Components of the cell (II)

Question 1

What are the 2 groups of bacteria?

Answer 1

Archaebacteria, Eubacteria

Question 2

What are the 3 common shapes of bacteria?

Answer 2

1. Rod shape called bacillus (bacilli)
2. Spiral shape
3. Sphere shape called coccus (cocci)

Question 3

What are the components of a prokaryotic cell? (8)

Answer 3

Cell wall 
Cell/cytoplasmic membrane 
Capsule 
Cytoplasm 
Chromosomal DNA 
Ribosome 
Flagella 
Pili

Question 4

Describe the structure of the cell wall

Answer 4

Contains tiny pores
Works like a filter
Tough flexible and sometimes rigid

Question 5

What is the function of the cell wall?

Answer 5

Allows wastes to flow out
Maintains cell shape
Allow water and dissolved substances to flow into the cell
Provides cell with structural support, protection and filtering mechanism

Question 6

What is the key chemical component in bacteria cell?

Answer 6

Peptidoglycan

Question 7

Gram positive and Gram negative

Answer 7

2 large groups of bacteria (gram positive and negative) are differentiated based on their different cell wall constituents

Question 8

Differences between gram positive and gram negative bacteria:

Answer 8

Gram positive
purple stain
thick layer of peptidoglycan
Teichoic acid is present
Outer membrane is absent
Lipopolysaccharide (endotoxin) is absent
Porin protein is absent (unnecessary as there is no outer membrane)

Gram negative
pink stain
thin layer of peptidoglycan
Teichoic acid is absent
Outer membrane is present
Lipopolysaccharide (endotoxin) is present
Porin protein is present (allow molecules to pass through outer membrane)

Question 9

Examples of gram positive bacteria:

Answer 9

Rods:
Bacillus
Clostridium
Diphtheria

Cocci:
Staphylococci
Streptococci
Entercocci

Question 10

Examples of gram negative bacteria:

Answer 10

Rods:
Proteus
E coli Escherichia
Salmonella

Cocci:
Neisseria
Moraxella

Question 11

Describe the structure of the cell membrane:

Answer 11

composed of 2 layers of flexible (fluid like) lipid molecules (phospholipid bilayer)

• polar heads facing watery medium
• non polar tails face each other

Question 12

What is the function of the cell membrane?

Answer 12

-Separates the cell’s contents from its surrounding fluids
-Selectively permeable, allows easy diffusion of small, non polar molecules
-Regulates passage of larger or charged molecules
different to eukaryotic cell: they have sterols cholesterol

Question 13

What is the function of the capsule?

Answer 13

[] Polysaccharide layer that lies outside the cell envelope

• Thick covering of cell wall that protect bacteria from white blood cells, chemicals and dehydration
• Sticky nature allows it to adhere to other cells or surfaces

Question 14

Describe the structure and function of the cytoplasm:

Answer 14

[] Semi fluid (jelly like solution) that fills the cell

• contain cytosol and insoluble components
• composed of 65 % water (favourable conditions for chemical reactions to occur)

function: responsible for cell growth, metabolism, elimination of waste and replication (reproduction) of the cell.

Question 15

What is chromosomal DNA?

Answer 15

It is also called nucleoid (nucleus like). It consists of only DNA

• Not enclosed by a membrane
• Located within the cytoplasm

Question 16

Describe the structure of Bacterial DNA:

Answer 16

Composed of 1 single coiled chromosome located in nucleoid region and multiple copies of circular DNA (plasmids)

Question 17

What are plasmids?

Answer 17

short def: naturally occurring extrachromosomal DNA molecules, small, circular and double stranded

-often associated with conjugation, a mechanism of horizontal gene transfer

function:

• carry genes that build resistance against antibiotics or poisons
• code for protein that can kill other bacteria
• enable digestion of unusual substances
• turn the host of the plasmid into a pathogen

Question 18

Function of ribosome:

Answer 18

• only organelle in prokaryotes

- protein factory, site for synthesis of proteins

Question 19

Function of the Flagella:

Answer 19

Main role is locomotion (movement of bacteria)
serves as a “sensory unit”
“choose” to move forward towards a favorable environment or away from a hostile

-most cocci don’t have this, they are non mobile

Question 20

Name an application of plasmids in real life:

Answer 20

production of human insulin in bacteria by inserting insulin genes into plasmid vector then transfer them into bacterial cells for mass production of insulin

Question 21

Steps to using plasmids as a vector for production:

Answer 21

1. cut plasmid using restriction enzymes
2. insert gene/ plasmid into vector
3. ligase joins them together
4. plasmid vector- bacterial cells mass production

Question 22

Describe how the structure of Pili serves its function:

Answer 22

• Hair like projections surrounding the outer layer of the cell
• Enables bacteria to stick on surfaces or latch on other cells
• Also involved in process called “conjugation” where genetic material is transferred from 1 bacterium to another

Question 23

What do you call a bacteria with one or more pilis?

Answer 23

one pili- monotrichous
two- amphitrichous
four-lophotrichous
more… peritrichous

Question 24

What components of plant cell is not in animal cell?

Answer 24

• central vacuole
• cell wall
• chloroplast

Question 25

What components of animal cell is not in plant cell?

Answer 25

• Lysosome
• Centrioles
• Flagella (in some plant sperm)

Question 26

Describe the structure of plant cell wall:

Answer 26

composed of cellulose
pores enable small water soluble molecules (water, gases, ions, sugars) pass freely into and out of the cell wall

-contains plant wastes that taste bitter to certain insects, discouraging them from feasting on the plant

Question 27

Describe how the structure of cellulose supports the function of the cell wall:

Answer 27

strength of the cell wall enables the plant cell to absorb water into the central vacuole and swell without bursting

-the resulting pressure in the cells provides plants with rigidity and support for stems, leaves and flowers
(without sufficient water pressure, become dehydrated, will collapse)

Question 28

What is Plasmodesmata (plural)?

Answer 28

cell wall has canal like apertures which allows cells to remain connected with adjacent cells

-They are channels through the cell wall that allow cell-to-cell transport and communication

Question 29

What is the function of the central vacuole?

Answer 29

[] maintain the turgor pressure in the cell

• contribute to rigidity of plant cells
• Turgor pressure is the pressure of the cell contents pushing against the cell wall

Question 30

What is the function of chloroplast in the cell wall?

Answer 30

convert light energy (from the sun) into glucose (energy for plants) via photosynthesis

photosynthesis:
capture light energy and use some of that energy to synthesize organic molecules such as glucose

Question 31

Stroma is located in chloroplasts, explain the 3 membrane system they have:

Answer 31

they have a double membrane enclosing the stroma and the 3rd membrane is called Thylakoid which contains pigments that capture solar energy

Question 32

Granum:

Answer 32

Stacks of thylakoid, network of embedded stacked sacs