Exam 1 - Mic 329A

1. Cytoplasm

2. Cell membrane

3. Ribosomes

4. DNA

-Macromolecules

-Ribosomes

-Small organic molecules

-Inorganic ions

-Particle-like structure composed of RNA that interact with several soluble proteins and messenger RNA in the central process of protein synthesis.

-Not all organisms have ribosomes

-Viruses do not have ribosomes. Therefore, they cannot form proteins from messenger RNA; this is why viruses must have host cells in order to replicate.

-Viruses also lack nuclei and mitochondria. Cytoplasm is missing from some viruses, as well.

-All cells have ribosomes

-Cells need ribosomes in order to form proteins from messenger RNA

-Cytoplasm

a) Cytoplasm

b) Rough ER

c) Mitochondria

d) Chloroplasts

- 1-5 μm long, 1 μm wide

- An Archaen or a Bacterium

1) Eukaryotes have membrane enclosed organelles; prokaryotes have no organelles.

2) Eukaryotic cells are usually bigger than prokaryotic cells.

3) Eukaryotic cells are structurally more complex than prokaryotic cells.

4) Eukaryotic cells have DNA present in linear molecular within the nucleus; prokaryotic cells have circular DNA.

-Yes

-No

- A segment of DNA that encodes a protein (via messenger RNA) or another RNA molecule, such as ribosomal RNA.

- The genetic makeup of the organism

- a, c, d, e, f

- No nucleus

-1900

-SSU rRNA

-All cellular organisms contain ribosomes.

Carl Woese

1) Archaea, 106℃

2) Bacteria, 85-95℃

3) Bacteria, 50-95℃

The hypothesized process by which prokaryotes gave rise to the first eukaryotic cells

- Mitochodria and chloroplasts have their own genome.

- Mitochodria and chloroplasts have double membranes.

- Plylogenetic analysis places mitochodria and chloroplasts with bacterial lineages.

1) Uses light as energy through photosynthesis

2) Obtains energy from organic compounds

3) Obtains energy from inorganic compounds

- Chemoorganotroph

- Same

Bacteria

-Staphylococcus

-Streptococcus

-Lactobacillus

-Thick peptidoglycan cell wall

-Single membrane

-Endospore-forming

-Spirochetes

-Deinococcus

- Several lineages of Bacteria branch off very early on the phylogenetic tree, very near the root.

- These groups are unified by the common property of growth at high temperature (thermophily).

-Prokaryote-like cell

-Single cell

-Autotrophic

-Small cell

-Few or no internal membrane-bound structures

-Small genome

-Proteobacteria

1. 1993

2. 70%

3. Sin Nombre virus

4. Deer mice

An alternate or passive host or carrier that harbors pathogenic organisms without injury to itself and serves as a source from which other individuals can be infected.

- Darwin

-Used this term to describe evolutionary patterns that link all life on earth

-1859

-Haemophilus influenzae

-Bacteria

-1995

-About 1 million of individual cells of bacteria

-About 10 million individual viruses

- Bacteria

- Vibrio Chlorea

- Bacteria

- Buchnera

- Bacteria

- 150-250 million years

-It shows massive gene reduction in Buchnera

-Ocean

- Discovering new harmful pathogens

1. Discovering novel drugs

2. Discovering new data about microganisms living as extremophiles.

3. Understanding the history of life on earth.

-The structure by which the virus genome is carried from the cell from which it has been produced to another cell where the viral nucleic acid can be introduced

- A virion is composed of protein and either RNA or DNA

- When a virus genome is introduced into a host cell and reproduces

False

True

False

True

A virus that infects and replicates within a bacterium

a) Bacteriophages are model systems in molecular biology.

b) Bacteriophages can be used to evaluate viral ecology and evolution.

c) Bacteriophages can be explored for new applications in phage therapy.

"to eat"

- True

- Viridae

Mimivirus

- Large virus

- 400 nm in Diameter

Poliovirus

- Small virus

- 28 nm in diameter

- 0.2 microns (µm)

1. 1000-5000 kb

2. 5-230 kb

- They are obligate intracellular symbionts that replicate in host cells.

- Within the particle, surrounded by a protein coat called the capsid.

1. Capsid

2. Protein coat

3. Shell

- Nucleocapsid

Naked

- HPV (Human papillomavirus)

Enveloped

- HIV (human immunodeficiency virus)

- Influenza Virus

- TMV (Tobacco mosaic Virus

- Lipid layer

- Glycoproteins

1. Helical symmetry, Rod-shaped, 18x300 nm

2. Icosahedral symmetry, Spherical, 55 nm in diameter

- No

1. Lipids

2. Glycoproteins

- Cell lysis during invasion/viral entry and transport of nucleic acid.

