Transcript The Tiny Living World Around Us

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!
What is a cell?
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
Different Types of Cells
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”
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
Mitochondrion
• Stores and releases energy in the form of ATP (adenosine
triphosphate)
• Has its own genetic material plus special enzymes and proteins
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
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
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)
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
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
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
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
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
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
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
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!
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
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
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
Question Period 