SPLASH class by Natalie Hollister

1. The Tiny Living World Around Us SPLASH class by Natalie Hollister

2. For Starters • My name is Natalie  • Please feel free to ask questions • Let me know if I go too quickly or too slowly • Have fun!

3. What is a cell?

4. Think of cells as living bricks • Bricks are the basic unit that some buildings are made of, cells are the basic unit that living things are made of • A house (organism) gets bigger when more bricks (cells) are added to it • When a brick breaks (or a cell dies) it has to be replaced with a new brick (cell) • Young humans grow because the number of cells being made surpasses the number of cells dying

5. Different Types of Cells

6. Cells have organs just like human bodies do! • Except in cells we call them organelles • Nucleus, Golgi apparatus (Golgi body), smooth/rough endoplasmic reticulum, ribosomes, lysosomes, mitochondria, cell membrane, chloroplast in plant cells, and others • A cell is eukaryotic if it has a nucleus (plant and animal cells) • A cell is prokaryotic if it does not have a nucleus (bacterial cells) • Red blood cells in our bodies are the weird ones – they have no nucleus even though they are considered “animal cells”

7. Nucleus • Like the “brain” of our cells • Tells the cells when to divide and tells the organelles what to do • Contains a nucleolus and is wrapped in nuclear envelope • Contains the genetic material that makes complex life possible

8. Mitochondrion • Stores and releases energy in the form of ATP (adenosine triphosphate) • Has its own genetic material plus special enzymes and proteins

9. Endoplasmic Reticulum (smooth and rough) • Rough endoplasmic reticulum (sometimes abbreviated ER) has ribosomes and is responsible for protein synthesis • Smooth ER has no ribosomes and instead performs lipid/carbohydrate synthesis and buds off vesicles carrying proteins

10. Golgi Apparatus (or Golgi Body) • Golgi body is like a UPS center • It packs different carbohydrates, proteins, and lipids into containers called vesicles to be shipped to other parts of the cell • Named after its discoverer, Camillo Golgi

11. Cells communicate using genetic material • DNA – deoxyribonucleic acid • RNA – ribonucleic acid • In complex organisms, DNA is the genetic material that holds literally everything about us • Simple organisms just use RNA • Not all cell organelles know how to use DNA, so DNA  RNA  proteins in certain parts of a cell (transcription then translation)

12. More on DNA • Shape is called a double helix • Chemically, a deoxyribose sugar is bound to a phosphate group and a nitrogenous base (adenine, thymine, cytosine, or guanine) • Together the sugar, phosphate, and base make a nucleotide • When a bunch of DNA is put together it makes a chromosome

13. Cells divide to make new cells • Unless a cell is a reproductive cell (egg or sperm) it will divide into two identical cells • Division process is called mitosis • It happens in four phases…more on next slide • When an egg or sperm divides, it uses a process called meiosis • Resulting cells are not identical

15. How can we look at cells? • Most cells can be seen with microscopes • Basic microscopes have magnifying lenses that can let us see microscopic cells/organisms • Really powerful microscopes let us see the small details of cells • Special microscopes or microscope slides can let us see things while they are still alive

16. Some cells are bad for certain organisms • Tiny organisms (called microorganisms or microbes) live inside our bodies and interact with our cells all the time • The good microbes are called normal flora • Some microbes make us sick and those are called pathogens • We categorize pathogens into three main areas: viruses, bacteria, and parasites

17. Viruses – a subject of much debate • Viruses are not technically living things • They can’t reproduce on their own (criteria of life is reproducibility) • They attack “host cells” and inject their RNA into them, then they can reproduce inside the host cells • They are sub-microscopic (harder to fight with medicine) • Cold, flu, HIV, and right now Ebola

18. Bacteria • Actual living things that are not sub-microscopic • They reproduce on their own and crowd out/kill our own cells when they are inside us • We fight them with antibiotics • Note: antibiotics cannot kill viruses – only bacteria and some parasites • There are also things called probiotics that help good bacteria live in our bodies (mostly in our digestive systems) • Strep throat, pink eye, some forms of meningitis

19. Parasites • Typically multicellular organisms that attack a host • Often reproduce inside their host but on their own (unlike virus) • Some are single-celled organisms like amoebas • Some form protective coating called a cyst • Ticks, fleas, maggots, worms, amoebas, and plenty of others

20. How our bodies fight pathogens • White blood cells are the soldiers of our body • When there is a pathogen they are alerted and they go to directly take on the enemy and solve the problem • Some medicine can help the white blood cells if the pathogen is very strong and the white blood cells can’t fight it alone • Skin is actually the first line of defense – wash those hands!

21. Different types of white blood cells • Neutrophils – eat bacteria • Eosinophils – allergies and attacking multicellular parasites • Basophils – also allergies • Dendritic cells – marks pathogens with antibodies • Macrophages – big, tough cells that eat other big, tough cells • Lymphocytes – regulate the immune system

22. What your “blood type” means • Antibodies mark pathogens once they are discovered in the body so the immune system can find and destroy them • We are born with or without certain sets of antibodies (A and B) • If you have type O, you have neither A or B antibodies • The plus or minus means you have/don’t have a certain protein • No blood type is better or worse than any of the others – we mostly care about it because of blood transfusions

23. The good and bad of medicine • Medicines, especially antibiotics, are good and help fight pathogens • Pathogens can mutate as a species over time though and become immune to medications if they are used too often • These immune pathogens are called “superbugs” and are very hard to kill (the most famous one is called MRSA) • Pathogens are becoming resistant faster than we can develop new medications, so avoiding overmedication is important

24. Question Period 