Prokaryotic Cells Flashcards
(52 cards)
1
Q
What features define prokaryotes?
A
- semi-permeable barrier
- all contain ribosomes
- do not contain membrane-bound organelles or a nucleus
- genetic material organized into a single circular molecule of DNA concentrated in the nucleoid region
- single-celled organisms
- primitive cytoskeleton
- lack mitochondria so use cell membrane for ETC and generation of ATP
2
Q
What are the 3 domains that classify life?
A
- archaea (prokaryote)
- bacteria (prokaryote)
- eukarya
3
Q
Archaea
A
- single-celled organism
- live in really extreme environments
- similar overall structure to bacteria
- genes and metabolic pathways similar to eukaryotes
- use photosynthesis or chemosynthetic sources or inorganic compounds to generate energy
- contain a single chromosome
- divide by binary fission or budding
- resistant to many antibiotics
4
Q
Why is it believed that eukaryotes and archaea share common origin?
A
both start translation with methionine, contain RNA polymerases, and associate their DNA with histones
5
Q
Bacteria
A
- all contain cell membrane and cytoplasm – some have flagella or fimbriae
- share analogous structure to eukaryotes
6
Q
What is the ratio at which bacteria outnumber human cells in the body?
A
10:1
7
Q
Explain the relationship between the human body and mutualistic symbiotic bacteria
A
- both benefit from relationship
- Ex: bacteria in gut produce vitamin k and biotin which prevents overgrowth of harmful bacteria
8
Q
Explain the relationship between the human body and pathogens/parasites
A
- provide no advantage to the host
- cause disease
- can live intra- or extra-cellularly
9
Q
Bacteria Classification by Shape (3)
A
- cocci: spherical, “___coccus”
- bacilli: rod-shaped, “_____bacillus”
- spirilli: spiral-shaped, “_____spirella”; subset of these called spirochetes that have a very flexible twist in them
10
Q
Bacteria Classification by Temperature (3)
A
- psychrophiles: cold temp
- mesophiles: medium temp
- thermophiles: hot temp
11
Q
What is a bacteria cell wall made of?
A
peptidoglycan (combination of amino acid + sugar)
12
Q
What are auxotrophs?
A
- type of bacteria that can’t do something
- “arg-“ then can’t make arginine
- “leu-“ then can’t make leucine
- “lac-“ then can’t metabolize lactate
- amino acids = can’t make*
- sugars = can’t metabolize*
13
Q
Obligate Aerobe
A
- bacteria
- O2 present: can survive, can carry out aerobic metabolism
- O2 absent: can’t survive, can’t carry out anaerobic metabolism
14
Q
Facultative Anaerobe
A
- bacteria
- O2 present: can survive, can carry out aerobic metabolism
- O2 absent: can survive, can carry out anaerobic metabolism
15
Q
Obligate Anaerobe
A
- bacteria
- O2 present: can’t survive, can’t carry out aerobic metabolism
- O2 absent: can survive, can carry out anaerobic metabolism
16
Q
Aerotolerant Anaerobe
A
- bacteria
- O2 present: can survive, can’t carry out aerobic metabolism
- O2 absent: can survive, can carry out anaerobic metabolism
17
Q
What structures does a prokaryotic cell contain?
A
- cell wall
- flagella
- plasma membrane
- plasmids
18
Q
Cell Wall
A
- provides structure and controls movement of solutes
- two main types found in bacteria: gram-positive and gram-negative
19
Q
Gram-Positive Cell Wall
A
- envelope absorbs violet stain and appears deep purple
- has a thick cell wall composed of peptidoglycan (amino sugars put together)
20
Q
Gram-Negative Cell Wall
A
- does not absorb violet stain but envelope absorbs safranin counterstain which makes it appear pink-red
- thin wall with small amounts of peptidoglycan
- cell wall is separated from the cell membrane by the periplasmic space
- tend to be more antibiotic resistant
- carbohydrates and lipopolysaccharide (carbohydrate linked to membrane by a lipid) are found on the outer membrane
21
Q
What part of gram-positive bacteria triggers an immune response in humans?
A
lipoteichoic acid
22
Q
What part of gram-negative bacteria triggers an immune response in humans?
