Chapter 6 flashcards
What do Autotrophs do?
Make CO2 into their organic carbon supply (AKA, sugars, lipids,proteinsandnucleicacids)
3 Things all cells need for metabolism
1) A carbon source
2) A source of energy
3) A source of electrons or hydrogen atoms
Heterotrophs relies on?
They rely on autotrophs in the food chain to make their organic C source
Organisms that utilize an inorganic source of carbon (that is, carbon dioxide) as their sole source of carbon are called?
Autotrophs, so named because they “feed” themselves
Autotrophs make organic compounds from?
CO2 & thus need not acquire carbon from organic compounds from other organisms
Catabolize reduced organic molecules (such as proteins, carbohydrates, amino acids, & fatty acids) they acquire from other organisms
Heterotrophs
Carbon fixation allows a?
Food chain including heterotrophs
– PRIMARY PRODUCERS
What are chemotrophs?
Organisms that acquire energy from redox reactions involving inorganic & organic chemicals
Phototrophs are?
Organisms that use light as their energy source
Lithotrophs get e- from?
Inorganic sources.
- Photoautotrophs
- Chemoautotrophs
Organisms can be categorized based on their carbon & energy sources into one of four basic groups
1) Photoautotrophs
2) Chemoautotrophs
3) Photoheterotrophs
4) Chemoheterotrophs
Plants, some protozoa, and algae are?
Photoautotrophs
Animals, fungi, and other protozoa are?
Chemoheterotrophs
Members in all four groups?
Bacteria & archaea
The most common chemical elements in cells
Hydrogen
Never a limiting agent
Hydrogen because it is so common in organic molecules and water
Hydrogen is essential for?
Hydrogen bonding and electron transfer
Heterotrophs acquire electrons (typically as part of hydrogen atoms) from the same organic molecules that provide them carbon and are called?
Organotrophs
Organotrophs get e- from?
Organic sources
- Photoheterotrophs
- Chemoheterotrophs
Sunlight for energy; CO2 as carbon source
- Called primary producers (Plants)
Photoautotrophs
Inorganic compounds (H2S) for energy; use CO2 as carbon source
Chemoautotrophs
Sunlight for energy; organic compounds as carbon source
Photoheterotrophs
Organic compounds for energy and as carbon source
Chemoheterotrophs
Lithotrophs are?
Autotrophic organisms that acquire electrons or hydrogen atoms from inorganic molecules such as H2, No2-, H2S, and Fe2+
Oxygen is essential for _______ ________ because it serves as the final electron acceptor of electron transport chains, which produce most of the ATP in these organisms
obligate aerobes
Oxygen is a deadly poison for?
Obligate anaerobes
The toxic forms of O2 are those that are?
Highly reactive
There are 4 toxic forms of O2
1) Singlet oxygen (102)
2) Superoxide radical (O2-)
3) Peroxide anion (022-)
4) Hydroxyl radical (OH)
Molecular oxygen w/electrons that have been boosted to a higher energy state, typically during aerobic metabolism. Very reactive oxidizing agent. Phagocytic cells use it to oxidize pathogens. Also photochemically produced by the reaction of oxygen & light, phototrophic microorganisms often contain pigments called carotenoids that prevent toxicity by removing the excess energy of these
Singlet oxygen (1O2)
A few of these form during the incomplete reduction of O2 during electron transport in aerobes & during metabolism by anaerobes in the presence of O2. So reactive & toxic that aerobic organisms must produce enzymes to detoxify them
Superoxide radical (O2-)
These enzymes, which have active sites that contain metal ions, depending on the organism- combine two superoxide radicals & two protons to form hydrogen peroxide & molecular oxygen
Superoxide dismutases
Hydrogen peroxide formed during reactions catalyzed by superoxide dismutase (and during other metabolic reactions) contains ______ _____, another highly reactive oxidant. It is this that makes hydrogen peroxide an antimicrobial agent. Aerobes contain either catalase or peroxidase, enzymes that detoxify this.
Peroxide anion (O22-)
Catalase converts hydrogen peroxide to?
Water & molecular oxygen
Breaks down hydrogen peroxide without forming oxygen, using a reducing agent such as the coenzyme NADH
Peroxidase
Obligate anaerobes either lack both catalasse and peroxidase or have only a small amount of them, so they are susceptible to the toxic action of?
Hydrogen peroxide
These result from ionizing radiation & from the incomplete reduction of hydrogen peroxide. The most reactive of the 4 toxic forms of O2, but because hydrogen peroxide does not accumulate in aerobic cells, the threat of this is virtually eliminated in aerobic cells
Hydroxyl radical (OH)
Not all organisms are either strict aerobes or anaerobes; many can live in various oxygen concentrations between these two extremes. Some aerobic organisms can maintain life via fermentation or anaerobic respiration, though their metabolic efficiency is often reduced in the absence of O2. Such organisms are called?
