Chapter 4- Prokaryotic Profiles

Question 1

What contains DNA in a prokaryotic cell?

Answer 1

Chromosomes

Question 2

Where are prokaryotic cells found?

Answer 2

Bacteria and Archae

Question 3

What are cell walls made of?

Answer 3

Peptidoglycan

Question 4

What structures are common to ALL bacterial cells?

Answer 4

They all have a cell membrane, cytoplasm, ribosomes, and atleast one (or a few) chromosomes.

Question 5

What structures are found in MOST bacterial cells?

Answer 5

Cell walls and a surface coating or glycocalyx.

Question 6

What structures are found in SOME bacterial cells?

Answer 6

Flagella, Pili, Fimbriae, Capsules, Slime layers, Inclusions, Actin Cytoskeleton, and Endospores.

Question 7

What makes up flagella?

Answer 7

Filament, hook (sheath), and basal body.

Question 8

What is the function of flagella?

Answer 8

Chemotaxis which is the attraction or repellant to a chemical response, and Phototaxis which is the positive or negative response to light.

Question 9

What are the types of cells with multiple flagella?

Answer 9

1. Monotrichous- single flagellum
2. Lopotrichous- small bunches or tufts of flagella emerging from the SAME SIDE
3. Peritrichous- dispersed randomly over the cell
4. Amphitrichous- one flagellum at both ends of cell

Question 10

Axial Filaments

Answer 10

Type of internal flagellum that is enclosed in the space between the cell wall and cell membrane. Also called PERIPLASMIC FLAGELLA and found in SPIROCHETES.
They move by expanding and contracting causing a wiggling motion.

Question 11

Pili

Answer 11

Elongate, rigid tubular structures made from the protein PILLIN. These are found on GRAM NEGATIVE bacteria and used in CONJUGATION (cell sex).

Question 12

Fimbrae

Answer 12

Small fibers containing protein that stick to each other and surfaces. Examples inlude e-coli and gonorrhea.

Question 13

What is a glycocalyx?

Answer 13

An outer coating of repeating polysaccharide units, protein, or both that protects the cell and can sometimes help the cell adhere to the environment.

Question 14

What are the different types of glycocalyxes?

Answer 14

1. Slime layer- a loose sheild that protects some bacteria from loss of water and nutrients.
2. Capsule- when the glycocalyx is bound more tightly to the cell and is denser and thicker. This inhibits phagocytosis.

Question 15

What is the function of the glycocalyx?

Answer 15

Formed by many pathogenic bacteria to protect itself from phagocytosis. This is important in the formation of biofilms.

Question 16

Biofilm

Answer 16

Layer of microscopic organisms that cover the surface of an object. This has serious medical implications as it is often found on indwelling devices.

Question 17

What is the cell envelope?

Answer 17

Present in the majority of bacteria. It lies outside of the cytoplasm and is composed of a CELL WALL, CELL MEMBRANE, and in some bacteria an OUTER MEMBRANE. The group of bacteria is determined by how many layers are present in the cell envelope.

Question 18

What determines if bacteria is gram POSITIVE?

Answer 18

The cell envelope of a gram POSITIVE bacteria will have two layers such as the cell wall and cytoplasmic membrane.

Question 19

What determines if bacteria is gram NEGATIVE?

Answer 19

The cell envelope of a gram NEGATIVE bacteria will have three layers such as the outer membrane, cell wall, and cytoplasmic membrane.

Question 20

What is the purpose of a cell wall?

Answer 20

To help determine the shape of bacteria and provide strong, structural support due to peptidoglycan. This also keeps cells from rupturing because of changes in pressure due to osmosis. It is the target of many antibiotics.

Question 21

What is the structure of a gram POSITIVE cell wall?

Answer 21

A thick (20-80nm), homogenouse sheath of peptidoglycan that contains tightly bound adicid polysaccharides.

Question 22

What is the structure of a gram NEGATIVE cell wall?

