Bacteria And Viruses (9th Grade BIO)

What is the significance of the origin of replication in bacteria?

• Specific site on bacterial chromosome

• Initiates DNA replication

• Moves toward opposite cell end during replication and is crucial for proper cellular division.

What are the steps of the lysogenic cycle?

1. Attachment: Virus binds to cell receptors

2. Entry: Viral DNA injected into the cell

3. Integration: Phage DNA integrates into host DNA

4. Replication: Host cell reproduces with viral DNA

5. Trigger: Environmental factor activates lytic cycle

   The lysogenic cycle consists of several steps where the viral DNA incorporates into the host genome, lying dormant until triggered to enter the lytic phase.

What are the steps of the lytic cycle?

1. Attachment: Virus binds to cell receptors

2. Entry: Viral DNA injected into the cell

3. Synthesis: Host's resources create virus parts

4. Assembly: Parts self-assemble into viruses

5. Release: Cell bursts, releasing viruses

   The lytic cycle is a viral replication process characterized by five main steps: attachment, entry, synthesis, assembly, and release, leading to the destruction of the host cell.

What happens to the viral DNA after it enters the host cell?

It integrates into the host DNAor exists as an independent plasmid.

What is reverse transcriptase?

An enzyme that transcribes RNA into DNA and is essential for retroviruses to replicate.

What is a viral envelope?

Outer membrane of some viruses

What triggers the lysogenic cycle to switch to the lytic cycle?

An environmental trigger such as stress or DNA damage that prompts the viral DNA to initiate replication and produce new virions.

What is a prophage?

Combination of phage DNA and host DNA that remains dormant within the host's genome until activated.

What characterizes the lysogenic cycle?

Virus replicates without destroying the host cell and integrates its DNA into the host's genome, remaining dormant for extended periods.

What is lysis in the context of the lytic cycle?

Bursting of the host cell to release new viral particles.

What happens during the synthesis stage of the lytic cycle?


Host cell's resources create more virus parts

What happens during the synthesis stage of the lytic cycle?


Host cell's resources create more virus parts and assemble them into complete viruses.

Why can't a virus infect just any cell?

It must bind to specific receptors on the surface of a host cell.

Adenovirus

Viruses that infect respiratory tracts of animals and are known to cause respiratory infections in humans.

What are the two cycles through which bacteriophages replicate?

Lytic and lysogenic cycles

The two cycles through which bacteriophages replicate are:

Lytic cycle, which leads to the destruction of the host cell.

Lysogenic cycle, where the viral DNA integrates into the host genome and replicates with it.

What are bacteriophages?

Viruses that infect bacteria. They are composed of genetic material surrounded by a protein coat and can lead to bacterial lysis.

What are viruses made of?

RNA or DNA enclosed in a capsid that can infect host cells and hijack their machinery to replicate.

How do viruses multiply?

Only within the host they infected by hijacking the host's cellular machinery.

Bacteria

Single-celled microorganisms that lack a nucleus and can be found in various environments. They can be beneficial or pathogenic, playing critical roles in ecosystems and human health.

Enveloped vs non-enveloped viruses

Enveloped viruses have an outer lipid membrane acquired from host cells

Non-enveloped viruses lack this membrane and are typically more resistant to environmental factors.

What did Edward Jenner do? What did his experiment include?

He pioneered vaccination by developing the first smallpox vaccine using cowpox material to create immunity.

What are the different types of vaccines? And what do they all do?

Different types of vaccines include

1. live-attenuated

2. inactivated

3. subunit

4. recombinant

5. mRNA vaccines

Each designed to elicit an immune response without causing the disease.

inactive virus

a virus that has been killed or modified in such a way that it cannot replicate or cause disease but is still able to stimulate an immune response when introduced into the body.

Antibiotic

a substance that can be obtained from microorganisms that kill or inhibit the growth of bacteria.

What are subunit viruses?

Subunit viruses are vaccines made from specific pieces of the virus, such as proteins or sugars, that trigger an immune response without using the whole virus or its genetic material.

What are antigen viruses?

Antigen viruses refer to viruses that contain proteins or molecules, known as antigens, which are recognized by the immune system to trigger a response without causing infection.

What is a live attenuated virus?

A weakened form of a virus used in vaccines that can replicate and provoke a robust immune response without causing disease.

Vaccine function and meaning

A vaccine stimulates the immune system to recognize and fight specific pathogens, providing immunity against infectious diseases.