Do Now How can you visually distinguish between newly formed cells and older cells?

Regulating the Cell Cycle 5.3

Apoptosis Means “a falling off” Programmed cell death. What causes it? When internal or external signals activate genes that help produce self destructing enzymes. Nucleus shrinks and breaks apart. Immune cells recognize this and “gobble up” the cell and recycle its parts. Fun Fact- Blood cells only live about 120 days, Colon cells only 4 days, Skin cells 2-3 weeks!

Apoptosis During Embryo Development Example: A human embryo has webbed fingers/toes. The cells between the digits undergo apoptosis during later development resulting in a baby born with unwebbed fingers/toes

Uncontrolled Division Cancer cells continue to divide and form tumors Benign - cells remain clustered in one area and are often easier to remove Malignant- some cells break away and spread through the body via bloodstream Tumors - cause harm because the cells in that area don’t do their specialized function

5.4 - Asexual Reproduction Creating of identical offspring from a single parent Most prokaryotes reproduce through Binary fission Very similar to mitosis Both form two identical daughter cells BUT prokaryotes have no nucleus and have much less DNA which forms a circular shape, not several chromosomes.

Asexual Eukaryotes Flatworms and sea stars = fragmentation Many plants can reproduce asexually through stems or underground structures that are connected to the original plant (runners) Some organisms reproduce sexually and asexually! Sea anemones bud or break off small pieces asexually and also make eggs/sperm

Pros and Cons of Asexual Reproduction More efficient if the environment stays the same Doesn’t require finding a mate! Less time and energy Cons: No diversity Could all be wiped out if susceptible to a disease or environmental condition https://www.youtube.com/watch?v=jk2RJm5RBEk https://www.youtube.com/watch?v=z7I0mw4ZDJA https://www.youtube.com/watch?v=G41EANkcMvg http://www.scientificamerican.com/article/asexual-lizards/

5.4 Multicellular Life Cells -> tissues -> organs -> organ systems -> organisms

Cell differentiation Process by which unspecialized cells develop into their mature forms/functions Almost each cell in your body has a full set of DNA but only uses specific genes needed to carry out its job

Examples of Differentiated cells Skin cells - help prevent infection and dehydration Bone cells- for a hard matrixes that support and protect organs Intestinal cells- have large surface area to increase absorption of nutrients

Stem Cells Divide and renew themselves Remain undifferentiated Develop into a variety of specialized cell types When it divides it either forms 2 stem cells or one stem cell and one specialized cell