Model Organisms

Question 1

What is A Model Organism?

Answer 1

Organisms Whose Biology is Well Known and Accessible For Lab Studies that are Suitable to Study Specific Traits, Diseases and Phenomenon

Question 2

What Are Some Desired Characteristics Of ‘Good Model Organisms’?

Answer 2

• Small Physical Size
• Small Genomic Size
• Short Generation Time
• Short Life Cycles
• High Fertility Rates
• High Mutation Rates

Question 3

What Are Some Model Organisms?

Answer 3

• Mice
• Mustard Plant
• Fruit Fly
• Yeast
• Roundworm
• Zebrafish
• Frog

Question 4

What Is Evolutionary Conservation?

Answer 4

Genetic Sequences, Proteins and Biological Structures Remaining Unchanged Across Different Species over Periods of Evolution

1. Many Genes Across Different Species Share
   Similar Sequences
2. Encoded Proteins Perform Similar Functions
3. Between Hamsters and Humans:
   Only 1 Amino Acid Differs in C-Terminal
   Domain of Largest Subunit of RNA Pol II

Question 5

Why Are Drosophila model Organisms?

Answer 5

• Short Generation Time (Egg → Adult = 10 D)
• Complex Behaviors
  (Aggression, Addiction, Learning, Memory)
• High Homology with Mammals
• Adapt Physiological Responses To
  Environment (Homeostasis)
• Well Defined Tissue/Organ Systems

Question 6

What Is The Drosophila Life Cycle?

Answer 6

Egg

(1 Day)

1st instar larvae

(1 Day)

2nd instar larvae

(1 Day)

3rd instar larvae

(2 Days)

Pupa

Adult

Question 7

How many Autosome pairs and Sex Chromosomes Do Drosophila Have?

Answer 7

3 Pairs Of Autosomes
1 Pair Of Sex Chromosomes

Total: 8

Question 8

Why Are Drosophila used?

Answer 8

60% of Genetic Code Shared between Drosophila and Human Genomes

75% Of Genes Linked To Human Diseases Have Direct Functional Equivalent in the fly

Gene In Fly Can Be Directly Manipulated To Observe Its effect

Human Disease-Causing Mutations Can Be Expressed In Fly → Useful To Screen For Novel Drugs

Question 9

What Are Some limitations Of Model Organisms?

Answer 9

• Genetic and Physiological Differences
• Simplified/ Incomplete Disease Models (some
  Medical Conditions Involve Gene Interaction
  With Environment, Hard To Replicate)
• Behavioral/Cognitive gaps (Human Specific
  Traits Hard To Model In Other Organisms)
• Lab Settings lack Generalizability Due To
  Environmental Factors