Bacteriophage and Viral Genetics Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What direction does DNA polymerase III add nucleotides to the template strand?

3’ to 5’

5’ to 3’ (correct)

5’ to 5’

3’ to 3’

What characterizes the lagging strand during DNA replication?

It requires RNA primers to start synthesis. (correct)

It is synthesized continuously.

It does not require Okazaki fragments.

It is built in the 3’ to 5’ direction.

What is the role of RNA polymerase in transcription?

It connects RNA nucleotides to form a strand. (correct)

It unwinds the DNA double helix.

It catalyzes the joining of amino acids.

It synthesizes DNA from an RNA template.

Where does transcription occur in eukaryotic cells?

In the nucleus Signup and view all the answers

Which process is responsible for protein synthesis?

Translation Signup and view all the answers

What is a characteristic feature of lytic viruses?

They replicate and kill the host cell. Signup and view all the answers

In the lysogenic cycle, what occurs after the bacteriophage DNA integrates into the host genome?

The host cell divides, replicating the viral DNA. Signup and view all the answers

How do bacteriophages penetrate bacterial cells?

By injecting DNA into the cell while leaving the protein capsid outside. Signup and view all the answers

What process allows bacteria to become more pathogenic through lysogenic conversion?

Integration of viral DNA that confers new genetic traits. Signup and view all the answers

Which nucleic acid configuration is characteristic of RNA?

Single-stranded. Signup and view all the answers

What occurs during the stationary phase of bacterial growth?

The rate of new cells equals the rate of dying cells. Signup and view all the answers

During the viral life cycle, what distinguishes the release of enveloped viruses from nonenveloped viruses?

Enveloped viruses can bud from the host cell. Signup and view all the answers

In what phase of bacterial growth does binary fission occur rapidly?

Exponential phase Signup and view all the answers

What type of nucleic acid can viruses possess?

Either DNA or RNA, but not both. Signup and view all the answers

Which statement accurately describes semiconservative DNA replication?

Each new double helix is made from an old strand and a new strand. Signup and view all the answers

What is the key difference in penetration between bacteriophages and animal viruses?

Animal viruses enter by endocytosis, unlike bacteriophages that inject DNA. Signup and view all the answers

What is a common characteristic of both osmophiles and halophiles?

Both are types of extremophiles. Signup and view all the answers

During which phase of bacterial growth do cells begin to die?

Death phase Signup and view all the answers

What best describes the role of a gene?

A carrier of hereditary information in the form of DNA. Signup and view all the answers

Which enzyme is responsible for unwinding the DNA double helix during replication?

Helicase Signup and view all the answers

How is the population growth rate calculated?

Subtract the initial population from the final population, divide by the initial size, and multiply by 100. Signup and view all the answers

What type of reproduction is binary fission?

Asexual reproduction Signup and view all the answers

What is the primary structure of a protein defined by?

The sequence of amino acids Signup and view all the answers

Which of the following is NOT a component of nucleic acid?

An amino acid Signup and view all the answers

What bond type connects amino acids in proteins?

Peptide bond Signup and view all the answers

Which structures are determined by the hydrogen bonding in polypeptide chains?

Secondary structure Signup and view all the answers

Which of these is a role of globular proteins?

Assist in metabolic reactions Signup and view all the answers

What supplies the structural backbone of nucleotides in RNA?

Ribose sugar Signup and view all the answers

Which type of organisms are alkaliphiles typically found in?

Alkaline pH environments Signup and view all the answers

What is the primary role of a codon in mRNA?

To determine the position of amino acids during protein synthesis Signup and view all the answers

Which type of ribosome is smaller in size?

Prokaryotic ribosomes Signup and view all the answers

What is the process of conjugation in bacteria?

Transfer of DNA between two bacteria through direct contact Signup and view all the answers

What distinguishes facultative anaerobes from aerotolerant anaerobes?

Facultative anaerobes can utilize oxygen, while aerotolerant cannot Signup and view all the answers

Which statement defines transformation in the context of horizontal gene transfer?

The absorption of naked DNA from the environment Signup and view all the answers

What characterizes organic compounds?

They contain carbon and are usually derived from living organisms Signup and view all the answers

In the context of growth phases in bacteria, what is the lag phase?

The period where bacteria have just been introduced to a fresh medium and are adapting Signup and view all the answers

Which statement is true about the lytic and lysogenic cycles of viruses?

The lysogenic cycle does not immediately kill the host cell Signup and view all the answers

What nitrogenous base replaces thymine in RNA?

Uracil Signup and view all the answers

What process do autotrophs perform to produce their own food from carbon dioxide?

