Advanced Cell Biology

2014 1nd Semester

Department of Animal Science

Chungbuk National University

3rd Lecture

1st week : Introduction

3rd week :Research Strategies For Cell Biology

5nd week : Nucleus, Transcription and Splicing

7nd week : Membrane and Channel

9nd week : Membrane Trafficking

11nd week : Cell Signaling

13nd week : Cytoskeleton

15nd week : Cell Cycle

Central Dogma of Molecular Biology

In Eucaryotic Cell, DNA Replication, Transcription and Splicing happen at Nucleus

Structure of Nucleus

Cajal Bodies : snRNA/snoRNP assembly

Nucleolus : rRNA transcription / Processing / Preribosomal assembly

PML Bodies, Speckles

The Nucleolus: The Most Prominent Nuclear Subdomain

rRNA transcription : by RNA Polymerase I 50% of RNA transcription is the cell is rRNA

Nucleuos in Oocyte

Nuclear Membrane and Nuclear Pore Complex : Gateways between Nucleus and Cytoplasm

Nuclear Membrane: two concentric membranes separating the perinuclear space.

Outer nuclear membrane is continuous with and functionally part of the endoplasmic reticulum.

Inner nuclear membrane has many novel transmembrane and peripheral proteins that anchor the nuclear lamina and interact with chromatin.

Lipid bilayers of the two membranes are connected around the nuclear pore complexes.

Lamina : a protein meshwork lining the inner surface of the inner nuclear membrane.

Disassembly of the nuclear envelope is a critical aspect of mitosis (and meiosis) in higher eukaryotes

It is also called as ‘GVBD’ (Germinal Vesicle Breakdown) in Oocyte..

Traffic between Nuclues and Cytoplasm

Nuclear Pore Complex : Gateway betweeen Cytoplasm and Nucleus

Nuclear Localization Signal (NLS) : Tickets for the Nucleus Localization

PKKKRKV

KRPAATKKAGQAKKKK

Highly Positive Charged Residues

nuclear export sequence (NES)

The human immunodeficiency virus I Rev protein provides one example of a leucine-rich sequence (LQLPPLERLTL) that is recognized by the carrier CRM1.

Importin + NLS

Negative Positiv

Ran GDP & GTP Transition

RanGDP

GDP

RanGTP

GTP

Importin beta-RanGTP

Mitotic chromosome

One DNA Molecule Per chromosome

Chromosome DNA Packaging : The Nucleosome

E.coli

Genome Size :4.6Mbp

Human Genome Size :3100MbpProtein Coding Gene :20000-25000

Protein Coding Gene : 4288

S.cerevisiae

Genome Size : 13.8MbpProtein Coding Gene : 6604

Drosophila Genome Size : 140MbpProtein Coding Gene : 13525

900X time of genome size5X times of proteins?

Transposon : Junk DNA? Make up much of genome of higher eucaryotes

-Retrotransposon : transcribe as RNA -> Convert RNA into DNA-> inserted back to genome

- LINE(long interspered nuclear elements)- SINES (short interspersed nuclear elements)

- Is ‘junk DNA’ really junk?

- Junk is not a Trash!

Centromeres : the region where the chromosome becomes attached to the mitotic spindle

Histone Tail and Histone Code

Second Level of Chromosomal DNA Packaging

Euchromatin : contains almost all of the genes, both actively transcribed and quiescentHeterochromatin : tranascriptionally inert, generally more condensed than the euchromatin

Imprinting

Kinetochore - Button-like structure located in the surface of the centromeric hetrochromatin

Link between DNA and Microtuble at mitotic spindle