introduction to bacteria

Question 1

Describe the ways in which bacteria are identified by using particular features of their size, shape, growth requirements and staining characteristics.

Answer 1

Staining:

• Gram positive: purple
• Gram negative: pink

-Different strains-
Bacci are spherical
Cocci are rod-shaped

- can be identified via flagella:
monotrichous
lophotrichous
amphitrochous
petritrichous

Question 2

Describe the main structures and functions of a typical bacteria cell: chromosome, cytoplasm, cell wall, ribosome, penicillin binding proteins, peptidoglycan, lipopolysaccharide, capsule, flagella, fimbriae, plasmid, bacteriophage, spores.

Answer 2

chromosome- Genetic material
penicillin binding proteins- present in cell-surface membrane. Form crosslinks- can be carboxypeptidases, endopeptidases, transpeptidases
Peptidoglycan: main component of cell wall
formed by cross links between carbohydrates and amino acids. Give cell wall strength and structure.
Lipopolysaccharide- present in gram negative. Allow strong immune response in animals and humans
Fimbrae- allow attachment
Plasmid- antibiotic resistant form of genetic material which can be transferred between cells
bacteriophage- a virus which kills bacteria
spores- structures which allow the genetic material in a bacterial cell to be maintained in adverse conditions

Question 3

Explain the classification of and nomenclature used for bacterial species.

Answer 3

Based on genus and species.

Bacteria of same species have similar characteristics.

Question 4

Explain the difference between gram negative and gram positive bacteria and describe the features of the cell surface in both types

Answer 4

Gram positive bacteria have peptidoglycan as the main component of the cell wall. They are stained purple
Gram negative bacteria have lipopolysaccharide as their main component. cell surface-periplasmic space- peptidoglycan- lipopolysaccharide. They stain pink.

Question 5

Describe how bacteria replicate and create genetic variation

Answer 5

Binary fission- forms genetically identical bacteria.

Genetic variation- occurs via random mutations or by transfer of DNA.

Question 6

Describe brie y the detection and culture of bacteria

Answer 6

Can grow a bacteria culture.
Use a light microscope.
Can stain bacteria.
Use Gram microscope.
Can use DNA typing to distinguish between different strains.
Different types of medium-
basic agar or enriched( has something else like blood)