - keep the bacterium from drying out and protect it from phagocytosis (engulfing) by larger microorganisms. 3. **CYTOPLASM** - Also called the store house of all the chemicals and components that are used to sustain the life of a bacteria. **Function**: - for cellular growth, metabolism and replication of genetic material of bacterial cell 4\. **PLASMA MEMBRANE** Also called the cytoplasmic membrane, a semi permeable membrane which allows only selected materials to move inside and outside of the cell. **Function**: - helps in transportation of substances including removal of wastes from the body and providing a mechanical barrier to the cell. 5\. **RIBOSOMES** Function:- for protein synthesis \- helps in transferring the genetic material of bacterial cells. **Note:** The main difference between bacterial ribosomes and eukaryotic ribosomes is that some anti biotics will inhibit the function of bacterial ribosomes, but not in the casae of eukaryotes. 6\. **FLAGELLA** -a cellular component that can only be found mostly in prokaryotes like bacteria. \- hair like structure that provides a means of locomotion Function: - Helps the bacterial cell to move in clockwise and counter- clockwise, forward and helps the cell to spin \- They can be found at either or both ends of a bacterium or all over its surface. \*Flagella can be found in eukaryotic cell. Example is the sperm cell. 7. **PILI** - Small hair like projections emerging from outside of the cell surface Function: - assist the bacteria in attaching or adhering on a surface or sometimes to host. \- also involved in gene transfer mechanism called **sex pill** or **fertility pill** - the gene is transferred through the pilus from donor to recipient cell, this process is called **conjugation** 8\. **Plasmid** -- they are small cellular DNA Function: To exchange DNA between bacterial cells **MODULE 7: THE DIFFERENCE BETWEEN EUKARYOTIC AND PROKARYOTIC CELLS** **PROKARYOTES** - an organism made of one cell that does not have a nucleus or other organelles covered by a membrane. **BACTERIA** -the most common prokaryotes -singular, bacterium -the smallest know cells 1. No nucleus 2. Circular DNA shaped like a twisted rubber band 3. No membrane-bound organelles 4. A cell wall outside the cell membrane 5. A flagellum, a tail like structure that some bacteria use to help them move Looks like under a light electron microscope