first half bio
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- Cleavage (4)
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within an hour of fertilization the zygote divides rapdily into blastomeres
no increase in size, slows after 12 divisions, animal and vegetal end created, no major developmental genes are expressed - Prokaryotes
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Very little space that doesn't have genes
transcribed and translated at the same time
genes are called operons - Eukaryotes
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made up of exons and introns, only exons part of mRNA to be translated
Modifications: revomove introns, add 5' cap and poly A tail - RNA polymerase
- only functions in the 5-3 prime direction
- Stem Loop
- As the palindromic sequences are transcibed a stem loop forms which causes the RNA polymerase to pause and the RNA transcript to dissociate
- Chargraff
- said A/T = a, and C/G =1
- Phosphodiester bond
- how DNA forms a complex macromolecule
- Avery
- DNA holds genetic information
- Hershey-Chase
- T-even bacteriophages, P32, S35
- Bacteriophage
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attaches to cell wall
replication of DNA
assemply of mature phages
new phages released - Rosalind Franklin
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bombarded DNA with X-ray source
concluded DNA was an alpha helix, 10 bp per turn, 2 nm - Cloning experiment
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remove nucleus from egg and inserted into mammary epithelial cells
epithelials are constantly dividing
mammary are not fully differentiated - Hammerling
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two different species of green algae with nucleus at base
Crossed green cap with brown base and got green cap because RNA can go outside of nucleus
after got brown cap and brown base - Totipotency
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Depending on when the nucleus was taken from the cell determines whether or not it can be redirected
neuronal cells cannot be regenerated because there is no mitosis - Transgenetic organism
- has a gene from a different species inserted into it
- Stem cells
- undifferentiated and dividing cells
- Heriditary information must have
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information
able to replicate accuratly
able to change - Origins of replication
- sequence of repeated nucleotides that bind to a protein in replication
- Helicase
- unzips the DNA
- SSB protein
- maintains the parental strand as single stranded
- Primase
- DNA polymerase only adds nucleotides if there is already a base, so primase puts down an RNA primer at the beginig of each 5' end
- Dispersive model
- Two strands come apart and have mixture of the two, all are hybrids
- Conservative model
- parental strands unzip and replicate and parental strands come together and conservative come together
- tRNA
- bring amino acids to ribosomes during traslation
- Aminoacytyl-tRNA-synthesase
- adds the correct amino acids to the tRNAs
- Initiation complex
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leader sequences orient the 5' end of the mRNA on the ribosome
has tRNA, mRNA, IF, small subunit - Termination in translation
- release factors recognize stop codons and polypeptide is released
- Leader sequences
- orient the 5' end fo of the mRNA on the ribosome
- Promotor
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In eukaryotes transcription starts at the RNA polymerase binding sites called promoters
In Prokaryotes sigma factor unwinds the DNA to be used as a template strand - Template vs. codon strand
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template = 3-5
codon = 5-3 - rRNA vs. tRNA
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rRNA makes up ribosomes with ribosomal proteins
tRNA brings amino acids to ribosomes during translation - Gene expression
- converting helix into single stranded RNA coded by ACGU
- Transcription
- using the template strand to create mRNA which can leave the nucleus
- Translation
- translating the triplet code into the amino acid sequence
- Biochemical pathways
- one gene codes for one polypeptide
- Bidirectional replication
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bacteria genomes have 4.6x10^6 bp and replicate 1000 nucleotides/second
eukaryotes have linear DNA 3.1x10^9 bp, so takes longer to replicate - DNA ligase
- joins okazaki fragments (forms a phosphodiester bond to from the sugar phosphate backbone_
- DNA Polymerase III
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doughnut shaped, clamp protein and subunit that adds nucleotides
is the main rep. enzyme, proofreading, adds nucleotides, clamping - DNA polymerase I
- Replaces RNA in the primer with DNA
- Initiation of translation
- needs mRNA, initiation factor, tRNA and small subunit
- Syncytial blastomere
- 4000 nuclei in the cell with free communication between them
- Neuralation
- ectoderm thickens, neural tissue forms neural groove(becomes brain and spinal cord)
- First stage of embryogenesis
- nurse cells deposit maternal effect genes which determine basic polarity - cells do mitosis to have 4000 nuclei - go to periphery and form cell membrane
- Larval Stage
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growing and shedding exoskeleton
imaginal disks present which become the head, wings, lefs and adult fly - Pupal Stage
- hard exoskeleton is breaking down and providing nutrients
- Cell movement
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move by adhesion molecules
use cytoskeleton space and cadherdin molecules as a road map - Cell induction
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cells secrete proteins that act as signals
Organizer cells produce morphagens which convey information
cell movement responds to morphagen gradietn - Connective tissue
- intracellular space filled with polysaccharide chains and proteins
- Determination
- commitment to a developmental path (process of moving to a correct location and expressing genes)
- Transcription factors
- proteins that bind to the promoters to stimulate transcription
- Homeotic genes
- stimulate expression of genes for a particular anatomical structure
- Homeobox genes
- same order between organisms
- Cleaving DNA
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Sticky end - different fragments have overhang
Blunt end cutters - cut in the middel - Restriction endonucleases
- sequences that are 4-6 nucleotides long, when sticky ends combine with complimentary ends are joined together with DNA ligase
- Genetic engineering experiment
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restriction enzymes cut DNA
fragments inserted into vectors
cloning - Beadle-Tatum experiment
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damage DNA and grows on complete medium, to detemrmine nutritional defficiency grow on different medium
one gene-one enzyme - Ti Plasmid
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vector for plants
herbicide resistance
flavr. savr tomatoe
nitrogen fixation
insect resistance -
Genomic libraries
cDNA -
genomic - entire genome of an organism
cDNA - all expressed genes - Hybridization process
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plate bacteria on agar
lay filter paper to pick up DNA
denature DNA
hybridize with probe
dark spots where DNA is complimentary - Hybridization
- use another gene as a probe. if the probe is similar they will hybridize together
- Pair - Rule genes
- establish segments in cellular blastoderm
- Gastrulation
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some of the cells are pushed inward to make an invaginated gastrule
meso - bone, muscle, blood
endo gut, liver lungs - End of cleavage
- blastomeres pump water inside the cell and end with a hollow mass of cells
- Nucleic acids
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5 carbon sugars
nitrogen base, purines (ag) pyrimidines (ctu)
base at 1 carbon and PO4 at 5 carbon - Watson and Crick
- double stranded, 10 bp per turn, AT-two bonds, GC-three bonds
- Briggs-King
- took an early egg cell and inserted into an epithelial cell
- Maternal effect genes
- bicoid and nanos set up transcription factors and stimulate gap genes which divides the cell into subsections
- Transcription bubbel
- contains RNA polymerase, DNA, and RNA transcript