Photosynthesis Signup and view all the answers

What is the optimum temperature range for mesophiles?

37°C Signup and view all the answers

How do thermophiles adapt to high temperatures?

By having heat-stable proteins. Signup and view all the answers

In which two categories are organisms based on their source of carbon?

Autotrophs and heterotrophs Signup and view all the answers

What is binary fission in bacteria?

A method of asexual reproduction. Signup and view all the answers

What distinguishes lithotrophs from other types of trophic levels?

They utilize inorganic compounds as their energy source. Signup and view all the answers

What characterizes psychrophiles in terms of temperature preference?

They prefer cold temperatures, with an optimum at around 8°C. Signup and view all the answers

How do Okazaki fragments contribute to the replication of the lagging strand?

Okazaki fragments are short segments synthesized on the lagging strand, as DNA can only be built in the 5' to 3' direction, requiring small stretches of RNA primers to initiate replication. Signup and view all the answers

What is the significance of primase in DNA replication?

Primase synthesizes a short RNA primer needed for DNA polymerase to initiate DNA synthesis on both leading and lagging strands during replication. Signup and view all the answers

In what way is RNA synthesized during transcription?

RNA is synthesized by RNA polymerase connecting complementary RNA nucleotides to one of the DNA strands used as a template. Signup and view all the answers

Describe the role of exonuclease in the process of DNA replication.

Exonuclease removes RNA primers from both strands after Okazaki fragments are formed, ensuring that gaps are filled with DNA nucleotides. Signup and view all the answers

Explain how the directionality of DNA synthesis affects the replication of the lagging strand.

Since DNA can only be synthesized in the 5' to 3' direction, the lagging strand is produced in short segments, or Okazaki fragments, in the opposite direction of the overall replication fork movement. Signup and view all the answers

What structural differences distinguish DNA and RNA at the primary level?

DNA is double-stranded, while RNA is single-stranded. Signup and view all the answers

How do lytic and lysogenic viruses differ in their impact on host cells?

Lytic viruses destroy the host cell after replication, while lysogenic viruses integrate their DNA into the host’s genome, remaining dormant during cell division. Signup and view all the answers

Explain the concept of lysogenic conversion and its significance in bacterial pathogenicity.

Lysogenic conversion enables bacteria to acquire new genetic material from a virus, potentially producing toxins and increasing their virulence. Signup and view all the answers

Describe the penetration mechanism of a bacteriophage compared to an animal virus.

Bacteriophages inject their DNA into the host, leaving the protein capsid outside, whereas animal viruses enter through endocytosis or membrane fusion. Signup and view all the answers

What occurs during the step of viral replication when the host cell is said to undergo lysis?

The host cell ruptures, releasing new virions that can infect additional cells. Signup and view all the answers

What roles do the four levels of nucleic acid structure (primary, secondary, tertiary, quaternary) serve in genetic function?

They determine the stability, functionality, and interactions of nucleic acids, impacting processes such as replication and transcription. Signup and view all the answers

In terms of viral replication, differentiate how enveloped viruses bud from host cells compared to nonenveloped viruses.

Enveloped viruses bud from the host cell, taking part of the membrane with them, while nonenveloped viruses typically cause lysis of the host cell. Signup and view all the answers

What is the significance of the host cell's susceptibility in the context of viral inactivity?

Viruses are inactive outside host cells and require a living susceptible cell to replicate and cause infection. Signup and view all the answers

What is the main difference between eukaryotic and prokaryotic ribosomes?

Eukaryotic ribosomes are 80S and larger, while prokaryotic ribosomes are 70S and smaller. Signup and view all the answers

Describe the process of transformation in horizontal gene transfer.

Transformation involves the uptake of free genetic material from the environment by bacterial cells. Signup and view all the answers

How do facultative anaerobes and aerotolerant anaerobes handle oxygen differently?

Facultative anaerobes can utilize oxygen for growth, while aerotolerant anaerobes cannot use it but tolerate its presence. Signup and view all the answers

What does conjugation in bacteria entail?

Conjugation involves the transfer of plasmids between two bacteria via cell-cell contact. Signup and view all the answers

What roles do capsids and capsomeres play in viruses?

Capsids are the protein shells that protect viral genetic material, while capsomeres are the individual protein subunits that make up the capsid. Signup and view all the answers

Explain what occurs during the lytic cycle of a virus.

During the lytic cycle, a virus infects a host, replicates using the host's machinery, and ultimately causes the host cell to lyse, releasing new virus particles. Signup and view all the answers

What is the significance of codons in mRNA?

