Cell Interactions and Stem Cells

Transcription

1 Cell Interactions and Stem Cells Recognize the importance of cell interactions, cell signaling and cell-cell interactions, for coordination of functions in a multi-cellular organism. Learn the three stages of cell signaling, the different types of first messengers (external signals including hormones), internal messengers, and different cellular responses. Explain why different body cells respond in specific yet different ways to the same chemical signal. Recognize the importance of cellular adhesion molecules in cell-cell interactions and the difference between selectins, integrins, and adhesion receptor proteins Review the steps of early embryonic development from the fertilized egg to a multicellular organism with differentiated cells. Distinguish between stem, progenitor, and differentiated cells in terms of ability to self renew (replicate) and gene expression. Define and explain the difference between totipotent, pluripotent, and multi-potent cells with examples. Learn the three general sources of stem cells, and how they differ.

2 Cell Interactions Make multi-cellular life possible Two broad types 1) Cell Signaling 2) Cellular adhesion Defects cause certain inherited disorders Figure 2.3

3 Cell signaling: allows cells to receive and respond to surrounding biochemical signals The same basic cellular function is involved in: Sensing pain Inflammation & wound healing Diabetes Anxiety Learning & memory Psychoactive substances- caffeine, nicotine, marijuana, etc

4 Cell Signaling Reception Signal Transduction Figure 2.20 Response Figure 2.19

5 Signal Transduction The process of transmitting a signal from the environment to a cell - Receptor binds to first messenger - Interacts with regulator - Causes an enzyme to produce second messenger - Elicits cellular response, which is typically enzyme activation Figure 2.3

6 Cell signaling in apoptosis c&feature=related

7 Cell Signaling Leads to Specific response to a specific signal Amplified responses due to cascade ancer/images.html

8 The response of a particular cell to a signal depends on its particular collection of receptor proteins, and other cellular proteins needed to carry out the response

9 Insulin Signaling

10 Cellular Adhesion A precise sequence of interactions among proteins that connect cells, important for cellcell interactions Example = Inflammation - Three types of Cellular Adhesion Molecules (CAMs) help guide WBCs to the injured area Selectins Integrins Adhesion receptor Figure 2.3 proteins

11 Cellular Adhesion Figure 2.21 The inner life of the cells main/searchlist/6850.html or tch?v=mszlckmc4hw eo/551/the-inner-life-of-a- Cell-HQ Figure 2.20

12 Stem Cells From a Fertilized egg (zygote) to a multi-cellular organism Sperm cell Inner Cell Mass Nuclei containing DNA Egg cell Fertilized egg with DNA from both parents Embyro s cells with copies of inherited DNA Offspring with traits inherited from both parents

13 Stem Cells All cells in the human body descend from stem cells via mitosis and differentiation Cells differentiate down cell lineages by differential gene expression Stem cells are present throughout life and provide growth and repair Figure 2.3

14 Stem Cells A stem cell divides by mitosis - Produces daughter cells that retain the ability to divide and some that specialize Progenitor cells do not have the capacity of self-renewal Figure 2.3 Figure 2.22

15 Differentiation produces a variety of cell types, each expressing a different combination of genes Muscle cell Pancreas cells Blood cells Nerve cell

16 Figure 2.23 Figure 2.3

17 Stem Cells Stem cells and progenitor cells are described in terms of their developmental potential Totipotent Can give rise to every cell type Embryonic Stem (ES) Cells Pluripotent Have fewer possible fates Progenitor cells Multipotent Have only a few fates Daughters of Progenitor cells Figure 2.3

18 Stem Cells in Health Care There are 3 general sources of human stem cells 1) Embryonic stem cells Created in a lab dish using the inner cell mass (ICM) of an embryo 2) Induced pluripotent stem (ips) cells Somatic cells reprogrammed to differentiate into any of several cell types 3) Adult stem cells Tissue-specific or somatic stem cells Figure 2.3

19 Stem Cells in Health Care Figure 2.24 Figure 2.24

20 Under the right conditions, cultured stem cells derived from either source can differentiate into specialized cells.