CHAPTER 3.1-3.2 Flashcards
Where is DNA in bacteria and archaea
Cytoplasm
Bacterial cell walls are made of _____
Peptidoglycan
T/F: Bacteria and archaea have cell wals that are different tan any eukaryotic structure
TRUE
Bacteria and archaea _____ have organelles like eukaryotes
DO NOT
what is the cytoplasm made of ?
mostly water (80), but it also contains dissolved ions, nutrients, enzymes and various other molecules
What are the other structures in bacterial cells
- Cell wall
- cytoplasmic membrane
- cytoplasm
- chromosomes
- ribosomes
- flagella
- pili and fimbriae
- plasmids
Flagella and its function
Flagella- long, whip-like appendages that protrude from the cell body of bacteria and archaea
Function- responsible for mobility
Chemotaxis
Movement of bacteria toward or away from a chemical stimulus
What makes up a ribosome?
Ribosomal DNA and proteins
Positive chemotaxis
towards the attractant (nutrients)
Negative chemotaxis
away from the repellant (toxins)
Running
when the flagella rotate in one direction, allows the bacteria to move in a straight line
Tumbling
when the flagella reverse rotation, causing the bacteria to change direction
Pilus
- found in gram negative bacteria
- facilitates genetic diversity through DNA transfer
- longer and few in number
Fimbria
- protein subunits
- found in both gram negative and gram positive bacteria
- functions to adhere to surfaces/ promotes colonization
- shorter and more numerous
S Layer
- referred to as the armor of bacteria
- single layer of proteins or glycoproteins
- provides structural support and protection
- found in more extreme environmental conditions
Glycocalyx
- polysaccharide based coating (slime layer or capsule) —> bacterial
- involved in adhesion to surfaces and protextion against desiccation
Slime layer
- made of glycoproteins
- loosely attached to bacterial surface
- less organized
- helps bacteria evade host immune system but not as effective as capsule
Capsule
- Firmly attached and organized
- Composed of polysaccharides, in some cases polypeptides
- provides a strong defense against phagocytosis, desiccation and immune evasion
Main difference between: Slime layer and capsule
-Slime layer is loosely attached and more diffuse
- Capsule is firmly attached and more organized. Also provides stronger protection
Main difference between: S Layer and Glycocalyx
S Layer is a crystalline protein layer that offers structural integrity and protection
Glycocalyx is a polysaccharide based coating used for adhesion, protection and immune evasion
Main difference between Pilus and Fimbriae
Pili are longer, fewer and involved in DNA conjugation/mobility
Fimbriae are shorter, more numerous and specialized for adhesion
Biofilm
Complex, multilayer community of bacteria that adhere to surfaces and are embedded in a self-produced matrix of extracellular polymeric substances
Properties of Gram-negative bacteria
- cell wall is thick
- periplasmic space between the cell wall and cell membrane
- another layer
