Model Systems: L20

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Questions and Answers

What is the main reason researchers use model systems in biological studies?

To study complex entities directly in humans

To capture key characteristics of the entity needed for research (correct)

To simplify all biological processes for analysis

To avoid ethical concerns regarding human subjects (correct)

Which of the following is a limitation of using E.coli as a model organism?

It is relatively cheap to culture in the laboratory

It lacks a nucleus and certain protein modification mechanisms (correct)

It has extensive knowledge of genetics and genomics

It can rapidly grow in a chemically defined medium

What is an advantage of using yeast as a model organism?

It is pathogenic to humans

It has a complex genetic structure like humans

It grows slowly, allowing for longer experiments

Essential cellular processes are similar to those in humans (correct)

Which of the following correctly describes a feature of mammalian systems like mice?

Mice closely resemble humans in terms of physiology and genetics Signup and view all the answers

Which type of model organism is best characterized by rapid growth and efficiency in genetic manipulation?

S.cerevisiae Signup and view all the answers

Which aspect is NOT a purpose of commonly used experimental techniques in model systems?

To establish new disease pathways in humans Signup and view all the answers

What is a key disadvantage of single-cell model organisms like E.coli?

Not all protein modification mechanisms are represented Signup and view all the answers

Which statement is true regarding the growth characteristics of yeast?

Yeast has a rapid growth rate of approximately 1.5 to 2.5 hours Signup and view all the answers

What is the average generation time for a mouse?

10 weeks Signup and view all the answers

What is a primary disadvantage of using transformed cell lines?

They can lead to artefacts in research findings. Signup and view all the answers

Which type of stem cells can be used to initiate organoids?

Embryonic stem cells, induced pluripotent stem cells, or tissue resident stem cells Signup and view all the answers

Why are organoids considered to be more physiologically relevant than traditional 2D cultures?

They represent a 3D structure and function more like actual tissues. Signup and view all the answers

What feature of neurons in cerebral organoids was observed in 2017?

They exhibit action potentials and spontaneous ensemble activities. Signup and view all the answers

How do organoids contribute to genetic manipulation compared to in vivo models?

They are more amenable to manipulation of niche components and signalling pathways. Signup and view all the answers

Which of the following best describes organoids?

They are 3D cellular clusters that mimic organ properties. Signup and view all the answers

What is the central feature of the mouse intestinal organoids identified in 2009?

Formation of distinct crypt-like and villus-like domains bordering a central lumen Signup and view all the answers

Study Notes

Model Systems in Cell Biology

Model systems are simplified versions of complex entities, capturing key characteristics needed for study.
Using models is often more practical or ethical than studying the actual entity (e.g., human disease).

Types of Model Systems

Single-cell organisms (e.g., E. coli):
- Fast growth in chemically defined media.
- Relatively inexpensive culture media.
- Extensive knowledge of genetics and genomics.
- Knowledge of transcriptome, proteome, and metabolome.
- Some strains are considered biosafety level 1 (e.g., E. coli K12).
- Disadvantage: may not have the same protein modifications (e.g., glycosylation) as more complex systems.
Single-cell eukaryotes (e.g., Yeast):
- Rapid growth (1.5-2.5 hours)
- Non-pathogenic
- Efficient transformation by exogenous DNA.
- Efficient homologous recombination.
- Simple genetic screens.
- Similar cellular processes to humans
Mammalian systems (e.g., Mice):
- Closely related to humans, with similar anatomy, physiology, and genetics.
- Short generation time (approx. 10 weeks).
- Amenable to genetic manipulation (e.g., knockouts, knock-ins).
- Conditional expression lines exist for targeted gene manipulation.
Cell culture:
- Cells isolated from a system and grown in vitro.
- Cheaper than studying a whole organism.
- Greater opportunities for perturbation and measurements.
- Often transformed, losing some in vivo properties and introducing artefacts.
Organoids:
- In vitro 3D cellular clusters derived from stem cells (ESCs, iPSCs, or tissue resident stem cells).
- Self-organization and self-renewal abilities.
- Model diverse tissues (e.g., brain, intestine, liver, pancreas).
- More physiologically relevant than 2D cultures.
- More amenable to manipulation of niche components, pathways, and genome editing compared to in vivo models.

Learning Outcomes (Lecture 20)

Explain why researchers use models.
Describe different types of model systems, including their advantages and limitations. Examples; Single-cell, Multicellular, Mammalian systems, Computational models.
Describe the purpose of commonly used experimental techniques.

Model Organisms for Biological Processes

A diverse range of non-human species, such as Zebrafish, Mice, Drosophila (fruit flies), and E. coli, are valuable model systems.

Measurement Methods

Different levels of biological analysis (DNA, RNA, protein) require specialized methods.
Examples include qPCR (Quantitative PCR), in situ hybridisation, SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis, western blotting), immunochemistry and ELISA (enzyme-linked immunosorbent assay).
Whole genome sequencing, RNA sequencing and Mass Spectrometry

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Description

Explore the use of model systems in cell biology, focusing on various types such as single-cell organisms, single-cell eukaryotes, and mammalian systems. Understand their advantages, disadvantages, and applications in studying complex biological processes. This quiz covers key characteristics needed for the study of these simplified biological models.