LECTURE 8

Question 1

what is the cytoplasm composed of?

Answer 1

90% water
it is a very thick, gel like composition

Question 2

what can be seen by microscopy in the cytoplasm and what are the functions of those elements?

Answer 2

1. nucleoid
   - irregular mass of DNA, circular, no nucleus
2. ribosomes
   - produce proteins
   - 20,000 ribosomes/cell
   - large and small subunits made of rRNAs and proteins
3. inclusion bodies (non or single layer membranes)
   - storage granules, store nutrients
   - carbon, sulfur, nitrogen, phosphate
   - gas vacuoles, help bacteria float
   - magnetosomes for magnetotaxis (iron containing)

Question 3

how is the cytoplasm organised?

Answer 3

organised by a cytoskeleton, less complex than eukaryotic cells

Question 4

what type of bacteria can make endospores?

Answer 4

gram positive, and even then it’s only some

Question 5

what are endospores?

Answer 5

most resistant biological structures known
can resist harsh environmental conditions
non growing, resting, no metabolism, survival state
can survive for millions of years (heat, radiation, dehydration)

Question 6

when is the formation of endospores induced?

Answer 6

when growth conditions are unfavorable

Question 7

what happens to endospores when the conditions are favorable again/

Answer 7

they start growing again (germinate)
these growing cells are called vegetative cells

Question 8

what is the formation of endospores called and what happens to the cell composition?

Answer 8

sporulation
reduction of the water content from 90% to 15%
increase concentrations of calcium and dipicolinic acid

Question 9

what is the process of sporulation?

Answer 9

from a vegetative cell to an endospore
- cell divides into two unequal parts
- the larger part engulfs the smaller part (forespore)
- forespore matures to become an endospore
- synthesis of a protective thick wall
inner cortex (peptidoglycan)
spore coat (keratin-like protein)
exosporium (proteins, polysaccharides, lipids)
- dehydration of the endospore (90% to 15%)
- lysis of the vegetative cell to release the endospore

Question 10

what is the process of germination?

Answer 10

from an endospore to a vegetative cell, when things are good again
- permeability of the wall changes, water entry
- endospore swelling and rupture of the coat
- germ tube grows out of the protective coat

Question 11

what are the types of bacterial division?

Answer 11

binary fission: divide near the midpoint to form two daughter cells
bacteria, algae, most protozoa and fission yeast

budding: forming a bubble like structure that comes out and eventually separates from the parent cell
some bacteria, budding yeast

others: fragmentation (filamentous growth), exospore formation

Question 12

what is the process of bacterial cell division?

Answer 12

1. chromosome replicates as the cell grows
2. daughter chromosomes separate by mechanism that remains unknown
3. new membrane and wall material starts growing through mid section
4. membrane and wall material deposited at the cell midsection divide the cytoplasm in 2

Question 13

what happens if bacteria divide but stay attached?

Answer 13

that is when they form chains/other forms of groupings