HS-LS3-2. Make and defend a claim based on evidence that inheritable genetic variations may result from: (1) new genetic combinations through meiosis, (2) viable errors occurring during replication, (3) mutations caused by environmental factors and/or (4) genetic engineering.

Inheritable genetic variation is a key factor in the diversity of traits seen in populations. This variation arises from several processes, including new genetic combinations during meiosis, errors during DNA replication, environmental-induced mutations, and genetic engineering. Understanding these sources of variation helps explain how traits are inherited and how genetic diversity is maintained within populations.

Main Concepts

New Genetic Combinations through Meiosis: Meiosis is the process by which gametes (sperm and egg cells) are produced. During meiosis, genetic material is shuffled through crossing over and independent assortment, leading to new combinations of genes. This genetic reshuffling results in offspring with unique genetic profiles, contributing to genetic diversity.

Errors During DNA Replication: DNA replication is essential for cell division. However, errors can occur during this process, leading to changes in the DNA sequence. These errors can result in mutations that are passed on to the next generation if they occur in gametes. Such mutations introduce new genetic variations into a population.

Mutations Caused by Environmental Factors: Environmental factors such as radiation, chemicals, and viruses can induce mutations in DNA. These mutations can alter the genetic code and create new variations that may be inherited if they occur in germ cells (sperm or egg cells).

Genetic Engineering: Genetic engineering involves modifying an organism's DNA through biotechnological methods. This can include adding, removing, or altering genes to create new traits or genetic combinations. Genetic engineering can introduce variations that do not occur naturally and can be inherited by future generations.

Using Data to Support Claims: To make and defend claims about genetic variation, evidence from experiments, genetic studies, and biotechnological advancements is essential. Data such as experimental results, genetic sequences, and observed traits help support arguments about how genetic variation occurs.

NGSS Aligned Testing Question

Prostaglandins cause inflammation by attaching to protein receptors on the surface of some cells, as shown in the model below.

	Which claim could be used to describe a possible cause of the new variation in the gene that codes for the production of the prostaglandin receptor?
1	The changed receptor will produce a new DNA sequence with different functions that change the inflammatory response.
2	Events during reproduction or exposure to some environmental factors could result in a new inheritable variation in the DNA that codes for the production of prostaglandin receptors
3	The protein will no longer be able to produce the gene that codes for prostaglandins, resulting in a weaker inflammatory response.
4	The changed DNA will be passed on through reproduction and result in a different order of simple sugar subunits that make up the C-enzyme protein.

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Review Questions and Answers

1. How does meiosis create new genetic combinations?

Meiosis creates new genetic combinations through processes like crossing over, where homologous chromosomes exchange genetic material, and independent assortment, where chromosomes are randomly distributed into gametes. This shuffling of genes leads to genetic diversity in offspring.

2. What are the possible effects of errors during DNA replication?

Errors during DNA replication can lead to mutations, which are changes in the DNA sequence. If these mutations occur in germ cells, they can be inherited by the next generation, introducing new genetic variations into the population.

3. How can environmental factors lead to genetic mutations?

Environmental factors such as UV radiation, chemical pollutants, and viral infections can cause damage to DNA, resulting in mutations. These changes can alter the genetic code and may be passed on to offspring if they occur in germ cells.

4. What role does genetic engineering play in creating genetic variation?

Genetic engineering can create genetic variation by directly modifying an organism's DNA. This can include adding new genes, removing existing ones, or altering gene sequences to produce new traits that are inherited by subsequent generations.

5. Why is it important to use data when supporting claims about genetic variation?

Using data is important because it provides concrete evidence to support claims about how genetic variation occurs. Data from genetic studies, experiments, and biotechnological research help validate explanations and understand the mechanisms behind genetic changes.

6. What is the significance of crossing over during meiosis?

Crossing over is significant because it allows for the exchange of genetic material between homologous chromosomes, leading to new combinations of genes in gametes. This process increases genetic diversity in offspring.

7. How do environmental mutations affect genetic diversity?

Environmental mutations can increase genetic diversity by introducing new variations into the genetic pool. These mutations can lead to new traits that may be beneficial or neutral, contributing to the overall diversity of the population.

8. How can genetic engineering be used to study genetic variation?

Genetic engineering can be used to create specific genetic modifications in organisms, allowing scientists to study the effects of these changes on traits and inheritance. This helps researchers understand how genetic variation influences various characteristics.

9. What evidence supports the claim that genetic variations are inheritable?

Evidence supporting the claim includes experimental data showing that genetic variations can be passed from parents to offspring, observations of inherited traits, and research on mutations and genetic engineering demonstrating how new variations are introduced and inherited.

10. What is the impact of understanding genetic variation on evolutionary biology?

Understanding genetic variation is crucial for evolutionary biology because it explains how populations adapt to changes in their environment, how new traits arise, and how genetic diversity contributes to the evolutionary process.

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