DNA replication - DNA polymerase, lagging stand, leading stand, parent DNA, topoisomerase, primase, helicase, RNA primer, okazaki fragment, and original DNA

Question

Where would a mutation be introduced during replication?

What nucleotide bases pair together to create new strands of DNA?

Where do environmental factors impact DNA?

How does crossing-over and independent assortment contribute to genetic variation?

Answer 1

1. Where would a mutation be introduced during replication?

Mutations during DNA replication can be introduced at various points, primarily due to:

• Errors in Base Pairing: DNA polymerase may incorporate an incorrect nucleotide opposite a base on the template strand. If these errors are not repaired by proofreading mechanisms or repair systems, they can lead to mutations.
• Issues with the Lagging Strand: The formation of Okazaki fragments on the lagging strand can lead to mutations if the RNA primers are not replaced accurately or if there are errors in the joining of Okazaki fragments.
• External Factors: Environmental factors (e.g., radiation or chemical exposure) can cause damage to DNA, leading to mutations that may be copied during replication.

2. What nucleotide bases pair together to create new strands of DNA?

The nucleotide bases pair together as follows:

• Adenine (A) pairs with Thymine (T)
• Cytosine (C) pairs with Guanine (G)

These base pairs are held together by hydrogen bonds and maintain the double-helix structure of the DNA molecule.

3. Where do environmental factors impact DNA?

Environmental factors can impact DNA in several ways:

• Chemical Exposure: Carcinogens and chemicals may cause DNA adducts, leading to mutations if they interfere with nucleotide pairing during replication.
• Radiation: Ionizing radiation (like X-rays) or UV radiation can cause direct DNA damage, including breaks in the DNA strands or thymine dimers, which can lead to erroneous replication.
• Biological Agents: Viruses and other pathogens can insert their genetic material into the host DNA, leading to genetic changes or mutations.

4. How does crossing-over and independent assortment contribute to genetic variation?

• Crossing-Over: During meiosis, homologous chromosomes can exchange segments of DNA through a process called crossing-over. This results in new combinations of alleles on the chromosomes, leading to genetic diversity in gametes.

• Independent Assortment: The law of independent assortment states that alleles for different genes segregate independently of one another when forming gametes. This means that the distribution of one set of alleles is not influenced by another set of alleles, further increasing variability in the genetic combinations of offspring.

Together, these processes create a diverse pool of genetic combinations, contributing to evolutionary adaptability within populations.