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Trends in Biotechnology

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Title: Trends in Biotechnology


1
Trends in Biotechnology
  • Quick Review of Chapter 2 Cellular Processes

2
  • Eukaryotic and prokaryotic cells, and the major
    organelles of eukaryotic cells.

3
Fig. 2.1 Cell structure and organization (a)
Bacteria cell.
4
http//en.wikipedia.org/wiki/Cell_28biology29
5
Fig. 2.1 (b) Animal cell.
6
  • Diagram of a typical animal cell. Organelles are
    labelled as follows
  • Nucleolus
  • Nucleus
  • Ribosome
  • Vesicle
  • Rough endoplasmic reticulum
  • Golgi apparatus (or "Golgi body")
  • Cytoskeleton
  • Smooth endoplasmic reticulum
  • Mitochondrion
  • Vacuole
  • Cytosol
  • Lysosome
  • Centriole

http//en.wikipedia.org/wiki/FileBiological_cell.
svg
7
Fig. 2.1 (c) Plant cell.
8
http//commons.wikimedia.org/wiki/FilePlant_cell_
structure.png
9
  • Structure of the cells macromolecules, and how
    they are constructed Lipids, carbohydrates,
    proteins, and nucleic acids.

10
  • Two different classes of lipids have fatty acids
    in their structure.

11
Fig. 2.2 Triglycerides have a three-carbon-OH
backbone called glycerol with a fatty acid chain
attached to each carbon.
12
Fig. 2.2 (b) Phospholipids are structurally
similar to triglycerides except one fatty acid
chain is replaced by a phosphate.
13
Fig. 2.2 (c) Phospholipid bilayer
14
  • Cell membranes are very complex with a
    phospholipid bilayer embedded with proteins,
    carbohydrates, and glycoproteins.

http//commons.wikimedia.org/wiki/FileCell_membra
ne_detailed_diagram_en.svg
15
Fig. 2.3 Structure of fatty acids showing the
carbon backbone.
16
Fig. 2.4 Monosaccharides, (a) glucose and (b)
fructose shown as both straight-chain and ring
forms. (c) The formation of a disaccharide
from two joined monosaccharides.
17
Fig. 2.5 Cellulose, a structural polysaccharide
composed of glucose monomers, found in plant cell
walls.
18
Cellulose.
http//commons.wikimedia.org/wiki/FileCellulose-3
D-balls.png
19
Fig. 2.6 Chitin, a structural polysaccharide
composed of N-acetyl glucosamine, is found in the
exoskeletons of insects.
20
Fig. 2.7 The 20 amino acids used in protein
synthesis.
21
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24
  • In the above structures, the top circle
    represents the amino acid backbone (H2NCHCOOH),
    with the R group depicted.
  • In the case of proline, which is an alpha imino
    acid, rather than an amino acid, the circle
    represents the CHCOOH group, the imino nitrogen
    shown as an element in the proline ring.

25
Fig. 2.8 Peptide bond formation between two amino
acids.
26
http//commons.wikimedia.org/wiki/FilePeptidforma
tionball.svg
27
Fig. 2.9 The four nucleotides of DNA.
28
http//commons.wikimedia.org/wiki/FileDNA_chemica
l_structure.svg
29
Fig. 2.10 The double-strand structure of DNA
showing the nucleotides, each made of a
deoxyribose sugar, a phosphate, and a
nitrogen-containing base.
30
Fig. 2.11 The Watson-Crick model of DNA. Two
strands of a hydrogen bonded DNA double helix
spiraling around a central axis.
31
Fig. 2.12 The deoxy-ribonucleotide monomers of
DNA connected by phospho-diester bonds.
32
Fig. 2.13 The nucleotide structure of RNA.
33
Fig. 2.14 Base pairing, A-T in DNA and A-U in
RNA.
34
http//commons.wikimedia.org/wiki/FileDifference_
DNA_RNA-EN.svg
35
Fig. 2.15 Transfer RNA showing the anticodon and
3 amino acid binding regions.
36
  • A different model of transfer RNA.

http//commons.wikimedia.org/wiki/File3d_tRNA.png
37
Fig. 2.16 Central dogma of molecular biology.(a)
38
Fig. 2.16 Central dogma of molecular biology.(b)
39
http//commons.wikimedia.org/wiki/FileRibosome_mR
NA_translation_en.svg
40
Fig. 2.17 The stages of nuclear division in a
process called mitosis, and cell division.
41
http//commons.wikimedia.org/wiki/FileMitosis.png
42
Fig. 2.18 Semiconservative replication of DNA.
43
  • Semiconservative replication of DNA showing the
    direction of replication.

