Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CELS191 > Prokaryotic Cells > Flashcards

Prokaryotic Cells Flashcards

1
Q

How many bacterial cells are estimated to be on earth?

A

5x10^30

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the size of bacterial cells?

A

Approximately 10^-18m^3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How much of the biomass of earth do bacteria make up?

A

Half

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many bacterial species are there?

A

10^19 across two kingdoms (bacteria and archaea)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many species of mammals are there?

A

4300

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does the structure of bacteria include?

A

Fimbriae, nucleoid (where DNA sits but is not bound by a membrane), ribosomes, plasma membrane, cell wall, capsule and flagella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is cell wall peptidoglycan in bacteria?

A

A rigid macromolecular layer that provides strength to the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of peptidoglycan in cell walls?

A

Protects the cell from osmotic lysis (bursting) and confers cell shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the structure of peptidoglycan?

A

Carbohydrate backbone made of alternating NAG and NAM linked together. Cross linking of carbohydrate backbone with a peptide cross bridge of amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is transpeptidase?

A

The enzyme that cross links the peptidoglycan chains to form rigid cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the result of a gram stain?

A

A mixture of gram positive cocci appearing in purple and gram negative bacilli appearing in red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the first step of a gram stain?

A

Application of crystal violet (purple dye) to a mixed culture of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens after application of crystal violet?

A

Application of iodine which is a mordant that fixes the dye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens after application of iodine?

A

Alcohol wash which causes decolorisation of the gram negative cells while gram positive remains violet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens after the alcohol wash?

A

Application of safranin which is a counterstain that will only show up on gram negative cells as the violet in gram positive cells masks any effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the structure of a gram positive cell wall?

A

Thick peptidoglycan layer (20-80nm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the gram positive cell wall do in a gram stain?

A

Traps the crystal violet which masks the red sarafanin dye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the structure of a gram negative cell wall?

A

Thin layer of peptidoglycan (5-10nm) with inner and outer membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does the gram negative cell wall do in a gram stain?

A

Crystal violet is easily rinsed away revealing the red safranin dye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are some bacteria capable of?

A

Movement in a liquid medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How can bacteria move?

A

Motile bacteria produce flagella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are flagella?

A

Long flexible appendages reassembling tails

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are flagella made of?

A

Proteins (they are proteinaceous)

24
Q

What is the diameter of flagella?

A

10-20nm

25
Q

How many flagella are on a bacteria?

A

5-10 on average

26
Q

What to do with flagella varies?

A

The number of flagellant location on the cell surface

27
Q

What does a flagella act like?

A

A propeller. The cell rotates them to move through a liquid medium

28
Q

What is the 3 major sections of a flagella?

A

Long filament (F), Hook (H) and Basal Body (B)

29
Q

What does the long filament do?

A

Extends into surrounding medium. Composed of subunits (protein=flagellin)

30
Q

What is the hook?

A

A curved section connecting the filament to the cell surface

31
Q

What does the basal body do?

A

Anchors the flagellum into the cell membrane of the bacterium by special disc shaped structures called rings or plates

32
Q

What happens in chemotaxis?

A

Bacteria move along a concentration gradient towards a chemical attractant (positive)or away from a chemical repellent (negative)

33
Q

What does being able to move allow bacteria to do?

A

Sense and respond to their environment

34
Q

How does chemotaxis occur?

A

Bacteria sense the change in chemical concentration outside the cell over time “TEMPORAL GRADIENT” and thus respond to the change in concentration as the cell moves

35
Q

Why can’t bacteria use a spatial gradient for chemotaxis?

A

Because they are too small

36
Q

What are the bacterial adherence factors?

A

Fimbria and glycocalyx

37
Q

What are Fimbria?

A

Structures with adhesive properties that cause bacteria to stick/adhere to surfaces

38
Q

What type of trait is fimbria?

A

It is an inherited trait so not all bacteria have them

39
Q

What can fimbria be mistaken for?

A

Flagella, but they are not involved in motility

40
Q

How many fimbria on a bacteria cell?

A

100-1000

41
Q

What is the diameter of fimbria?

A

2-8nm

42
Q

What is the length of fimbria?

A

1 micrometre

43
Q

What is they types of glycocalyx?

A

Capsules and slime layers

44
Q

What is the glycocalyx?

A

A gelatinous polysaccharide and/or polypeptide outer covering. Forms a sticky meshwork of fibres/

45
Q

What is a capsule?

A

Glycocalyx organised into a defined structure attached firmly to the cell wall

46
Q

What is a slime layer?

A

Glycocalyx disorganised without cell shape, attached loosely to the cell wall

47
Q

What is the function of capsules?

A

They are virulence factors, help with adherence to cell surfaces and structures and also prevent the cell drying out (desiccation)

48
Q

What is meant by virulence factors?

A

Protecting bacteria from phagocytosis and engulfment by immune cells

49
Q

When are bacterial endospores formed?

A

During unfavourable growth conditions

50
Q

When are bacterial endospores germinated?

A

Under favourable conditions

51
Q

What do bacterial endospores do?

A

Protects the cell from stress

52
Q

What cells are bacterial endospores present in?

A

Only present in some gram-positive bacteria (genus = bacillus and clostridium)

53
Q

What stressors trigger endospore formation?

A

Nutrient starvation and high cell density (competition)

54
Q

What are endospores?

A

Highly differentiated cells resistant to heat, harsh chemicals, antibiotics, disinfectants and radiation

55
Q

What stage of the bacterial life cycle are endospores found?

A

The dormant stage and they may stay dormant for a very long time

CELS191 (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions