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Unit 5 - Coggle Diagram

- - - - a cells endowment of DNA, genetic information
    - - structures of packaged DNA, make replication and distribution manageable
    - - complex of DNA & proteins that is the biulding blocks for chromosomes
    - - cell or organism that has only a single set of chromosomes, gamete sex cells, 23 in humans, meiosis
    - - cell or organism that has paired chromosomes, 46 in humans, somatic body cells, created by mitosis
    - - joined copies of original chromosomes
    - - region of chromosomal DNA where chromatid is attached most closely to the sister chromatin
    - - begins formation in cytoplasm during prophase, made of fibers, microtubules, & associated proteins
    - - subcellualr region containing material that functions throughout cell cycle to organize the cells microtubules
  - - - first gap
        
        checkpoint: no go ahead signal causes cell to exit cycle and enter G0
    - - synthesis
        
        DNA is only replicated during synthesis
    - - second gap
    - - non-dividing stage
  - - - chromatin fibers become more tightly coiled, condensing into discrete chromosomes
      - nucleoli disappear
      - sister chromatids disappear
      - miotic spindle begins to form
      - centrosomes move away from eacother
    - - centrosomes @ opposite ends of cell
      - all chromosomes @ metaphase plate
      - kinetochores of each sister chromatid attached to kinetochore microtubules
    - - cohesion proteins are cleaved
      - each chromatid becomes full chromosome
      - 2 daughter chromosomes move to opposite ends of cell
      - cell elongates
      - non-kinetochore microtubliles lengthen
    - - 2 daughter nuclei formed in cell
      - nucleoli reappear
      - remaining spindle microtubules are depolymerized
    - - 2 daughter cells appear
      - involves formation of cleavage furrow in animal cells
      - plant cells
        
        no cleavage furrow, cell plate instead
        
        cell plate enlarges until surrounding membrane fuses with perimeter of plasma membrane
      - animal cells
        
        actin filaments interact w/ myosin molecules
        
        ring contracts
        
        cleavage furrow deepens
    - - nuclear envelop fragmanets
      - chromosomes continue condensing
      - each of 2 chromatids each has a kinetochore
  - - - when cells get too crowded, they stop dividing
    - - where cells need something to cling onto in order to divide
  - - - malignant
        
        able to spread to other parts of the body, can/will kill you
      - benign
        
        abnormal cells in one spot, not spreading/can't move to other parts of the body, won't kill you
    - - spread of cancer cells from their original location
- - - - short DNA sequence
      - each restriction enzyme recognizes a very specific restriction site
        
        cuts both DNA strands at precise points within restriction site
    - - created from restriction enzymes cleaving sugar phosphate backbones in the 2 DNA strands in a staggered manner
      - can form hydrogen bonded base pads (hybridize) with complimentary sticky ends on any other DNA molecules cut with the same enzyme
        
        temporary pairing, can be made permanent by DNA ligase
  - - - first step is to obtain a plasmid (originally isolated from a bacterial cell and genetically engineered for efficient cloning)
      - then insert DNA from another source (foreign DNA) into it
      - resulting plasmid is recombinant dna
        
        a molecule containing DNA from 2 different sources, often different species
      - after process is complete, the plasmid can be turned back into a bacterial cell, called a recombinant bacterium
- - - - segment containing operator, promotor, and genes they control
        
        operator
        
        "on-off switch"
        
        segment of DNA
        
        positioned within promotor or between promoter and enzyme coding genes
      - trp operon
        
        one of many operons in E.Coli genome
        
        trp operon turned on in default state
        
        means that RNA polymerase can bind to the promoter and transcribe regions of the gene
        
        can be switched on and off by trp repressor
        
        trp repressor protein
        
        expressed continuously at a low rate
        
        when tryptophan binds to trp repressor at an allosteric site the repressor protein changes to the active form to sttscth to the operator, turn the operon off
        
        is the protein product of a regulatory gene
        
        inactive by itself, needs tryptophan as corepressor in order to bund to operator
        
        repressible operon because its transcription is usually on but can be inhibited
      - lac operon
        
        inducible operon because it is usually off but can be stimulated into transcription
        
        gene for β-galactose (lacZ) is part of lac operon which includes 2 other genes for coding enzymes that function in the use of lactose
        
        entire transcription unit is under the command of one main opener and promoter
        
        regulatory gene: lacI
        
        located outside operon
        
        codes for allosteric repressor protein that can switch off the lac operon by binding to the operator
        
        lac repressor
        
        active by itself
        
        binds to operator and switches lac operon off
        
        inducer inactivates it
      - CRP
        
        cAMP receptor protein
        
        activator
        
        binds to DNA and stimulates transcription
        
        when cAMP binds to it, CRP assumes active shape and can attach to a specific site at the upstream end of the lac operon
    - - binds to operator and blocks attachment if RNA polymerase to the promoter
      - preventing transcription of the genes
      - specific for the operator of a particular operon
      - corepressor
        
        small molecule that cooperates with a repressor portion to switch an operon off
      - binding of repressors to operators is reversible
    - - inactivates the repressor
      - specific small molecule
    - - protein that binds to DNA and stimulates transcription of a gene
      - cAMP is an activator
  - - - DNA packed into elaborate complexes called chromatin
      - chromatin helps regulate gene expression
      - DNA attaches to protein scaffolding at promoter
      - chemical modifications to histone can influence protein structure and gene expression
      - modifications catalyzed by enzymes
      - chromatin modifications do not change DNA sequence, but they can still be passed down to daughter cells
    - - enhancer
        
        group of distal elements control elements
      - transcription
        
        general transcription factors
        
        act @ promoter of all genes
        
        essential for all protein coding genes
        
        a few bind to TATA box, many bind to proteins
        
        interaction of general factors & RNA Pol 3 w/ a promoter usually leads to low rate of initiation and production of a few RNA transcripts
        
        RNA trancripts come from non-expressed genes
        
        specific transcription factors
        
        bind to control elements
        
        high levels of transcription in specific proteins depend on specific factors
        
        proximal and distal control elements
        
        each enhancer associated with one gene
        
        activator proteins -> DNA binding domain & activation domains
        
        facilitates series of protein-protein interactions, results in enhanced transcription
    - - alternative RNA splicing
        
        different mRNA molecules produced from same primary transcript, depends on introns and exons
        
        can significantly expand the repertoire of a eukaryotic genome
      - regulatory proteins specific to a cell type control intron-exon choices by binding to RNA sequences w/ in primary transcript
    - - gene expression also regulated in translation
      - many proteins undergo chemical modifications to make them functional
      - selective degradation
        
        strictly regulates how long each protein is functional
  - - - small single stranded RNAmolecules
      - capable of binding to complementary to complementary sequences in mRNA molecules
      - longer precursor is processed by cellular enzymes into an miRNA
      - single stranded RNA about 22 nucleotides long hat forms a complex with one or more proteins
    - - distinction based on subtle differences in the structure of precursers
      - blockage of gene expression by siRNA is called RNA interference (RNAi)
      - associate with same protiens, produce similar results
- - - - cancer causing genes
    - - code for proteins that stimulate normal cell growth & division
  - - - guardian angel gene
      - codes for specific transcription factor that codes for specific synthesis of proteins to inhibit cycle
      - codes for release of other inhibitors to the cell cycle