Biology Chapter 18 Flashcards
Viruses
Non-living particles with nucleic acid genomes.
Nonliving
Don’t use energy, carry out metabolism, maintain homeostasis, or reproduce by themselves.
Virus
A small infection particle that consists of nucleic acid enclosed in a protein coat.
Host cell
A cell that is infected by a virus.
Host species
A species that can be infected by a specific virus.
Host range
The number of species and cell types a virus can infect.
Capsid
Protein coat of virus, enclosing a genome with one or more molecules of nucleic acid (DNA or RNA).
Viral envelope
Lipid bilayer of a virus that is derived from a cellular membrane from the host cell and is embedded with virally encoded spike glycoproteins.
Viral genome
Genetic material in a virus. RNA or DNA.
Bacteriophages
Viruses that infect bacteria. (phages)
Single stranded and double stranded
Some viruses have single stranded and others have double stranded.
Viral reproductive cycle
Series of steps leading to the production of new viruses.
Integrase
Enzyme made by a gene carried y viruses that are capable of integration.
Prophage
Phage DNA in a bacterium after integration.
Lysogenic cycle
Viral reproductive cycle while virus exists as a prophage.
Reverse transcriptase
Enzyme that copies RNA into DNA. (HIV)
Provirus
Integrated viral DNA in a eukaryotic cell. Retroviruses.
Lytic cycle
Steps 1, 2, 4, 5, and 6 lead to cell lysis.
Viruses can integrate what?
Their genomes into a host chromosome.
Latent
Inactive
Temperate phages
Bacteriophages that can alternate between lysogenic and lytic cycles.
Virulent phages
Only have lytic cycles.
Six stages of genetic material reproduction in bacteriophage with a double stranded DNA genome
Attachment, entry, integration, synthesis of viral components, viral assembly, and release.
Six stages of genetic material reproduction in a virus with a single stranded RNA genome
Attachment, entry, integration, synthesis of viral components, viral assembly, and release.
Stages of lytic cycle
- Phage injects its DNA into cytoplasm. 2. Phage DNA directs the synthesis of many new phages. 3. Cell lyses and releases the new phages. 4. New phages can bind to bacterial cells.
Lysogenic cycle
Phage DNA integrates into host chromosome. Prophage DNA is copied when cell divides. On rare occasions, a prophage may be excised from a host chromosome.
Episome
A genetic element that replicates independently of the chromosomal DNA but also can occasionally integrate into chromosomal DNA.
Emerging viruses
Viruses that have arisen recently or are likely to have a greater probability of causing infection.
Human immunodeficiency virus (HIV)
the causative agent of acquired immune deficiency syndrome (AIDS).
Vaccination
An inoculation with a substance or a group of substances that causes the immune system to respond to and destroy infectious agents such as bacteria or viruses.
Viroid
Composed solely of RNA, infect plants.
Prion
Composed solely of protein, have no genes and cannot be copied by replication of cell. Cause neurodegenerative diseases.
Bacteria are usually?
Unicellular organisms.
Nucleoid region
Contains a bacterial chromosome. DNA is in direct contact with the cytoplasm of the cell.
Loop domains
Chromosomal segments that are folded into loops.
DNA supercoiling
Twisting can dramatically change DNA conformation.
Bacterial enzymes called topoisomerases twist the DNA and?
Control the amount of DNA supercoiling.
Plasmids
Small, circular pieces of DNA. Exist separately from the bacterial chromosome. Have own origin of replication - can replicate independently. May provide a growth advantage or aid in survival under certain conditions.
Resistance plasmids (R factors)
Contain genes that confer resistance against antibiotics and other types of toxins.
Degradative plasmids
Carry genes that enable the bacterium to digest and utilize an unusual substance.
Col-plasmids
Contain genes that encode colicius (proteins that kill other bacteria).
Virulence plasmids
Carry genes that enable the bacterium todigest and utilize an unusual substance.
Fertility plasmids (F factors)
Allow bacteria to transfer genes to each other.
Bacterial colony
A clone of genetically identical cells.
Binary fission
A cell divides into 2 daughter cells.
Bacterial cell division
- Bacterial chromosome replicates and cell enlarges. 2. Cell begins to divide. 3. A cell wall is formed between the two cells. 4. Cell division is replicated.
Strain
Lineage in a given bacterial species that has genetic differences compared to another strain.
Gene transfer
Genetic material is transferred from one bacterial cell to another.
Conjugation
Direct physical interaction between 2 bacterial cells. One is a donor and transfers DNA to a recipient cell.
Transformation
DNA is released into the environment and taken up by another bacterial cell.
Transduction
When a virus infects a bacterial cell and transfers some of that cell’s DNA to another bacterium.
Sex pili
Made by F+ cells that bind specifically to F- cells.
Competent
Ability to take up DNA from the environment.
Horizontal gene transfer
A process in which an organism incorporates genetic material from another organism.
Acquired antibiotic resistance
A previously susceptible strain becoming resistant to a specific antibiotic.
