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55 Cards in this Set

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How do red blood cells and immune cells very from other cells in the body?
Red Blood Cells - lose thier nuclei

Immune Cells - Undergo gene rearrangement to generate antibody diversity
How do you determine if a gene is expressed?
If it is transcribed into RNA and then translated into protein
What proteins are expressed in all cells?
Protein components of the ribosome
What accounts for the difference in time it takes for cells to divide when they are younger, versus when they are older?
Growth factor production
Why are some genes expressed at times and in places where they have no identified function?
Genetic redundancy - several genes have similar functions and teh loss of one gene may be compensated for by another gene
Does the coding region for a gene contain instructions for where and when the gene will be expressed?
No, that information is contained in regulatory DNA sequences that flank the coding region, called promoters, enhancers, and silencers.
What must all genes contain at the ATG start site?
A promoter 5'
What is the minimal that a promoter can be?
A binding site for RNA oplyermase
Besides binding sites for RNA polymerase, what else might promoters contain?
Binding sites for transcription factors that activate or repress transcription at the appropriate time and place
What do enhancers do?
Bind transcription factors that activate transcription.
What do silencers do?
Bind transcription factors that repress transcription
How close are promoters, enhancers, and silencers typically to the start site?
Promoters are within a few thousand base pairs, whereas enhancers and silencers may be several million base pairs away.
Where at enhancers and silencers, relative to the gene?
Upstream, downstream, or in the introns of a gene.
How can it be demonstrated that the expression pattern of a gene is determined by the romoter?
Fuse the promoter toa completely different gene adn then introduce it into the organism; the new gene will be expressed at the same time and place as the original gene controlled by the promoter.
What is a reporter gene?
Any gene that can be easily detected.
What is a popular reporter gene that was originally isolated from ejlyfish?
Green flurorescent protein, (GFP)
What does GFP do?
Fluoresces green in livin ells under specia light
What reporter gene are we looking for?
lacZ,w hich was originally isolated from bacteria
What does lacZ do?
Codes for the enzyme beta-galactosidase, which cleaves the disaccaride lactors into the isimple sugars glucose and galactose.
What substrate will we use?
Xgal, which is noramlly colorless, but turns blue when cleaved by beta-galactosidase
What is C. Elegans?
A 1 mm long nematode worm that lives in the sil and feeds on baceri
What are adult nematodes esentailly made up of?
A tube, the exterior cuticle, contianing two smaller tubes, the pharynx and gut, and the reproductive system
Who used nematodes to study animal development and behavior in 1965?
Sydney Brenner
Describe the nervous system of C. Elegans.
It has a 302 neuron nervous system that allows it to respond to taste, smell, and growth to an adult.
What mysteries of biology does C. elegans exhibit?
Embryogenesis, morphogenesis, develpment, nervous function, behavior, and aging.
HOw many somatic cells does C elegans have?
959
How long is the average life span of C. elegans?
2-3 weeks
How any sexes do E. elegans have?
Hermaphrodites and males
How many genes does C. Elegan's genome encode? How many genes does the human genome encode?
C. Elegans - 19,000 genes

Human - 40,000 genes
What are the strains of C. Elegans we have labeled?
A, B, and C
After you wash the worms off the plate, where do you transfer them to?
A 1.5 mL tube
What do you do with tubes A, B, C after all the water and worms have been transfered to it?
Put them in a balanced microcentrifuge and spin for 10 seconds
What do you do after you are left with just the worms in the tube, (water has been removed)?
Add acetone from the dropper bottle to a final volume of 1.0 ml
What does acetone do to the worms?
Permeailizes the worms so that the staining reagent can diffuse into all cells; acts as a fixative and keeps them from staining
What do you do after the acetone has been removed from the worms?
Wash the animals three times in PM buffer, (Phosphate Magnesium Buffer) to remove the acetone
How do strains with high levels of lacZ react with Mix SL?
They stain quickly, (within the first 10 to 15 mnutes)
How long should it take our strains to stain?
They should all stain within 2 hours
What does eat-4 promoted do?
Encodes a transmembrane glutamate transporter that is expressed in 15 different neurons, concentrated in the head and control chemotaxis and feeding
What does egl-5 promoter do?
Encodes a homeodomain transcription factor, orthologous to Drosophila Abd-B and the vertebrate Hox9-13 proteins, that is required for specification of cell fates within the tail region; egl-5 is expressed in the posterior of the animal
What does lin-3 promoted do?
Encodes a member of the EGF family of peptide growth factors that afects induction of vulval development; lin-3 is expressed inthe anchor cell of the gonad, adjacent to the vulva
What does myo-2 promoter do?
Encodes a muscle-type specific myosin heavy chain isoform; expressed in at high levels in phayngeal muscle and at lower lelves in the body wall muscle
What does unc-54 promoter do?
Encodes the major mysoin heavy chain expressed in C. elegans and is required for locomotion and egg-laying; expressed at high leve sl in the body wall muscle, (essentially surrounding the entire worm)
Where was the original wild-type strain, N2, isolated?
English mushroom farms in the 1950's
Which worms are the largest?
Adult hermaphrodites filled with 20-3o embryos
How many larval stages does C. Elegans go through?
4, (L1, L2, L3, and L4); each larval stage ends with a molt
What type of pattern do the worms move in?
Sinusoidal
Where was the wild-type strain, CB4855, isolated and how is it different from E. elegans?
A garden compost heap in Palo Alto, California; slightly smaller than E. elegans; exhibites social behavior; tend to clump together in contrast to solitary N2 worms; males have higher fertility than N2 males, and deposit copulatory plugs
Describe dpy-1, "Dumpy."
Much shorter than wild-type, but are roughly the same girth; not all of the dpy genes encode cuticle collagens
Describe rol-6, "Roller."
Roll about their long axes as they move; tend to move in circles; caused by a dominant mutation in a collage gene; transgenic - they were produced by injecting DNA for the dominant roller mutation into wild-type worms
Describe lon-2, "long."
About 50% longer than the wild-type; gene encodes a grwoth-factor related molecule
Describe sma-2, "small."
Shorter tand thinner tan wild-type, but do not have the fat appearance o dpy mutants; have distinctive defects in the development of the tail; sma-2 encodes a Smad family member, involved in TGFbeta signaling
Describe unc-32, "uncoordinated."
Animals are unable to move well; they are able to lay eggs
Describe egl-23, "egg laying defective."
Lack a vulva; produce oocytes and fertilize them with their own sperms; embryos develop inside the mother, hatch, and eventually devour the mother; look similar to other plates, except there are no eggs on teh plate
Describe him-5, "high Incidence of Males"
X chromosome loss in hermaphrodite gamtogenesis; makes nondisjunction of the x chromosome much more common during meiosis ~ 30% of worms will be male
What are the sex chromosomes of C. Elegans of hermaphrodites and how do males result?
XX, so when a hermaphrodite undergoes self-fertilization, almost all of the progeny will be hermaphorodites ~ males are rare in nature, (they only result 1/1,000 of the time due to nondisjuncture during emiosis ~ one cell in herits the XX genotype and the other has no X)