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Science

Terms in this set (16)

All living things should be able to...
(You should be able to list 7 things)`
Made up of cells, Obtain & use energy, Respond to the environment, Reproduce to transfer genetic material, Growth and development, Adapt to the environment, & Maintain homeostasis.
When your oxygen levels decrease, your body starts making more red blood cells (which help carry oxygen to the cells of your body). Which characteristic of life does this demonstrate?
Maintain Homeostasis.
Living, Once Living, or Never Living? Evaluate and state your reasoning.
A tree in the wintertime that loses its leaves, and then grows them back in the spring - Living but dormant. It is living but dormant because it will die that winter but then it will grow again in the spring.
Snowflake - Never Living. Snowflakes have little to none characteristics of a living thing.
Strand of DNA - Living. It has all the characteristics of a thing.
Turkey slices - Once living. Turkey slices came from an animal but it was cooked so it is dead.
How do viruses compare to cells in complexity? Explain the parts of a virus. (suggestion - add an image and label it)
Spike Proteins: The spikes are protein. They recognize + interact with the surface of the host cell and later lock onto it. This allows entry into the cell.
Envelope: Some viruses may also have an extra outer, spiky layer called the envelope. These "spikes"
Capsid: Viruses are surrounded by a protein coat called a capsid.
Core: DNA/RNA
Blue is capsid
Black is envelope, Red is DNA/RNA, Black arrow is spike proteins
How is a virus able to enter a host cell?
Its lock mechanism enables it to enter a host cell. Spike proteins
After a virus infects a host cell, what happens after it injects its DNA?
The nucleus is then going to make copies of the DNA. After the DNA exits the nucleus, there are little chefs which cook the proteins that go back into the nucleus. Where they are reassembled into baby viruses and when they exit the nucleus, they get covered up and head to the surface where they get new spike proteins
What is a virus?
A virus is a tiny particle. Pathogenic: it causes diseases not beneficial to living things.
Tom says, "Victor the Virus is guilty! He is a living thing because he is able to move around from place to place on his own, and he can even reproduce!" Respond directly to Tom's statements with counter arguments supporting the idea that viruses are nonliving.
I argue that the statement Tom made is incorrect because although Victor the virus has some of the traits of a living thing, he doesn't have all of them so Victor is considered as non-living.
Bob plucks some berries off the bush and says, "These are living things because they can still reproduce and respond to their environment. They are also made of cells and they might even grow."
As soon as Bob plucked the berries of the trees, the berries will be considered non-living but if it was still a part of the tree, it would be considered living. For example, a virus won't maintain homeostasis because it isn't complex enough.
John is about to bite into a hamburger. He makes a comment to his friends that he is technically about to eat a living thing because the meat came from an animal.
The meat that came from the animal is once living because it died.
Hailey says, "All living things need to fulfill certain characteristics. For example, beavers respond to the environment by developing strong, large front teeth so that they can gnaw on trees that they then use to build their homes. This trait helps them better survive."
First, living things need to fulfill ALL characteristics not CERTAIN characteristics.
Second, beavers don't respond to the environment by developing strong large front teeth. That process is growth and development, not responding to the environment. Responding to the environment won't help the beaver survive, the trait that does that is called Adaptation to the environment.
Joe says, "A tornado is a living thing because it can grow and develop. It changes in size and follows its own life cycle. It also obtains and uses energy in order to power itself. These are the main characteristics of life that need to be satisfied in order for something to be considered living."
Those are only some of the characteristics of living things. In order to be considered as a living thing, the tornado has to have all the characteristics of a living thing not some. Therefore, a tornado is not a living thing.
Jill says, "When viruses attack a host cell, they recognize the host cell through proteins on the envelope. When the virus touches the host cell, the host cell lyses on contact."
The host cell will not burst and die right on contact but, when the virus has finished its job, then the host cell lyses.
Virus Reproduction steps.
Adsorption, entry, replication, assembly, release.
1. Attachment - Viruses will identify an adequate host cell and attach to the surface of that cell. The envelope of the virus, which contains proteins, will recognize an appropriate host cell.
2. Entry - The virus enters the cell by fusing with the cell membrane.
3. Release genetic material - The virus breaks down and releases its genetic material into the host cell.
4. Reproduction - Uses parts of host cell to make copies of capsid, DNA/RNA
5. Assembly of viral components
6. Release of the virus- Exits host cell to infect others.
Cell lyses (bursts & dies)
Characteristics of a virus.
Cells: A virus is not a cell, however, it can infect & become part of a cell.
Reproduction: Yes, but not on its own. Needs Host cell.
Grow & development: New viruses are assembled within host cells only.
Obtain/use of energy: Rely on the energy of the host cells, don't need food.
Homeostasis: Do not, not complex enough, they rely on the host cell.
Adaptation to environment: DNA can mutate overtime (due to vaccines).
Respond to environment: Recognize host cell if contact made otherwise, cannot move around on its own.
Virus entering host cell.
Spike proteins have to lock with the surface of the host cell. Then, the host cell is tricked and pulls the virus towards the nucleus. The capsule of the virus is then unleashed and the DNA/RNA goes into the nucleus. In the nucleus, there is a mini factory molecule that is a copying machine where the DNA goes into it and comes out with a new instruction set. They then go out of the nucleus, and there are 'chefs' outside cooking up the proteins, they then go inside the nucleus where they are reassembled into baby viruses. After that, they exit the nucleus and get covered up. They then exit the host cell where they will earn the new spike proteins. Finally, the host cell lyses and the new viruses go out to infect other cells.
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