Codons are sequences of three nucleotides in mRNA that specify which amino acids are to be added during protein synthesis. Signup and view all the answers

Differentiate between organic and inorganic compounds.

Organic compounds contain carbon atoms typically bonded with hydrogen, derived from living organisms, while inorganic compounds lack carbon and originate from non-living sources. Signup and view all the answers

What is the role of mRNA in protein synthesis?

mRNA carries the genetic information from DNA and serves as a template for synthesizing proteins by specifying the sequence of amino acids. Signup and view all the answers

Explain the significance of the anticodon in tRNA.

The anticodon on tRNA ensures that the correct amino acid is added to the growing polypeptide chain by matching with the corresponding codon on the mRNA. Signup and view all the answers

Describe the Central Dogma of molecular biology.

The Central Dogma describes the flow of genetic information from DNA to RNA through transcription and from RNA to protein through translation. Signup and view all the answers

Differentiate between DNA and RNA in terms of structure.

DNA is double-stranded and contains deoxyribose sugar, while RNA is single-stranded and contains ribose sugar. Signup and view all the answers

What is the function of rRNA in the process of translation?

rRNA forms the structural and functional core of ribosomes, facilitating the assembly of amino acids into proteins. Signup and view all the answers

Outline the sequence of events in DNA replication.

DNA replication begins with helicase unwinding the DNA, followed by primase synthesizing a primer, and then DNA polymerase extending the new strand. Signup and view all the answers

What occurs during transcription and how is it different from translation?

During transcription, RNA polymerase synthesizes mRNA from a DNA template, while translation involves using mRNA to assemble amino acids into a protein at the ribosome. Signup and view all the answers

Why are codons important in the genetic code?

Codons are important because each one specifies a particular amino acid, dictating the primary structure of proteins during translation. Signup and view all the answers

Study Notes

Bacteriophage Genome

A bacteriophage genome can be integrated into the circular bacterial chromosome or exist as an extrachromosomal plasmid.

Nucleic Acid Configurations

Nucleic acid can be either DNA or RNA.
DNA is double-stranded.
RNA is single-stranded.
Nucleic acids have four levels of structure: primary, secondary, tertiary, and quaternary

Viral Replication

Viruses are inactive except in living susceptible cells.

Lytic vs Lysogenic Viruses

Lytic viruses take over the host cell, replicate, and kill the host cell
Lysogenic viruses integrate their DNA into the host's DNA and remain dormant until later replication.

Lysogenic Conversion

Bacteria obtain genetic material from lysogenic viruses, enabling them to produce new toxins.
This can make bacteria more pathogenic, leading to diseases like diphtheria and scarlet fever.

Compare & Contrast Animal Virus Life Cycles vs Bacteriophage Life Cycles

Compare: Both go through absorption, penetration, and replication
Contrast:
- Penetration:
  - Prokaryote (bacteriophage): DNA injected into the cell, protein capsid remains outside the bacteria
  - Eukaryote (animal virus): whole virus engulfed by endocytosis, membrane invaginates, bringing the virus into the cell, uncoating: viral nucleic acid released from capsid into cytoplasm of eukaryotic cell
- Release:
  - Prokaryotic: host cell lysis resulting in virion release
  - Eukaryotic: Enveloped viruses bud from the host cell and take part of the cell membrane which becomes the envelope of the virus, Nonenveloped viruses typically undergo lysis

Summary of Bacteriophage vs Animal Virus

Bacteriophages inject DNA into the host cell, whereas animal viruses enter by endocytosis or membrane fusion

The Four Groups of Macromolecules

Proteins:
- Monomer: Amino Acids
- Polymer: Polypeptides
- Bond: Peptide
Polysaccharides (carbohydrates):
- Monomer: Monosaccharides
- Polymer: Polysaccharides
- Bond: Glyosidic bond
Lipids (fats):
- Monomer: Fatty Acids + Glycerol
- Polymer: Lipids
- Bond: Ester
Nucleic Acids:
- Monomer: Nucleotides
- Polymer: Nucleic Acids
- Bond: Phosphodiester

Protein Structures

Primary: The amino acid sequence of the polypeptide chain
Secondary: The folding of the polypeptide chain due to hydrogen bonds. This can form α-helices or β-sheets
Tertiary: The overall three-dimensional shape of the polypeptide chain.
Quaternary: Two or more polypeptides connected together.

Protein Functions

Structural/Fibrous: provide strength and shape to hold structures together
Globular: perform activities
- Enzymatic: speed up chemical reactions, enzymes typically end in "ase"
- Transport: help materials to enter/exit cells
- Antibodies: help fight infections

Nucleic Acids

Three components of nucleic acid: a sugar, a base, and a phosphate.

