Flashcards in Lecture 2 Deck (71):
What is a flagellum?
Structure that allows for motility in some orgs
3 patterns of flagella distribution in a cell
Polar- at one end
Peritrichous- all over
Lophotricious- multiple at one end
Regardless of distribution, flagella use a lot of ________ which will cause what to happen?
H+, will deplete H+ that are in H+ gradient, decreases ability of cell to produce ATP
Describe the speeds of a flagellum
There are no speeds and you cannot turn it off
Because of massive H+ demand of flagella, what does cell do?
It can "drop" flagella
Highly resistant to temp, desiccation, chemicals, etc.
Form of survival
Occurs in response to stress
Sporulating cell becomes the spore, 1 cell becomes 1 spore
No chromosomal replication, original chromosome gets packaged into the spore
Not metabolically active
Layers of prokaryotic spore
Core wall and core
Sticky, more likely to be transported, helps with dispersion, can have different chemical compositions
Contains enzymes that will help with germination
Thick layer of peptidoglycan
ONLY GRAM + can sporulate (not all do)
Core wall and core
-high conc. of Ca2+ and dipicolinic acid (not found in any other biological system) (help with resilience but don't know how)
- high number of ribosomes
Structure of flagellum
Support rings embedded in cell layers, anchored in cell wall
Extending out from cell wall or outer membrane, a hook structure
Helical in shape
Flagellum engine located just inside of cell membrane so it can turn flagellum itself and have access to H+
Determines direction of rotation
Counter clockwise: forward (run)
Motile cells response to environmental cues
Mostly applies to flagellate motility
Response to enviro cues via series of runs and tumbles; length of runs increase in detection of nutrients
Examples of taxis
Chemotaxis: response to chemicals
Thermotaxis: response to temp
Phototaxis: response to light
Surface area to volume ratio
Based on sphere
Larger cells - less metabolically efficient
Prok. More efficient than euk. Metabolically
Definition of metabolism
All chemical processes in a cell
1. Anabolism: biosynthesis (building cellular materials - requires energy
2. Catabolism - degradation (releases energy)
Energy molecules in a cell
ATP- assists for breakdown and work
NADPH- used in biosynthesis
Amount of free energy associated with substrate
(-) exergonic - readily give up e
Example: ATP ΔG=-7.3 exergonic, used in endergonic reactions
Eo = reduction potential
(-) likely to release e
(+) likely to accept e
Energy source classifications
Chemoorganotroph- use organic C for energy (eg. Glucose)
Chemolithotroph- use inorganic electron donors for energy (eg. H, N, S, Fe
Heterotroph- use organic C as carbon source (eg. Glucose)
Autotroph- use inorganic C as carbon source (eg. CO2)
What are the different parts of respiration
Glycolysis, pentose phosphate pathway (PPP), TCA cycle, electron transport chain (ETC)
Two forms of respiration
- aerobic: use O2 as terminal electron acceptor
- anaerobic: use something other than O2 as TEA (eg. N, S, Fe, etc.)
TEA other than O2 has slower growth
Total energy balance from glycolysis in aerobic respiration
2 NADH --> 6 ATP
Total energy balance from TCA cycle in aerobic respiration
8 NADH---> 24 ATP
2 FADH2---> 4 ATP
2 GTP ---> 2 ATP
Total ATP produced in aerobic respiration
Pathways in fermentation
Glycolysis, TCA cycle, PPP, fermentation steps
Use pyruvate from glycolysis
End products include alcohols and organic acids
No ETC; no H gradient, no ATP production via oxidative phosphorylation
Limitations to fermentation
No oxidative phosphorylation so produce very little ATP
Make end products that are toxic to the cell that generated it
Reduction in bio synthetic intermediates
TCA cycle intermediates and products
Pentose phosphate pathway
Starting substrate is glucose-6-phosphate
Produces Biosynthetic intermediates
What happens as electrons move down the electron transport chain?
H+ pumped into periplasmic space
What is the terminal electron acceptor in aerobic respiration?
What is the terminal electron acceptor in anaerobic respiration?
Something other than O2
What is the initiator of the electron transport chain in respiration?
NADH dehydrogenase- releases H+ and electrons
Where is the ATPase?
In the cell membrane, has 30 degree rotations
Purpose: recycles NADH into NAD+
Unless genetically modified orgs have several pathways
Toxic end products eg. Ethanol, lactic acid, propionate
Organisms that use chemolithotrophy are
Chemolithoautotrophs: use inorganic source of electrons and CO2 as source of C
Do all chemolithotrophs use chemolithotrophy?
No, some use photosynthesis
Where does the inorganic e donor donate it's es to in chemolithotrophy?
Directly to the ETC, don't need to be shuttled
How are Biosynthetic intermediates made in chemolithotrophy?
Turn CO2 into organic C by the Calvin cycle or reverse TCA cycle
Reverse TCA cycle
Requires energy from NADH or NADPH
6CO2 ---> fructose-6-PO4
Requires 12 NADPH and 18 ATP per cycle
A species will use _____ reverse TCA or Calvin to fix CO2
Either, they do not flip flop
Calvin cycle produces _____, which can go into:
Fructose-6-PO4---> glycolysis--->pyruvate--->TCA cycle
Reverse TCA cycle produces _____, which can go into:
Pyruvate---> TCA cycle
Glycolysis, TCA, PPP, ETC, and Calvin or reverse TCA to fix CO2
In aerobic chemolithotrophy what is the TEA?
In anaerobic chemolithotrophy what is the TEA?
Something other than O2
What is the enzyme responsible for incorporation of CO2 into the Calvin cycle?
Calvin cycle input needs
Calvin cycle product
In oxygen if photosynthesis what is each photo system?
An electron transport chain
What is the electron donor in oxygenic photosynthesis?
What role does light play in photosynthesis?
Stimulator, does not provide energy; it drives energy production
Oxygenic photosynthesis has what that makes it have a stronger gradient?
Photo system I is a second pathway that makes NAD(P)H; producing twice as strong of a gradient
Where are the photosystems located?
Cell membrane because goal is to build H+ gradient
There are more gram ___ that use photosynthesis, why?
Negative because cell wall doesn't retard light as much as a gram positive cell wall would
Anoxygenic photosynthesis uses what as an electron donor and where is it donated to?
Something other than H2O eg. H2S, Fe2+ and to a cytochrome
Anoxygenic photosynthesis uses what to drive the reverse e flow to make ____?
In anoxygenic potosynthesis, NAD(P)H is:
Made but is not the TEA
What organisms use photosynthesis for metabolism?
Chemolithoautotrophs: use inorganic e donor (H2O) and CO2 as C source
How do orgs that use photosynthesis fix CO2?
What are the 2 types of photosynthesis?
Oxygenic: produces O2; uses H2O as donor
Anoxygenic: O2 not produced; H2O not e donor but stil inorganic donor (can only be bacteria and archea)