Lab 7 Chi-Square Genetics Lab: Drosphilia

ANIMOTO VIDEO:

http://animoto.com/play/19FpJMW7BW0tNSqA1LfnFw

• wild type normal nature, not mutated
• mutate quickly
• What is the chi square test used for?
• statistical test that makes a comparison between the data collected in an experiment versus the date you expected to find
• chi square test is a way to evaluate this variability to get an idea of the difference between real and expected results are due to normal random chance
• or if there is some other factor involved (like an unbalanced coin or a different inheritance scheme than the one you predicted

Why is probability important to genetics?

• classical genetics research where you are trying to determine the inheritance pattern of a phenotype --> establish a predicted genetic explanation and expected phenotype rations in the offspring (from Punnett square) = null hypothesis
• compare observed results against your genetic hypothesis (Punnett square)

A geneticist crossed wild gray-colored mice with white (albino) mice. All the progeny were gray. These progeny were intercrossed to produce an f2 which consisted of 198 gray and 72 white mice. Propose a hypothesis to explain.

http://images.google.com/imgres?imgurl=http://insects.eugenes.org/species/about/species-gallery/Drosophila_melanogaster/Drosophila_melanogaster.jpg&imgrefurl=http://insects.eugenes.org/species/about/species-gallery/Drosophila_melanogaster/&usg=__BBVbWH2EwV9sRuZHB9m7zaEloGU=&h=1152&w=1728&sz=96&hl=en&start=2&um=1&itbs=1&tbnid=L-xJGZ5q0ywqsM:&tbnh=100&tbnw=150&prev=/images%3Fq%3Ddrosophila%26hl%3Den%26client%3Dsafari%26rls%3Den%26sa%3DX%26um%3D1

http://celebritygeckos.com/Portals/28/Genetics/Genetics/basicpunnetsquare.JPG

http://www.stat.lsu.edu/exstweb/statlab/Tables/chi-dist-5df.jpg

http://www.geography-site.co.uk/pages/skills/fieldwork/statimage/chisqu.gif

http://faculty.southwest.tn.edu/jiwilliams/probab2.gif

Chi Squared

The Purpose of Chi Squared the observed Distribution of numbers among a group of categories with a hypothesized distribution.

Class Notes Chapter 18

Qualities of a Virus:

• protein coat called a capsid and has receptors


• non-living (lives off host), parasitic


• Retrovirus (RNA), example: HIV


• Replicate by lysogenic or lytic cycle


• Encloses viral genome (RNA or DNA)


• Tail fibers


• Bacteriaphage

Qualities of Bacteria:

• Prokaryotic


• Binary Fission


• Shapes: coccus, coccobacillus, sprillium, bacillius (these determine whta kind of bacteria they are)


• only 1% are harmful


• DNA processes: Transformation, Transduction, and Conjugation


• 2 Domains: Archebacteria and Bacteria


• 1 Kingdom = Monera


• unicellular organism


• Prophage


• Nutrition Modes

Notes From Class:

• MRSA is a bacteria that can't be fought with antibiotics

LAC OPERON:

• inducable


• turn off


• allolactose helps to turn it back on, inducer

• Allolactose (sugar), is an isomer of lactose, depresses the operon by inactivating the repressor. In this way the emzymes for lactose utilization are induced.


• Tryptophan is an amino acid produced by an anabolic pathway catalyzed by repressible enzymes.


• The trp operon is turned on; a RNA polymerase can bind to the promoter and transcribe the genes of the operon. The operon can be switched off by a protein called the trp repressor.


• RNA polymerase attaches to the DNA at the promoter and transcribes the operon's genes.


• As tryptophan accumulates, it inhibits its own production by activating the repressor protein, which binds to the operator, blocking transcription.


• Protein ---> sequence determines the function

Glogster

Ch. 18 - Bacteria

Today in class we discussed the genetics of bacteria.

-Conjugation is a means of genetic variation in bacteria. A bacteria with the presence of the F factor in their genes will produce a pili. The pili will allow the two bacteria to get close enough to each other so that a conjugation bridge may form. The conjugation bridge not the pili is where the genetic material of the bacteria is exchanged.

