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Explore the wonders of cell growth, division, and reproduction limits, and understand how your body expands through your life cycle. Discover the comparison between the cells of a baby penguin and its parent. Delve into the challenges posed by information overload and traffic problems in cellular processes. Learn about the importance of cell division in maintaining an optimal surface area-to-volume ratio. Differentiate between asexual and sexual reproduction and grasp the intricate phases of cell division, from prokaryotic to eukaryotic cycles. Gain insights into cell differentiation, stem cells, regenerative medicine, and ethical concerns in cellular research, including cellular reprogramming by Dr. Shinya Yamanaka.
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Limits to Cell Size Throughout your lives, how has your body gotten larger? How will this baby penguin grow? How do the cells making up its body compare to those making up the parent’s body?
A Visual Analogy – what does this town represent Information overload Traffic problems
Cell Growth Limitations Information crisis: too many demands placed on DNA Traffic problems: volume grows too fast relative to surface area, material exchange is insufficient
Smaller cells have a larger (better) surface area to volume ratio
Cell Division Produces two daughter cells Cell must replicate DNA before cell division. Dividing to make more, smaller cells keeps SA to V ratio high.
Comparing Asexual and Sexual Reproduction Asexual Produce many offspring in short period Don’t need to find a mate In stable environments, genetically identical offspring thrive. If conditions change, offspring not well adapted. • Sexual • Relatively fewer offspring; growth takes more time • Need to find a mate • In changing environments, genetic diversity can be beneficial. • Offspring may be less well adapted to current conditions.
Chromosomes In prokaryotic cells, DNA is packaged into a single, circular chromosome.
Chromosomes In eukaryotic cells, DNA is packaged into multiple chromosomes. DNA double helix duplicated chromosome coils centromere sister chromatids nucleosome supercoils histone proteins
Prokaryotic Cell Cycle Prokaryotes undergo binary fission.
Eukaryotic Cell Cycle Eukaryotic cells have a more complex cell cycle than prokaryotic cells.
Which Cell Cycle? bacteria plants
M Phase Cell division occurs during M phase.
Prophase The nucleus condenses and chromosomes become visible. The spindle begins to form.
Metaphase Chromosomes line up at the center of the cell. centrioles chromatid centromere chromosome
Anaphase Chromosomes move toward opposite poles. individual chromosomes
Telophase The cell begins to divide into daughter cells. nuclear envelopes re-forming
Cytokinesis In animal cells, the cell membrane pinches in the center to form two daughter cells.
Mitosis Overview List and describe the phases of mitosis. Interphase Cytokinesis Prophase 1 Telophase 4 Metaphase 2 3 Anaphase
We start of as one cell. • But after over 47 rounds of the cell cycle you have 47 trillion cells!
Defining Differentiation During the development of an organism, cells differentiate to become . specialized Carry out photosynthesis Transport materials Store sugar
Mapping Differentiation C. elegans 32 256 28 = 25 =
What Are Stem Cells? Stem cells are the cells from which differentiated cells develop. Totipotent: can develop into any type of cell in the body (including the cells that make up the extraembryonic membranes and placenta) – only the fertilized egg and the cells produced by the first division Pluripotent: cells that are capable of developing into most, but not all, of the body’s cell types unspecialized
Embryonic Stem Cells Hollow ball of cells (4 days) • capable of dividing and renewing themselves for long periods; • unspecialized; • give rise to specialized cell types. embryonic stem cells
Adult Stem Cells Multipotent: limited potential to develop into many different types of differentiated cells Mainly found in bone marrow, hair follicles (cells have a limited life span) Also some in brain, heart, and skeletal muscle
Regenerative Medicine Undifferentiated cells are used to repair or replace damaged cells and tissues.
Ethical Issues Human adult stem cell research is rarely controversial because of willing donors. Human embryonic stem cell research is controversial because arguments for and against involve ethical issues of life and death.
Cellular Reprogramming Induced Pluripotent Stem Cells (iPS cells) Convert human fibroblast cells into cells that closely resembled embryonic stem cells May ultimately help society reframe the debate over use of stem cells Dr. Shinya Yamanaka