Chapter 16

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Chapter 16
2011-12-12 15:20:44

Control of Gene Expression
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  1. Regulatory Proteins
    Gene expression is often controlled by regulatory proteins binding to specific DNA

    Some stimulate transcription, while others inhibite
  2. Prokaryotic regulation
    • Control of transcription initiation
    • Positive control- increases frequency
    • Activators enhance binding of RNA polymerase to Promoter in DNA

    • Negtive Control- decreases frequency
    • Repressors bind to operatiors in DNA.

    Prokaryotic cells often respond to their enviornment by chnanges in gene expression

    Genes involved in the same metabolic pathway are organized in operons
  3. lac Operon
    CODING REGION contains genes for the use of lactose as an energy source

    REGULATORY REGION contains DNA sequences used to control transcription of coding region.

    • The lac operon is negatively regulated by a represor protein
    • - lac repressor binds to the operator to block trascription,
    • - In the presence of lactose, an inducer (allolactose0 binds to repressor
    • - Repressor can no longer bind to opperator
    • - Transcripton proceeds as BASAL LEVEL.
  4. Glucose Repression
    • Glucose is preferred sugar
    • - Catabolic activator protein (CAP) is an activator with cAMP as EFFECTOR
    • - Level of cAMP in cells is reduced in the presence of glucose, which prevents CAP from binding to DNA

    INDUCER EXCLUSION: presence of glucose inhibits the transport of lactose into the cell.
  5. trp Operon
    Genes for the biosynthesis of trypthon

    The operon is not expressed when the cell contains sufficient amounts of tryptophan

    The operon is expressed when levels of tryptophan are low

    • The trp is negatively regulated
    • - trp repressor bind to the opperator to block transcription

    -Binding of the repressor to the operator requires a COREPRESSOR which is tryptophan

    Low levels of tryptophan prevent the repressor from binding to the operator
  6. Eukaryotic Regulation
    • Control of transcription more complex
    • - Eukaryotes have DNA organized into chromatin (protein-DNA)

    Amount of DNA involved in regulation eukaryotic genes is much larger.
  7. Transcription factors
    • General transcription factors
    • - Bind to TATA box on promoter
    • -Necessary for RNA polymerase to bind to promoter

    • Specific transcription facors (activators)
    • -Bind to enhancer sites on DNA
    • -Increase the level of transcription
  8. Eukaryotic chromatin structure
    Structure is directly related to the control of gene expression

    DNA wound around histone proteins to form nucleosomes

    Nucleosomes may block access to promoter

    • Histones can be modified
    • - Correlated with active versus inactive regions of chromatin
    • - Can be METHYLATED- found in inactive regions
    • - Can be ACETYLATED- found in active regiond

    • - Modify histones and DNA
    • - Also change chromatin structure
  9. Posttranscriptional Regulation
    • Posttranscriptional control of gene expression
    • - Small RNAs- miRNA and siRNA

    -Alternative splicing

    - RNA editing

    -mRNA degradation
  10. Micro RNA (miRNA)
    miRNA gene transcribed in the nucleus

    • Groomed in nucleus and again in cytoplasm
    • - Ends with a ~22 nucleotide miRNA

    • miRNA loaded into RISC
    • - RISC uses miRNA to bind to complementary sequence on mRNA- Cleaves mRNA- inhibits translation
  11. siRNA
    siRNA arise from long dsRNA

    Dicer cuts yield multiple siRNAs to load into RISC

    Target mRNA is cleaved
  12. miRNA or siRNA?
    Biogenesis of both miRNA and siRNA involves cleavage by Dicer and incorporation into RISC

    • Main difference is target
    • - miRNA repress genes different from their origin
    • - siRNAs tend to repress genes they are derived from
  13. Alternative splicing
    Introns are spliced out of pre-mRNAs to produce the mature mRNA

    Detemined by tissie- specific factors that regulate how pre-mRNA is spliced

    • Initiation of translation can be controlled
    • - Ferritin mRNA only translated if iron is present

    Mature mRNA molecules have carious half lives

    Translation can be controlled by regulating any number of proteins that are required
  14. RNA editing
    Creates mRNA not truely encoded by genes

    Involves chemical modification of bases

    • Apolipoprotein B exists in 2 forms
    • - One is produced by editing yhe mRNA to create a stop codon
  15. Posttranslational Regulation
    Phosphorylation or other chemicl modifications alter protein activity

    Protein degradation removes damaged or unwamted proteins
  16. Protein Degradation
    Protein produced and degraded continually

    Lysosomes for nonspecific protein digestion

    • UBIQUITIN for specific destruction
    • - Degradation of proteins marked with ubiquition occurs at the PROTEASOME
  17. Weight and length
    Double birth weight between 5 and 6 months

    Much weight gain is baby fat

    Birth length is about 1/4 of ultimate adult height
  18. Head physical growth
    Disproportionally large- may be a fourth to a third of body length of the baby

    Arms and kegs disproportionately short until about age 6 or 7
  19. Long Bones
    Made up of two parts:

    Ends are Called Epiphysis- one on each end of long bone

    • Center or Shaft of long bone is called Diaphysis.
    • In between epiphysis and diaphysis is cartilage line or "growth line".
  20. Moral Development, Piagetian Approach, Pre-moral Period (0- 7 years)
    Evaluates the right or the wrong of the situation by the consequences rather than intention.

    Egocentric attitude
  21. Moral Development, Piagetian Approach, Moral Reciprocity (8-11 years)
    Moral relationship based on mutual respect

    "Ill be nice to you if you are nice to me."
  22. Moal Development, Piagetian approach, Moral Relativity,
    (12 years- older)
    Realistic application- take all factors into consideration befor you judge.
  23. Moral Development, Kohlberg's Approach, Pre-Conventional Morality (0-9 years)
    Child decides what is right or wrong on the basis of what will be punished.
  24. Moral Development, Kohlbergs Approach, Conventional Morality
    Live up to what is expected of you.

    Good boy or girl
  25. Moral Development, Kohlbergs Approach, Post Conventional Morality (Over 20 years )
    Principled morality- achieve the greatest good for the greatest number.

    Rules should be based on mutual agreement, not blind authority.
  26. Moral Development,Gilligans Approach boy
    Boys think girls feel
  27. Gilligans Stages of moral development, 1. Survival Orientation
    Lack awareness of others needs
  28. Gilligan's Stages of Moral Development, 2. Conventional Care
    "Right" is whatever pleases others best.
  29. Gilligans Stages of Moral Development, 3. Integrated Care
    Right action takes account of self as well as others
  30. Learning Theory, Stimulus Response Reinforcement
    Baby sees what he wants, makes a sound to indicate what he sees. Cargiver responds by producing the ball. Next time baby wants a ball, he will say ba. rewarded behavior will be repeated
  31. Learning Theory, Social Learning Theory Bandura
    Learning by listening- observing and imitating
  32. Nativist or Psycholinguistic Theory, Noam Chomsky
    This is a biologically based theory. Chomsky believed that children have an inborn capacity to learn. The innate capacitiy is called LAD ( Language Acquisition Device) road map to appropriate words.
  33. Interactionist Theory- Piaget
    Bothe the linguistic enviornment and the inate biological structure combines to help the child learn language
  34. Phonology
    They must learn sounds of the lanuage
  35. Lexicon
    learning the language words
  36. Semantics
    Learning the mening of words
  37. Syntax
    Must learn to be able to piece together thae organization of words into sentences and connected thoughts.
  38. Stage 1 dialation and effacement
    Dialation and Effacement

    Dilation - widening of the cervix to allow fetus to come out

    Effacement- flattening or thinning out of the cervix
  39. Stage 2- delivery of the infant
    Presentation: Head- 95%

    Breech- 3-4%


    Double shoulders- Footing-1%

    Epistomy: Stitches
  40. Stage 3 Delivery of placenta
    Examined and sent to lab for further examination
  41. Lemaze Method of parenting parents
    Labor and delivery should be a natural process
  42. LeBoyer Method
    wrote book Birth without trama
  43. Rh Facotr
    cross blood contamination between placenta from mother and baby, treat with Rho Gam
  44. Newborn Assessment APGAR(1953)
    Checks for

    Heart Rate


    Reflex Irritability

    Muscle Tone

    Color 2 points for each 10 good to 0 bad
  45. brazelton Neonatal behavior assessment Scale (BNBAS
    the most inconvience that is Having in most