12. C. elegans

Question 1

What type of organism is C. elegans?

Answer 1

Free-living roundworm (nematode)

Not segmented like earthworms

Question 2

Where can C. elegans be found?

Answer 2

Soil, compost heaps, and rotting fruit

Part of the most abundant animal group on Earth

Question 3

What is the approximate duration of the life cycle of C. elegans at 20°C?

Answer 3

About 3 days

Question 4

Who introduced C. elegans as a multicellular model system?

Answer 4

Sydney Brenner in the 1960s

Question 5

What was the significance of C. elegans in genomic studies?

Answer 5

First multicellular organism to have its genome fully sequenced

Question 6

What is the size of the C. elegans genome?

Answer 6

100 megabases with 5 pairs of chromosomes

Question 7

What type of food is used to maintain C. elegans in lab conditions?

Answer 7

E. coli

Question 8

At what temperature can C. elegans be frozen for long-term storage?

Answer 8

-80°C

Question 9

What are the two sexual forms of C. elegans?

Answer 9

Hermaphrodites (XX) and Males (XO)

Question 10

What is the reproductive capability of hermaphrodites in C. elegans?

Answer 10

Can self-fertilize to produce genetically identical offspring

Question 11

What role do males play in the reproduction of C. elegans?

Answer 11

Needed for genetic crosses to create new genetic combinations

Question 12

Describe the body structure of C. elegans.

Answer 12

Cylindrical body tapered at both ends, protected by a cuticle

Question 13

What types of tissues are present in C. elegans?

Answer 13

• Muscles
• Reproductive system
• Intestine
• Nervous system

Question 14

What is the function of the fluid-filled body cavity in C. elegans?

Answer 14

Allows for circulation of signaling molecules

Question 15

What are the types of muscles found in C. elegans and their functions?

Answer 15

• Pharyngeal muscles (for feeding)
• Body wall muscles (for movement)
• Head/neck muscles (for sensory exploration)
• Vulval muscles (for egg laying)
• Intestinal and anal muscles (for defecation)

Question 16

How many neurons are in the hermaphrodite C. elegans?

Answer 16

302 neurons

Question 17

What types of neurons are present in the nervous system of C. elegans?

Answer 17

• Sensory neurons
• Interneurons
• Motor neurons

Question 18

What are the conserved neurotransmitters used by C. elegans?

Answer 18

• Acetylcholine
• Glutamate
• GABA

Question 19

What are some unique neurotransmitters found in C. elegans?

Answer 19

• Tyramine
• Octopamine

Question 20

What are the advantages of using C. elegans in genetics?

Answer 20

• Complete genome map available
• Easily manipulated through genetic techniques
• Compatible with modern techniques like CRISPR-Cas9

Question 21

What is forward genetics?

Answer 21

Screen for phenotypes, then identify genes

Question 22

What is reverse genetics?

Answer 22

Mutate specific genes, then observe effects

Question 23

What experimental advantages does C. elegans provide for visualization?

Answer 23

• Transparent body allows direct observation of cells and tissues
• Can use fluorescent markers to track gene expression
• Laser ablation can remove specific neurons to study function

Question 24

What does the ‘connectome’ refer to in the context of C. elegans?

Answer 24

Maps all neural connections

Question 25

True or False: C. elegans shares many conserved mechanisms with humans.

Answer 25

True

Question 26

Fill in the blank: C. elegans is an excellent model for understanding how organisms adapt their physiology to _______.

Answer 26

[environmental changes]