Biology Development ( ch 1)

Microscopes, Model Organism and Human cell cultures

What is a model organism…

To understand cells and thus biological organisms, we must study something that resembles/ has charactertriats were trying to understand.

• Our understanding of cell biology comes from experimental models

Properties of a model organism

• Easy to cultuvate/bred in lab

• Short life cycle

• Few(er) cells

• Able for genetic analyses

• Being meaningful evolutionarily

• Having the experimental tools

• Biomendicine: similarity in structure, function, genetics, physiology to humans

• Fewer ethical dilemmas

HeLa cells

Cells created from Henrietta Lacks

• The first successful cultures of immortal human cell lines (cancerous cells)

In adult cells…

Most are terminally differentiated and post-miotic division, thus they can’t be kept in culture

Inherently Immortal Cells

• Embryonic cells (still in mitotic division)

• Cancerous cells that have re-entered the cell cycle

Generated Immortality

• Addition of foreign genes that inhibit senescence

• Engineered deletion of endogenous “pro-senescence” genes

How are human cells studied…

• Primary cell lines: (straight from tissue)

• Immortalized cell lines ( at least one generation in culture)

Common model organism…

Mus musculus: mouse

• Why : common mammalian physiology +

Drosophila melanogaster: fruit fly

• Why : great for development and adult studies / short generation time

Gallus gallus domesticus: Chicken

• Why : fewer genetic tools (microinjectables): great for live imaging development, long generation time

E. coli

• Key model org. for DNA replication, decoding the DNA to make proteins, etc.

The order of components and biochemical processes that best correlates with the tenets of the central dogma.

DNA [transcription] RNA [translation] protein

All different protiens in a cell are made from the same…

20 amino acids

Lenght used generally to measure a typical plant or animal cell…

micrometers

Conventional light microscope

Used typically for pathology photos

• Think typical microbiology microscope

• LED

Transmission electron microsope

Used for molecular resolution or seeing ribosomal proteins along cells

• Passes electrons through a thin sample to show internal details 2D

• Seeing things based on difference of densities (dyeing dense objects dark)

• Has the ability to resolve cellular components as small as 2 nm

• Laser (excitation of electrons)

Fluroescence Microscope

Used for viewing specific cells using (very specific fluroesence) dyes

Scanning electron mircoscope

• Bounces electrons off a sample’s surface, creating a 3D image.

• Laser (exated electrons)

Hepatocytes

Liver cells

Mus musculus

mouse

Drosophila melanogaster

fruit fly

Gallus gallus domesticus

Chicken