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DEOH102 > Prokaryotes > Flashcards

Prokaryotes Flashcards

1
Q

What are prokaryotes?

A
  • single celled organisms
  • no nucleus or other membrane-bound organelles
    (e.g. bacteria/arachae)
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2
Q

What are Eukaryotes?

A

single cell OR multi cell organism (mostly )
Contain nucleus and other membrane-bound organelles
e.g. fungi, plants, animals

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3
Q

What are the 3 common shapes of bacteria?

A

Cocci - spherical
Bacilli - Rod shape
Spiral

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4
Q

Name the 2 types of mouth bacteria.

A

Staphylococci
Streptococci

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5
Q

Explain staphylococci bacteria

A
  • tend to be in bunches (like grapes)-round “cocci”
  • cause skin infections
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6
Q

Explain Streptococci

A
  • round “cocci “,tend to be in chains
  • tend to be related to dental carries
  • bacterial infections of oral cavity
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7
Q

which bacteria is commonly associated with mouth disease/caries

A

Streptococci

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8
Q

Do bacterial cells have cell walls?

A

Yes

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9
Q

Do human cells have cell walls?

A

No

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10
Q

Name the parts of the bacterium

A

A- cytoplasm
B- Ribosome
C - DNA (circular)
D- Plasma membrane
E - Cell wall
F - Flagellum
G - Capsule
H - Plasmid
I - Pilus

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11
Q

Explain plasmids.

A
  • circular genetic material found outside of the main chromosome in prokaryote cells
  • independent replication from the main chromosome and transfer independently
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12
Q

Explain ribosomes

A
  • make proteins from mRNA
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13
Q

What does gram staining show?

A

Whether bacteria is gram positive or gram negative
G+ve stay purple
G-ve lose colour and look pink

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14
Q

How do G+ve and Gram -ve cells differ

A

G+ve. G+ve G-ve
Cell wall. single layer. Double layer
Peptidoglycans. Multi layers. Single layer
*Teichoic acid. Present. None
Outer membrane. No Yes
Morphology. Cocci. Rods
*Lipopolysaccharide No. Yes
Antibiotic resistance. More Less susceptible
Gram stain. stay purple. Pink
-
* in cell wall

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15
Q

Why are G+ve more susceptible to antibiotics than Gram -ve

A

Thick petidoglycans layers can absorb more of the antibiotic into them -so more concentrated in cell and fatal

No outer membrane wall as added barrier so
1. no lipopolysaccharides which do not let hydrophobic solutes ( e.g.antibiotics) in
2.No porin channels so unable to decrease number of channels/porins which then would decrease diffusion of the antibiotic into the cell

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16
Q

Why can G-ve be less susceptible to antibiotics than G+ve

A

Can alter their porins/so less number and decrease entry hydrophobic solutes ( antibiotics ) in

Less peptidoglycan in cell so absorb less antibiotic and outer membrane

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17
Q

Name 3 mechanisms antibiotics kill bacteria/fungi with example and how not harm human cells

A

1, INHIBITS CELL WALL SYNTHESIS - block peptidoglycan synthesis of bacteria - so cell fragile and bursts( eg penicillin)
2.INHIBIT PROTEIN SYNTHESIS- target 30S bacterial ribosome ( mRNA not translate into proteins)
eg tetracycline -
( humans not concentrate in large concentration to cause an affect or target different ribosome )
3. DISRUPTS MEMBRANE INTEGRITY- interacts with the lipopolysaccharide bacteria (lipid part ) or ergosterol in fungi production - so structure of membrane breaks down -leakage and death of the cell ( humans only have minimal ergosterol and no LPS in cell membrane so not harmed)

18
Q

Why are viruses not affected by antibiotics

A

No peptidoglycan cell walls, no ribosomes, not replicate their own DNA
Need host cells to replicate not replicate by themselves

19
Q

Why humans cells not harmed by antibiotics /antifungals

A

Human- minimal ergosterol and no LPS in cell membrane so not harmed by targeting or disrupting this process of cell membrane integrity which how some antibiotic /antifungal work

Human cells no peptidoglycans hence not susceptible to blocking of peptidoglycan synthesis

20
Q

How do micro-organisms develop antibiotic resistance ( 4 ways)

A
  1. PRODUCE ENZYMES( ie Beta lactamases against penicillins beta lactase ring ) that hydrolyse the ring and makes it inactive-
  2. ALTER TARGET SITE- so ribosomes proteins develop less binding sites for the tetracycline so less effective
  3. REDUCE PERMEABILITY OF DRUG - alter or decrease membrane channels ie porins, altering the ability to uptake the drug
  4. increase EFFLUX PUMPS to pump it back out ion the cell membrane

