Viruses Living or Non-Living?
Firstly what classifies an organism as living or nonliving? It is hard to determine if some organisms are living or nonliving. Therefore, scientists have developed a list of traits that all living things have in common. If an organism abides all eight of the characteristics then it is classified as living, but if it doesn't then it is nonliving.
While viruses are complex organisms that contain proteins, nucleic acids and carbohydrates they cannot operate until they hijack a living cell. If it weren't for the cells they take over then viruses would be unable to reproduce on their own. Viruses only function within a host cell. Furthermore, viruses do not maintain homeostasis, grow, obtain energy, respond to stimuli, or are made up of more than one cell. These are characteristics of living things that viruses do not have. Therefore ,viruses do not meet all eight characteristics so we can say that viruses ,no matter how complex, are nonliving.
While viruses are complex organisms that contain proteins, nucleic acids and carbohydrates they cannot operate until they hijack a living cell. If it weren't for the cells they take over then viruses would be unable to reproduce on their own. Viruses only function within a host cell. Furthermore, viruses do not maintain homeostasis, grow, obtain energy, respond to stimuli, or are made up of more than one cell. These are characteristics of living things that viruses do not have. Therefore ,viruses do not meet all eight characteristics so we can say that viruses ,no matter how complex, are nonliving.
Bacteria
Form and Arrangement
Form: Shape of bacteria Arrangement: How the bacteria arrange themselves spatially Bacteria can form is three ways: 1. Bacillus form 2. Coccus form 3. Spirillum form Bacillus bacteria have a rod shape, being longer than wide. They generally arrange themselves so they're solo (bacilli), in pairs (diplobacilli) or chains (streptobacilli). Coccus bacteria have a spherical shape. They generally arrange themselves in pairs (diplococci) , chains (streptococci), grapelike clusters (staphylococci), group of four (tetrads) and two tetrads back to back (sarcina). Spirillum bacteria have a curved shape, being in a "spirally" state. Spiral bacteria can be sub-classified into three types based on their distinctive spirals which are mostly in solo arrangements. The three types of spirillum: 1. Vibrio 2. Spirillum 3. Spirochete |
How Bacteria Obtain Energy and Carbon
All prokaryotes need a carbon source and energy in order to survive. There are in total four ways that bacteria can obtain the carbon and energy sources they need for survival.
Autotrophic: Organisms that make their own food. Require inorganic carbon source. 1. Photoautotrophs: ✏ Use light energy with CO₂ to make organic compounds ✏ Example: Cyanobacteria 2. Chemoautotrophs: ✏ Use energy from inorganic molecules and CO₂ ✏ Example: NH₃ aka Nitrogen Fixing Bacteria Heterotrophs: Require an organic carbon source. 1. Photoheterotrophs: ✏ Require light energy (to make ATP) and an organic food source ✏ Very few prokaryotes do this ✏ Example: Purple non-sulphur bacteria 2. Chemoheterotrophs: ✏ Require organic carbon sources for energy and their carbon intake ✏ Very common among prokaryotes ✏ Examples: E.coli and Salmonella |
Bacterial Reproduction, Antibiotic Resistance and Evolution
All organism are rapidly evolving and bacteria are no exception. Bacterial reproduction, antibiotic resistance and evolution are all closely related but how?
Bacteria reproduce asexually, more specifically through a process called binary fission. Since they reproduce asexually this means that they are constantly making clones of themselves. This means that their offspring have exactly the same genetic coding. If that's so then how come we haven't developed an antibiotic that can take them all out? If bacteria really are all the same then why are we facing the problem of antibiotic resistance? Our problem is that bacteria have a system for creating new combinations of genes through plasmids.
Bacteria carry their genes in two ways. One is in circular bacterial DNA and the other is in free-floating strands of DNA called plasmids. Different bacteria have different plasmids that benefit them, but what is extraordinary is that bacteria are able to "share" their plasmids with other bacteria. Bacteria can gain new plasmids through three different processes: Transduction, Conjugation and Transformation. Transduction is when genes are introduced from viruses to bacteria. Conjugation is the direct transfer of plasmids between bacteria. Lastly, transformation is when the bacteria take up genes from the environment in a process called Heat Shock.
These newly gained plasmids give the bacteria new traits such as antibiotic resistance. This makes the new resistant bacteria the better fit organisms of their population. Therefore when we try to use antibiotics against them we only wipe out the bacteria without any antibiotic resistance. In a way we help speed up the process of natural selection, leaving only the antibiotic resistant bacteria alive. This gives the bacteria a better chance to reproduce and thus pass on the new favourable trait to their offspring. Thus antibiotic resistance is passed on. This is somewhat problematic due to the fact that bacteria reproduce fairly quickly. Therefore antibiotic resistance can also widespread further passing on the antibiotic resistance genes. Since antibiotics play a role in natural selection (which is a type of evolution) we can say that antibiotic resistance is indeed an example of evolution. Unluckily for us.
Bacteria reproduce asexually, more specifically through a process called binary fission. Since they reproduce asexually this means that they are constantly making clones of themselves. This means that their offspring have exactly the same genetic coding. If that's so then how come we haven't developed an antibiotic that can take them all out? If bacteria really are all the same then why are we facing the problem of antibiotic resistance? Our problem is that bacteria have a system for creating new combinations of genes through plasmids.
Bacteria carry their genes in two ways. One is in circular bacterial DNA and the other is in free-floating strands of DNA called plasmids. Different bacteria have different plasmids that benefit them, but what is extraordinary is that bacteria are able to "share" their plasmids with other bacteria. Bacteria can gain new plasmids through three different processes: Transduction, Conjugation and Transformation. Transduction is when genes are introduced from viruses to bacteria. Conjugation is the direct transfer of plasmids between bacteria. Lastly, transformation is when the bacteria take up genes from the environment in a process called Heat Shock.
These newly gained plasmids give the bacteria new traits such as antibiotic resistance. This makes the new resistant bacteria the better fit organisms of their population. Therefore when we try to use antibiotics against them we only wipe out the bacteria without any antibiotic resistance. In a way we help speed up the process of natural selection, leaving only the antibiotic resistant bacteria alive. This gives the bacteria a better chance to reproduce and thus pass on the new favourable trait to their offspring. Thus antibiotic resistance is passed on. This is somewhat problematic due to the fact that bacteria reproduce fairly quickly. Therefore antibiotic resistance can also widespread further passing on the antibiotic resistance genes. Since antibiotics play a role in natural selection (which is a type of evolution) we can say that antibiotic resistance is indeed an example of evolution. Unluckily for us.
Gram Staining
Gram staining is a common procedure done to be able to differentiate between two different groups of bacteria depending on their distinct cell walls. Those with thin cells walls (Gram Positive) and those with thick cell walls (Gram negative).
Gram Positive Bacteria: ✏ Have thin cell walls with lots of peptidoglycan ✏ Appear purple (retain crystal violet stain) ✏ More susceptible to antibiotics ; especially Penicillin Gram Negative Bacteria: ✏ Have thick cell walls with less peptidoglycan ✏ Appear red/pink (retain counterstain safranin) ✏ More resistant to antibiotics Post gram staining we can learn if the bacteria has a thick or thin wall with lots or little peptidoglycan. This can help doctors prescribe antibiotics depending on the constituency of the bacteria's cell wall. |
Collections Lab
Ms.Nickel has a hard copy, but i will post it as soon they get handed back.