Lesson 1 - Prokaryotic cells

Question 1

meaning hypertonic solution

Answer 1

a solution with a higher concentration of solutes and lower concentration of water than the surrounding solution

Question 2

meaning peptidoglycan

Answer 2

a large, net-like molecule found in all bacterial cell walls made up of many parallel polysaccharide chains with short peptide cross-linkages

Question 3

meaning pili

Answer 3

thread-like protein projections found on the surface of some bacteria

Question 4

meaning bacteriophages

Answer 4

viruses that attack bacteria

Question 5

meaning flagella

Answer 5

many-stranded helices of the contractile protein flagellin found on some bacteria. They move the bacteria by rapid rotations

Question 6

meaning mesosomes

Answer 6

infoldings of the cell membrane of bacteria

Question 7

meaning nucleoid

Answer 7

the area in a bacterium where we find the single length of coiled DNA

Question 8

meaning plasmids

Answer 8

small, circular pieces of DNA that code for specific aspects of the bacterial phenotype

Question 9

meaning Gram staining

Answer 9

a differentiation staining technique used to distinguish types of bacteria by their cell wall

Question 10

meaning gram-positive bacteria

Answer 10

bacteria that contain teichoic acid in their cell walls and stain blue/purple with Gram staining

Question 11

meaning gram-negative bacteria

Answer 11

bacteria that have no teichoic acid in their cell walls. They stain red with Gram staining

Question 12

meaning teichoic acid

Answer 12

a chemical found in the cell walls of Gram-positive bacteria

Question 13

meaning cocci

Answer 13

spherical bacteria

Question 14

meaning bacilli

Answer 14

rod-shaped bacteria

Question 15

meaning spirilla

Answer 15

bacteria with a spiral shape

Question 16

meaning vibrios

Answer 16

comma-shaped bacteria

Question 17

meaning obligate aerobes

Answer 17

organisms that need oxygen for respiration

Question 18

meaning facultative anaerobes

Answer 18

organisms that use oxygen if it is available, but can respire and survive without it

Question 19

meaning obligate anaerobes

Answer 19

organisms that can only respire in the absence of oxygen and are killed by oxygen

Question 20

what is peptidoglycan made up of

Answer 20

many parallel polysaccharide chains with short peptide cross-linkages forming a net-like structure

Question 21

what may capsids be made up of

Answer 21

starch, gelatin, protein or glycolipids

Question 22

what is the function of capsids

Answer 22

covers the cell markers from phagocytosis by white blood cells. And, makes it harder for the immune system to identify the bacterium

Question 23

Give 2 examples of bacteria with a capsule

Answer 23

meningitis and TB

Question 24

give 2 examples of bacteria with pili

Answer 24

E. Coli and Salmonella spp.

Question 25

what is flagella made up of

Answer 25

many-stranded helix of the protein flagellin

Question 26

how do plasmids reproduce

Answer 26

they reproduce themselves independently of the nucleoid, and can be transferred from one bacterium to another by of sexual reproduction using pili

Question 27

why do gram-positive bacteria become purple-blue during gram staining

Answer 27

gram-positive bacteria have a thick layer of peptidoglycan containing teichoic acid. The crystal violet/ iodine complex is trapped in the thick peptidoglycan layer, resisting decolourising when the bacteria are dehydrated, using alcohol. So, do not pick up the red safranin counterstain

Question 28

why do gram-negative bacteria become red during gram staining

Answer 28

gram-negative bacteria have a thin layer of peptidoglycan, with an outer membrane above it. After the crystal violet/ iodine complex is washed out, the bacteria is dehydrated using ethanol, which dissolves the outer membrane. This leaves the peptidoglycan cell wall exposed, which takes up the red safranin counterstain, appearing red.

Question 29

what do antibiotics target bacterial pathogens

Answer 29

cell walls, cell membranes, genetic information, enzymes and ribosomes

Question 30

what are the 3 types of antibiotics

Answer 30

- Beta-lactam antibiotics - Glycopeptide antibiotics - Polypeptide antibiotics

Question 31

give 1 example of a Beta-lactam antibiotics

Answer 31

penicillins

Question 32

have do Beta-lactam antibiotics affect bacterial pathogens

Answer 32

inhibit the formation of peptidoglycan layer of the bacterial cell wall

Question 33

how effective is beta-lactam antibiotics against gram-positive or -negative bacteria

Answer 33

- very effective against gram-positive bacteria as have a thick peptidoglycan cell wall

Question 34

give 1 example of a glycopeptide antibiotics

Answer 34

vancomycin

Question 35

why do glycopeptide antibiotics not effective against gram-negative bacteria

Answer 35

they can't penetrate the outer membrane layer

Question 36

give 1 example of polypeptide antibiotics

Answer 36

polymixins

Question 37

how do polypeptide antibiotics affect gram negative bacteria

Answer 37

interact with the phospholipids in the outer membrane