Lecture 13 (Cell Basics)

Question 1

What is the cell theory?

Answer 1

1) All living organisms are composed of one or more cells

2) the cell is the basic unit of life

In 1855, Rudolf Virchow added the third tenet to cell theory:

3) All cells arise ONLY from pre-existing cells (omnis cellula e cellula)

Question 2

What is the primary distinction between prokaryotic and eukaryotic cells?

Answer 2

eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do not

Question 3

Outside cells, viruses exist as an inanimate particle called a

Answer 3

Virion

Question 4

What is a virion made of?

Answer 4

• Small amount DNA (DNA virus or RNA (RNA virus) that encodes a few hundreds of genes

Question 5

H

Question 6

Example of a retrovirus

Answer 6

HIV - can insert a copy of its genome into the DNA of a host cell

Question 7

Example of a hepadnavirus (DNA type)

Answer 7

Hepatitis B - affects human liver and can cause serious infections

Question 8

Example of a filoviruses

Answer 8

Ebola virus - encode their genome in the form of single-stranded negative-sense RNA

Question 9

What are adenoviruses?

Answer 9

group of viruses that cause respiratory illnesses (bronchitis) or an eye infection (conjunctivitis)

Question 10

What is bacteriophage?

Answer 10

a virus that infects and replicates within bacteria and archaea

Question 11

How does a virus enter the cell?

Answer 11

It binds to a cell surface VIA specific proteins and then enters into the cell

Question 12

What do NARROW host range (human cold and influenza) infect?

Answer 12

Epithelial cells of human respiratory system

Question 13

WIDE host range (rabies) can infect cells in

Answer 13

dogs, foxes, bats, racoons, and humans

Question 14

What happens when the virus is inside the cell?

Answer 14

The virus hijacks cellular machinery to synthesize nucleic acids (DNA/RNA) proteins

Question 15

LYTIC Infection:

Answer 15

Production of virus particles ruptures and kills the cell (e.g. influenza)

Question 16

Non-Lytic or Integrative or Lysogenic:

Answer 16

Viral DNA is inserted in host genome = PROVIRUS. Cell can survive, often with impaired functions (e.g. HIV)

Question 17

What does the RNA genome encode?

Answer 17

• nucleoprotein
• phosphoprotein
• matrix protein
• glycoprotein
• RNA polymerase

Question 19

What is meant by a. “amphipathic molecule”

Answer 19

They have both hydrophobic (non-polar) and hydrophilic (polar regions)

Question 20

How do RNA vaccines work?

Answer 20

trick the body’s cells into producing a fragment of a virus, an antigen, from an RNA template.