Chapter 11 - Microbial Nutrition Flashcards
What three things do Microbes need?
Carbon, Energy and Electrons
All Organisms are what based?
Carbon - proteins, carbohydrates, lipids, nucleic acids - fundamental cores of Carbon
Heterotrophs
Other eaters - Use reduces, performed organic substances as the carbon source
Autotrophs
Self Feeders - rely on CO2 as carbon source, reducing or fixing it
Two sources of Energy
Light or Chemical Energy
Light Energy
comes from the sun :P
Chemical Energy
Comes from organic or inorganic chemicals
Phototrophs
Use Light Energy (light eaters)
Chemotrophs
Use Chemical energy (Chemical eaters)
Chemical Energy can come from where?
Inorganic or Organic sources
Inorganic Chemical Energy Source?
Lithotroph (Rock eater)
Organic Chemical Energy Source?
Organotroph (organic eater)
Macronutrients
Other elements needed by cells - such a Nitrogen, phosphorus, Sulfur, potassium, and Magnesium (C, H and O also considered macros)
What is Nitrogen needed for?
Formation of proteins, nucleic acids and other cell components
What is Phosphorus needed for?
crucial component of nucleic acid (sugar-phosphate backbone) phospholipids, ATP
What is Sulfur needed for?
necessary for a few amino acids, as well as several Vitamins
What is Potassium needed for?
enzymes
What is Magnesium needed for?
Stabilize Ribosomes and membrane
Growth Factors
Organic molecules that fall into 3 categories - 1. Amino acids 2. Purines and pyrimidines 3. Vitamins
Passive Diffusion
aka simple diffusion - passage across the cell membrane of simple molecules and gasses (CO2, O2, H2O). Must use a concentration gradient with higher concentration on outside than inside. As more transported, gradient goes down and slows rate of diffusion.
Facilitated Diffusion
Uses concentration gradient with higher on outside of cell, but differs w/ use of carrier proteins (permeases). Part of Passive Transport.
Carrier proteins - Facilitated Diffusion
Embedded w/in a cell membrane and provide a channel across the membrane barrier to allow for passage of larger molecules. Each typically exhibits specificity. As Gradient dissipates, passage of molecules stops
Active Transport
use of metabolic energy to transport substance through carrier proteins against a concentration gradient - all types of active transport utilize carrier proteins
Primary Active Transport
Involves the use of chemical energy, such as ATP. An example is the ABC system.
ABC system
Utilizes ATP-Binding Cassette transporters. Composed of 3 parts 1. Membrane spanning proteins that form across cell membrane, 2. ATP binding region that hydrolyzes ATP 3. substrate-binding protein that binds and ferries appropriate substance to the membrane spanning proteins.
Secondary Active Transport
Utilizes energy other than ATP, such as proton motive force.
Proton Motive Force
An Ion gradient that develops when cell transports electrons during energy conserving processes. Positively charged protons accumulate along outside of negatively charged cell, creating a proton gradient between inside and outside.
Uniport
Type of Simple transport. Transfer single substance across the membrane - either in or out
Symporters
Transport two substances across the membranes at the same time, typically proton paired with another molecule.
Antiporters
Transport two substances across the membrane, but in opposite directions. As one enters, the other transports out.
Group Translocation
Distinct type of active transport - uses energy from energy rich organic compounds that are not ATP. Also differs from simple and ABC in that the substance being transported is modified.
phosphoenolpyruvate: sugar phosophotransferase system (PTS)
best studied example of group translocation. Uses molecule PEP to transport sugar into cell. Phosphate is transferred from the PEP to incoming sugar during process.
Iron
Required by microbes for function of their cytochromes and enzymes. Growth-limiting micronutrient
Siderophores
Organic Molecules that chelate or bind ferric iron with high affinity. Released by the organism into surrounding environment, where they bind to any available ferric iron. The complex is then bound by a specific receptor on outside of cell, transporting iron into cell.