Answer 22

A single, thin (1 to 3nm) sheet of peptidoglycan surrounded by periplasmic space.

Question 23

Mycoplasmas

Answer 23

Bacteria that lack cell wall entirely. Only stabalized by steriods in membrane and range in different shapes. They are found in many environments and do not need a host.

Question 24

What happens when bacteria lose their cell wall?

Answer 24

1. gram POSITIVE- becomes a protoplast
2. gram NEGATIVE- becomes a spheroplast
   This can happen naturally mostly due to mutation.

Question 25

What is the outer membrane of a gram NEGATIVE bacteria composed of?

Answer 25

It is similar to the cell membrane but contains specialized polysaccharides and proteins. The UPPERMOST layer contains lipopolysaccharides. The INNERMOST layer is a phospholipid layer anchored by lipoproteins to the peptidoglycan layer below. The OUTER MEMBRANE serves as a partial chemical sieve and contains PORIN PROTEINS to act as a chemical pathway to the outside.

Question 26

What is the CELL MEMBRANE structure?

Answer 26

Very thin composed of phospholipids and proteins. It acts as a semipermeable barrier between the cell and the environlemt. The plasma membrane determines which molecules are transported by SIMPLE DIFFUSION, FACILITATED DIFFUSION, and ACTIVE TRANSPORT. The membrane provides a site for functions such as energy reactions, nutrient processing, and synthesis. It also regulates transport and aids in secretion.

Question 27

What is simple diffusion?

Answer 27

Passive, high to low to equal equilibrium. Osmosis uses this. Takes place in plasma membrane.

Question 28

What is facilitated diffucion?

Answer 28

High to low but too large to pass through without protein transport. Takes place in plasma membrane.

Question 29

What is active transport?

Answer 29

Against the gradient; low to high. Requires energy and transport protein. Takes place in plasma membrane.

Question 30

What is cytoplasm?

Answer 30

Gelatinous solution made up of 79-80% water that is the site for many biochemical and synthetic activities. Contains chromatin, ribosomes, granules, and actin strands.

Question 31

Bacterial Chromosomes

Answer 31

Single circular strand of DNA aggregated in dense area of the cell. It takes up much space.

Question 32

Plasmids

Answer 32

Nonessential pieces of DNA and if destroyed, cells will not die. They often confer protective traits such as drug resistance or the production of toxins and enzymes. Mostly GRAM NEGATIVE.

Question 33

Ribosomes

Answer 33

Made of RNA and protein, characterized by S units 3+5=7. They are the site of protein synthesis.

Question 34

Inclusions

Answer 34

"Cellular pantry" for bacteria. Serve as a storehouse when nutrients become depleted. Some aquatic bacterial inclusions include gas vesicles to provide buoyancy and flotation.

Question 35

Granules

Answer 35

A type of inclusion containing crystals of inorganic compounds that are used for cellular processes later on. They are not enclosed by membranes.

Question 36

Actin Cytoskeleton

Answer 36

Contribute to cell shape. Arranged in helical ribbons around the cell just under the cell membrane.

Question 37

Endospores

Answer 37

"Safety deposit box" that forms when cell encounters stress. In phase One, the cell is vegetative. In phase TWO it becomes an endospore.

Question 38

What is Phase One of endospore forming bacteria?

Answer 38

Vegetative cell. Can be induced by the environment to undergo spore formation (sporulation) due to the depletion of nutrients. It undergoes a conversion to be a sporangium.

Question 39

What is Phase Two of endospore forming bacteria?

Answer 39

The Sporangium formed in phase one transforms into an endospore. It can withstand extremes in heat. It then goes through germination which ensures the survival of bacteria for long periods of time. It will now be very hard to destroy.

Question 40

What are the three general shapes of bacteria?

Answer 40

1. Coccus- spherical 2. Bacillus- rod shaped 3. Spirillum- curviform or spiral shaped

Question 41

Archae

Answer 41

Prokaryotic cells that live in unconventional environments. They are mostly related to eukarya. They can be decomposers.