TOPIC 4: Bacteria Cell Structure

Question 1

Cell structure is correlated to ______

Answer 1

Cellular function

Question 2

What are 4 things that every cell has?

Answer 2

• Cytosol
• ribosomes
• membrane
• DNA

Question 3

What are the size ranges of cells for prokaryotes and eukaryotes?

Answer 3

Prokaryotes: 1um-10um
Eukaryotes: 10um-100um

Question 4

Describe the main features of a prokaryotic cell

Answer 4

-No nucleus
- DNA in an unbound region (nucleod)
- no membrane bound organelles
- cytoplasm bounded by a plasma membrane
- circular chromosomes

Question 5

As the cell size increases in a prokaryote, what happens to the volume?

Answer 5

The volume will increases faster than the SA.
Cytosol volumes does not have enough membrane to metabollically support it (remember there are no membrane bound organelles)

Question 6

True or False: Nearly all prokaryotes have a cell wall

Answer 6

True

Question 7

What are eukaryote cell walls made up of?

Answer 7

Cellulose or chitin

Question 8

Bacterial cell wasll are made up of _______ which is a network of __________ cross linked by _______

Answer 8

1. Peptoglycan
2. Sugar polymers
3. Polypeptides

Question 9

Please review the cell structure photo for prokaryotic cells

Answer 9

Yuh

Question 10

What are the two tyoes of cell walls in bacteria?

Answer 10

• gram positive
• gram negative

Question 11

What is gram staining

Answer 11

A method in which that aids to classify bacteria due to their cell wall structure

Question 12

Gram staining procedure

Answer 12

1) primary stain (crystal violet)
2) wash
3) counter stain ( stain red, safranh)

Question 13

What happend if you gram stain a cell well made up of peptoglyden?

Answer 13

The thick peptoglyden later will trap crystal violet crystals. Violet is very intense so the bacteria will be a violet/purple colour

Question 14

What colour does a gram positive prokaryote make?

Answer 14

Violet

(Bc gram positive bacteria have a thick layer of peptoglycan)

Question 15

What happens when you gram stain a gram-negative bacteria?

Answer 15

The crytsal violetis is easily washed away, revealing the red safranin dye.

Question 16

Why does a negative gram bacteria turn red?

Answer 16

Because a negative gram bacteria has a more complex cell wall (two phospholipid bilayers with a thin layer of peptoglyden in between) and the crystal violetis cannot get through the outer membrane and becomes washed away, revealing the red dye

Question 17

What is the structure of a gram positive bacteria and why does it stay violet after staining?

Answer 17

Thick peptoglyden cell wall layer

Peptoglyden traps violet crystals, causing the membrane to be stained violet after the wash

Question 18

Many antibiotics target ______ and damage _____ cell walls

Answer 18

Peptidoglycan, bacterial

Question 19

What does the antibiotic penicillin do?

Answer 19

Disrupt transpeptidation cross link formation

Question 20

Which gram bacteria cell wall will be hit the hardest by penicillin?

Answer 20

Gram positive

Question 21

A polysaccharide or protein layer called a _____ covers many prokaryotes

Answer 21

Capsule

Question 22

Where is the bacterial capsule located?

Answer 22

On the top of the cell wall, being in the exterior

Question 23

Example of a bacterial capsule

Answer 23

Glycocalyx

Question 24

Two types of glycocalyx

Answer 24

1) capsule - fluffy outside, more intacts

2) slim layer - biofilms, more gooey, less intact)

These are both function in adhereance

Question 25

Some prokaryotes have _____ which allow them to stick to their substrate (the organism that they are attatched too) or other individuals in a colony

Answer 25

Fimbriae (the little stick tail)

Question 26

This fimbriae is a long type of fimbriae and allows prokaryotes to exchance small circular DNA called plasmids

Answer 26

Pili or sex pili

Question 27

In heterogeneous environments, many bacteria exhibit ____

Answer 27

Taxis (directional movement)

Question 28

What are two examples of taxis?

Answer 28

1) chemotaxes (moving away or twrd chemicals)

2) phototaxes (moving away or twrd from light)

Question 29

Flagella of bacteria of Eukaryotes and prokaryotes are composed of different proteins and likely evolved independantly

Answer 29

True

Question 30

What is a prokaryotic flagellum composed of? And how does it move?

Answer 30

Motor, hook and filament.
The flagellum moves like a rotating cork screw

(Pls see diagram in notes)

Question 31

What do prokaryotic cells usually lack?

Answer 31

Complex compartmentalizion
- some prokaryotes have plasma membrane unfoldings

Question 32

What crucial roles do prokaryotes play in the ennvironment?

Answer 32

• recycle: chemoheterophic (metabolism type) prokaryotes function as decomposers and break down waste and dead things
• play the role of primary producer

Question 33

Chemoheterotrophic prokaryotes function as what?

Answer 33

Decomposers

Question 34

Prokaryotes help eukaryotes get nutrition, give an example of this

Answer 34

Microbiome in soil

Question 35

Can prokaryotes sometimes increase the availability of nitrogen, phosphorus and potassium for plant growth?

Answer 35

Yes

Question 36

What are the four types of symbiosis

Answer 36

• mutualistic 😼😼
• commensalism 😼😐

-parasitic 😼🤕

• competition 🤕🤕 (neither benefit)

Question 37

What are the 5 functional roles of the human microbiome?

Answer 37

1) protect us from pathogens (competative with microbiome)

2) microbiomes are required for development ( help trigger gene expression)

3) provide vitamins and nutrients (ecoli gives us vitamin k, provides seratonin)

4) aid w/ digestion

5) make up our immune system (interations from pathogens help build our immune system)