UNIT 3 PART 2

Define antiparalleism in DNA and explain why continuous synthesis of both DNA strands is not possible

Antiparalleism: two biopolymers are antiparallel if they run parallel to each other but with opposite directionality.

Not possible

Continuous synthesis of both DNA strands is not possible because it needs to build a little bit of DNA then back tract, then build then backtrack.

Briefly describe the process of DNA replication and explain the role of helicase, DNA polymerase, and ligase

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. Once the DNA in a cell is replicated, the cell can divide into two cells, each of which has an identical copy of the original DNA.

Describe a basic virus "life" cycle

Entry, Assimilation, self assembly.

Briefly describe the process of DNA replication

Helicase enzyme unwinds part of DNA helix, DNA polymerase is the enzyme that adds new nucleotides to create the new strand, ligase is used in cells to join together the Okazaki fragments which are formed on the lagging strand during DNA replication.

Viruses that appear to cause certain human cancers

Hepatitis B (liver), Epstein-Barr (lymphoma) Papilloma viruses (cervical) HTLV-1 retrovirus (leukemia)

Be able to list several viral illnesses in humans

Hepatitis, measles, polio, chicken pox, influenza

Explain the difference between lytic and lysogenic bacteriophages

Lytic: Reproduce virus in bacteria, release virus by rupturing bacterial host. Lysogenic: Intergate viral DNA into bacterial DNA, reproduce with bacteria.

What is an Okasaki fragment?

Okazaki fragments are short sequences of DNA nucleotides that are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication.

When and why must DNA replicate?

Replication is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, as the parent cell.

Describe binary fission in bacteria:

Replication of bacterial chromosome. Asexual reproduction, -offspring genetically identical to parent.

What characteristics do all viruses share

They can mutate. They are acellular, that is, they contain no cytoplasm or cellular organelles. They carry out no metabolism on their own and must replicate using the host cell's metabolic machinery. In other words, viruses don't grow and divide. The vast majority of viruses possess either DNA or RNA but not both.

What are the characteristics that all prokaryotes share?

Unicellular, size, internal structure -no interal compartments, no membrane-bound organelles, only ribosomes, -circular chromosomes, naked DNA, not wrapped around proteins.

What are the various classes of viral genomes?

Viral nucleic acids, DNA, RNA, Linear or circular.

Describe the structure of a bacteriophage

Viruses that infect bacteria, 20 sided capsid head enclosed DNA, -Protein tail attaches phage to host & injects phage DNA inside.

Explain how viruses can be associated with cancer (Example: HPV)

When viruses cause an infection, they spread their DNA, affecting healthy cells' genetic makeup and potentially causing them to turn into cancer. HPV infections, for instance, cause the virus' DNA to combine with the host's DNA, disrupting the normal function of cells.

How is a medical treatment for a bacterial infection different from medical treatment for a viral infection?

bacterial vaccines.

Distinguish between the leading and lagging strands

leading: continuous synthesis Lagging strand: Okazaki fragments joined by ligase, "spot welder" enzyme

Be able to list several bacterial illnesses in humans

yellow fever, bluonic plage.