THES GENE ALTERATIONS CAN OCCUR THRU MUTATION OR HORIZONTAL TRANSFER OR PASSED ON FROM PARENT TO DAUGHTER CELLS

21
Q

What is horizontal gene transfer

A

A process where an organism transfers genetic material into another organism that is not its offspring ( this can spread antibiotic resistance)

22
Q

3 mechanisms of horizontal gene transfer

A

TRANSFORMATION- bacteria takes up free DNA from environment
CONJUGATION- bacteria directly transfers gene into another bacteria (cell to cell )
TRANSDUCTION- bacteriophage transfers gene from 1 cell to another

23
Q

What is transduction in horizontal gene transfer

A

A Bacteriophage incorporates a fragment of bacterial DNA into its genome ,then this piece of DNA transfers into a newley infected cell during the phage infection by the virus
Only short DNA segments can be transferred

24
Q

What’s transformation in horizontal gene transfer

A

A type of horizontal gene transfer where DNA is released from bacteria by cell lysis and the “free DNA” is taken up by a competent bacteria cell that then t incorporates it into its genome
Multiple genes may transferred

25
Q

What’s conjugation in horizontal gene transfer

A

Bacteria directly transfer genes into another bacteria due to cell to cell contact thru a sex pilus and phormones . DNA/plasmid moves from 1 cell into other cell
Long strands DNA can be transferred

26
Q

What are lipopolysaccharides

A

Found in G-ve cells - in the outer cell membrane -

27
Q

How do prokaryotes reproduce

A
  1. Binary fusion- grow and divide - replicating their DNA that stays same in each cell
  2. Conjugation - a form of horizontal gene transfer then 1 cell transfers DNA ( usually a plasmid ) to another cell thru pilus
  3. Endospores- in G+ve cells
28
Q

what’s an endospore

A

In G+ve cells -produced then dormant under stressful conditions that reactivate and generate further viable bacteria once conditions improve

29
Q

What colour do G+ve bacteria stain

A

Violet purple

30
Q

What colour do G-ve bacteria stain

A

Pink

31
Q

Give 3 reasons Why are G-ve bacteria have more resistance to antibiotics than Gram +ve

A
  1. Less peptidoglycan in outer membrane so less absorption antibiotic
  2. have a outer membrane with porins ( that can decrease number or alter structure ) so less antibiotic penetration
  3. Have LPS ( lipopolysaccharides) in outer membrane ) so maintain a barrier and decrease diffusion of hydrophobic solutes ( eg antibiotics )
32
Q

List similarities between eukaryote and prokaryote cells

A

Both have cell membranes and ribosomes

33
Q

List differences between eukaryote and prokaryote cells

A

Eukaryote Prokaryote
Cell wall - no LPS/petidoglycans. Have LPS/peptidogl

Nucleus - No true nucleus

Linear DNA in nucleus Single circular DNA
( not in a nucleus) &
Plasmids- small
circular DNA seperate
from main
chromosome

Contain membrane No membrane bound
bound organelles: organelles
Golgi
Lysosomes
endoplasmic reticulum
Mitochondria -

Ribosome 80S. Ribosome 70S

Mitosis for cell division Binary fusion
/endospores
/conjugation cell division

34
Q

What do mitochondria do

A

Energy production

35
Q

Name 4 organelles in eukaryote not prokaryote cells

A

Golgi/lysosomes /endoplasmic reticulum/Mitochondria

36
Q

What do endoplasmic reticulum do

A

Protein synthesis

37
Q

What do lysosomes do

A

intracellular digestion

38
Q

What do Golgi apparatus do

A

protein modification

39
Q

What cell has ribosomes of 70s

A

Prokaryote

40
Q

What cell has ribosomes 80S

A

Eukaryote

41
Q

Name 2 main components in prokaryotes and not eukaryotes and why this is therapeutically important

A

Prokaryotes have
1. petidoglycans in cell wall for cell rigidity shape - antibiotics that inhibit peptidoglycan synthesis won’t harm eukaryote cells as not contain these ( eg penicillin )

  1. Lipopolysaccharides in outermembrane G-ve so if disrupt this lipid component ( polymyxins ) membrane breaks and contents leak out and cell dies
    ( ( not in eukaryote cells so not harmed )

By targeting these components only in bacteria cell walls can kill bacteria cell but not damage host cells )

DEOH102 (25 decks)

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