Cancer II

Six ways of losing the remaining good copy of a tumor suppressor gene

When proto-oncogene becomes overactive it becomes an oncogene

Myc Gene Amplification

Mitogens stimulate G1-Cdk and G1/S-Cdk activities

Ocogene collaboration in transgenic mice

Viruses May cause Cancer

Papillomavirus causes warts and subverts the control of cell division

Pap smears

normal abnormal invasive

How papillomaviruses are thought to give rise to cancer of the uterine cervix

Activation of cell proliferation by DNA tumor virus

Sequence of genetic changes underlying the development of a colorectal carcinoma

Each tumor will contain a different set of mutations

Effect of ionizing radiation on normal and cancer cells

Chapter 19

Cell Junctions, Cell Adhesion, and the Extracellular Matrix

Cross sectional view of intestinal wall

Tracer molecules can not cross tight junctions

Structure of tight junction

Electron Micrograph of tight junctions

Model of tight junction

Claudins are main component of sealing strands

Anchoring junctions in an epithelium

Anchoring junctions are formed by proteins

Cadherins connect actin filaments of different cells

DVD Clip 82

Desmosomes and hemidesmosomes both link to intermediate filaments

Cadherins also bind intermediate filaments together

Integrins link extracellular matrix to cytoskeleton

Size of gap junction channel can be determined with fluorescent molecules of different sizes

A Gap junction connexon is made up of 6 transmembrane connexin subunits

Images of gap junctions

The permeability of gap junctions can be regulated

dopamine treatment reduces permeability of gap junctions to a fluorescent dye

Summary of cell junctions found in the cell

Summary of cell junctions found in the cell

In plant cells plasmodesmata perform many of the same functions as gap junctions

View of plasmodesmata

Structure of Cadherin – responsible for cell to cell adhesion in vertebrate cells

Ca2+ is required to establish cell to cell connection through cadherin

Three mechanisms that mediate cell-cell adhesion

least commoncadherins

Cadherins allow cells to sort themselves

Catenins join cadherins to actin filaments in adherence junctions

Summary of junctional and non-junctional adhesive mechanisms