Cell membrane , Gram Positive and Gram Negative, Bacterial Structures

Describe the first step of the gram-staining process

1. Add crystal violet; add iodine The crystal violet attaches to the peptidoglycan and the iodine helps with the attachment process. The crystal violet give the purple stain. Both gram positive and gram negative will stain purple.

Describe the second step of the gram-staining process

2. Destain with alcohol The destaining takes away all of the stain on gram negative because there is less peptidoglycan in the cell wall for the stain to stick to in the first place. Additionally, it is harder for the stain to stick to the peptidoglycan since gram negative bacteria have an outer cell membrane. Because the stain sticks better to gram positive, when the destaining process is done, the gram positive remain purple and the gram negative lose all stain.

Describe the third step of the gram-staining process

3. Counterstain with safranin This adds a pink stain. Since purple is a more dominant color and gram positive is already purple, the gram positive will remain stained with pruple even after the safranin is added. Since the gram negative has no previous color after the destaining, the gram negative stains pink. The last step is to double check the staining and to help locate the cells with color under a microscope.

How many flagellum can a bacteria have?

As many as necessary; one or multiple

Describe endospore formation

At the beginning, the vegetative cell is actively growing. The process truly starts due to a change in environment. A harsh environment leads to a stop in the cell's metabolism and the replication of DNA. Following this, the cytoplasmic membrane pinches in and creates a wall of-sorts around the replicated DNA. A cortex is then established around the DNA. Afterwards, a spore coat forms to surround the cortex. Lastly, the mother cell shrivels away and lyses, thus releasing a free endospore.

What is the purpose of pili?

Attachment and exchanging of genetic information

What does the core contain?

Bacterial DNA, RNA, ribosomes, and most essential enzymes.

What are the functions of a cell membrane?

Barrier: resists osmotic pressure, controls what goes in and out Communication Structure and protection

Are gram-negative bacteria more resistant to antibiotics?

Generally, yes. This is because gram-negative bacteria have an outer membrane that excludes certain drugs and anitbiotics from penetrating the cell.

What is the function of the exposporium?

Gives the spore inherent hydrophobic characteristics and makes it insoluble

Why might the ability of endospore formation be more common in gram positive bacteria?

Gram positive bacteria have a thicker layer of peptidoglycan and when spores are made, the cortex is made of a thick layer of peptidoglycan.

What are the two components of the phospholipid bilayer?

Hydrophylic head and hydrophobic tail

Describe endospore structure

Inside to outside: core, inner membrane, germ cell wall, cortex, outer membrane, coat, exosporium

Where does the ability to make endospores come from?

It is genetic

What is the function of the coat in an endospore?

It is the initial permeability barrier because it sieves out thelarger molecules and allows for the permeation of smaller molecules

What is the function of the cortex in an endospore?

It is the main structure that is robust and offers the hardiness that the endospore has

Describe a saturated lipid tail

Linear structure No double bonds All carbons are "saturated" with hydrogens

What is the hydrophobic tail composed of?

Lipids

Why does a happy bacteria have saturated and unsaturated lipids?

Membranes need fluidity and the bent shape allows for the dynamacity

Do bacteria have a nuclei?

No

Is the exposporium always present in endospores?

No

Do all bacteria have a capsule, pili, and flagellum?

No, it depends on what there genetic code says

What does PAMP stand for?

Pathogen associated molecular patterns

What is the cortex made of?

Peptidoglycan

What is the germ cell wall made of?

Peptidoglycan

What is the inner membrane made of?

Phospholipids and proteins just like the cytoplasmic membrane

What is the purpose of spores?

Spores are formed when environmental conditions get difficult. Since the spores are extremely hardy, they allow the cell to survive through tough conditions.

What is the difference between pili and cilia?

Pili can exchange genetic information but cilia cannot.

What is the capsule made of?

Polysaccharide

What are porins?

Porins are proteins that form pores which allow for the transport of small ions and molecules

Are bacteria prokaryotic or eukaryotic?

Prokaryotic

What is the exosporium made of?

Proteins, lipids, and carbohydrates

What are the different types of lipids that can be in a phospholipid bilayer?

Saturated and unsaturated

What is the function of the inner membrane in an endospore?

Serves as a barrier to the core by preventing molecules from passing through; highly impermeable to molecules such as even water. Additionally, the inner membrane contains surface germinant receptors which bind germinants and initiate germination and vegetative growth

What are plasmids?

Smaller pieces of circular DNA that can be transferred

What are spores?

Structures formed by bacteria in protection against harsh environmental conditions.

What is the capsule?

The bacterial capsule is a protective layer that lies outside of the cell envelope

What is BAC?

The bacterial chromosome that contains the main set of DNA

What is the purpose of the capsule?

The capsule offers protection to the bacterial cell from the host cell's immune system. It makes it so the bacteria's pattern associated molecular patterns cannot be recognized and it prevents macrophages from eating the cell.

How does the structure of the core contribute to the function of the endospore as a whole?

The core has a dehydrated state which contributes to the enzymatic dormancy and heat resistance of the spore. The bacterial DNA inside the core is also bound to small acid-soluble spore proteins that physically shield the DNA from harmful chemicals and enzymes.

What is the function of the outer membrane in an endospore?

The function is not yet known

What is the function of the germ cell wall in an endospore?

The germ cell wall develops into the bacterial cell wall when the endospore becomes a vegitative cell. This is because structural differences between the germ cell wall and the cortex lead to the cortex being degraded upon germination.

Why is the hydrophobic tail water-hating?

The lipid structure is non-polar since it has en even electron distribution, so the lipid does not attract to water and no hydrogen bonds are formed

Why is the hydrophyllic head water-loving?

The phosphate group is polar and water is polar, so hydrogen bonds are formed

How does the flagellum spin?

The spin is caused by a proton gradient. There is a type of motor that is connected to the filament using a hook and this motor is activated by a proton gradient. Once the motor is activated, it causes the filament to spin.

What is pili?

A hair-like appendage found on the surface of bacteria

What is a lipoprotein?

A part lipid, part protein that anchors the membrane to the cell wall and holds peptidoglycan in place

What is the hydrophylic head composed of?

A phosphate group

What is the cell membrane composed of?

A phospolipid bilayer

What is peptidoglycan?

A polymer consisting of sugars and amino acids It is a PAMP

What are pili made of?

A protein called pillin

What is the flagellum?

A slender, threadlike structure that enables the bacteria to move.

What is a periplasmic space?

A thin layer of peptidoglycan that contains proteins concerned with the cell's metabolish

Where is bacterial DNA located?

Cytoplasm

What directions can the bacteria go in depending on the spin of the flagellum

Depending on if the flagellum spins clockwise or counterclockwise, the bacteria can either go straight or it can tumble.

Describe an unsaturated lipid tail

Double bond between carbons Bent at double bond

What would do the problem be with saturated lipids only?

There would be complete rigidity and the osmotic pressure would break the membrane

Why can pili exchange genetic information?

They are hollow so the genetic information can travel through

What is the coat made of?

Thin protein layers that are composed of coat proteins which are heavily cross linked via disulfide bonds

Why do we gram stain?

To determine whether a bacteria is gram positive or gram negative