Experimental Models - Molecular and Cell Bio Exam 1

Why can we use cells that aren’t human?

non-human cells easier to study and can be used as a model since they have the same overall components as human cells

E. coli models

• bacteria

• help understand how DNA replication, gene expression, and protein synthesis work

• Easy to keep, simpler genome, short life cycle (divides every 20 mins)

Yeast models

• Simplest eukaryotes

• distinct nucleus, contains organelles, DNA organized in 16 linear chromosomes

• Easy to keep, larger genome than e. coli, short life cycle (divides every 2 hours)

• For studying the nucleus

C. elegans

• eukaryotic + multicellular (nematodes)

• for studying animal development and cell differentiation

• use mutations to study developmental abnormalities (similar genes in humans)

• small # of genes and cells

Dresophilia melanogaster (fruit fly)

• studying molecular mechanisms of development, similar genes and mechanisms exist in humans

• genome larger than C. elegans, easy to maintain, short (2 week) life cycle

Arabidopsis thaliana

• Simple plant, small genome, easy to maintain

• methods for molecular genetic manipulations available

• identify genes involved in plant development

Zebrafish

• vertebrates

• Easy to maintain, reproduce rapidly (3-4 months)

• embryos develop outside of mother and are transparent

• can map mutations

• useful for studying brain development

Mice

• vertebrates, mammal

• more complex than other models

• Many mutations identified, mutant mice available

• good for studying lactation, development after birth, or more complex studies

• More applicable to medicine: similar genomes, mutations in homologous genes result in similar phenotypes

Purpose of cell culture

• controlled manipulations

• easier to study signaling mechanisms

Primary cultures

Cells eventually die after many replications b/c of the environment. Eventually gets more expensive

Immortal cultures

Cells that keep replication and won’t die. HeLa cells: first human cell line, helped develop polio vaccine

Viruses

Parasite, needs to live inside cell to survive since can’t replicate on their own.

• can be studied in cultured cells

• smaller and simpler genomes

• some viruses lead to cancers