4 modes of nutrition for bacteria

-photoautotroph: photosynthetic organisms that capture light and use it to drive synthesis of organic compounds.

-chemoheterotroph: consume organic molecules to obtain energy and carbon.

-chemoautotroph: need an inorganic compound such as carbon dioxide as a carbon source.

-photoheterotroph: harness energy from light but must obtain carbon in organic form.

-bacteria is an essential decomposer in the world.

Genetics

-bacteria have the ability to control gene expression, allowing them to adjust their metabolism to environmental change. Cells control metabolism by regulating enzyme activity or by regulating enzyme synthesis through activating or inactivating genes

-bacteria cell that can conserve resources and energy have a selectable advantage over cells that are unable to do so. Thus, natural selection has favored bacteria that express only the genes whose products are needed by the cell.

-An operator is a segment of DNA that acts like a switch to either turn on or off a gene. Basically the operator is the access point to the RNA polymerase. If the polymerase can get to the gene to code it, it will be expressed.

LAC Operon

-Inducible operon, it is usually off and can be induced/stimulated when a specific small molecule interacts with a regulatory protein.

-Alla lactose, an isomer of lactose, derepresses the operon by inactivating the repressor. In this the enzymes for lactose utilization are induced.

Citation:

http://scienceblogs.com/retrospectacle/upload/2007/02/Prion2.gif

December 4, 2009 Blog

Transduction- a virus that infects bacteria, bacteria goes into lytic/ lysogenic cycles

Conjugation- bacteria to bacteria. Sexpilus facilitates transfer of DNA; requires F plasmid

Transformation- bacteria receives DNA from the environment; requires plasmid, occurs under fixed conditions in laboratory

Transduction, conjugation, transformation: bacteria can evolve; DNA mutates

Lytic Cycle

• Lysis of host cell releases phages
• Destruction of host
• Production of new phages
• Temperate phage only

Lysogenic Cycle

• Can be induced to leave and enter lytic cycle
• Replicated and passed on
• Genome integrates into bacterial DNA (progphage)
• Virulent or temperate phage

Retroviruses

• RNA viruses
• Use reverse transcriptase (enzyme) to transcribe DNA from RNA template
• New DNA integrates into chromosome in nucleus of animal cell
• Host transcribes viral DNA into RNA

Example: HIV (no cure)

Viral diseases in animals

• Symptoms may be caused by
• Direct viral effect on cells
• Immune response of host
• Vaccines stimulate immune system to defend host against specific viruses

Prions

• Infectious proteins
• Misfolded proteins
• Cause misfolding of normal proteins

Virus

• Nucleic acid surrounded by protein coat
• Single or double-stranded
• RNA or DNA

Viroid

• Small, simple virus
• Circular RNA molecules
• Infect plants
• Do not encode proteins
• Naked nucleic acid

Gram +

• Bacteria with simple walls with a large amount of peptidoglycan
• Modified sugar polymers cross-linked with polypeptides
• Stain is not removed
• Dark violet or blue color

Gram –

• Less peptidoglycan
• Structurally more complex
• Outer membrane contains lipopolysaccharides
• Gram stain washes away
• Leaves pink or red cell

http://scienceblogs.com/retrospectacle/upload/2007/02/Prion2.gif

Chapter 18

Viruses:
~ the genetic make-up can be double or single stranded DNA or RNA
~ enclosed by protein shell (capsid)
*has receptors so it knows what host to accept
*envelopes surround capsid and aid in infecting the host
Lytic cycle
~only reproduce within a host (most only reproduce within a certain host)
~the reproductive cycle ends in the death of the host cell
1. attatches to host cell with receptors
2. injects viruses Dna into cell
3. replicates its own DNA into host
4. new phages are assembled
5. produce lysozome (disintegrates cell wall; cell dies)
6. the new phages are released ~viral DNA (prohage) when integrated into bacterial chromosome's DNA

http://www.youtube.com/watch?v=wVkCyU5aeeU&feature=fvw


Lysogenic cycle
~the phage DNA becomes part of the host and is replicated
~ more dormant (cell is not killed with reproduction)
~ can move into the lytic cycle

http://www.youtube.com/watch?v=_J9-xKitsd0