Nuclear Function

1
Nuclear Function

• Nuclear Membrane
• Nuclear Pore Complexes
• Double Membrane
• Inner (Nucleoplasm)
• Outer (Cytoplasm)
• Endoplasmic Reticulum

2
NUCLEAR PORE COMPLEX

• Nucleoplasm
• Nuclear Basket
• Nuclear Ring
• Nuclear Membrane
• Central Transporter
• Spoke Ring
• Cytoplasm
• Cytoplasmic Ring
• Cytoplasmic Filaments

3
LECTURE 4aNUCLEAR FUNCTION
1.8 The nuclear pore complex acts as a
supramolecular sieve
1.8 The nuclear pore complex acts as a
supramolecular sieve

• Nuclear Membrane
• Nuclear Pore Complexes
• Double Membrane
• Inner (Nucleoplasm)
• Outer (Cytoplasm)
• Endoplasmic Reticulum

4
1.9 The mechanism of protein import into the
nucleus
5
CHROMOSOME STRUCTURE

• DNA
• Double Helix
• Nucleosomes
• Histone Proteins
• Linker DNA
• Chromatin Fiber
• Coiled Coils

6
Chromosome Structure

• Looped Domains
• Condensed Chromatin
• Metaphase Chromosome
• Homologous Chromosomes
• 1 from Male Parent
• 1 form female Parent

7
Gene Structure

• DNA
• Four Bases deoxyribose phosphate
• A (deoxy-Adenosine) (dA) - Purine
• T (deoxy-Thymadine) (dT) - Pyrimidine
• G (deoxy-Guanosine) (dG) - Purine
• C (deoxy-Cytidine) (dC) - Pyrimidine
• Double helix
• A - T base pairs
• P P
• G - C hold two strands together
• Gene is a string of bases along 1 strand of DNA
• A-T-G-C-C-G-T-A-A-A-C-T...

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DNA Bases
C
5
d-Ribose
3
9
DNA Replication

• SISTER CHROMATID T-T-G-A...
• / / / / / A-A-C-T...
• HOMOLOGOUS A-T-G-C-C-G-T-A
• CHROMOSOME / / / / / / / / DNA
  T-A-C-G-G-C-A-T POLYMERASE
• \ T-T-G-A....
• / / / / SISTER CHROMATID A-A-C-T....
  

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DNA Replication

• DNA Replication
• DNA Polymerase
• 2 Homologous Chromosomes
• 4 Sister Chromatids

11
RNA Transcription

• RNA
• four bases ribose phosphate
• A
• U (Uridine instead of Thymadine)
• G
• C
• Transcription
• Single Strand copy of DNA
• RNA Polymerase (TATA Box)
• DNA A-T-G-C-G-T-A-A-A-C-T...
  -
• / / / / / / / / / /
  /
• RNA U-A-C-G-C-A-U-U-U-G-A... -

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DNA TRANSCRIPTION AND TRANSLATION
1.11 (A) Basic steps in gene expression (Part 1)

• Transcription
• Nucleus
• DNA?RNA
• RNA Polymerase
• mRNA, tRNA, rRNA
• Transfer
• Nucleoplasm?Cytoplasm
• Nuclear Pore Complex
• Translation
• Cytoplasm
• RNA?Protein

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Triplet Code

• Genetic Code
• 20 Amino Acids
• 4 RNA Bases (A,U,G,C)
• 1 base/amino acid 4 possible specified
• 2 bases/amino acid 42 or 16 possible
  combinations
• 3 bases/amino acid 43 or 64 possible
  combinations
• Degenerate Triplet Code
• Redundancy or more than 1 triplet per amino
  acid
• Helps prevent mistakes
• DNA TAC- ATG-CAT-GCA-TGC- CGT-AAT ...
  ACT
• Transcription
• mRNA AUG-UAC-GUA-CGU-ACG-GCA-UUA
  ...UGA
• Translation
• amino acids Met---Tyr---Val---Arg---Thr---Ala-
  -Leu.......Stop

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TRANSLATION OF DNA MESSAGE

• Ribosome
• Large Small Subunits
• A-site, P-site, E-site
• mRNA
• Triplet Codons
• tRNA
• Triplet Anticodons
• Amino Acid Carriers
• Polypeptide Chain
• Amino Acid Sequence

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Rosetta Stone
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TRANSLATION ON ROUGH ER
1.11 (A) Basic steps in gene expression (Part 2)

• Polysome Assembly
• Ribosome mRNA tRNA Protein
• Attachment to ER
• Signal Peptide
• ER Receptor
• Protein Processing
• Vesicle Transport

Cytoplasm
17
mRNA
ribosomes
attached polyribosomes
free polyribosomes
Fig. 3-10, p. 38
18
Golgi Bodies
0.25 µm
internal spaces
vesicles
cisternae
Fig. 3-11, p. 38