44
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45
  • Some proteins involved in DNA replication.

http//commons.wikimedia.org/wiki/FileDNA_replica
tion_en.svg
46
  • Show video DNA Replication Process - Free Science
    Videos and Lectures
  • http//www.freesciencelectures.com/video/dna-repli
    cation-process/
  • Show video Mechanism of Replication
  • http//www.dnalc.org/resources/3d/04-mechanism-of-
    replication-advanced.html

47
Fig. 2.19 Bidirectional replication of DNA in
(a) prokaryotes and (b) eukaryotes.
48
Fig. 2.20 Replication of DNA at a replication
fork in bacteria.
49
Fig. 2.20 Replication of DNA at a replication
fork in bacteria.
50
Fig. 2.20 Replication of DNA at a replication
fork in bacteria.
51
Fig. 2.21 A DNA replication bubble showing the
direction of replication in the two replication
forks, leading and lagging strand synthesis, and
Okazaki fragments in the lagging strand.
52
  • After replication the DNA might be coiled in
    Eukaryotes
  • http//www.freesciencelectures.com/video/molecular
    -biology-visualization-of-dna/

53
Fig. 2.22 The amino acids arranged according to
their degeneracy.
54
Fig. 2.23 Codons read in-frame.
55
Fig. 2.24 RNA synthesis. (a) Transcription is
started when RNA polymerase binds to the DNA at
the promoter region.
56
Fig. 2.24 (b) The double-strand DNA unwinds. (c)
RNA polymerase travels along the DNA template,
nucleotides are added to the growing RNA strand.
57
Fig. 2.24 (d) RNA polymerase reaches a
terminator, the RNA transcript is released and
transcription is terminated.
58
  • Show video TranscriptionAdvancedXvid
  • http//vcell.ndsu.nodak.edu/animations/transcripti
    on/movie-flash.htm
  • Show video 13-transcription-advanced
  • http//www.dnalc.org/resources/3d/13-transcription
    -advanced.html

59
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60
Fig. 2.25 A stem-loop structure in the newly
synthesized RNA is one way that transcription is
terminated.
61
Fig. 2.26 Conserved sequences in (a) bacterial
promoters
62
Fig. 2.26 (b) Conserved sequences in eukaryotic
promoters.
63
Fig. 2.27 Enhancement of transcription by an
enhancer element. (a) Low level of transcription
without the effect of an enhancer.
64
Fig. 2.27 (b) An enhancer sequence increases the
level of transcription.
65
Fig. 2.28 After transcription and formation of a
pre-mRNA in eukaryotic cells, the transcript is
processed.
66
  • Fig. 2.28 After transcription and formation of a
    pre-mRNA in eukaryotic cells, the transcript is
    processed - a nucleotide with functional groups
    is added to the 5 end (5 cap) and adenine
    nucleotides are added to the 3 end (poly-A tail).

67
  • Show video mRNAProcessingAdvancedXvid
  • http//vcell.ndsu.nodak.edu/animations/mrnaprocess
    ing/movie-flash.htm
  • Show video 24-mrna-splicing http//www.dnalc.org/r
    esources/3d/24-mrna-splicing.html
  • Show video mRNA Splicing
  • http//vcell.ndsu.nodak.edu/animations/mrnasplicin
    g/movie-flash.htm

68
Fig. 2.29 The three types of RNA (rRNA, mRNA,
tRNA) and their role in protein synthesis.
69
Fig. 2.30 Ribosome structure.
70
http//commons.wikimedia.org/wiki/FileRibosome_mR
NA_translation_en.svg
71
Fig. 2.31 a) Translation initiation.
72
Fig. 2.31 b) Translation initiation.
73
Fig. 2.31 c) Translation initiation.
74
Fig. 2.32 a) b) Elongation during translation.
75
Fig. 2.32 c) d) Elongation during translation.
76
Fig. 2.32 e) Elongation during translation.
77
  • Show video 16-translation-advanced
  • http//www.dnalc.org/resources/3d/16-translation-a
    dvanced.html
  • Show video TranslationAdvancedXvid
  • http//vcell.ndsu.nodak.edu/animations/translation
    /movie-flash.htm

78
  • Regulation of Gene Expression.
  • The cell only makes what is needed and controls
    the production of products.
  • Both prokaryotes and eukaryotes control the
    stopping and starting of transcription.
  • Prokaryotes can lower the rate of translation.

79
  • Prokaryotic Gene Expression.
  • Bacteria use signals called inducers to turn
    genes on or off in response to environmental
    changes.
  • Usually these are in the form of a group of
    genes, with a promoter (called an operon).
  • There are two major operons that are well known
    in bacteria.

80
  • Operons have several parts
  • Promoter.
  • Several structural genes, all controlled by the
    promoter.
  • Repressor binding site, called an operator,
    which overlaps the promoter.
  • Repressor genes encode for repressor proteins,
    which bind to the operator to block RNA
    polymerase.

81
Fig. 2.33 A prokaryotic operon.
82
  • The lac Operon of E. coli
  • Contains three operon genes
  • lacZthe enzyme beta-galactosidase, which breaks
    down lactose.
  • lacYthe enzyme permease.
  • lacAthe enzyme acetylase.

83
Fig. 2.34 Regulation of the lac operon. (a) When
the active repressor binds to the operator in the
absence of lactose, RNA polymerase cannot bind to
the promoter and transcription is blocked.
84
Fig. 2.34 Regulation of the lac operon in the
presence of lactose. (b) Lactose inactivates the
repressor which releases from the operator, RNA
polymerase binds to the promoter and
transcription starts.
85
  • Without lactose, the lac repressor, encoded by
    the lacI gene, binds to the operator, keeping RNA
    polymerase from binding to the promoter.
  • When lactose is present, it attaches to the
    repressor which changes its shape and releases
    from the promoter.
  • Ribosomes immediately attach to the mRNA and
    start translation.
  • This is negative control - genes are not
    transcribed when the repressor is bound to the
    promoter.