- Production of lysozymes to destroy host cell wall, release virions

1. Attachment: The virus attaches to a host cell. In the case of the bacteriophage it will attach to a bacterium.

2. Entry: The virus forms a hole in the membrane or cell wall of the host. The nucleic acidof the virus enters the host cell.

3. Synthesis: The virus’ nucleic acid is used to make new viral nucleic acid and proteins for the new viruses being produced. (The host cells’ DNA becomes deactivated.)

4. Assembly: New viruses are made inside the host cell.

5. Release: The host cell bursts to release the new viruses. The bursting is called lysis.

DNA --> RNA --> protein

1. First arrow = transcription (information contained in a section of DNA is transferred to mRNA, facilitated by RNA polymerase and transcription factors)

2. Second arrow = translation (mRNA is translated in ribosome into a polypeptide chain, the basis of a protein)

These viruses:

(1) synthesize a complementary DNA strand, so that they become double-stranded, and then (2) proceed as described above.

In this case, the RNA of the virus itself serves as the mRNA.

These viruses have to make mRNA first. They do this by injecting RNA polymerase into the host cell, which allows the – strand to be transcribed, yielding a + strand of mRNA.

Like Class V viruses, they inject RNA polymerase into the host cell, which allows the – strand to be transcribed, yielding a + strand of mRNA.

- They use reverse transcriptase to make DNA from RNA.

- The process of making DNA from RNA is called reverse transcription.

- The Class VI viruses carry reverse transcriptase in their virions

Process:

1. ss RNA (+) undergoes reverse transcription to yield ds DNA

2. ds DNA is transcribed to yield mRNA

- Instead of acting like Class I viruses, they replicate through an RNA intermediate, which requires reverse transcriptase.

- Thus, class VII viruses also are retroviruses

- It is a virus that lyses its host immediately upon infection and often causes disease.

- Modify host RNA polymerase

A virus that does not cause immediate lysis following entry to its host but remains in a latent state, replicating its genome along with the host's genome

-Escherichia coli

True

In the lysogenic cycle, the viral DNA or RNA enters the cell and integrates into the host DNA as a new set of genes called prophage. That is, the viral DNA becomes part of the cell's genetic material. No progeny particles, like in the lytic phase, are produced. Each time the host cell DNA chromosome replicates during cell division, the passive and non-virulent prophage replicates too. This may alter the cell's characteristics, but it does not destroy it.

- The transmission of a symbiont (for example, a virus) from one generation to the next

- Temperate phage genomes can be duplicated along with that of the host. During cell division (by the host), the viral genome can be passed from one generation to the next.

1. Lysogenic pathway

2. Lytic pathway

- A latent infection is a situation in which a virus is present in the body, but it remains dormant, not causing any overt symptoms. It may become activated under certain circumstances and present symptoms.

- A classic example of a latent infection is herpes simplex, which periodically flares up to cause cold sores before going dormant again.

- Cellular phenomenon of uncontrolled growth.

1. Presence of growth inhibiting factors that prevent them from initiating cell division.

2. Transformation

In advanced stages of cancer, malignant tumors may develop the ability to spread to other parts of the body and initiate new tumors.

a) Carcinogens

b) UV exposure

c) Genetic mutations

d) Spontaneous mutations

A) Are enveloped

B) Use reverse transcriptase to transfer information ‘backward’ (from RNA to DNA)

C) Include Human Immunodeficiency Virus (HIV) D) Were the first viruses to be studied for their carcinogenic effects

The retrovirus genome can be integrated into the host genome by way of the DNA intermediate, and this integration process is being studied as a means of introduction foreign genes into a host, a process called gene therapy.

Because viruses are not cells but depends cells for their replication, viral diseases pose serious medical problems; it is frequently difficult to prevent antiviral drugs from doing some damage to host cells.

Small, circular, single-stranded RNA molecules that are the smallest known pathogens.

1. Infectious RNA particle

2. Formed of only a small single stranded circular RNA

3. Smaller than viruses

4. Infects only higher plants (Exception: Hepatitis D)

1. Infectious protein particle

2. Formed of only proteins

3. RNA or DNA is absent

4. Mostly, smaller than viroid

5. Infect animals causing neurological degenerative diseases. Ex: Mad cow disease

3600 virus 'species'

62 families

233 genera

Class V: (-) single-stranded RNA virus

1. Filoviridae

2. Marburg virus

Class IV: (+) single-stranded RNA virus

1. Picornaviridae

2. Hepatitis A virus

1. Flaviviridae

2. Class IV: (+) single-stranded RNA virus

3. Dengue Virus