Lecture 4: Model organisms

Question 1

What makes model organisms possible?

Answer 1

common ancestry -conservation of major aspects of biology

Question 2

typical considerations in selecting model organisms

Answer 2

rapid development with short life cycles
small adult size
availability and inexpensive maintenance and breeding
tractability to experimental methodology
relevance to humans

Question 3

bacteria used for

Answer 3

laid the foundations of molecular biology
antibiotics
recombinant DNA technologies

Question 4

Yeast used for

Answer 4

eukaryotic system
signaling molecules and cell cycle are nearly similar

to understand human diseases (nearly 20% human diseases genes have yeast homologues)
ease of genetic manipulation -> use for analyzing and functionally dissecting gene products from other eukaryotes

Question 5

Hydra used for

Answer 5

phylogeny (at the base of metazoan phyla)
evolutionary transition (body axis, germ layers, gonads, cell types)
pattern formation (peculiar tissue dynamics make hydra perpetual embryo)
regeneration, stem cells

Question 6

Anatomy of hydra

Answer 6

live in water
most have tentacles
catch food with stinging cells
gut for digesting
nerve net found througout the body

Question 7

What is unique in c. elegans?

Answer 7

can be grown and genetically manipulated with the speed and ease of microrganism + features of a real animal

genom is fully sequenced
full set of organ systems 
complex sensory systems
coordinated behavior
possible to trace the lineage of every one of its nearly 1000 constituent cells

Question 8

C. elegans used for

Answer 8

developmental and cell biology
neurobiology
aging
human disease studies (~75% genes have potential homologs)

Question 9

Drosophila used for

Answer 9

biomedical research
easy to manipulate -> study developmeny, physiology, behavior
insights into forms of cancer, neurodegenerative diseases, behavior, immunity, aging, multigenic inheritance, development

homologues of it ~ many organ systems in mammals

Question 10

Zebrafish is useful for

Answer 10

transparent egg (48 hours to develop) -> see the embryonic development
shared features - blood, kidney, optical systems
development in ex vivo

genome - half the size of mouse and human -> identification of key vertebrate genes

Question 11

Chick embryo used for

Answer 11

study development of higher vertebrates - growth accompanies morphogenesis

Question 12

Thale cress (Arabidopsis thailana)

Answer 12

relatively small genome -> easy to grow in lab

agriculture, energy, environment, human health