Topic 7- first life: prokaryotes

Question 1

prokaryotes have no ______________ unlike eukaryotes

Answer 1

membrane bound nucleus/ other organelles

Question 2

Which domains are prokaryotes?

Answer 2

domain bacteria and domain archaea

Question 3

The first unicellular organisms were ____( first life)

Answer 3

prokaryotes

Question 4

What 3 things makes prokaryotes so adaptable/ successful ?

Answer 4

1. small size (few needs)
2. reproduce via binary fission (fast, don’t need to find a mate)
3. short generation time (evolution can occur quickly, but may be inhibited by asexual reproduction)

Question 5

prokaryotic cells have ____ DNA, and a nucleus that __(is/ isn’t) enclosed by a membrane

Answer 5

circular

is not

Question 6

What does taxes mean? (singular = taxis)

give an example

Answer 6

movement away from or towards stimulus

eg. positive phototaxis is movement toward light

Question 7

Plasmids are present in prokaryotes. Define plasmid

Answer 7

small rings of dna containing a few “extra” genes

Question 8

prokaryotes have/ lack membrane enclosed organelles

some have ____ __ ____ ______

Answer 8

lack

infolding of cell membrane

Question 9

despite reproducing asexually, prokaryotes have high genetic diversity. how?

Answer 9

• short generation time and high mutation rate compared to eukaryotes = increased diversity

Question 10

how do bacteria exchange genetic info? (modify their genome)

Answer 10

genetic recombination via horizontal gene transfer

Question 11

name and explain the 3 types of horizontal gene transfer

Answer 11

1. transformation: ‘naked’ dna is picked up from dead bacteria in the environment (b/c when a cell dies, dna is released)
2. transduction: dna transferred by virus (bacteriophage)
3. conjugation: dna transferred between 2 bacteria

Question 12

define autotrophs and their 2 varieties

Answer 12

autotroph: make their own energy from inorganic sources
- chemoautotroph: use energy obtained by oxidizing inorganic chemicals, and co2 ( doesn’t need sunlight)- many prokaryotes
- photoautotrophs: use light energy and co2 (primary producers that support food web) eg. cyanobacteria–> O2!

Question 13

define heterotrophs and their 2 varieties

Answer 13

• don’t make their own energy! most bacteria must eat… enzymes digest organic molecules in environment absorbed through membrane
• photoheterotrophs: uses light energy; C source from organic molecules to help them process energy
• chemoautotrophs: use organic molecules for both energy and C source (eg animals, fungi, many prokaryotes, a few plants)

Question 14

many prokaryotes are symbiotic. If inside the host organism it’s ____

Answer 14

endosymbiotic

Question 15

define commensalism

Answer 15

A lives on/ with B, but neither harms nor benefits B

Question 16

define amensalism

Answer 16

A harms B, but A does not gain anything from it

Question 17

Studies of ___ structure revealed that there are actually __ very different lineages of prokaryotes

Answer 17

RNA

2

Question 18

bacteria have _____ in their cell walls

Answer 18

peptidoglycan

Question 19

archaea have more/ less variety in rna than bacteria

Answer 19

more

Question 20

why don’t archaea respond to antibiotics?

Answer 20

antibiotics act on the peptidoglycan in the cell wall & cause the cell wall to break (inhibits eubacterial growth)
therefore antibiotics only work on bacteria, not archaea

Question 21

most archaea live in ____ environments

Answer 21

extreme

Question 22

archaea methanogens live in _______

they produce ___ as a waste product

Answer 22

oxygen-free habitats such as swamp substrates and cow guts

methane

Question 23

archaea halophiles live in ____

Answer 23

very salty habitats

Question 24

archaea thermophiles live in ____

many are

Answer 24

very hot environments

chemoautotrophs

Question 25

cell wall in bacteria contains ____ which provides ___(list 3 things)

Answer 25

peptidoglycan

1. cell shape
2. protection
3. prevents cell form exploding when placed in hypotonic solution (lower in solutes than cell content)

Question 26

explain gram positive bacteria

Answer 26

they have peptidoglycan in cell wall in contact with external medium which traps purple stain

Question 27

explain gram negative bacteria

Answer 27

have lipopolysaccharide layer outside of cell wall, and thus do not absorb stain readily

Question 28

gram - species are often more ___ because the ____ layer can contain ___ and resist the action of ______

Answer 28

pathogenic
lipopolysaccharide
toxins
antibiotics

Question 29

scientists hypothesize that mitochondria evolved from ______ __ ____ through _____

Answer 29

aerobic alpha proteobacteria

endosymbiosis

Question 30

proteobacteria include ____mutualists called ____

describe the relationship

Answer 30

endosymbiotic
rhizobium which live in roots, and fix atmospheric nitrogen for the host to use in its metabolism
- the host plant then gives rhizobium carbohydrates

Question 31

e.coli is an example of a ____

Answer 31

proteobacteria

it’s a harmless commensal in human intestine

Question 32

______ and ____ are pathogenic bacteria

Answer 32

chlamydias and spirochetes

Question 33

cyanobacteria are ____trophs and produced O2 in atmosphere billions of yrs ago
- ___ evolved form cyanobacteria

Answer 33

photoautotrophs

chloroplast

Question 34

gram + pathogenic bacteria include

Answer 34

• clostridium botulinum (botox!)
• tuberculosis
• anthrax

Question 35

list 4 similarities among both domains of prokaryotes (bacteria and archaea)

Answer 35

• no membrane bound organelles
• single, circular chromosome structure
• small size
• cell wall is present

Question 36

list 4 differences among both domains of prokaryotes (bacteria and archaea)

Answer 36

• peptidoglycan in bacterial cell walls, not archaea
• plasma membrane is unbranched, Esther linkage in bacteria, and branched Esther linkage in archaea
• bacteria have linked RNA polymerase varieties, archaea have multiple