Blog 3A

3.C.1

1. Explain how alterations in a DNA sequence can lead to changes in the type or amount of the protein produced and the phenotype.

They can cause changes in the nucleotide sequences which can change the amino acids. This could possibly change the phenotype which would kill the organism or cause a simple change in the organism that could be an advantage or a disadvantage.

2. How can errors in DNA replication or DNA repair mechanisms, and external factors cause random changes.

The repair sequence could possibly change the original strand of DNA, making it a copy of the new strand. Radiation and carcinogens could also cause the DNA to mutate.

3. Explain how errors in mitosis or meiosis can result in changes in phenotype.

They can change the number of chromosomes and affect fertility and the phenotype. In plants, they could make a new type of plants, i.e one with thorns or without.

4. Explain how changes in genotype may affect phenotypes that are subject to natural selection.  Use the example antibiotic resistance mutations.

Mutations such as this cause the cell to produce enzymes that break down the antibiotics, therefore making the cell immune.

5. Genetic changes can enhance survival and reproduction. Explain how selection results in evolutionary changes.

3.C.2

1. What increases genetic variation? Eukaryotes: random mutation, random assortment, crossing over, random fertilization. Prokaryotes: random mutation. Bacterial conjugation, transformation, transduction.

2. Explain how the following increase variation: transformation, transduction, conjugation, and horizontal gene transfer.

3. How does sexual reproduction increase genetic variation? It causes the offspring to inherit its parents genetic information and also to combine and mix those chromosomes. It is a combination and mixture of the parents.

3.C.3

1. Explain how viruses replicate.

Viruses attach to bacterial and eukaryotic calls. They insert their genetic information and depending on what kind it is, the genetic information goes to the ribosomes or nucleus to be replicated. When the genetic information is replicated it uses the cell’s protein making mechanisms to make a new virus, over and over until the cell is full of viruses and lyses. The process repeats.

2. Explain the process of the lytic cycle.

Bacteria inserts its DNA into the host, the bacteria merges with the cell’s DNA, the DNA is replicated and through transcription in the host cell the ribosomes make copies of the virus until the virus load lyses the cell. The

3. Where do mutations occur during viral replication?

In the RNA.

4. Why do viruses have a higher rate of mutation? Because mistakes are easily made in transcription and the cell cannot check it for errors. And they replicate via RNA.

5. Explain HIV

HIV is an RNA virus that uses ribosomes in cells to replicate itself. It has a very high mutation rate so it is extremely difficult to cure.

6. How do viruses infect a host cell?

They latch onto the cell membrane and insert their genetic information which enters the nucleus an

7. What is a lysogenic(latent) infection? What can this result in?

It occurs when the viruses integrate their DNA into the host cell and the DNA is latent.