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55 Cards in this Set
- Front
- Back
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How do red blood cells and immune cells very from other cells in the body?
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Red Blood Cells - lose thier nuclei
Immune Cells - Undergo gene rearrangement to generate antibody diversity |
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How do you determine if a gene is expressed?
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If it is transcribed into RNA and then translated into protein
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What proteins are expressed in all cells?
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Protein components of the ribosome
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What accounts for the difference in time it takes for cells to divide when they are younger, versus when they are older?
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Growth factor production
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Why are some genes expressed at times and in places where they have no identified function?
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Genetic redundancy - several genes have similar functions and teh loss of one gene may be compensated for by another gene
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Does the coding region for a gene contain instructions for where and when the gene will be expressed?
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No, that information is contained in regulatory DNA sequences that flank the coding region, called promoters, enhancers, and silencers.
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What must all genes contain at the ATG start site?
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A promoter 5'
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What is the minimal that a promoter can be?
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A binding site for RNA oplyermase
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Besides binding sites for RNA polymerase, what else might promoters contain?
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Binding sites for transcription factors that activate or repress transcription at the appropriate time and place
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What do enhancers do?
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Bind transcription factors that activate transcription.
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What do silencers do?
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Bind transcription factors that repress transcription
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How close are promoters, enhancers, and silencers typically to the start site?
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Promoters are within a few thousand base pairs, whereas enhancers and silencers may be several million base pairs away.
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Where at enhancers and silencers, relative to the gene?
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Upstream, downstream, or in the introns of a gene.
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How can it be demonstrated that the expression pattern of a gene is determined by the romoter?
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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.
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What is a reporter gene?
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Any gene that can be easily detected.
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What is a popular reporter gene that was originally isolated from ejlyfish?
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Green flurorescent protein, (GFP)
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What does GFP do?
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Fluoresces green in livin ells under specia light
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What reporter gene are we looking for?
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lacZ,w hich was originally isolated from bacteria
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What does lacZ do?
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Codes for the enzyme beta-galactosidase, which cleaves the disaccaride lactors into the isimple sugars glucose and galactose.
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What substrate will we use?
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Xgal, which is noramlly colorless, but turns blue when cleaved by beta-galactosidase
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What is C. Elegans?
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A 1 mm long nematode worm that lives in the sil and feeds on baceri
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What are adult nematodes esentailly made up of?
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A tube, the exterior cuticle, contianing two smaller tubes, the pharynx and gut, and the reproductive system
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Who used nematodes to study animal development and behavior in 1965?
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Sydney Brenner
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Describe the nervous system of C. Elegans.
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It has a 302 neuron nervous system that allows it to respond to taste, smell, and growth to an adult.
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What mysteries of biology does C. elegans exhibit?
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Embryogenesis, morphogenesis, develpment, nervous function, behavior, and aging.
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HOw many somatic cells does C elegans have?
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959
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How long is the average life span of C. elegans?
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2-3 weeks
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How any sexes do E. elegans have?
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Hermaphrodites and males
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How many genes does C. Elegan's genome encode? How many genes does the human genome encode?
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C. Elegans - 19,000 genes
Human - 40,000 genes |
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What are the strains of C. Elegans we have labeled?
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A, B, and C
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After you wash the worms off the plate, where do you transfer them to?
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A 1.5 mL tube
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What do you do with tubes A, B, C after all the water and worms have been transfered to it?
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Put them in a balanced microcentrifuge and spin for 10 seconds
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What do you do after you are left with just the worms in the tube, (water has been removed)?
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Add acetone from the dropper bottle to a final volume of 1.0 ml
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What does acetone do to the worms?
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Permeailizes the worms so that the staining reagent can diffuse into all cells; acts as a fixative and keeps them from staining
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What do you do after the acetone has been removed from the worms?
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Wash the animals three times in PM buffer, (Phosphate Magnesium Buffer) to remove the acetone
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How do strains with high levels of lacZ react with Mix SL?
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They stain quickly, (within the first 10 to 15 mnutes)
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How long should it take our strains to stain?
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They should all stain within 2 hours
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What does eat-4 promoted do?
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Encodes a transmembrane glutamate transporter that is expressed in 15 different neurons, concentrated in the head and control chemotaxis and feeding
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What does egl-5 promoter do?
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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
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What does lin-3 promoted do?
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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
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What does myo-2 promoter do?
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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
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What does unc-54 promoter do?
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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)
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Where was the original wild-type strain, N2, isolated?
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English mushroom farms in the 1950's
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Which worms are the largest?
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Adult hermaphrodites filled with 20-3o embryos
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How many larval stages does C. Elegans go through?
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4, (L1, L2, L3, and L4); each larval stage ends with a molt
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What type of pattern do the worms move in?
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Sinusoidal
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Where was the wild-type strain, CB4855, isolated and how is it different from E. elegans?
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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
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Describe dpy-1, "Dumpy."
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Much shorter than wild-type, but are roughly the same girth; not all of the dpy genes encode cuticle collagens
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Describe rol-6, "Roller."
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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
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Describe lon-2, "long."
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About 50% longer than the wild-type; gene encodes a grwoth-factor related molecule
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Describe sma-2, "small."
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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
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Describe unc-32, "uncoordinated."
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Animals are unable to move well; they are able to lay eggs
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Describe egl-23, "egg laying defective."
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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
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Describe him-5, "high Incidence of Males"
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X chromosome loss in hermaphrodite gamtogenesis; makes nondisjunction of the x chromosome much more common during meiosis ~ 30% of worms will be male
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What are the sex chromosomes of C. Elegans of hermaphrodites and how do males result?
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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)
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