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mic 102 > M1 > Flashcards

M1 Flashcards

1
Q

Why dont microbiologists study human eggs and sperm cells?

A

They dont study eukaryotes. They focus on bacteria and archaea.

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2
Q

Whats the difference between cellular and acellular

A

Acellular microbes rely on cellular microbes to grow bc they are unable to metabolize organic materials by themselves.

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3
Q

Describe how LUCA branched off to BAE. How do we know?

A

B and E first split then A split from E. This means that Eand A are closely related.

We know this from using molecular clocks which tend to have conserved regions, neutral changes, and found in all the organisms we’re trying to compare. A good example is small unite rRNA

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4
Q

Describe how SA:Volume ratio affects growth

A

In order for a bacterial cell to grow efficiently, it wants a larger SA because this allows diffusion of nutrients, waste, etc better.

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5
Q

Define resolution and what factors increase it?

A

resolution is the shortest distance between two objects that can still be distinguished as two separate objects.

High resolution = shorter distance differentiation

limit of resolution is defined as d = 0.5 (wavelength) / NA
-the shorter the wavelength, the lower the limit of resolution so the higher the resolution

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6
Q

Describe when to use each microscope:

Light Microscopy:
Phase Constant:
Fluorescence:
Electron Microscope:
Atomic Force Microscopy:
A

Light microscopy w/ staining: to identify the basic cell wall structure of an unknown bacteria
- ex: gram +/-

Phase contrast: to identify if a bacterium can swim in a liquid fluid

  • phase contrast doesnt need staining / fixing of cells so we can keep cells alive
  • can see flagella / pili

Fluorescence: to watch proteins of the divisome to see how they change their location in dividing cells
-fluorochromes are engineered into the genes = can still be alive

Electron: to visualize the repeating crytsalline structure of s-layer

  • Scanning EM views exterioir
  • Transmission EM views internal structures

Atomic Force Microscopy: to see a single membrane complex on the surface of a cell
-can see porins

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7
Q

What does penicillin do to cell walls?

A

Inhibits peptidoglycan synthesis. Since peptidoglycan protects against osmotic stress its easier to burst the cell when penicillin is given.

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8
Q

What are the main differences between gram + and gram - bacterias?

A

Gram (-) bacterias have a thin wall of peptidoglycan which requires the cell to have an outer membrane and inner memebrane for protection. Outer membrane has LPS which trigger immune system reaction

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9
Q

What type of bond does peptidoglycan have and what type of protection do we have against bacteria with peptidoglycan?

A

It has B-1,4 bonds between NAG and NAM. Our tears heave lysozymes the can cleave this bond = degrades peptidoglycan

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10
Q

Whats the benefit of having both S-layer and capsule?

A

the capsule covers the s layer that has glycans that can trigger an immune response. In other words it helps avoid the detection form immune cells.

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11
Q 
Describe each flagellar arrangement of :
monotrichous:
lopotrichous:
peritrichous:
axial filament:
A

monotrichous: 1 flagella @ one end
lopotrichous: 2+ flagella coiming out of either / both ends
peritrichous: lots of flagella coming out of perimeter
axial filament: flagella remains inside of cell

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12
Q

what powers the rotation of the flagella?

A

PMF

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13
Q

What are the three functions of a pilus?

A

conjugation, attachment (with fimbria tip that is sticky to certain receptors), and twitching motility

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14
Q

Describe how the singular circular chromosome of bacterias superocoils?

A

Negative supercoil: done by gyrase which is ATP dependent. Most bacterias have a negative supercoil

Positive supercoil: done by reverse gyrase that is also dependent on ATP. Bacterias will only revert to this supercoil if they are growing in v. high temps

Topoisomerase I relaxes the chromosome and does not need ATP

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15
Q

Describe the specialized structures bacteria can use for metabolic rxns with toxic side products

A

Protein shells to enclose reactions

  • gas vessicles: protein shell is only permeable to gas and not water
  • thylakoids: enhances light gathering abilities (note that membrane is from cell membrane extension)
  • carboxysomes: enhances RuBisCo environment to fix CO2
  • enterosome: pumps out only non toxic end products
  • storage granules: stores useful materials when abundant to release later when lacking
  • magnetosomes: iron containing structures that can serve as compass needle
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16
Q

Why are archaea more suited to live is extremely high temperatures in comparison to bacteria?

A

Archaea can have monolayer membranes which are more rigid

17
Q

Define each type of growth media:

  • minimal medium
  • defined medium
  • Undefined medium
  • Rich Medium
A

Minimal medium: only contains the absolute necessary components for minimal growth (defined bc we know each exact quantity)

Defined medium: every component and quantity is known (usually defines the chemical composition)

Undefined: some components are not know exactly (ex: yeast extract)

Rich medium: contains components allowing for hugh grwoth rates

18
Q

Define the ways to count the # of cells in a medium

  • Optical density absorbance (turbidity)
  • Viable Cell count
  • Direct cell count
  • Flow cytometry
A
  • Optical density absorbance (turbidity) : can determine doubling time of bacteria
  • Viable Cell count : can count how cells are left living (can be useful in assessing cleansing agents to kill bacteria)
  • Direct cell count : count cells one by one by viewing inmicroscope (can’t tell between live or not live)
  • Flow cytometry: count cels with laser detector (can be used with staining for specific interesting feature)
19
Q

