BIOL4004 EXAM 1 QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
What are model organisms and what is the rationale behind them?
Model organisms - species that are extensively studied to understand particular
biological phenomena
Discoveries made in the model will provide insight into the systems of other organisms.
They are widely used to explore potential causes and treatments for human disease
Rationale: basic biology is conserved throughout evolution
Key Concept: studies have been focused on particular species called model
organisms, but discoveries made from these studies have universal application
Escherichia coli as a model organism (why use, primarily used for, and
limitations)
Why use:
-Grow easily in a culture bottle
-Reproduce rapidly
Fundamental mechanisms of life: DNA replication, transcription, and translation
Limitations: they are prokaryotes (we are eukaryotes)
Francois Jacob, Andre Lwoff, Jacques Monod
Discoveries concerning genetic control of enzyme and virus synthesis
,Saccharomyces cerevisiae as a model organism (why use, primarily used for, and
limitations)
Why use:
-rapid growth
-ease of mutant isolation
-DNA transformation system
-complete genome sequenced
-systematic investigation of the possible functions of all yeast genes
Used primarily to study cell division
-identification of cell-division-cycle (cdc) genes
-yeast and human cdc genes are functionally interchangeable (prove by incorporating
human cdc gene in the yeast genome. If it can replicate, they are interchangeable and
that cdc gene is conserved)
Limitations: They are eukaryotic but they are unicellular so it's hard to study multicellular
organisms
Leland Hartwell, Tim Hunt, Sir Paul Nurse
Discoveries of key regulators of the cell cycle
Caenorhabditis elegans (C. elegans) as a model organism (why use, primarily
used because, and limitations)
Why use:
-small, harmless nematode
,-first multicellular organism whose genome was completely sequenced
-19,000 genes identified (we have 20,000)
-a wealth of mutants
-simple body plan: 959 somatic cells in adult worm
-highly precisely regulated development (timing, cell fate)
-entire cell lineage of all the cells from a single fertilized egg to the adult has been
mapped out
Primarily used because: cells are all mapped out
-we know how they all developed from one egg/sperm cell
-all the cells in different stages are named and identified
Also use because we have identified cell death mutants
-we can make mutants that do not die by targeting cell death (ced) genes which control
programmed cell death
Sydney Brenner, Robert Horvitz, and John Sulston
Discoveries concerning genetic regulation of organ development and programmed cell
death
Drosophila melanogaster as a model organism
Why use:
-broad knowledge base
-easy and cheap to rear in the lab (fast generation time, simple growth media)
-a large number of mutants available
, -sophisticated genetic tools (easy to make transgenics, conditional expression systems,
clonal analysis)
-entire genome sequenced (13,600 genes) - more complex body than C. elegans but
less genes
-cell culture and organ culture systems
-highly developed informatics infrastructure (we know mutants)
-evolutionary conserved mechanisms
-in-vitro system
Homeotic mutations
Transform parts of the body into structures appropriate to other positions (homeotic)
They have the correct body parts but they're in the wrong place
ex. Antennapedia - Drosophila mutant that has legs on its head
Homeotic genes (Hox)
Determine the identity of the segments of the fly
They encode gene regulatory proteins
When you have a mutation in this gene, body parts can grow in places they don't belong
(ex. Antennapedia Drosophila mutant)
Conserved during evolution
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
What are model organisms and what is the rationale behind them?
Model organisms - species that are extensively studied to understand particular
biological phenomena
Discoveries made in the model will provide insight into the systems of other organisms.
They are widely used to explore potential causes and treatments for human disease
Rationale: basic biology is conserved throughout evolution
Key Concept: studies have been focused on particular species called model
organisms, but discoveries made from these studies have universal application
Escherichia coli as a model organism (why use, primarily used for, and
limitations)
Why use:
-Grow easily in a culture bottle
-Reproduce rapidly
Fundamental mechanisms of life: DNA replication, transcription, and translation
Limitations: they are prokaryotes (we are eukaryotes)
Francois Jacob, Andre Lwoff, Jacques Monod
Discoveries concerning genetic control of enzyme and virus synthesis
,Saccharomyces cerevisiae as a model organism (why use, primarily used for, and
limitations)
Why use:
-rapid growth
-ease of mutant isolation
-DNA transformation system
-complete genome sequenced
-systematic investigation of the possible functions of all yeast genes
Used primarily to study cell division
-identification of cell-division-cycle (cdc) genes
-yeast and human cdc genes are functionally interchangeable (prove by incorporating
human cdc gene in the yeast genome. If it can replicate, they are interchangeable and
that cdc gene is conserved)
Limitations: They are eukaryotic but they are unicellular so it's hard to study multicellular
organisms
Leland Hartwell, Tim Hunt, Sir Paul Nurse
Discoveries of key regulators of the cell cycle
Caenorhabditis elegans (C. elegans) as a model organism (why use, primarily
used because, and limitations)
Why use:
-small, harmless nematode
,-first multicellular organism whose genome was completely sequenced
-19,000 genes identified (we have 20,000)
-a wealth of mutants
-simple body plan: 959 somatic cells in adult worm
-highly precisely regulated development (timing, cell fate)
-entire cell lineage of all the cells from a single fertilized egg to the adult has been
mapped out
Primarily used because: cells are all mapped out
-we know how they all developed from one egg/sperm cell
-all the cells in different stages are named and identified
Also use because we have identified cell death mutants
-we can make mutants that do not die by targeting cell death (ced) genes which control
programmed cell death
Sydney Brenner, Robert Horvitz, and John Sulston
Discoveries concerning genetic regulation of organ development and programmed cell
death
Drosophila melanogaster as a model organism
Why use:
-broad knowledge base
-easy and cheap to rear in the lab (fast generation time, simple growth media)
-a large number of mutants available
, -sophisticated genetic tools (easy to make transgenics, conditional expression systems,
clonal analysis)
-entire genome sequenced (13,600 genes) - more complex body than C. elegans but
less genes
-cell culture and organ culture systems
-highly developed informatics infrastructure (we know mutants)
-evolutionary conserved mechanisms
-in-vitro system
Homeotic mutations
Transform parts of the body into structures appropriate to other positions (homeotic)
They have the correct body parts but they're in the wrong place
ex. Antennapedia - Drosophila mutant that has legs on its head
Homeotic genes (Hox)
Determine the identity of the segments of the fly
They encode gene regulatory proteins
When you have a mutation in this gene, body parts can grow in places they don't belong
(ex. Antennapedia Drosophila mutant)
Conserved during evolution
