7. The Heterotrophic Way of Life Flashcards
What are heterotrophs?
Organisms that use organic molecules to satisfy carbon, energy, and electrons.
Describe the use of glucose in glycolysis and heterotrophs.
Well it is true that the ability to use glucose is widespread in heterotrophic prokaryotes, some lack the genetic ability to do so. Not all prokaryotes metabolize it using glycolysis as well.
How is glucose present in nature?
Glucose mostly occurs as the building blocks of plant macromolecules, starch and cellulose, and as a part of the more complex plant sugar sucrose. Accessing glucose is dependent on a prokaryote possessing specific extracellular hydrolytic enzymes.
Describe specialized and versatile heterotrophs.
Most heterotrophs are versatile and use a variety of organic energy, electrons, and carbon sources. However, some heterotrophs are more specialized. And example of this are the methylotrophs.
Describe the extracellular enzymes used in heterotrophs.
To use cellular macromolecules as nutrient, heterotrophic prokaryotes digest them in reactions catalyzed by extra cellular and periplasmic enzymes. Proteases for proteins, lipases for lipids, nucleases is for DNA or RNA. Cellulase for cellulose, amylase for starch, pectinase for pectin.
Describe the catabolism of heterotrophs.
Most heterotrophs make ATP by both oxidative phosphorylation and substrate level phosphorylation.
How is an electro chemical concentration gradient made?
Through transport of protons, deposition of protons, and production or consumption of protons.
Describe the degradation of energy source is an oxidation of carbon in heterotrophs.
Some heterotrophs oxidize glucose using oxygen as a TEA. The six carbon molecules are fragmented into six carbon dioxide molecules. This is a decarboxylation reaction and the glucose is completely oxidized. Not all heterotrophs completely oxidized organic carbons though.
What’s the difference between classic fermentation and non-classic fermentation?
Non-classic fermentation yields hydrogen gas as a waste product.
Describe classic fermentation.
In classic fermentation, there is no net oxidation of carbon. There is no hydrogen gas waste product.
Describe non-classic fermentation.
There is net oxidation of carbon because some of the electrons removed from carbon do not return to carbon but are instead combined with H plus yielding hydrogen gas. It yields a little more ATP then classic fermentation because of the net oxidation of the carbon in the energy source.
Describe the difference between complex anabolism and simple anabolism in heterotrophs.
Heterotrophs with a complex anabolism possess the genetic information including an extensive set of anabolic enzymes allowing them to synthesize all cellular organic molecules from a single organic nutrient and the in organic forms of nitrogen, sulfur, and phosphorus sources of the other major bioelements. Heterotrophs that require a mixture of organic molecules because they lack the genetic information that encodes particular anabolic enzymes are said to have a simple anabolism.
Ecologically, what is the most important role of heterotrophic prokaryotes?
It is to return the organic forms of major bio elements to their organic forms for subsequent used by plants.
Describe myxobacteria.
They are a predator. They typically live on solid substrata, were they move around in search of nutrients. When starved for nutrients, tens of thousands of individual vegetative bacteria come together to form a fruiting body composed of a resting form called a myxospore. Predatory myxobacteria secrete a wide range of antibiotics capable of killing other microbes. They also secrete a number of extra cellular processes that degrade the proteins and yield amino acids which are used as nutrients.
