microbial diversity 1

Question 1

microscopic

Answer 1

too small to be seen easily with the naked eye ( need a microscope )

Question 2

osmotrophy

Answer 2

feeding mechanism involving the movement of dissolved organic compounds by osmosis for nutrition

Question 3

number of microbes

Answer 3

5 x 10^30 : bacteria, archaea and protists

10^31 : viruses

Question 4

the origin of life

Answer 4

• earth formed : 4.5 billion years ago
• oceans of liquid water : 4 billion years ago
• evolution of cellular organisms ( ‘bacteria
like’ microfossils ) : 3.8 billion years ago
•microbial formaions ( stromatolites ) : 3.5
billion years ago

Question 5

hydrothermal vents

Answer 5

life arose from gases ( H2 , CO2 , N2
H2S ) - energy from geothermal gradients created at a deep sea hydrothermal vent ( with tiny inter-connected compartments or pores

vents provided energy - in form of reduced elements ( H2 and H2S )

Question 6

lipid membranes : origin of cells

Answer 6

• synthesis of phospholipid vesicles could have enclosed the replication and biochemical reactions
• LUCA - population of primitive cells
• life divereged into 2 distant directions ( maybe due to physio chemical differences in their niche )
• natural selection : two distinct linneages - archaea and bacteria

Question 7

feeding : bacteria and archaea

Answer 7

feed by absorption of nutients

huge diversity of nutrional types :
heterotrophs , photoautotrophs , chemoautotrophs

Question 8

feeding : protists

Answer 8

feed by engulfing particles or other organisms or by photosynthesis ( or both )

Question 9

feeding : fungi

Answer 9

osmotrophs

feeding mechanism involving the movement of dissolved organic compounds by osmosis for nutrition

Question 10

feeding : viruses ( non-cellular )

Answer 10

replicate in host cell by assembly of pre-formed parts

Question 11

Linnaeus ( 1730s )

Answer 11

2 kingdoms :

• vegetabillia
• animalia

Question 12

Haeckel ( 1866 )

Answer 12

3 kingdoms :

• protista
• plantae
• animalia

Question 13

Chatton ( 1937 )

Answer 13

2 kingdoms :

• prokaryote
• eukaryote

Question 14

Copeland ( 1938/1947 )

Answer 14

4 kingdoms :

• monera
• protoctista
• plantae
• animalia

Question 15

Whittaker ( 1968 )

Answer 15

5 kingdoms :

• monera
• protoctista
• plantae
• fungi
• animalia

Question 16

Woese et al ( 1990 )

Answer 16

3 domains :

• bacteria
• archaea
• eukarya

in 1970s he pioneered the use of ribosomal RNA sequencing and devised the 3 domains of life

Question 17

16S ribosomal RNA

Answer 17

found in all bacteria and archaea
found in chloroplasts and mitochondria in eukaryotes

different regions have different levels of variability :
from highly conserved to highly variable

conserved : used to target gene
variable : used to distinguish between groups

Question 18

chimera

Answer 18

an organism or tissue that contains at least two different sets of DNA

Question 19

evidence for supporting the endosymbiotic theory

Answer 19

organelles have a small genome that encodes some proteins for respiratory chain ( mitochondria ) or photosynthetic apparatus ( chloroplast )

phylogenetic studies using rRNA gene-sequencing indicate that :

• Alphaproteobacteria are the ancestors of mitochondria
• cyanobacteria are the ancestors of chloroplasts