Facultative anaerobes. E. coli is an example
These do not use aerobic metabolism, but they tolerate O2 by having some of the enzymes that detoxify O2’s poisonous forms
Aerotolerant anaerobes
Ulcer causing pathogen
Helicobacter pylori
This concentration of O2 is found in the stomach. They are damaged by the 21% concentration of O2 in the atmosphere. Requires O2 levels of 2% to 10%.
Microaerophiles
Algae, most fungi & protozoa, and many prokaryotes have what type of O2 requirements?
Obligate aerobes
A few yeasts & numerous prokaryotes have what type of O2 requirements?
Facultative anaerobes
Many prokaryotes and a few protozoa have what type of O2 requirements?
Aerotolerant, microaerophilic, or obligate anaerobes
Why are temperatures important?
Because they have an effect on the three-dimensional configurations of biological molecules. To function properly, proteins require a specific three-dimensional shape that is determined in part by temperature-sensitive hydrogen bonds, which are more likely to form at lower temps. and break at higher temps. Lipids are also temp. sensitive, if temp is too low membranes become rigid & fragile; if temp. is too high lipids become too fluid
When hydrogen bonds break in proteins what happens?
They denature and lose function
The lowest temperature at which an organism is able to conduct metabolism is called the?
Minimum growth temperature. Microbes (particularly bacteria) can survive at temps. far below this.
The highest temperature at which an organism continues to metabolize is called the?
Maximum growth temperature. When an organism exceeds this value, its proteins are permanently denatured, & it dies
The temperature at which an organism’s metabolic activities produce the highest growth rate is the?
Optimum growth temperature
Based on their preferred temperature ranges- the temperatures w/in which their metabolic activity and growth are best supported- microbes can be categorized into four overlapping groups
1) Psychrophiles- Below 15 degrees C & continue to grow at temps. below 0 degrees C
2) Mesophiles- 20-40 degrees C
3) Thermophiles- Above 45 Degrees C
4) Hyperthermophiles- Above 80-100 Degrees C
Process in which a cell grows to twice its normal size and divides in half to produce two daughter cells of equal size
Binary fission
Steps of binary fission
1) Cell replicates chromosome (DNA molecule) & attaches to cytoplasmic membrane
2) Elongation, growth between attachment sites pushes chromosome apart
3) Forms new cytoplasmic membrane & wall (septum) across midline
4) Septum completed daughter cells may stay attached or separate. When attached, further binary fission in parallel lines produces a chain. When divisions are in diff. planes cell becomes a cluster
5) Process repeats
log means
Logarithmic
In a log scale, each division is ___ times longer than the preceding one
10
During the lag phase the cells are?
Adjusting to their new environment; most don’t reproduce immediately instead synthesis enzymes to utilize novel nutrients in medium. Can last less than an our for for days depending on the species & chemical & physical conditions of medium
What happens during the log phase?
Rapid chromosome replication, growth, and reproduction. Reproductive rates reaches a constant as DNA and protein syntheses are maximized. Preferred for industrial & lab purposes
Populations in which phase of microbial growth are susceptible to antimicrobial drugs?
Log phase
What is the stationary phase
As nutrients are depleted & wastes accumulate, rate of reproduction decreases. Number of dying cells equals number be reproduced, size of population constant. Metabolic rate of surviving cells declines
What is the death phase?
If nutrients aren’t added & wastes aren’t removed, the population reaches point where cells die faster than they are produced. Decline phase. Some remain alive & continue metabolizing & reproducing
Photoautotrophs use?
Carbon dioxide as a carbon source and light energy to make their own food
Chemoautotrophs use?
Carbon dioxide as a carbon source but catabolize organic molecules for energy
Photoheterotrophs are?
Photosynthetic organisms that acquire energy from light & acquire nutrients via catabolism of organic compounds
Chemoheterotrophs use?
Organic compounds for both energy and carbon
Organotrophs acquire?
Electrons for redox reactions from organic sources
Lithotrophs acquire electrons from?
inorganic sources
From coldest to warmest temperature requirements
Psychrophiles, mesophiles, thermophiles, or hyperthermophiles
Superoxide dismutase
Detoxifies superoxide radicals
The most reactive of the four toxic forms of oxygen is?
The hydroxyl radical
Microaerophiles that grow best with a high concentration of carbon dioxide in addition to a low level of oxygen are called?
Capnophiles
