Lecture 14: Cell Diversity And Viruses

Question 1

The genome is a dynamic…

Answer 1

Information system which impacts how cells respond and what actions they take

Question 2

Cells contain a large number of…

Answer 2

Components

Question 3

Cells are organized with respect to…

Answer 3

Time and space

Question 4

Eukaryotic cells are structurally more _____ than prokaryotic cells

Answer 4

Complex

Question 5

Protista are…

Answer 5

Enormously diverse

Question 6

Protista basic features (6)

Answer 6

• Mostly unicellular
• Mostly aquatic
• Often contain flagella or cilia - ability to be motile
• Sexual and asexual reproduction
• Diverse nutrition lifestyles
• Link between prokaryotes and eukaryotes

Question 7

Protista nutrition lifestyles include… (5)

Answer 7

Photosynthetic
Holotrophic - ingest other organisms and digest that (e.g. amoeba)
Saprotrophic - ingest dead material
Parasitic
Symbiotic - Protista and microalgae work together to form lycans

Question 8

Examples of Protista… (4)

Answer 8

• Protozoans
• Unicellular red and green algae
• Diatoms
• Slime molds

Question 9

Protista are found where on the phylogenetic tree?

Answer 9

Between the fungi and the prokaryotes

Question 10

Slime molds were previously identified to be a part of the ______ kingdom, but are now grouped into the kingdom _____ - it is not a _______

Answer 10

Fungal
Protista
Mold

Question 11

Slime mold basic features

Answer 11

• Eukaryotic
• Single celled
• Use spores as form of sexual reproduction
• Size: less than 1 dm to several square metres
• Multinucleate (1 cell has 1000s of nuclei)
• Have capacity to move around and respond to their environment

Question 12

What is the sole purpose of viruses?

Answer 12

To make more of themselves

Question 13

The virosphere is…

Answer 13

All of the viruses present on planet earth

Question 14

There are probably millions of distinct viruses because…

Answer 14

Each microbe is associated with at least one virus

Question 15

How many viruses have we characterized so far?

Answer 15

About 5000

Question 16

Viruses are not ______

Answer 16

cells

Question 17

Viruses reproduce only…

Answer 17

Within living cells

Question 18

Outside of a cell, a virus is a…

Answer 18

Virion - when a virus exists as an inanimate particle outside of a cell

Question 19

Basic properties of viruses

Answer 19

1. Highly complex and organized
2. Activity controlled by a genetic program - however coding capacity can be low
3. Can reproduce - make copies of themselves
4. Can evolve - very rapidly - variants

Question 20

Structure of viruses

Answer 20

• All have a nucleic acid
• Protein coat (capsid - composed of capsid proteins) that surrounds nucleic acid
• Enclosed in a protein-containing membrane (enveloped - many) or not (naked or in enveloped)
• Nucleic acid either RNA or DNA; encodes viral proteins - thus either RNA or DNA viruses

Question 21

HIV features

Answer 21

• Retrovirus
• RNA - can be converted to DNA
• Insert copy of its genome into the hosts DNA
• Permanent - AIDS

Question 22

Hep-B features

Answer 22

• Hepadnavirus
• DNA virus
• Affects human liver and causes infection

Question 23

Ebola virus features

Answer 23

• Filovirus
• Encode their genome in the form of single-stranded negative-sense RNA
• Kills cells quickly

Question 24

Bacteriophage is a virus that

Answer 24

Infect prokaryotes - within bacteria and archaea

Question 25

Adenovirus features

Answer 25

- Large group - Respiratory illness

Question 26

Tobacco Mosaic virus is…

Answer 26

One of the smallest viruses we know of, about 300 nm in size

Question 27

Bacteriophages bind to bacteria through…

Answer 27

Tail fibers

Question 28

Inside capsid head of bacteriophage, it contains…

Answer 28

Nucleic acid, which is mostly DNA

Question 29

Sheath of a bacteriophage…

Answer 29

Injects DNA into bacteria

Question 30

DNA of bacteriophage…

Answer 30

insert into bacteria genome and starts to replicate itself to be released from bacteria

Question 31

CRISPR-Cas is…

Answer 31

A way to battle continuous attacks from bacteriophages, CRISPR-Cas is an evolved-like immune system.

Question 32

Types of host ranges that viruses can have are… (2)

Answer 32

- Narrow host range - cold - Wide host range - rabies

Question 33

Once inside a cell, the virus…

Answer 33

Hijacks cellular machinery to synthesize nucleic acids (DNA/RNA) and proteins, which are assembled to make new viruses (viruses replicate within the host)

Question 34

What are the two main types of viral life cycles?

Answer 34

- Lytic - Non-lytic (lysogenic)

Question 35

Non-lytic (lysogenic) viral life cycle is…

Answer 35

- Viral nucleic acid is replicated in the host; viral proteins produced - Virus reproduces without destroying the host cell

Question 36

Lytic viral life cycle is…

Answer 36

- Production of virus particles ruptures (and kills) host cell (e.g. bacteriophages; Ebola virus)

Question 37

Combination of both ____ and ____ life cycles are found in nature

Answer 37

Lysogenic and Lytic - e.g. cold sores

Question 38

Lysogenic life cycle:

Answer 38

- Once enveloped virus proteins recognizes proteins on the surface of host, goes through endocytosis, and virus is internalized - Virus ejects capsid, and separates nucleic acid from capsid - Separated nucleic acid creates envelope that goes to plasma membrane and also created capsid proteins that form around a new nucleic acid - exocytosis takes place and new virus is created

Question 39

Rabies has an…

Answer 39

Enveloped single-stranded RNA genome

Question 40

How do RNA vaccines work?

Answer 40

Trick the body’s cells into producing fragment of virus

Question 41

Glycoproteins are…

Answer 41

A gene that is on the outside of the cell

Question 42

COVID-19 Spike protein

Answer 42

Binds to cells, and have evolved through many spike variants

Question 43

What is a provirus?

Answer 43

Virus that can integrate into host genome

Question 44

HPV virus is a…

Answer 44

DNA virus

Question 45

What is a strategy to make RNA vaccines more effective?

Answer 45

Replicate, makes lots of copies of the RNA template for producing antigens

Question 46

What is the main factor that determines what cell type a virus can infect?

Answer 46

Surface expression of a specific protein