Adhesion structures

Question 1

What is adhesion?

Answer 1

Attachment to a surface

Question 2

Why would cells want to attach to something?

Answer 2

Stops them from being flushed out of a particular location, or if a pathogen needs to stay near its host cells, biofilm formation, cell-cell attachments

Question 3

What is an adhesin?

Answer 3

A cell surface component that assists in attachment to a surface

Question 4

What are adhesins made of?

Answer 4

Sugars or proteins

Question 5

What is the structure of protein adhesins?

Answer 5

Filaments made of 1-2 polymerized proteins that extend out from the cell. They’re anchored in the cell wall and membrane with the basal body made of a bunch of proteins

Question 6

Which part of a protein adhesin is adhesive?

Answer 6

The tip

Question 7

What are fimbriae?

Answer 7

Short, hollow protein filaments that cover the cell

Question 8

Are fimbriae specific or non-specific?

Answer 8

Specific

Question 9

How do fimbriae allow tight interaction between the cell and the surface?

Answer 9

The cell can attach with all their fimbriae at once and create a really tight interaction

Question 10

What are pili?

Answer 10

Long protein filaments that stretch several cell-lengths away. Cells only usually have a few per cell

Question 11

What are 2 types of pili?

Answer 11

Sex pili and type IV pili

Question 12

Why can only some cells produce sex pili?

Answer 12

It requires the F plasmid to make, since it contains the gene for the pilus

Question 13

What is the sex pilus used for?

Answer 13

For bringing two cells close together to allow horizontal gene transfer and exchange of genetic info

Question 14

Does the sex pilus carry the DNA from cell to cell?

Answer 14

No, it brings the cells close together to allow the cells to fuse, and the DNA is exchanged at the fusion site

Question 15

What are type IV pili used for?

Answer 15

Adhesion of pathogens to host cells and twitching motility

Question 16

What is twitching motility?

Answer 16

When type IV pili extend out of the cell, retract, and pull the cell along a surface in a jerky movement that requires ATP

Question 17

What are hami?

Answer 17

The archaeal version of pili

Question 18

Are hami specific or non-specific?

Answer 18

Non-specific

Question 19

What is the structure of hami?

Answer 19

Protein filament with a barbed hook on the end

Question 20

How do hami work?

Answer 20

They act like grappling hooks and grab on to impurities in the soil and rocks so they don’t get washed away, as well as to each other to form biofilms

Question 21

What are capsules and slime layers?

Answer 21

Polysaccharide adhesins found outside the cell

Question 22

What are capsules?

Answer 22

Tightly organized and cross linked polysaccharide matrix that is tightly attached to the cell

Question 23

What do capsules do?

Answer 23

Assist in immune system evasion, exclude large molecules from getting into the cell, protect from desiccation

Question 24

What are slime layers?

Answer 24

Looser and more easily deformed polysaccharide layer around the cell

Question 25

How tightly are slime layers associated with the cell?

Answer 25

Not very much. They are loose a don’t exclude particles, and tend to be lost quite easily

Question 26

What are 3 functions of capsules and slime layers?

Answer 26

1. Attachment to solid surfaces
2. Protection from phagocytosis by immune cells
3. Protection from desiccation

Question 27

Are capsules and slime layers specific or non-specific adhesins?

Answer 27

Non-specific

Question 28

What are 3 other adhesive structures that aren’t adhesins?

Answer 28

LPS, S-layers, protein holdfasts in appendaged bacteria

Question 29

How do protein holdfasts in Caulobacter species work?

Answer 29

Extremely tight non-specific association with polysaccharides. They stick so tight that they never move again once stuck to a surface