Horizontal Gene Transfer

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[h] Horizontal Gene Transfer Flashcards

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[q]What is vertical gene transfer?
[a]Parents transmit all or half of their genome to their offspring. Example: A bacterium reproducing and passing its entire genome to the next generation.

[q]What is horizontal gene transfer?
[a]Genes are transferred between organisms that are not offspring.

[q]What happens to acquired genes in unicellular organisms during horizontal gene transfer?
[a]Newly acquired genes are integrated into the genome and passed to offspring during reproduction.

[q]What must happen for horizontal gene transfer to have intergenerational effects in multicellular organisms?
[a]The genes must be transferred into the germline.

[q]What is bacterial conjugation?
[a]A process where bacteria transfer plasmids (small loops of DNA) to another cell.

[q]What role does a pilus play in bacterial conjugation?
[a]The pilus contacts a recipient cell, enabling the plasmid to be copied and transmitted.

[q]What is the significance of bacterial conjugation in medicine?
[a]It plays a key role in spreading antibiotic-resistant genes through bacterial populations.

[q]What is bacterial transformation?
[a]A process where bacteria pick up DNA fragments or plasmids from the environment and incorporate them into their genome.

[q]How is bacterial transformation used in genetic engineering?
[a]It is used to introduce foreign genes, such as human genes, into bacterial cells.

[q]What is viral transduction?
[a]A type of horizontal gene transfer where viruses transfer DNA from one host to another due to errors in the viral replication cycle.

[q]How does viral transduction occur?
[a]During viral infection, host DNA fragments are mistakenly incorporated into new viral particles and transferred to a new host.

[q]What is viral recombination?
[a]A process where two different viruses infect the same host cell, and their DNA mixes, creating new viral strains.

[q]What is the significance of viral recombination in public health?
[a]It leads to the emergence of novel viral strains, such as new flu strains, which can cause pandemics.

[q]How does horizontal gene transfer drive evolution?
[a]It introduces new genes across species boundaries, enabling genetic diversity and rapid adaptation.

[q]Why is horizontal gene transfer important in microbial populations?
[a]It spreads beneficial traits like antibiotic resistance, enhancing survival and adaptation.

[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|177d4fdc05110″ question_number=”259″ topic=”6.7.Mutation”] Contrast “horizontal gene transfer” with “vertical gene transfer.”

[a] In vertical gene transfer, parents transmit all or half of their genome to their offspring (depending on whether reproduction is asexual or sexual, respectively). In horizontal gene transfer, one organism transfers genes to another organism that is not its offspring. If the recipient is unicellular, then these newly acquired genes become part of the recipient’s genome, and will then get passed to its offspring. In a multicellular organism, horizontal transfer only has long-lasting results if the genes are transferred into the germline (the cells that create an egg or sperm cells).

[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|1773ffac75110″ question_number=”260″ topic=”6.7.Mutation”] Describe bacterial conjugation.

[a] Bacteria have, in addition to their main chromosome, small circles of DNA called plasmids (b). These plasmids can be copied in one bacterial cell, with the copy transmitted to a second bacterial cell via a membrane extension called a pilus (c). This transfer of plasmids transfers whatever genes are encoded on the plasmid to the second cell, which can, in turn, transmit this plasmid to another bacterial cell (or its offspring).

[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” topic=”6.7.Mutation” dataset_id=”AP_Bio_Flashcards_2022|128360de709c14″ question_number=”261″] Describe bacterial transformation.

[a] In bacterial transformation, bacteria pick up DNA fragments (a) from the environment, which become incorporated into the genome (c). In genetic engineering, small loops of DNA called plasmids can be forced into bacterial cells, and this forced uptake of plasmids is also referred to as transformation.

[q json=”true” yy=”4″ unit=”6.Gene_Expression_and_Regulation” dataset_id=”AP_Bio_Flashcards_2022|176aaf7ce5110″ question_number=”262″ topic=”6.7.Mutation”] Describe how horizontal gene transfer can occur through viral transduction.

Importance for the AP exam: High 

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Transduction is a type of horizontal gene transfer that can occur through viruses. During viral infections, the virus breaks apart the host’s genome. Sometimes, DNA fragments from the host are mistakenly incorporated into a virus. As a result, when that virus infects a cell in another organism, it can bring in that other organism’s DNA. If the virus infects a germ-line cell, then new genes can be incorporated into the gene pool of the recipient.

[q] Using the diagram below as a stimulus, describe what happens in antigenic drift.

[a] Antigenic drift is the process by which mutations in the influenza virus (5) cause its surface proteins (6) to change. Because these surface proteins are the antigens that our immune systems use to recognize, overcome, and remember the virus, the result is that long-term immunity to influenza is impossible. While immunization with a flu vaccine (or an influenza infection) can keep you safe for the remainder of any one flu season, it won’t give you immunity to the influenza viruses that emerge in the coming years.

[q] Using the diagram below as a stimulus, describe what happens during an antigenic shift.

[a] During an antigenic shift, strains of the influenza virus that infect humans (A) and birds (B) co-infect a third host (a pig). In the pig’s cells, the genetic material of the avian and human strains recombine. This creates a new strain of the virus (E) with significantly different genes and proteins from anything that humans have experienced before. Since viral proteins serve as the antigens that enable the human immune system to recognize, overcome, and remember previous infections, this new viral strain will have a much greater capacity to infect and cause serious disease, setting the stage for an influenza pandemic.

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