exam 2

Question 1

what is growth is prokaryotes

Answer 1

o You need a microscope to view prokaryotes
o Time-lapse photography was used to study growth
 Cells reproduce as time goes on

Question 2

what is a single cell study

Answer 2

a method for studying cell cycle,
 Looks at simple cell
 You have to have a scope to watch it
 Starts off as a single cell (decreases in size) and then it divides and becomes two cells

Question 3

what are synchronized cultures

Answer 3

 Need to have a lot of cells, all the individuals have to be the same

Question 4

what is environmental manipulations

Answer 4

temp, photosynthesis, germination, starvation

Question 5

temperature in environmental manipulation

Answer 5

 You can do repetitive shifts
 42°C to 28°C
 Do this several times
 The microorganisms start growing at same pace

Question 6

photosynthesis in environmental manipulations

Answer 6

 Is good if the organism is photosynthetic
 Alternates light and dark
 Light allows it to grow
 Stop growing in the dark (won’t work for E. coli)

Question 7

germination in environmental manipulations

Answer 7

 Good if microorganisms make spores
 Good for bacillus (not for E. coli)

Question 8

starvation in environmental manipulation

Answer 8

 Will work with almost everything
 Shift from poor to rich medium
 In rich, everything grows at the same time and stays in the same stage
 If in poor medium, it doesn’t grow

Question 9

what is selection techniques

Answer 9

Done when we do studies on people
2 ways: Membrane filter technique and density centrifugation technique

Question 10

what is membrane filter technique

Answer 10

 First pass culture through a filter
 When culture passes filter, the cells can’t get through and line up on one side of the filter
 Then flip the filter over
 Very slowly pass fresh medium through
 Fresh medium feeds layers of cells, but they have no place to go
 They go down in the drop

Question 11

what is density centrifugation technique

Answer 11

 More common technique
 Make a gradient
 Gradient is made with gradient mixer
 Example: 5% sucrose and 35% sucrose gradient solution is filled in tube
 After making a gradient, you take the cells and put them on top of the gradient
 Since there is a different population of cells, they will end up in different layers after the centrifuge
 Example: layer cells on top of 5% and migrate to a point where their density is equal to sucrose solution

Question 12

what does the cell envelope and division in cocci consist of?

Answer 12

wall bands, wall notches, septum

Question 13

what are wall bands

Answer 13

 Little places that can be seen on microscope
 Sites from cells left over from previous cell cycle
 This is where cell is going to grow into new cell

Question 14

what are wall notches

Answer 14

 Invagination of new synthesis from wall bands
 Invagination continues until we get a complete separation

Question 15

what is a septum in cocci

Answer 15

 Point of cell division/synthesis

Question 16

what does the cell envelope and division in rod-shaped bacteria consist of?

Answer 16

rods dont have cell bands, multiple sites of new wall synthesis, septum, minicells,

Question 17

what is multiple sites of new wall synthesis

Answer 17

 New walls inserted in multiple sites during synthesis

Question 18

what is septum in rod

Answer 18

 There is still a septum that is made which leads to 2 new daughter cells

Question 19

what are minicells

Answer 19

 These are tiny cells that come off parent special mutant bacteria cell
 They don’t live long and can’t reproduce because they LACK GENES: nucleic acid/ chromosomes (DNA)
 Scientists put DNA inside them to see how a gene is expressed- that way there’s no background gene noise

Question 20

growth in eukaryotes

Answer 20

o DNA synthesis is not continuous
o Division is about 2 hours at the fastest to many days
o G1→ Preparation for DNA synthesis
o S→ DNA synthesis (chromosome replicates)
o G2→ Migration of the nucleus
o M→ Mitosis