Some Biology Behind Chemical

1
Some Biology Behind Chemical Biomolecular
Engineering.

• Dr. Annette M. Parrott

2
What is the Central Dogma of Biology?
3
What is Gene Expression ?

• Gene expression the ability of a gene to produce
  a biologically active protein (transcription
  translation)
• Gene Regulationthe controls that act on gene
  expression

4
Gene Expression

• The ability of a gene (DNA sequence) to
  synthesize a protein is accomplished in 2 steps,
  known collectively as Protein Synthesis

5
Transcription

• Transcription occurs when a portion of DNA is
  complimentarily copied into an mRNA strand.
  Substituting the base U for T
• When mRNA is transcribed from DNA both the exon
  and intron noncoding sequences are transcribed.
  However, before the mRNA can leave the nucleus it
  must be processed.
• http//www.nobel.se/medicine/educational/dna/b/tra
  nscription/transcription_ani.html

6
Introns Exons

• Because introns interrupt coding nucleotide
  sequences, they first were called interrupted
  genes. The "int" in intron refers to intervening
  because introns always exist between exons. In
  eukaryotes, intron removal and splicing is
  completed within the nucleus. Sequences that
  code for protein are called exons because they
  travel (exit) outside the nucleus to code for
  proteins, and thus are the DNA sequences that are
  expressed (the prefix ex in the term exon is from
  expressed).

7

• After the introns are cut out, the exon RNA is
  spliced back together by RNA ligase so that the
  final mRNA used to code polypeptides normally
  consists only of exons, and is packaged (capped
  and adenylated) for transport.

8
Translation

• At the ribosome, the mRNA sequence is read in
  codons (base triplets). Corresponding amino
  acids are brought by tRNA that have anticodon
  that are complimentary to mRNA codons.
• Amino acids are connected with peptide bonds to
  form a polypeptide, or gene product.
• http//student.ccbcmd.edu/biotutorials/protsyn/tra
  nslat.html

9
Mutations

• With all this copying what happens if a mistake
  is made?

10
Single Gene Diseases

• Thousands of disorders are caused due to
  mutations in a single gene including
• Achondroplasia,Adrenoleukodystrophy
  ,Alpha-1-antitrypsin deficiency,Alport
  syndrome,Amyotrophic lateral sclerosis ,Angelman
  syndrome,Ataxia telangiectasia, Autoimmune
  polyglandular syndrome, Burkitt lymphoma,
  Congenital adrenal hyperplasia, Cystic fibrosis,
  Diastrophic dysplasia, Duchenne muscular
  dystrophy, Ellis-van Creveld syndrome,Familial
  Mediterranean fever, Fragile X, Gaucher
  disease,Glucose galactose malabsorption, Gyrate
  atrophy, Hemophilia, Hereditary hemochromatosis ,
  Huntington disease, Lesch-Nyhan syndrome, Maple
  syrup urine disease,Marfan syndrome, Menkes
  syndrome, Myotonic dystrophy, NeurofibromatosisNF1
  , Paroxysmal nocturnal hemoglobinuria, Pendred
  syndrome, Phenylketonuria, Refsum disease,
  Retinoblastoma ,Rett syndrome,Sickle cell anemia
  ,Spinal muscular atrophy , Spinocerebellar ataxia
  ,Tangier diseaseABCA1 , Tay-Sachs diseaseHEXA,
  Thalassemia, Hemoglobin alpha, Von Hippel-Lindau
  syndrome, Werner syndrome, Wilson's disease,
  Zellweger syndrome

11
Sickle Cell Anemia

• Official Gene Symbol HBB
• Name of Gene Product hemoglobin, beta
• Alternate Name of Gene Product beta globin
• Locus 11p15.5 - The HBB gene is found in region
  15.5 on the short (p) arm of human chromosome 11.
  
• Gene Structure The normal allelic variant for
  this gene is 1600 base pairs (bp) long and
  contains three exons.
• mRNA The intron-free mRNA transcript for the HBB
  gene is 626 base pairs long.
• Coding Sequence (CDS) 444 base pairs within the
  mRNA code for the amino acid sequence of the
  gene's protein product.
• Protein Size The HBB protein is 146 amino acids
  long and has a molecular weight of 15,867 Da.

12
(No Transcript)
13

• The SCA substitution creates a hydrophobic spot
  on the outside of the protein structure that
  sticks to the hydrophobic region of an adjacent
  hemoglobin molecule's beta chain. This clumping
  together (polymerization) of Hb S molecules into
  rigid fibers causes the "sickling" of red blood
  cells.

14

• Polymerized sickle hemoglobin does not form
  single strands. Instead, the molecules group in
  long bundles of 14 strands each that twist in a
  regular fashion, much like a braid
• These bundles self-associate into even larger
  structures that stretch and distort the cell. An
  analogy would be a water balloon which was
  stretched and deformed by icicles.

15

• Cycling between polymerization and
  depolymerization causes red blood cell membranes
  to become rigid. The rigidity of these red blood
  cells and their distorted shape when they are not
  carrying oxygen can result in blockage of small
  blood vessels.
• This blockage can cause episodes of pain and can
  damage organs.

16
What does Sickle Cell Anemia have to do with this
ChBE lab?
17

• HBB is one of many human genes that have homologs
  in Caenorhabditis elegans.
• HBB Homologue in C. elegans C24A3.4, 41.1
  amino acid similarity
• In fact, about 35 of C. elegans genes have human
  homologues

18

• Other applications where C. elegans is a model
  for H. sapiens include...
• cancer genes such as p53, RB, RAS, BRCA1, PTEN
• human inherited degenerative diseases (Duchenne's
  muscular dystrophy, Huntington's
  neurodegenerative disease)
• pharmacological model for Parkinson's disease
• fat storage genes
• aging studies
• effects of microgravity and space travel
• neurological and muscular systems
• memory

19
How do scientists manipulate C. elegans?

• Genetic Engineering

20
(No Transcript)
21

• The plasmid is cut across both strands by a
  restriction enzyme, leaving loose, sticky ends to
  which DNA can be attached.
• Special linking sequences are added to the human
  cDNA so that it will fit precisely into the loose
  ends of the opened plasmid DNA ring.
• The plasmid containing the human gene, also
  called a recombinant plasmid, is now ready to be
  inserted into another organism, such as a
  bacterial cell or nematode.

22
What organisms are genetically engineered (and
what for)?

• It might be easier to ask what organisms are NOT

23
Can and do we genetically engineer humans?

• YES!

24
Gene Therapy

• Gene therapy is an experimental treatment that
  involves introducing genetic material (DNA or
  RNA) into a persons cells to fight disease.
  These genes are inserted via viruses or liposomes.

25
(No Transcript)
26
Any Questions, Difficulties or Comments ? ? ?