Study guide ch. 4 A

Question 1

What are the 5 distinguishing characteristics of prokaryotic cells?

Answer 1

• unicellular bacteria and archaea
• DNA not enclosed within a nuclear membrane, usually have singular chromosomes
• No histones (proteins) or membrane bound organelles
• Cell walls almost always contain peptidoglycan
• Usually divide via binary fission

Question 2

What are the size ranges of prokaryotes?

Answer 2

• 0.2 to 2.0 micrometers in diameter
• 2.8 micrometers in length

Question 3

Which arrangement of bacteria divide at random planes and form GRAPE-like clusters or board sheets?

Answer 3

Staphylococcus

Question 4

Which arrangement of bacteria has two cocci?

Answer 4

diplococcus/diplobacilli

Question 5

Which arrangement of bacteria have cocci in chains?

Answer 5

streptococcus

Question 6

Which arrangement of bacteria is similar to the staphylococcus but divide in different angles?

Answer 6

Palisades

Question 7

Which arrangement of bacteria have groups of 4 cocci?

Answer 7

Tetrads

Question 8

TRUE OR FALSE: coccobacilli is NOT a cocci

Answer 8

TRUE
- true cocci have same measurements throughout, whereas coccobacilli does not

Question 9

What is the glycocalyx and where is it usually found?

Answer 9

• It is a gelatinous polymer composed of polypeptide, polysaccharide, or both. Sticky material on cell surface
• found external to the cell wall

Question 10

What is the slime layer and what is it used for?

Answer 10

• It is a type of glycocalyx that is loosely organized and attached
• used to protect bacteria cells from environmental threats

Question 11

What is the capsule and why is it so important?

Answer 11

• It is a type of glycocalyx that is highly organized and tightly attached
• It is important because they prevent phagocytosis and dehydration and allow for substrate attachment

Question 12

Which of these is NOT a function of the glycocalyx?
- Attachment: formation of biofilms
- Inhibit killing by white blood cells by phagocytosis, contributing to pathogenicity
- maintain shape of bacterium
- Protect cells from dehydration and nutrient loss

Answer 12

Maintain shape of bacterium

Question 13

When a bacterium moves in one direction for a period of time it is called a _______. When is it used by bacteria?

Answer 13

• Run
• Used when its flagella rotate counterclockwise and bundle together

Question 14

When a bacterium has abrupt random changes in direction it is called a _______. When is it used by bacteria?

Answer 14

• Tumble
• Caused by a reversal of flagellar rotation

Question 15

What is taxis?
Phototaxis?
Chemotaxis?
Attractants?
Repellents?

Answer 15

• The movement of bacterium towards or away from a particular stimulus
• movement of bacterium if the stimulus is light
• movement of bacterium if the stimulus is chemical
• movement of bacterium if it is a positive chemostatic stimulus
• movement of bacterium if it is a negative chemostatic stimulus

Question 16

What are pilli and which bacteria have it?

Answer 16

• They are rigid tubular structures made of pilin protein responsible for conjugation
• only found in gram-negative cells

Question 17

Cell wall of bacteria is found surrounding the _________ and is made up of _____,______, and_____.

Answer 17

• surrounding the plasma membrane
• peptidoglycan, alternating NAG and NAM which form the carbohydrate backbone, and polypeptide links

Question 18

Name the 4 functions of the cell wall

Answer 18

• To prevent rupture of bacterial cells
• maintain the shape of the bacterium
• serve as a point of anchorage for flagella
• produce symptoms of disease in some species

Question 19

What is the composition of the gram positive cell wall?

Answer 19

Thick peptidoglycan, teichoic acids, lipoteichoic acid, 1 periplasmic space

Question 20

What is the composition of the gram negative cell wall

Answer 20

Thin peptidoglycan, outer membrane, 2 periplasmic spaces

Question 21

What are the functions of teichoic and lipoteichoic acid?

Answer 21

• function in cell wall maintenance and enlargement during cell division
• move cations across the cell envelope
• stimulate a specific immune response

Question 22

TRUE OR FALSE:
Gram negative bacteria has teichoic and lipoteichoic acid

Answer 22

FALSE
Gram positive bacteria has it

Question 23

What do cell walls of acid-fast bacteria consist of?

Answer 23

• Large amounts of mycolic acid within their cell walls (fatty waxes)

Question 24

What does the outer membrane of the gram-negative cell wall provide a barrier to?

Answer 24

• Heavy metals
• Bile salts
• Digestive enzymes
• Certain dyes

Question 25

Transmembrane channels found in the outer membranes of bacteria are known as...

Answer 25

Porin proteins

Question 26

Proteins that permit passage of specific molecules are called __________

Answer 26

Specific channel proteins

Question 27

What genus of bacteria do not have any cell walls but have sterols in its plasma membrane?

Answer 27

mycoplasma

Question 28

How does mycolic acid help bacteria evade our immune system?

Answer 28

It contains a waxy hydrophobic barrier that prevents our immune cells from easily recognizing and engulfing it

Question 29

Which enzyme breaks down the cell walls of gram positive bacteria and where is it found?

Answer 29

- Lysozyme - in the rough ER

Question 30

What part of the cell does penicillin interfere with?

Answer 30

Outer membrane of gram negative bacteria

Question 31

What molecules make up the plasma membrane of prokaryotes?

Answer 31

Proteins and phospholipids (polar head and hydrophobic tail)

Question 32

Explain the structure of the plasma membrane

Answer 32

- Viscuous like olive oil, as the proteins move freely for various functions while phospholipids rotate and move laterally. Also self sealing

Question 33

What are the functions of the plasma membrane?

Answer 33

- It is selectively permeable, allowing passage of some molecules, but not others - Contains enzymes for ATP production - some membranes have photosynthetic pigments on foldings called chromatopheres

Question 34

What substances can destroy plasma membranes?

Answer 34

- Certain alcohols - quatenary ammonium compounds - antibiotics such as polymyxins

Question 35

Explain simple diffusion. What molecules can enter the cell via simple diffusion?

Answer 35

- When lipid soluble substances move from an area of high concentration to low concentration through a gradient - oxygen, carbon dioxide, and nonpolar organnic molecules

Question 36

What is facilitated diffusion and what molecule uses this to enter cells?

Answer 36

- Diffusion with the help of a carrier protein to transport molecules across the membrane - Glucose

Question 37

What is osmosis?

Answer 37

The movement of water molecules from an area of high water concentration to low water concentration

Question 38

What would happen if a bacterium was placed in an isotonic solution?

Answer 38

the bacteria would remain normal due to the balance of water and solute

Question 39

What would happen if a bacterium was placed in a hypertonic solution?

Answer 39

It would crenate due to the solute being more abundant than water, causing the water to be drawn out of the bacteria

Question 40

What would happen if a bacterium was placed in a hypotonic solution?

Answer 40

the bacteria would swell and lyse, due to excess water

Question 41

What is plasmolysis? | (think solutes and water)

Answer 41

The shrinking of a cell due to water loss in a hypertonic solution

Question 42

Explain active transport

Answer 42

The movement of substances against the concentration gradient across a membrane depending on a carrier protein