Covid - 19 module 1 and 2

Directional selection

Favors one extreme or another for a trait.

Disruptive selection

favors both extreme variations, selecting against the most common variant.

Stabilizing selection

favors the most common variant for a trait.

Lysogenic cycle

following penetration into the cell, the viral DNA integrates into the host cell's DNA. Unlike the lytic cycle, the virus remains inactive (or latent).

Select all of the following that are structural components of viruses.

genetic material protein capsid

In some cases, coronaviruses are known

to cause mild illness such as respiratory and intestinal diseases, especially in livestock (chickens, pigs, and cattle). In humans, some variants are more lethal.

A virus is a

type of intracellular parasite that finds a host cell and hijacks its metabolic machinery so that cell may produce more copies of the virus.

Varying considerably in shape and the different types of cells they infect, all ______ have two components.

viruses

Evolution

a unifying theme of biology, refers to changes in a species or population over time.

Local SARS-CoV-2 outbreaks are most likely the result of which mechanism of influenza evolution?

antigenic drift

Which method of viral evolution can be attributed in large part to the efficiency of RNA polymerase?

antigenic drift

What is an antigen?

any substance that brings about an immune response

Some viruses may also possess an ______ that surrounds the capsid. This outer layer is actually a remnant of the host cell , and not made by the virus.

envelope

Select the explanation for one of the processes by which coronaviruses virus evolve.

A mutation that changes the viral spikes is introduced into the genetic material.

Maturation

Also known as assembly, this is when the pieces of the virus are assembled.

When a gene mutation occurs, which of these are possible outcomes?

An abnormal protein is synthesized. An incomplete protein is synthesized. A normal protein is synthesized.

Lysogenic cycle part two

As the host cell divides, the viral DNA is replicated along with the host cell DNA, thus creating new cells that contain the virus. The virus remains latent until some environmental factor signals it to reenter the lytic cycle and begin the process of biosynthesis and maturation.

Attachment

As we previously discussed, the structure of the proteins in the capsid allows it to recognize and target specific cells for infection.

Biosynthesis

At this point, the virus hijacks the host cell's machinery to manufacture new capsid proteins and copies of its genetic material. Energy and materials for these processes are all provided by the host cell.

Why do some scientists think that viruses should be classified with the living organisms?

Because of the discovery of a new group of viruses, some of which can produce their own proteins

Release

Finally, the new viruses are ready to leave the cell. This is possible by either causing the host cell to burst (called lysis) or by exiting through the plasma membrane (exocytosis). Viruses that possess an outer envelope leave by endocytosis. As they exit, they often create an envelope about themselves by acquiring pieces of the host cell's plasma membrane.

Lysogenic cycle part three

HIV is an example of a virus in humans that used the lysogenic cycle. Scientists have estimated that almost 8% of the human genome is actually viral in nature, and thus evidence of how active the lysogenic cycle has been in our evolutionary history

By recognizing the mechanisms through which organisms change over time, or evolve, scientists can gain insight into which of the following? Select all that apply.

How to design better medications such as antiviral agents and vaccines Resistance to insecticides and antibiotics How the organization of life on our planet reflects evolutionary history

Natural selection

Individuals vary in their traits- Individual organisms within a species exhibit variation that can be passed from one generation to the next. Individuals struggle to exist- Organisms compete for available resources. Individuals differ in their fitness- Individual organisms within a population differ in terms of their ability to compete for resources, survive, and reproduce. Populations become adapted to the environment- Organisms become adapted to conditions as the environment changes.

(the lytic cycle)

It can either immediately begin using the resources of the host cell to manufacture new viruses.

229E, NL63, OC43, and KHU1

Known to produce symptoms similar to the common cold

Antigenic drift

May make vaccines less effective and cause local outbreaks. Can be attributed to RNA polymerase inefficiency. Results in a change to the surface spikes of the virus

How is evolution related to natural selection?

Natural selection is one mechanism that causes evolution to take place.

What Is the General Life Cycle of a Virus?

Once the virus has entered the target cell, there are two pathways, or cycles, it can follow It can either immediately begin using the resources of the host cell to manufacture new viruses (the lytic cycle). or it can integrate directly into the host cell genome and delay its own reproduction until a later time (the lysogenic cycle)

Penetration

Once the virus has identified the host, its genetic material enters the cell. This can occur by injecting the genetic material directly into the host cell (leaving the capsid outside), or by convincing the host cell to engulf the entire virus (a process called endocytosis). In the case of influenza, the latter process occurs and once in the cell the virus releases its genetic material into the host cell.

Which of the following is true of Hox genes?

They are similar in closely related organisms.

Which of these explains one of the processes by which coronaviruses can evolve?

Two different forms of the same virus infect the same host cell and a new virus is created with parts of each form.

Antigenic shift

Typically involves animal hosts. Delays immune response and may cause an outbreak A host cell manufactures particles from two forms of the virus.

Select reasons that viruses have not historically been classified as living things.

Viruses cannot process energy or material. Viruses need a host cell to reproduce.

Coronaviruses

are a group of related RNA viruses that infect avian and mammalian species.

The Lytic Cycle

attachment, penetration, biosynthesis, maturation, release

The evolution of a species is driven by genetic________which can be passed from one generation to the next.

change

Which of the following would you expect to see between two species that have a close evolutionary relationship?

closely matching genetic information

Mutations arise over time, so when two organisms are closely related (in time), there has been

little time for mutations to alter their genes.

The discovery of giant viruses, some of which can produce their proteins, has

made some scientists think that viruses should be classified with the living organisms.

(the lysogenic cycle)

or it can integrate directly into the host cell genome and delay its own reproduction until a later time.

Biologists use five characteristics to determine if something is considered alive or not. These include the ability to:

process energy and materials. • maintain an internal environment. • respond to stimuli from the environment. • reproduce. • adapt to changing environmental conditions.

comparative anatomy

studies structural similarities, including structures that serve the same function but evolved independently, or those that have been inherited from a common ancestor.

Coronaviruses structure

Enveloped. Crown-like spikes emerging from the surface of the virus.