Biology Unit 3 Part 2 Flashcards

Questions and Answers

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. Helicase unwinds the DNA helix, DNA polymerase adds new nucleotides to create the new strand, and ligase joins Okazaki fragments on the lagging strand.

What is an Okazaki fragment?

Okazaki fragments are short sequences of DNA nucleotides synthesized discontinuously and later linked together by DNA ligase.

When and why must DNA replicate?

DNA must replicate whenever a cell divides to ensure each daughter cell contains the same genetic information as the parent cell.

What are the characteristics that all prokaryotes share?

All of the above Signup and view all the answers

Describe binary fission in bacteria.

Binary fission is the process of replicating the bacterial chromosome and asexual reproduction, resulting in offspring genetically identical to the parent. Signup and view all the answers

What characteristics do all viruses share?

All of the above Signup and view all the answers

What are the various classes of viral genomes?

Viral genomes can be classified as DNA, RNA, linear, or circular. Signup and view all the answers

List several viral illnesses in humans.

Hepatitis, measles, polio, chicken pox, influenza. Signup and view all the answers

List several bacterial illnesses in humans.

Yellow fever, bubonic plague. Signup and view all the answers

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

Bacterial infections are typically treated with antibiotics, while viral infections may require antiviral medications or vaccines. Signup and view all the answers

Describe a basic virus 'life' cycle.

The basic virus life cycle includes entry, assimilation, and self-assembly. Signup and view all the answers

Explain the difference between lytic and lysogenic bacteriophages.

Lytic bacteriophages reproduce viruses in bacteria and release them by rupturing the bacterial host. Lysogenic bacteriophages integrate viral DNA into bacterial DNA and replicate with the bacteria. Signup and view all the answers

Describe the structure of a bacteriophage.

Bacteriophages have a 20-sided capsid head that encloses DNA, and a protein tail that attaches to the host and injects the phage DNA inside. Signup and view all the answers

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

Viruses can affect healthy cells' genetic makeup, potentially leading to cancer. HPV infections, for example, integrate viral DNA with the host's DNA, disrupting normal cell functions. Signup and view all the answers

List viruses that appear to cause certain human cancers.

Hepatitis B (liver), Epstein-Barr (lymphoma), Papilloma viruses (cervical), HTLV-1 retrovirus (leukemia). Signup and view all the answers

Study Notes

DNA Replication Process

DNA replication produces two identical DNA molecules from a double-stranded DNA molecule.
Essential for cell division so each daughter cell inherits the same genetic information.

Key Enzymes in DNA Replication

Helicase: Unwinds the DNA helix to separate the two strands.
DNA Polymerase: Adds new nucleotides to form a complementary strand.
Ligase: Joins Okazaki fragments on the lagging strand, acting as a "spot welder."

Leading vs. Lagging Strands

Leading Strand: Synthesis occurs continuously.
Lagging Strand: Synthesized in short segments called Okazaki fragments, which are later joined by ligase.

Antiparalleism in DNA

Antiparalleism refers to the orientation of the two DNA strands running in opposite directions.
Continuous synthesis of both strands is hindered due to the need for backtracking while building the lagging strand.

Okazaki Fragments

Short sequences synthesized discontinuously during DNA replication on the lagging strand.
Later linked together by DNA ligase.

Importance of DNA Replication

Occurs prior to cell division to ensure each daughter cell has the same DNA as the parent cell.

Characteristics of Prokaryotes

Unicellular organisms with no internal compartments or membrane-bound organelles.
DNA is circular and not associated with proteins (naked DNA).

Binary Fission in Bacteria

Asexual reproduction method where the bacterial chromosome replicates and divides.
Offspring are genetically identical to the parent.

Common Characteristics of Viruses

Acellular: lack cytoplasm and cellular organelles.
Cannot metabolize independently; rely on host cells for replication.
Typically contain either DNA or RNA, but not both.

Classes of Viral Genomes

Viral genomes can be composed of DNA or RNA and can exist in linear or circular forms.

Viral Illnesses in Humans

Examples include hepatitis, measles, polio, chicken pox, and influenza.

Bacterial Illnesses in Humans

Notable infections include yellow fever and bubonic plague.

Treatment Differences

Bacterial infections may be treated with antibiotics or vaccines, whereas viral infections often require antiviral therapies.

Virus Life Cycle

Basic stages include entry into a host cell, assimilation of host cellular machinery, and self-assembly of new virus particles.

Lytic vs. Lysogenic Bacteriophages

Lytic: Destroy host cell to release new virus particles after replication.
Lysogenic: Integrate viral DNA into the host's DNA and replicate along with the host's cellular division.

Structure of a Bacteriophage

Comprises a 20-sided capsid head containing DNA, and a protein tail that attaches to the bacterial host to inject viral DNA.

Viruses and Cancer Association

Certain viruses can integrate their DNA into host cells, altering genetic function and potentially leading to cancer.
HPV is a notable example, combining its DNA with the host's DNA, disrupting normal cell processes.

Viruses Linked to Human Cancers

Examples include Hepatitis B (liver cancer), Epstein-Barr virus (lymphoma), Papillomaviruses (cervical cancer), and HTLV-1 retrovirus (leukemia).

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Description

Explore the fundamentals of DNA replication in this flashcard quiz, focusing on key enzymes such as helicase, DNA polymerase, and ligase. Test your understanding of how these components work together to ensure genetic material is accurately copied for cellular division.