module 5

• cell wall

  -is composed of

  peptidoglycan - a protein-sugar

  (polysaccharide) molecule.

  -This gives the cell its shape and

  surrounds the cytoplasmic membrane

  protecting it from the environment.

  -The main function of it is it

  helps in providing support, mechanical

  strength and rigidity to cell. It also

  protects cell from bursting in

  hypotonic medium.

  
• Gram Staining

  -it is a process of dying

  bacteria and then viewing them

  beneath a microscope. This technique

  was proposed by Christian Gram to

  distinguish the two types of bacteria

  based on the difference in their cell wall

  structures.

  -Gram-positive bacteria show blue or

  purple after gram-staining in a

  laboratory test. They have thick cell

  walls. Gram-negative bacteria show

  pink or red on staining and have thin

  walls.

  
• Capsule

  -it 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.

  -Bacteria can also have a slime layer which covers the outside part of the cell wall. It works also as food reserve and sticks the cells together.

  
• 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. It helps

  in transportation of substances

  including removal of wastes

  from the body and providing a

  mechanical barrier to the cell.

  
• Cytoplasm

  The function of it is for cellular growth, metabolism and replication of genetic material of bacterial cell.

  -it is also called the store house of all the chemicals and components that are used to sustain the life of a bacteria.

  
• Ribosome

  -Can be found in eukaryotic and

  prokaryotic organisms.

  this functions for protein synthesis.

  Proteins are molecules that

  perform all the functions of cells

  and living organisms.

  -Some antibiotics will inhibit the

  function of bacterial ribosomes.

  It helps in transferring the

  genetic material of bacterial

  cells.
• Flagella

  -A cellular component that can only be found

  mostly in prokaryotes like bacteria.

  -It is a hair like structure that provides a means

  of locomotion.

  -It helps the bacterial cell to move in clockwise

  and counter-clockwise, forward and helps the

  cell to spin.

  
• Pili

  -The small hair like projections

  emerging from outside of the

  cell surface.

  -These outgrowths assist the

  bacteria in attaching or

  adhering on a surface or

  sometimes to host.

  -It is also involved in gene

  transfer mechanism called sex

  pili or fertility pili.

  
• Plasmid

  -They are small circular DNA.

  The function of it is to

  exchange DNA between bacterial

  cells.

  -they are circular DNA pieces,

  they replicate independently from

  the host’s chromosomal DNA.

  -These molecules, naturally,

  provide various benefits to the

  host cell, such as antibiotic

  resistance and degradative

  functions.

  
• Nucleoid

  -this region is the irregularly

  shaped section of the

  prokaryotic cell where DNA is

  housed.

  -It lacks the membrane found in

  the nucleus of eukaryotic cells.

  -this is also contains RNA ,

  proteins and enzymes used for

  cellular processes.

  
• peptidoglycan - a protein-sugar

  (polysaccharide) molecule.
• conjugation

  the gene is transferred through the pilus from donor to recipient cell
• sex pili

  gene transfer mechanism