3B1 Causes of Genetic Variation for Praxis (5236)

What is genetic variation in biology?

The differences in the nucleotide sequence of DNA between individuals of a species. It is also known as the difference in allele frequencies between populations of a species.

This variation provides the fuel for evolution and, sometimes, speciation.

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What are genes made up of?

Specific sequences of DNA, or locations on chromosomes, that provide the necessary information for a trait.

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What are alleles?

Variations of a gene.

Examples: Brown hair or lactose intolerance.

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Define:

gene/allele frequency

It is the proportion of a specific allele among all alleles for a given gene in a population.

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What leads to natural selection?

genetic variation

Organisms with advantageous traits will go on to reproduce.

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What are the sources of genetic variation?

Mutation
Genetic recombination

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What is the main type of genetic variation?

mutation

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Define:

germline mutations

Mutations that occur in gametes - sperm and egg cells - and can be passed on to offspring.

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Define:

frameshift mutation

A mutation that shifts the reading frame of codons in DNA.

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What are the two types of traits for identifying genetic variation?

Discrete traits
Continuous traits

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Define:

discrete trait

A trait that is controlled by a small number of genes.

Examples: Flower color in pea plants.

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Define:

genetic recombination

It occurs when chromosome pairs exchange genetic information during meiosis.

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How does sexual reproduction contribute to genetic variation?

Sexual reproduction increases genetic diversity by allowing for a greater variety of allele combinations of alleles than found in either parent.

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What is independent assortment in sexual reproduction?

Chromosomes assort independently during gamete formation.

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What is crossing over?

The exchange of genetic material between homologous chromosomes during meiosis.

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What is the importance of crossing over in terms of genetic variation?

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It increases genetic variation.

What are gametes and their role in crossing over?

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Reproductive cells (eggs in females, sperm in males) that have only half the normal chromosomes and undergo meiosis, including crossing over, to create genetic variation.

How does crossing over lead to unique DNA sequences in chromatids?

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Chromatids undergo crossing over by exchanging segments of DNA with their homologs, resulting in unique DNA sequences.

What is the result of crossing over in meiosis?

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The creation of four new gametes, each with half the number of chromosomes as the parent cell had, and containing brand new gene sequences.

What is a continuous trait?

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A trait that shows a lot of variation among a population. These traits are influenced by multiple genes.

Examples: Human skin color, hair color, or height

What is gene flow?

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The movement of individual organisms and genes into or out of a population.

What is the founder effect?

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A phenomenon where a small group of organisms leaves a larger group to colonize a new area, carrying a reduced amount of the variation found in the original species.

What is a population bottleneck?

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A large population reduced in size, leading to a smaller subset of the original population’s genetic variation.

What is vertical gene transfer?

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The transfer of genetic material between a parent cell and daughter cells.

What are the mechanisms used for vertical gene transfer?

* Mitosis * Meiosis

What is the importance of vertical gene transfer through *mitosis*?

*To ensure cells are replaced in the body* with identical genetic material.

What is the importance of vertical gene transfer through *meiosis*?

To pass genetic material from *parent to offspring.*

What is **horizontal gene transfer (HGT)** also known as?

Lateral gene transfer | (LGT)

What is the natural mechanisms of lateral gene transfer? | (LGT)

* Bacterial transformation * Bacterial transduction * Bacterial conjugation

What is **bacterial transformation**?

When a bacterial cell takes up genetic material from the *environment.*

# Define: Artificial transduction | Bacteriophage-mediated gene transfer

The transfer of genetic material using a specific **bacteriophage**.

# Define: bacterial conjugation

When **two bacterial cells** join together to transfer genetic material using a pilus.

What is created when the genetic material becomes integrated into a plasmid or vector genetic material?

recombinant DNA

How does **artificial transduction occur**?

The bacteriophage infects bacterial or human cells and delivers the desired genetic material.

What is required for **artificial transformation** to occur in bacterial cells?

competence ## Footnote Cells must be able to take up foreign DNA.

How can bacterial cells become competent for artificial transformation?

By applying electrical pulses (electroporation) or chemical treatments such as calcium chloride.

3B1 Causes of Genetic Variation Flashcards

Describe how genetic variation is introduced and the benefits of sexual reproduction. (36 cards)