DNA Nucleotides

Phosphate group
Sugar: deoxyribose
Nitrogenous base pairs:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)

RNA Nucleotides

Phosphate
Sugar: ribose
Nitrogenous base pairs:
- Adenine (A)
- Uracil (U)
- Guanine (G)
- Cytosine (C)

Population Growth

To calculate population growth, subtract the initial population size from the final population size, then divide the difference by the initial population size and multiply by 100 to get the percentage growth rate.

Bacterial Growth Phases

Lag Phase: Dormant to active, new cells = old cells
Exponential Phase: Exponential growth, binary fission
Stationary Phase: Balanced growth, new ells = dying cells
Death Phase: Decline in population, cells are beginning to die

Distinguish between an Osmophile and a Halophile

Both are extremophiles that thrive in high solute concentrations.
Halophiles require high salt concentrations to survive

Chapter 8 Terms

Genome: All the DNA in a cell, can be in the form of chromosomes or chromatin.
Gene: Basic physical and functional unit of heredity, made up of DNA.
Chromosome: Carries genetic information, specifically DNA.
Replication: The process of duplicating chromosomes.

DNA Replication Steps

Unwinding: Topoisomerase helps unwind the DNA, helicase unwinds the double-stranded helix
Leading strand replication: DNA polymerase III adds nucleotides to the template in the 5' to 3' direction.
Lagging strand Replication: DNA polymerase III builds in the 5' to 3' direction, but the lagging strand goes in the 3' to 5' direction so it needs to use Okazaki fragments. Primase builds small stretches of RNA, DNA polymerase builds the fragment, Exonuclease removes the RNA primers, and DNA ligase fixes the strands

Transcription

The process of making any RNA from a DNA template (mRNA, tRNA, rRNA).
Occurs in the cytoplasm of prokaryotes and the nucleus of eukaryotes
Rna polymerase uses one strand of DNA as a template to create a strand of RNA.

Translation

The process of protein synthesis.
Occurs in the cytoplasm.
Codon: a sequence of 3 nucleotides in mRNA that determines the amino acid sequence of a protein.
Anticodon: A sequence of three nucleotides in tRNA that binds to the corresponding codon on mRNA.

Eukaryotic vs Prokaryotic Ribosomes

Eukaryotic: 80S, larger
Prokaryotic: 70S, smaller

Horizontal Gene Transfer in Bacteria

Conjugation: Transfer of genetic material between two bacteria through cell-to-cell contact.
Transformation: Bacteria take up free genetic material from the environment.
Transduction: Transfer of genetic material through viruses.

Vertical Mode

Refers to sexual reproduction, in contrast to horizontal gene transfer.

Test 2 Common Confusions

Aerotolerant Anaerobes vs Facultative Anaerobes: Both can grow with and without oxygen, but facultative anaerobes utilize oxygen when it’s present, while aerotolerant anaerobes simply tolerate oxygen’s presence, without using it.
Organic vs Inorganic Compounds: Organic compounds contain carbon atoms and are typically derived from living organisms, inorganic compounds do not contain carbon and are derived from minerals.
Heterotrophs vs Autotrophs: Heterotrophs consume organic compounds for energy, while autotrophs produce their own organic compounds from inorganic sources.
Lag Phase vs Log Phase: During lag phase, microbial populations have little to no growth, whereas exponential/log phase shows significant growth and multiplication.
Lytic Phase vs Lysogenic Phase: Lytic phages kill the host cell to release new viruses, while lysogenic phages integrate their DNA into the host genome and remain dormant until they are triggered to enter the lytic phase.
Capsid vs Capsomeres: Capsid is the protein shell that surrounds and protects the viral genome while Capsomeres are individual protein subunits that make up the capsid.
Transcription vs Translation: Transcription is DNA to RNA while translation is RNA to protein.
DNA vs RNA base pairing: DNA base pairing is adenine (A) with thymine (T) and guanine (G) with cytosine (C), while RNA base pairing is adenine (A) with uracil (U) and guanine (G) with cytosine (C).

Phage Genome Integration

Bacteriophages can integrate their genome into the host bacterial chromosome or exist as an extrachromosomal plasmid.
Phage genomes are made of either DNA or RNA, but not both.
DNA phages have double-stranded DNA.
RNA phages have single-stranded RNA.

Viral Replication: Lytic vs Lysogenic

Viruses are inactive outside of living cells.
Lytic phages take over the host cell, replicate, and kill the host.
Lysogenic phages integrate their DNA into the host cell's DNA, allowing the host to divide and carry the virus.
The viral DNA remains hidden within the host DNA in the lysogenic cycle.