R1 - Prokaryotes and Eukaryotes, Classification (CH. 1, 4, 10) , Bacterial Structure (Ch. 4 ) , Gram stain (Lab and Ch.3) Flashcards
Identify, describe and draw the variouse shapes and cell arrangements of bacteria.
- rod/ bacillus
- coccus
- spiral
- star
- pleimorphic
- coccobacillus
Bacillus
Rod shaped
“little staphs”
coccobacillus
look oval and so much like bacillus
Pleimorphic
They can have many shapes, not just one.
e.g. Corynebacterium dipnhtheriae
Spiral
have one or more twists and are never straight
- spirillium
- spirochete
Spirillium
Is under spiral
have helical shape, look like a corkscrew, and fairly rigid bodies
Has flagella.
Spirochete
Spiral
Helical and flexible;
move by means of axial filaments (internal) that rotate.
Coccus
spherical like berries
Cell arrangements of Bacteria
- strepto
- tetrad
- staphylo
- palisade
- diplococcus
Strepto -
occur in chains of cells
e.g . stepto bacilli
Tetrade -
Groups of 4
staphylo-
grape like clusters
Palisades
Picket fence like
Diplococcus
cocci that remain in pairs after dividing
Cell wall
a complex , semirigid structure resonsible for the shape of the cell. The cell wall surrounds he underlying, fragile plasma(cytoplasmic) membrane and protects it and the intertior of the cell from adverse changes in the outside environment.
- Almost all prokaryotes have cell walls
- The function of the cell wall is to prevent bacteria from rupturing when the water pressure inside the cell is greater than the outside of the cell
- Also helps maintain the shape of a bacterium and serves as a point of anchorage for flagella
- as the volume of a bacter ia increases it’s plasma membrane and cell wall extend as needed.
- Is the cite of action of some antibiotics
Cell Membrane
- encloses the cytoplasm and is a lipod bilayer with peripheral and intergral proteins.
- is selectively permeable
- contains enzymes for metabolic reactions such as nutrient breakdown , emergency reproduction , and photosynthesis
- mesosomes, irregular inforldings of the plasma membrane are artifacts , not true cell structures.
- plasma membranes can be destroyed by alcohols and polymyxns
Flagellum
- are long filamentous appendages that propel bacteria
- Gram-negative : contains 2 pairs of rings: the outer pair of the rings is anchored to variouse portions of the cell wall, and the inner pair of rings is anchored to the plasma membrane
- Gram-positive: only the inner pair is present in the plasma membrane.
-• Filament: outermost region that consists of proteins arranged in several chains that intertwine around a hollow core.
• Hook – which the filament is attached to. Outer part that rotates the flagellum clockwise.
• Basal Body – Anchors the flagellum to the cell wall and plasma membrane
Endospores
when necessary nutients are depleted, certain (not all) gram positive bacteria form specialized “resting “ cells. Inside bacteria endospores forms inside of vegetative bacterial cell (active metabolism) and then bursts out. Used for survival in poor conditions (lack of water, nutrients, etc)/
Cytoplasm
the substance of the cell inside the plasma membrane.
Ribosomes
function as sites for protein synthesis in the cytoplasm.
Inclusion body/cytoplasmic body
o (inclusions) for chemical storage in some bacteria; reserve deposits. Cell may accumulate certain nutrients when they are plentiful and use them when the environment is deficient.
- nutrient storage
- metachromatic granules
- magnetosomes
Plasmid
circular, double stranded DNA molecules. Replicate independently of the chromosomal DNA. Plasmids can be transferred from one bacterium to another.
Nucleoid
contains single long continuous and frequently circularly arranged thread of double-stranded DNA.
Fimbriae
Straight hairlike, attachment only
occur at the poles of the bacterial cell or can be evenly distributed over the entire surface of the cell. Straight, hair like, attachment only to surfaces. Involves in forming biofilms.
e.g. neisseria honorrhea
Pili
Straight , hairlike, gene transfer, ; can send DNA through for Bacteria to trade genes. Longer than fimbriar and number only one or two per cell.
o Functions: Involved in motility and DNA transfer.
capsule
if glycocalyx is organized and is firmly attached to the cell wall the glycocalyx is described as a capsule.
- thick
- tightly bound
- protects bacteria from phagocytosis
How is a capsule helpful to a bacterial cell?
Thick , tightly bound to cell, protects bacteria against phagocytosis
-Firmly attached to cell wall.
How is a slime layer helpful to a bacterial cell?
Flexible
helps bacteria attach to surfaces
protects cell against dehydration
2 main types of glycocalyx, including differences and similarieties
- slime layer
- capsule
Differences: Slime: loosely attached to cell wall Capsule : firmly attached to cell wall Slime: helps attach to surfaces capsule: no
Similarieties:
What are parts of an endospore?
components:
- cytoplasm
- plasma membrane
- peptidoglycan
- ribosomes
- dipicolinic acid
- spore coat (proteint)
Endospores are highly durable dehydrated cells with thick walls and additional layers.
where are endospores located in the cell?
they are formed internal to the bacterial cell membrane. True endospores are found in gam positive bacteria.
they can be located
- terminally
-central
-sub terminally - not at the tip but close enough to the en of the cell
Why are endospores hard to kill?
They can survive extreme heat, lack of water, and exposure to many toxic chemicals and radiation. Can withstand very little water and are resistant to disinfectants.
they need more time to be killed.
an autoclave may do that.
