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Flashcards in LECTURE 6 Deck (60)
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1
Q

Peptidoglycan

A

A thin sheet composed of

1) chains of repeating disaccharide unit composed of two monosaccharides
2) small peptides

2
Q

What are the two monosaccharides that compose the repeating chain of disaccharides in peptidoglycan

A

1) N-acetylglucosmine (NAG)

2) N-acetylmuramic acid (NAM)

3
Q

Small peptides that make up peptidoglycan

A
  • attaches to NAM peptides in adjacent chains, cross-linking the chain, making them stronger
4
Q

Where does the short peptide get added to?

A

Gets added to the NAM

5
Q

How do tw peptide side chains attach to each other

A

Via covalent bonds

6
Q

Transpeptidation

A

The cross linking reaction of two peptide chains, this adds strength

7
Q

Is peptidoglycan a barrier to solutes, why or why not?

A

No, because the opening are to large.

8
Q

As. A bacteria grows, peptidoglycan

A

Is produced more.

9
Q

Some antibiotics are specific to certain bacteria, what is this based on.

A

Based on their ability to target prokaryotic-specie structures.

10
Q

Two common targets for antibiotics are

A

1) Prokaryotic ribosomes

2) Prokaryotic cell walls

11
Q

What does it mean for a cell to lyse ?

A

For it to burst

12
Q

Lysozyme

A

An enzyme that catalysts hydrolysis of B 1-4 linkages between NAG and NAM

Peptidoglycan falls apart, causing the cell to lyse.

13
Q

Staphylococcus

A

Gram positive bacterium

14
Q

As bacterial cells grow, it synthesizes more

A

Peptidoglycan

15
Q

How does penicillin work?

A

1) transpeptidation is catalyze by a specific enzyme
2) penicillin inhibits this enzyme
3) peptidoglycan weakens
4) eventually the cells bursts (lysis)

16
Q

What does penicillin work best on ?

A

Gram positive cells

17
Q

Many bacteria besides having a cell wall also have a

A

Capsule

18
Q

What is a capsule made of

A

Mostly polysaccharides

19
Q

Capsules functions

A

1) protects from environment

2) stick bacteria to surface

20
Q

What i sa capsule rare is

A

Archaea

21
Q

Two types of pili

A

1) Fimbriae

2) sex pilus

22
Q

Fibriae

A

Attaches to surface of host cells

Gonorrhoea uses fumbriae to attached itself to mucus membranes

23
Q

Sex pilus

A

Transfers DNA or plasmid between bacteria cells

24
Q

Bacterial conjugation

A

DNA is transfers to another bacteria

25
Q

Plasmid

A

A small circular DNA distinct form the chromosome

26
Q

In a heterogenous environment, many bacteria exhibit

A

Taxis

27
Q

Taxis

A

The ability to move towards or away from a stimulus

28
Q

Chemotaxis

A

Movement towards or away from a chemical stimulus

29
Q

How do motile bacteria move

A

In a series of runs and tumbles

30
Q

What happenes if the concentration of the attractant increases during the run

A

The duration of the run is longer.

31
Q

Who has flagella

A

Bacteria, archaea, and eukaryotes

32
Q

What is the flagella composed of ?

A

Different proteins that evolved independently

33
Q

What is the flagella used for ?

A

Movement.

CCW = run 
CW = tumble
34
Q

What does E.coli use to power its motor

A

A proton-based (H+) electrochemical gradient

35
Q

Archaea cell walls

A
  • no outer membrane
  • coverings surrounding plasma membrane, produces a stronger membrane
  • no peptidoglycan
36
Q

What are some archaea covered in ?

A

Archaea specific lipopolysacchrides

37
Q

Eukaryotic cell walls

A
  • provides shape and protection

- cellulose chains embedded in a matrix of other polysaccharides and proteins

38
Q

Do animal cells have cell walls

A

NO

39
Q

Ho has cells walls

A

Plants and fungi

40
Q

Plant cell walls

A
  • young plant cells secrete a thin cell wall outside the plasma membrane
  • primary cell wall
  • secondary cell wall
41
Q

Primary cell wall

A
  • able to expand as the cell grows
  • older the cell, stronger the membrane
  • secrete hardening substances into primary
42
Q

Secondary cells wall

A
  • may have many layers

- made of matrix of strong materials

43
Q

Cells in wood have many layers of

A

Cellulose, lignin, proteins

44
Q

Between primary cell walls of adjacent plant cells is the

A

Middle lamella

45
Q

The middle lamella is composed of

A

Sticky polysaccharides called pectins

46
Q

Pectin

A

Glues the adjacent cells together

47
Q

How are pectin and amylopectin different

A

Pectin is referring to a mixture of polysaccharides, more complex structure.

48
Q

Ripening first gets soft in part due to the real down of

A

Pectin

49
Q

Because of the thick cell wall and middle lamella, plant cells are

A

Isolated form each other

50
Q

What enables plant cells to communicate with the thick cell wall and middle lamella ?

A

Plasmodesmata

51
Q

Plasmodesmata

A

Pores that allows H2O and small solutes to pass.

52
Q

The pores of plasmodesmata can open and close depending on

A

environmental conditions or age of plant

53
Q

What is the order or membranes in a plant cell from outermost to inner most

A

Plasma membrane
Secondary cell wall
Primary cell wall
Middle lamella

54
Q

Animal cella

A
  • no cell wall, but secrete proteins and polysaccharides = extra cellular matrix (ECM)
55
Q

How do cells attach to the ECM

A

Using additional specialized proteins

56
Q

What are the specialized protein see to attach to ECM?

A

Fibronectin

57
Q

Fibronectin

A

Interacts with Collagen, binds to a specific class of integral protein called integrins

58
Q

ECM consists of mostly

A

Glycoproteins and protein fibres (collagen)

59
Q

Collagen is

A

Embedded in network of glycoproteins called proteoglycans.

60
Q

Proteoglycan complex:

A) types of molecules

B) what is molecule made of?

A

A) proteoglycan molecules

B) carbohydrates and core protein