Describe the different phases of bacterial growth

A

1) Lag phase: cells adapting to new environment and changing their gene patterns to prepare for growth
2) exponential phase: cells grow and divide as quickly as possible
3) stationary phase: dying cells = new cells bc of limited resources
4) death phase: cell population lowers exponentially

20
Q

Describe how / why the death phase can be a long term stationary phase

A

as cell die other suck up their nutrients and mutations can also help cell outcompete others

21
Q

PRACTICE CELL GROWTH EQUATIONS # 21 #22

A

21 #22

22
Q

Since FtsZ can be a temperature sensitive mutant past temperautre higer than 42 Celsius they:

A

produce long filaments bc they are unable to divide

23
Q

What data shows that microbes are able to grow below their optimum temperature than above it?

A

In a temperature vs. growth graph there is a sharp right side (high temp) which suggests a fast decline of growth with higher temps.

high temps can denature proteins

24
Q

define and describe how to:

sterilization:
Disinfection:
Sanitization:
Antisepsis:

A

sterilization: destroys all living cells and spores - autoclave

Disinfection: killing / inhibitting growth of disease causing microbes (not 100%) - wiping down with alcohol

Sanitization: microbial levels are reduced below a set standard (washing dishes)

Antisepsis: killing / removal of microbes on living tissue (washing a cut under running water / soap

25
Q

what does the d-value tell you? how can you measure this?

A

d-value is the time it takes to kill 90% of the microbes in the sample. This can be measured for a minutes of exposure vs LOG number of survivors. a difference of 1 log = 90% death so just calculate the difference in time bwteen the logs.

large d-value = it takes a long time to kill the microbes
small d-value = it takes a short time to kill the microbes (strong)

26
Q

Describe what pasteurization does

A

kills the microbes responsible for spoiling. it does not kill all the microbes but is able to slow down spoilage by decreasing the # of microbes

27
Q

define the energy source and carbon source for:

photoautotrophs:
photoheterotrophs:
chemoautotrophs:
chemoheterotrophs:

A

photoautotrophs: Uses light an energy source and CO2 as a carbon source to make organic carbon compounds like glucose
photoheterotrophs: Uses light energy to break down organic compounds for further use in biosythesis
chemoautotrophs: uses inorganic compound as energy like sulfate reduction to convert CO2 into ogranic carbon
chemherotrophs: Uses organic compounds an energy an carbon source

28
Q

What is and are types or reducing powers in a cell?

A

they are stored reduced compounds used to power biosynthesis or other cellular needs like motility and quorom sensing. Ex: NADH ATP FADH

29
Q

Describe how electrons move in terms on reduction potentials

A

electrons will flow form a more negative reduction potential to a more positive one spontaneously. The larger the gap between the energy potentials.

The one with a more negative reduction potential will be the electron donor and the more positive reduction potential will be the electron acceptor

30
Q

what is substrate level phosphorylation and when / where does it occur

A

It is the addition of a phosphate from a high energy molecule dirctly onto ADP/ GDP

It occurs in TCA cycle and glycolysis

31
Q

Whats the main difference between fermentation and respiration?

A

Respiration can be aerobic or anaerobic and will produce alot more ATP because it is able to use the ETC for oxidative phosphorylation

Fermentation does not use ETC and only does substrate level phosphorylation so it doesnt make as much ATP. BUT its important in reproducing NAD+ which is needed in glycolysis

32
Q

whats the difference between cyclic and noncyclic photosynthesis?

A

cyclic : e- acceptor can be the OG chlorophyll that donated e-.

noncyclic: e- acceptor goes on to further rxns so it needs a new e-acceptor every time

33
Q

Whats the difference between anoxygenic photosynthesis and oxygenic photosynthesis?

A

anoxygenic photosynthesis do not generate O2. Some can even shift from photosynthesis to respiration. Can use cyclic on non-cyclic photosynthesis.

oxygenic photosynthesis: produces O2 and ALWAYS noncyclic

34
Q

what are chemoautotrophs and how do they use the ETC?

A

chemoautotrophs use respiration to make energy to fix CO2… They can run the ETC cycle forwards and back. Forward for NADH production which is needed for biosynthesis and forward of ATP is needed.

They need to run ETC backwards becuase they are using inorganic carbons an energy sources which means they are not running glycolysis so no formation of NADh.

35
Q

What is the autotrophic feeder pathway?

A

Fixes CO2 into organic carbons.

-calvin cycle, reductive TCA cycle, etc.

36
Q

What are the big 3 cycles of the central pathways

A

Glyoclysis, TCA, and PPP

note that they are all connected to one another. All together they make the 13 precursor metabolites

37
Q

assimilation of nitrogen and sulfur needs to be reduced into?

A

Nitrogen has to reduced to ammonium/ammonia

Sulfur has to be reduced to sulfide

38
Q

Why is the building block of DNA synthesis the most energetically expensive step of DNA synthesis and not polymerization?

A

It’s bc nucleotides are made in the activated state, ready for polymerization = they have enrgy needed to polymerize themsleves

mic 102 (2 decks)

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