Thursday October 29 2015 Biology Exam III Chapter 13 Stem Cells and Cell Differentiation Engineering Organs 1995 MIT researchers injected cow cartilage cells into an ear mold under the skin of a lab mouse formed cartilage in the shape of a human ear In 2001 Anthony Atala excised bladder tissue from the patient s own bladder and placed on a bladder shaped scaffold formed tissue used to reconstruct a new bladder bioprinting using computer graphics and cellular ink to manufacture organs What are stem cells stem cells immature cells that can divide and differentiate into specialized cell types are called Adult or somatic stem cells help maintain and regenerate tissues If you have damage to your skin your stem cells in your skin form new skin cells You are always replacing your liver cells and other cells in your body with stem cells Tissues are groups of cells that have a speci c function Four tissue types epithelial connective muscle nervous Organs consist of multiple tissue types and cooperate as part of organ systems Almost all tissues contain stem cells that contribute to the maintenance of those tissues Stem cells will divide to form both stem cells and differentiated cells Biological Hierarchy structural when you have cells of similar function that make up tissue that make up an organ that make up an organ system As of 2012 30 patients have received experimental bladders Atala and colleagues are also growing replacement urethras and other organs 1 Advantages of Bioengineering Organs compared to other techniques Avoids complications with tissues of other organs EX no longer have to take Thursday October 29 2015 tissue from colon to x the bladder No risk of tissue rejection from donors Avoid damaging other organs to harvest tissues Disadvantage Two surgeries Initially harvest tissues Repair with bioengineered organ Each tissue has its own turnover time Not all of our tissues are the same age some may be younger than your chronological age Some of the fastest are liver skin cheek blood Your body is younger than you think Each kind of tissue has its own turnover time depending in part on the workload endured by its cells Only the lens cells of the eye neurons of the cerebral cortex and the muscle cells of the heart will last a lifetime In order for tissues to heal stem cells not only have to divide but also undergo cellular differentiation immature cells form specialized cells Cells become specialized by turning some genes on and other genes off differential gene expression Example muscle cells vs B cells Regenerative Medicine The eld of research involved with stimulating stem cells to divide and differentiate to repair damaged tissue is called Regenerative Medicine Four Approaches to regenerative medicine Therapeutic Drugs stimulate stem cells to grow and differentiate into specialized cell types 2 Cell Therapy remove stem cells chemically induce to divide and then re Thursday October 29 2015 Biodegradable Scaffolds inside the Body implant scaffolds internally to support implant cells regeneration of tissues Biodegradable scaffolds outside the body seed cells on scaffolds externally grow organ and implant in patient Adult or somatic stem cells differentiate only into a limited number cell types and Stem Cell Types are called multipoint Embryonic Stem Cells ESCs cells dividing during early development those isolated from the blastocyst stage can differentiate into nearly any cell type are called pluripotent even earlier embryonic cells that can differentiate into any cell type are called totipotent Sources of Embryonic Stem Cells Discarded human embryos from fertility clinics are used to make stem cell cultures for research and treatment Cloning a nucleus of human egg cell is replaced with diploid nucleus of somatic cell which forms an embryo that can be cultured SCNT somatic cell nuclear transfer Induced Pluripotent Stem Cells A mature stem cell that is genetically manipulated to become an embryonic like stem cell that is called an induced pluripotent stem cell add genes or proteins to cell to dedifferentiate return cell to embryonic state may be able to create transplantable cells that match a patient without using embryos Induced Stem Cells take the adult somatic cells and insert genes or proteins ans de differentiate them so that they become induced pluripotent stem cells that can form almost any time of cell 3 Thursday October 29 2015 Chapter 14 Natural Selection and Adaptation MRSA Methicillin Resistant Staphylococcus Aureus staph MRSA is resistant to several types of antibiotics used to treat staph infections Healthy people can carry staph on their skin and in their noses colonized with staph staph can be passed from person to person through contact with skin objects or surfaces 11 03 Antibiotics Antibiotics Chemicals that either kill bacteria or slow bacteria growth by interfering with the function of cell structures The Beta Iactam class of antibiotics penicillin cephalosporin Interfere with bacteria cell wall formation A lot of times the bacteria interferes with the enzymes Non Beta Lactam antibiotics like vancomycin this is usually the last resort when an infection is immune to all other antibiotics these are used to treat MRSA infections In most bacterial cells a rigid cell wall surrounds the cell membrane Keeps cell in tact even with the ow of water Beta Lactam interfere with the synthesis of a cell wall and the cell will burst easily when in a hypotonic environment Bacterial Reproduction bacteria reproduce asexually by binary ssion in which one parental cell divdes into two identical daughter cells there will be no genetic variation that results from binary ssion So if bacterial cells reproduce asexually where does the genetic variation come from Acquiring Resistance 4 Bacteria can acquire genetic variation by 2 mechanism mutation mistakes during DNA replication that produces new alleles gene transfer bacteria swap pieces of DNA with other bacteria via pili or pilus Thursday October 29 2015 How Populations Evolve Population evolution Fitness Natural Selection A group of organisms of the same species living in the same geographic area When a population s environment favors some traits over others the frequencies of those alleles that code for those traits will change over time EX antibiotic resistant alleles in the presence of an antibiotic will increase over time In result you will have a change in allele frequencies in a population over time is populations evolve