Question

14. Explain how a virus can cause cancer, and give an example of a virus that causes cancer.

15. Describe a few of the major pieces of evidence for evolution (make sure you include molecular/genetic evidence for full points).

16. Compare and contrast non-specific immunity and specific immunity. Give a few (at least 2-3) examples of non-specific immunity in our bodies.

Answer 1

Q.14.

When viruses cause infection, they spread their DNA, affecting the healthy cells genetic makeup and potentially causing them to turn into cancer. Interactions between cell proteins and proteins produced by oncogenic viruses can lead to breaking down of immune defenses that may allow the development of cancer.

* The Viral genome integrates near one of the cell's proto-oncogene, near a strong promoter, resulting in higher levels of transcription and translation if proto-oncogenes unnecessarily.

* Virus may integrate a proto-oncogene into its genome and expression of proto-oncogene is now under the control of the viral promoter.

*Virus which contains oncogene can infect cells. Normal cells are now mutated and results in expression of viral oncogenes whereby the cells are dividing excessively, which cause cancer.

Hepatitis B virus which cause viral hepatitis, a kind of liver infection. HBV induced chronic liver infections are rare, but when they occur, they raise the risk of liver cancer. Less than half of liver cancers in the United States are linked to HBV infection.

Q.15.

Similarities between biological molecules can reflect shared evolutionary ancestry like structural homology.At most basic level, all living organisms share,

• Same genetic material (DNA)
• Same, or highly similar, genetic codes
• The same basic process of gene expression that is transcription and translation.
• The same molecular building blocks, such as amino acids.

These shared features suggest that all living things are descended from a common ancestor, and that this ancestor had DNA as its genetic material, used the genetic code, and expressed its genes by transcription and translation. Present-day organisms all share these features because they were "inherited" from the ancestor.

Although they're great for establishing the common origins of life, features like having DNA or carrying out transcription and translation are not so useful for figuring out how related particular organisms are. If we want to determine which organisms in a group are most closely related, we need to use different types of molecular features, such as the nucleotide sequences of genes.

The we can take a look on Homologous genes;

Biologists often compare the sequences of related genes found in different species which are homologous genes, to figure out how those species are evolutionarily related to one another.

The basic idea behind this approach is that two species have same gene because they inherited it from a common ancestor. For instance, humans, cows, chickens, and chimpanzees all have a gene that encodes the hormone insulin, because this gene was already present in their last common ancestor.

In general, the more DNA differences in homologous genes , between two species, the more distantly the species are related. For instance, human and chimpanzee insulin proteins are much more similar than human and chicken insulin protein, reflecting that humans and chimpanzees are more closely related than those humans and chickens.

Q.16.

Immunity from disease is described by defense systems, called nonspecific which is innate immunity and specific, which is aquired immunity.

* Nonspecific protective mechanisms repel all microorganisms equally, while the specific immune responses are tailored to particular types of invaders.

* Nonspecific protective mechanisms repel all microorganisms equally, while the specific immune responses are tailored to particular types of invaders.

* The specific immune system is antigen specific and reacts only with the organism that made the response happen. Whereas the non specific system is not antigen specific and reacts equally well to a all types of organisms.

* The specific immune system has a memory of what pathogenic agents that it had encountered before in the past, where as the non specific has no recollection of the pathogenic agents