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Flashcards in Prokaryotic Cells Deck (52)
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1

What features define prokaryotes?

-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

What are the 3 domains that classify life?

-archaea (prokaryote)
-bacteria (prokaryote)
-eukarya

3

Archaea

-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

Why is it believed that eukaryotes and archaea share common origin?

both start translation with methionine, contain RNA polymerases, and associate their DNA with histones

5

Bacteria

-all contain cell membrane and cytoplasm -- some have flagella or fimbriae
-share analogous structure to eukaryotes

6

What is the ratio at which bacteria outnumber human cells in the body?

10:1

7

Explain the relationship between the human body and mutualistic symbiotic bacteria

-both benefit from relationship
-Ex: bacteria in gut produce vitamin k and biotin which prevents overgrowth of harmful bacteria

8

Explain the relationship between the human body and pathogens/parasites

-provide no advantage to the host
-cause disease
-can live intra- or extra-cellularly

9

Bacteria Classification by Shape (3)

-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

Bacteria Classification by Temperature (3)

-psychrophiles: cold temp
-mesophiles: medium temp
-thermophiles: hot temp

11

What is a bacteria cell wall made of?

peptidoglycan (combination of amino acid + sugar)

12

What are auxotrophs?

-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

Obligate Aerobe

-bacteria
-O2 present: can survive, can carry out aerobic metabolism
-O2 absent: can't survive, can't carry out anaerobic metabolism

14

Facultative Anaerobe

-bacteria
-O2 present: can survive, can carry out aerobic metabolism
-O2 absent: can survive, can carry out anaerobic metabolism

15

Obligate Anaerobe

-bacteria
-O2 present: can't survive, can't carry out aerobic metabolism
-O2 absent: can survive, can carry out anaerobic metabolism

16

Aerotolerant Anaerobe

-bacteria
-O2 present: can survive, can't carry out aerobic metabolism
-O2 absent: can survive, can carry out anaerobic metabolism

17

What structures does a prokaryotic cell contain?

-cell wall
-flagella
-plasma membrane
-plasmids

18

Cell Wall

-provides structure and controls movement of solutes
-two main types found in bacteria: gram-positive and gram-negative

19

Gram-Positive Cell Wall

-envelope absorbs violet stain and appears deep purple
-has a thick cell wall composed of peptidoglycan (amino sugars put together)

20

Gram-Negative Cell Wall

-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

What part of gram-positive bacteria triggers an immune response in humans?

lipoteichoic acid

22

What part of gram-negative bacteria triggers an immune response in humans?

lipopolysaccharides

23

Flagella

-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

Plasmids

-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