Prokaryotic Cells: Internal & External Cell Structures

Question 1

Identification

• Protein synthesis
• Prokaryotic ____: 70s
• Subunits (Small: 30s, Large: 50s)
• Directly responsible for translation (RNA → proteins)
• Central dogma (Translation)

Answer 1

Ribosomes

Question 2

• unit used for weight
• ____s
• determined by placing object in centrifuge

Answer 2

Svedberg Sedimentation Coefficient / Svedberg Units

Question 3

• Visible mass of aggregated chromosomes
• Circular chromosomes in prokaryotes

Answer 3

Nucleoid

Question 4

• supplemental genetic material
• confirms advantages of prokaryotes
• not necessary for survival, more like “superpowers”
• Ex. antibiotic resistance, resisting/utilizing heavy metals

Answer 4

Plasmids

Question 5

Modified T/F

Plasmids are necessary for survival

Answer 5

F

not necessary

Question 6

• genes that can do horizontal gene transfer (instead of vertical/parent-child)
• when 2 cells exist and exchange with each other

Answer 6

jumping genes

Question 7

Kinds of Storage Polymeres

4

Answer 7

• carbon
• polyphosphate
• sulfur
• carbonate

Question 8

• particles of iron mineral magnetite (Fe3O4)
• Function: orientation to low O2 envi (ex. bottom of the lake) → #thriving
• for anaerobic, aquatic bacteria
• will not grow at high O2 envi
• gives appearance of movement

Answer 8

Magnetosomes

Question 9

allows cell to align to the earth’s gravitational pull

Answer 9

magnetotaxis

Question 10

• “balloons”
• for phototrophic, aquatic bacteria who thrive in high O2 envi
• ↑ cell buoyancy (makes cell lighter → cell floats)

Answer 10

gas vesicles

Question 11

Fill in the blank

____, aquatic bacteria prefer low O2 environments and have ____, while
____, aquatic bacteria prefer high O2 environments and have ____.

Answer 11

anaerobic, magnetosomes
phototrophic, gas vesicles

Question 12

• Resistant to heat, radiation, harsh chemicals
• only in G+ bacteria

Answer 12

endospores

Question 13

2 components responsible for endospore

Bonus: Give function

Answer 13

Calcium dipicolinate:
* Cell dehydration

Small acid-soluble proteins (SASP)
* DNA stability
* Carbon & energy source

Question 14

List all prokaryotic external Structures

Answer 14

1. Flagella
2. Gliding Motility
3. Chemotaxis
4. Phototaxis
5. Axial Filaments
6. Pilus & Fimbriae
7. Glycocalyx

GGCFAPP (Gliding, Glycocalyx, Chemo, Flag, Axial, Photo, Pilus)

Question 15

• Helical structure
• Rotational movement
• Rotor (Basal body) + Stator
• Powered by Proton Motive Force

Answer 15

flagella

Question 16

Protein subunit of flagella

Answer 16

flagellin

Question 17

List

Flagellar Arrangement

[4] Bonus: what are they? & how do they move?

Answer 17

Peritrichous [☀︎]
* Flagella spread and placed all over the cell
* tumble run movement

Polar [O~]
* One flagellum
* Reversible: CW move back, CCW move forward
* Unidirectiontal/Irreversible: CW move, CCW it stops & reorients

Lophotrichous [O≈]
* Bundle of flagella at one end of the cell

Amphitrichous [~O~]
* 2 flagella at both ends

Question 18

Parts of flagella

Answer 18

Basal Body (rotor)
* Rings (L, P, MS, C -> depends where they are embedded)
* Rod

Stator
* Mot proteins (torque)
* Fli proteins (directional)

Extra:
L - LPS
P – Peptidoglycan
MS – cytoplasmic M
C – in contact w/ cytoplasm

Question 19

• Filamentous and rod-
  shaped cells
• Constant contact with
  solid surface
• secrete slimy polysaccharides → slide on surface

Answer 19

Gliding motility

Question 20

Kinds of Gliding Motility Movements

Answer 20

Slime extrusion
* C. johnsoniae, oscillatoria

Twitching
* Type IV pilus (pili) used for movement

Ratcheting
* proteins embedded in the OM and CM act as legs and feet

Question 21

• Movement in response to chemical signals
• Tumble-run movement
• Temporal factors detected by chemoreceptors
• attractant / repellant
• “Capillary test”

Answer 21

chemotaxis

Question 22

Explain

Capillary Test

chemotaxis

Answer 22

• Attractant in capillary tube → cells move to tube
• Repellant → repelled
• Nothing → random movement (tumbles > runs)
• Attractant/Repellant present: directed movement (runs > tumbles)

Question 23

Movement in response to light

Answer 23

phototaxis

Question 24

Examples of Phototaxis

2

Answer 24

Scotophobotaxis
* avoids darkness kahit hindi nila kailangan ng light (arte lang)
* clump in scpecific wavelengths

True phototaxis
* less → more light

Question 25

• Endoflagella
• Corkscrew rotation
• Found in spirochetes

Answer 25

Axial Filaments

Question 26

Where are Axial Filaments found?

Answer 26

spirochetes

Question 27

• genetic transfer pathway
• Allows genetic variation (horizontal gene transfer)

——and——
* shorter, hair-like
* ↑ pathogenicity (Adherence to surfaces and tissues)
* Biofilm formation
* May form pellicles in broth
medium

Answer 27

Pilus and Fibriae

Question 28

Differentiate Pilus and Fimbriae

Answer 28

Pilus: longer & fewer; genetic transfer

Fimbriae: shorter, shorter, hair like; pathogenicity

Question 29

• External Structure
  Capsule + Slime Layer

Answer 29

Glycocalyx

Question 30

• Part of Glycocalyx
• Rigid, tight matrix
• ↑ pathogenicity
• Resists phagocytosis & desiccation

Answer 30

Capsule

Question 31

• part of glycocalyx
• Easily deformed, loosely attached
• Increases pathogenicity and attachment
• Resists desiccation
  Helps protect cell from drying up

Answer 31

Slime Layer