A
lipopolysaccharides
23
Q
Flagella
A
- used to propel bacteria
- allow a cell to detect chemical stimuli and move toward or away from the stimuli (referred to as chemotaxis)
- composed of: filament (hollow, helical structure made of flagellin), basal body (anchors flagellum to cytoplasmic membrane, motor), hook (connects filament and basal body, causes rotary movement)
24
Q
Plasmids
A
- small circular structures that carry DNA acquired from external sources
- external DNA is not necessary for survival of prokaryote
25
What subunits are found in prokaryotic ribosomes?
30s and 50s subunits
26
Binary Fission
- simple form of reproduction seen in prokaryotes
- leads to big increase in population size but no change in genetic diversity
- proceeds rapidly
27
Describe the 2 steps of binary fission
1. circular chromosome attaches to cell wall and replicated while cell grows in size
2. plasma membrane and cell wall grow inward along midline of cell (invagination) to produce two identical daughter cells
28
What are plasmids?
- involved in genetic recombination
- extrachromosomal material found in bacteria
- often carry genes that can benefit the bacterium -- genes for antibiotic resistance
29
What are virulence factors?
- involved in genetic recombination
- traits that increase how pathogenic a bacterium is
- includes: toxin production, projections that allow bacteria to attach to cells, evasion of host's immune system
30
What are episomes?
- involved in genetic recombination
| - subset of plasmids capable of integrating into the genome of bacteria
31
What is a vector?
- involved in genetic recombination, specifically transduction
- virus that carries genetic material from one bacterium to another
32
What are bacteriophages?
- involved in genetic recombination, specifically transduction
- viruses that infect bacteria
33
What are the different processes of recombination?
- transformation
- conjugation
- transduction
- transposon
34
Transformation
- results from integration of foreign genetic material into host genome
- foreign genetic material usually comes from other bacteria that spill their contents in the general vicinity via use of gram-negative rods
35
Conjugation
- leads to a big increase in genetic diversity without change in population size
- bacterial form of sexual reproduction
- use of a donor male (F+) and a recipient female (F-)
- allows for rapid acquisition if antibiotic resistance or virulence factors throughout a colony
36
Donor Male (F+)
- contains F (fertility) Factor (common plasmid that is a sex factor and contains necessary genes)
- forms the conjugation bridge (made from appendages called sex pili) which facilitates unidirectional transfer of genetic material to recipient female
37
Recipient Female (F-)
- accepts genetic material from donor male
| - does not contain sex factors that are necessary to form the pilus
38
Transduction
transfer of genetic material from one bacterium to another using a bacteriophage as a vector
39
Transposons
genetic elements that are capable of inserting and removing themselves from the genome
40
What are the phases of bacterial growth?
1. Lag
2. Exponential
3. Stationary
4. Death
41
Describe the features of the Lag Phase
- bacteria get used to environment
| - little growth during this time
42
Describe the features of the Exponential Phase
- bacteria use available resources to multiply at an exponential rate
- time of great growth
43
Describe the features of the Stationary Phase
- resources are used up
- bacterial multiplication ceases
- reached at carrying capacity
44
Describe the features of the Death Phase
- bacteria die as resources become insufficient to support the colony
- large decrease
45
Are ribosomes organelles?
NO
46
Cilia
- often found on prokaryotes
| - hairs that wave back and forth for motility
47
Are cell walls unique to Prokaryotes?
No -- all prokaryotes have these but some eukaryotes do too (Ex. plants, fungi)
48
What are the 2 amino sugars found in peptidoglycan?
1. N-acetyl glucosamine
| 2. N-acetylmuramic acid
49
What are the specialized coverings found on prokaryotic cells?
- capsule (resistant, protects bacteria from immune system)
| - slime layer (easily slips off bacteria, allows bacteria to escape from harm)
50
Bacteria have ___ growth
exponential
51
Symbiotic Relationship
- both bacteria and host benefit from interaction
| - ex. gut bacteria get nutrients from food we eat while bacteria digest some nutrients that we can't
52
Chemotaxis
-bacteria "senses" a chemical and can either move towards it or away from it
