developmental biology
Terms
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- differentiation
- The process by which cells or tissues undergo a change toward a more specialized form or function, especially during embryonic development
- epigenesis
- simple to complex, de novo, from scratch. proponents are aristotle and harvey
- preformation
- sperm were seeds, minature structures of bigger structures already in cell
- morphogenesis
- differentiation of cells and tissues in the early embryo establishing form and structure of various organs and parts of the body
- blastula
- metazoan embryo consisting of 60 blastomeres and containing a blastocoel in the center
- gastrula
- stage following the blastula consisting of a hollow, two layered sac of ectoderm and endoderm surrounding an archenteron that communicates to the exterior thru the blastopore
- archenteron
- turns into the intestinal or digestive cavity
- oviparity
- from eggs
- viviparity
- live birth
- ovoviparity
- from eggs that hatches inside the body
- holoblastic
- whole egg into smaller cells
- meroblastic
- only part of the cell becomes the embryo, the yolk for nutrition
- ex ovo omnia
- from the egg
- blastoderm
- yolk free cytoplasm that gives rise to the embryo
- neural groove
- precursor of the neural tube
- tripoblastic
- has three germ layers
- dipoblastic
- has two layers. lacks mesoderm
- notochord
- rod of dorsal most mesoderm that separates the embryo into the right and left halves, instructs the ectoderm to become the nervous system
- homologous structures
- organs whose underlying similarities arsie from their being derived from a common ancenstral structure
- malformations
- abnormalities caused by genetic events
- syndrome
- several abnormalities occuring at the same time
- piebaldism
- dominant mutation in the KIT gene on the long arm of chromosome 4 characterized by anemia, sterility, unpigemented regions, deafness, abscence of peristalsis
- KIT gene
- responsible for encoding the protein that is expressed in the neural crest cells
- syngamy
- fusion of genetic information from the sperm and oocyte as the male and female pronuclei fuse
- gonocyte
- a primordial, diploid cell of endodermal derivation, such as an oogonium. gives rise to germ cells.
- germ plasm
- a portion of the endoderm at the vegetal pole of a zygote. cells migrate to the mesodermal genital ridge and rise to gonocytes
- fibronectin
- glycoprotein found on the surface of cells and in connective tissue that directs the migration of cells by adhesion during development
- developmental genetics
- examines how genotype is expressed through phenotype, differential gene expression from the same nuclear repertoire
- chromatin
- complex of DNA+histone (protein)
- nucleosome
- basic unit of chromatin structure
- exon
- regions of DNA that code for a protein
- intron
- sections of hte DNA that do not code for protein
- promoter site
- site where RNA polymerase binds to initiate transcription
- RNA polymerase
- enzyme responsible for transcription, reads genetic code stored in DNA
- codon
- tri nucleotide unit (nucleotide unit composed of phosphate, dioxyribose and a nucleotide bases-adenine, guanine,cytosine, thymine or urasil in place of adenine in RNA)
- cap sequence
- site that receives the methylated guanosine after transcription. responsible for binding of RNA to ribosome
- polyadenylation
- placement of a tail of 200-300 adenylate residues on the RNA transcript (3' end)
- poly (A) tail
- confers stability on the mRNA, allows the mRNA to exit nucleus, permits RNA to be translated into protein
- TATA box
- RNA polymerase binding site, about 30 base pairs upstream from the site where the first base is transcribed
- transcription factor
- additional protein needed so that RNA polymerase would bind to the TATA box (DNA sequence) efficiently
- basal transcription factor
- nuclear proteins necessary for proper initiation of transcription by RNA polymerase II ( w/c in turn trascribes protein encoding genes)
- TFIID
-
1.first basal transcription factor taht recognizes the TATA box (via TATA binding protein or TBP)
2. foundation of the transcription initiation complex
3. prevents nucleosome from forming
4. stabilized by basal transcription factor to bind to TFIIB - TFIIB
- RNA polymerase binds once stabilized (w/ TFIIA)
- TFIIE, F, H
-
1.release RNA polymerase from complex to transcribe gene
2. unwind DNA helix so RNA polymerase have free template from which to transcribe - TBP-associated factors (TAF)
- stabilizes TBP
- mediator complex
- contains about 25 proteins that that can modulate the activity of RNA polymerase and TFIIH
- cell specific transcription factor
- can activate gene by stabilizing transcription initiation complex. can bind to TAF or directly w/ other factors, also destabilizes nucleosomes.
- enhancer
- DNA sequence that activates utilization of the promoter, controlls rate and efficiency and rate of transcription
- cis-
- same. as in enhancers only work on cis-linked promoters (on the same chromosome)but can function at great distances
- reporter gene
- bind them to a specific gene to determine if they are enhancers.
- Pax6 gene
- expressed in retina, neural tube, lens, pancreas
- silencers
- inhibits transcription
- DNA binding domain
- recognizes a particular DNA sequence
- trans-activating domain
- activates or suppreses the transcription of a gene whose promoter or enhancer is has bound
- protein-protein interaction domain
- allows the TFs to be modulated by TAFs or other TF
- reproduction
- creation of new individuals
- sex
- combining of two different sets of genes=new arrangements