86
  • Video LacOperonAdvancedXvid http//vcell.ndsu.nod
    ak.edu/animations/lacOperon/index.htm
  • Video Operon Lac
  • http//www.youtube.com/watch?vaEtuaEe0C-INR1
  • (web Animation The lac Operon
  • http//bcs.whfreeman.com/thelifewire/content/chp13
    /1302001.html )

87
  • The lac operon can also be regulated to allow for
    more transcription
  • If glucose is absent, the amount of a molecule
    called cyclic AMP (cAMP) increases inside the
    cell.
  • cAMP binds to a cAMP binding protein (CAP), which
    binds near the promoter region. This increases
    lac operon transcription.
  • cAMP is lower when glucose is present, and CAP is
    not active.

88
  • The trp Operon regulates the production of the
    amino acid tryptophan.
  • It has several parts
  • (a) Promoter.
  • (b) Operator gene overlapping the promoter
    region.
  • (c) Five genes encoding enzymes that catalyze
    the last steps of tryptophan synthesis.

89
  • The repressor is inactive unless tryptophan binds
    to it. The activated repressor attaches to the
    operator and blocks transcription.
  • If there is no tryptophan, the repressor cannot
    bind and transcription occurs.
  • Genes are repressed to avoid too much tryptophan
    production.

90
Fig. 2.35 The trp operon showing the five
structural genes and the promoter region.
91
  • Web Video of trp Operon look at
    http//bcs.whfreeman.com/thelifewire/content/chp13
    /1302002.html

92
  • Eukaryotic Gene Expression is much more
    complicated than in prokaryotes.

93
  • Eukaryotic cells regulate gene expression by
  • Regulating transcription of genes.
  • Controlling mRNA processing.
  • Controlling transport of mRNA to the cytoplasm.
  • Regulating the rate of translation.
  • Controlling availability of mRNA.
  • Protein processing.

94
Fig. 2.36 Transcription and translation in a
eukaryotic cell.
95
Fig. 2.37 Summary of some of the multiple levels
of eukaryotic gene regulation.
96
  • Transcriptional control
  • There are more promoters and regulatory sequences
    in eukaryotic cells.
  • Proteins called transcription factors interact
    with the promoter and RNA polymerase, forming the
    transcription initiation complex.
  • Gene-specific regulatory proteins bind to special
    DNA control sequences that contain regulatory
    protein binding sites.
  • Control sequences can be adjacent to or distant
    from structural genes.
  • Individual or distant genes often must be
    regulated in scattered groups or networks,
    sometimes on different chromosomes.

97
  • Video mRNAProcessingAdvanced
  • http//vcell.ndsu.nodak.edu/animations/mrnaprocess
    ing/index.htm

98
  • Regulation of RNA processing and transport out of
    the nucleus to the cytoplasm
  • Different cell types may process the same mRNA
    differently, by a process called alternative
    splicing, to yield different proteins (Figure
    2.38)
  • The pre-mRNA for the hormone calcitonin
    (non-processed mRNA) contains five introns
    separating six exons.
  • The transcript can be processed to generate
    calcitonin mRNA in thyroid cells or calcitonin
    gene-related peptide (CGRP) mRNA in hypothalamus
    cells.

99
Fig. 2.38 An example of alternative splicing to
yield two different mRNAs, calcitonin mRNA in
thyroid cells and calcitonin gene-related peptide
(CGRP) mRNA in hypothalamus.
100
  • Video mRNASplicingAdvancedXvid
  • http//vcell.ndsu.nodak.edu/animations/mrnasplicin
    g/index.htm

101
  • Translational control
  • Influences the final synthesis of a protein
    product (translation).
  • Translation is controlled by protein initiation
    factors and proteins that repress (inhibit)
    translation.
  • How quickly mRNA degrades influences when mRNA
    can be translated.

102
  • Posttranslational control is the changing of
    protein products after they are made.

103
  • Methods of changing them include
  • Protein folding and assembly with other proteins
    after synthesis.
  • The removal of amino acids.
  • Cleavage of the molecule, which is called
    proteolysis.
  • Modification of the protein molecule.
  • Addition of a sugar is called glycosylation.
  • Addition of a phosphate is called
    phosphorylation.
  • Importing proteins into organelles.
  • Protein degradation.

104
  • Video ProteinModification
  • http//vcell.ndsu.nodak.edu/animations/proteinmodi
    fication/index.htm
  • Note this is some of the protein changes in the
    Golgi body. There are many more different types
    of changes possible in other parts of the cell.

105
  • Draw and label a diagram of the Central Dogma
    of molecular biology.
  • On the diagram, show the ways that the flow of
    information in the cell can be regulated in
    eukaryotic cells, beginning at the DNA level and
    ending at the protein level.
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