Cells

Types of Cells prokaryotes no organelles bacteria cells eukaryotes organelles animal cells plant cells also fungus & protist cells

Cell size comparison Most bacteria 1-10 microns Eukaryotic cells microns Bacterial cell Animal cell  micron = micrometer = 1/1,000,000 meter  diameter of human hair = ~20 microns

Why study cells? Cells Bodies are made of cells Cells do all the work for life  Tissues  Organs  Bodies

The work for life STERNGRR Synthesis: build molecules (carbs, lipids, proteins, nucleic acids) Transport: move materials in/out & within the cell Excretion: remove wastes Respiration: gas exchange; make energy Nutrition: take in & digest food Grow & repair Regulation: control internal conditions (homeostasis) Reproduction: make more cells Respond to external environment ATP

The main jobs of cells Cells have 3 main jobs: Make energy Need energy for all activities Need to clean up waste produced by energy production Make proteins Proteins do all the work in the cell, so we need lots of them Make more cells For growth For repair (replace damaged or diseased cells) ATP Our organelles do All of these jobs?! AWESOME!!

Parts of the Cell Theory All living things are made of one or more cells Cells are the basic unit of structure & function in organisms Cells come only from the reproduction of pre- existing cells

Cell Scientists Robert Hooke looked at cork under a microscope 1 st to use term “cell”

Cell Scientists Anton van Leeuwenhoek looked at pond water 1 st to see living cells called them “animalcules”

Cell Scientists Schleiden, Schwann, & Virchow came up with the cell theory

Cell Scientists Schleiden 1838 claimed plants are made of “independent, separate beings” called cells

Cell Scientists Schwann 1839 claimed animals are also made of cells

Cell Scientists Virchow 1855 stated that living cells must come from other living cells

Cell Scientists Louis Pasteur 1860’s disproved spontaneous generation

The Cell Theory

Prokaryotic vs Eukaryotic Cells

Prokaryotic Cells Appeared 3.5 billion years ago Primitive, simple Small in size (less than 10 µm) No membrane-bound organelles DNA in cytosol (nucleoid region) Single, circular chromosome “Naked” DNA Smaller ribosomes (70S) BACTERIA

Eukaryotic Cells Appeared 1.5 billion years ago Complex More than 10 µm in size Contain membrane- bound organelles Larger ribosomes (80S) Paired, linear chromosomes DNA wrapped around histones (proteins) NUCLEUS

Let’s draw a prokaryotic cell and label it ….

Prokaryotic reproduction Asexual = binary fission Produces two identical daughter cells DNA Copies Cytokinesis Clones!

Prokaryotic reproduction Sexual = conjugation Uses conjugation pili to exchange plasmids

Parts of a Eukaryotic Cell

Plasma Membrane Also called the Cell Membrane Separates cell from its environment

Plasma Membrane Semi- permeable Allows only certain molecules to enter or exit

Plasma Membrane Phospholipid Bilayer Embedded with proteins Cholesterol is embedded in bilayer to help membrane fluidity

Nucleus “Boss” or “Brain” of the cell Controls cellular activities Contains DNA (chromosomes)

Nucleus Nuclear Membrane Surrounds nucleus Double membrane Contains nuclear pores (holes)

Nucleus Nucleolus Produces ribosomes Ribosomes leave through nuclear pores

Cytoplasm Cytosol Fluid portion Organelles Membrane-bound compartments that carry out specific functions

Mitochondria Breaks down glucose to CREATE ENERGY (ATP) Active cells (muscle) -> hundreds of mitochondria Inactive cells (fat) -> few mitochondria Have own DNA & ribosomes Have a double membrane

Ribosomes Create proteins Composed of 2 interlocking subunits Some float free in cytosol Some attach to the ER small subunit large subunit ribosome

Endoplasmic Reticulum (ER) Intracellular highway 2 Types Rough ER Smooth ER

Endoplasmic Reticulum (ER) Rough ER Covered in ribosomes Transport and develop proteins may be used in membranes, enzymes, and cell communication

Endoplasmic Reticulum (ER) cytoplasm cisternal space mRNA ribosome membrane of endoplasmic reticulum polypeptide signal sequence ribosome Synthesizing proteins

Endoplasmic Reticulum (ER) Smooth ER Lacks ribosomes Produces lipids, estrogen, & testosterone Helps detoxify drugs & poisons Increased use = increased smooth ER Possibly linked to increased tolerance

Endoplasmic Reticulum (ER)

Transport (FedEx/UPS of the cell) Collects, packages, modifies, and distributes materials made in the cell Prevalent in cells that secrete substances Golgi Apparatus

Lysosomes Contain digestive enzymes Digest organic molecules, worn organelles, or dying cells Vesicles lysosomes nucleus

Vesicle transport vesicle budding from rough ER fusion of vesicle with Golgi apparatus migrating transport vesicle protein ribosome

Central vacuole Large, fluid-filled organelle Stores water, ions, enzymes & waste Can be up to 90% of cell’s volume Why so big in plants? Vacuoles – Plant cells

Food vacuoles Store and process food Contractile vacuoles Removes excess water from cell Prevents cell from exploding Vacuoles – Animal cells

Working together … vesicle ER vesicle Golgi complex vesicle vacuole

Centrosome Assembles microtubules May contain centrioles Used during cell division Centrosome

Cilia Hair-like Short & numerous Flagella Tail-like Long & less numerous Cilia/Flagella

Plant Cell versus Animal Cell

Cytoskeleton Network of microtubules & filaments Gives the cell shape Holds organelles in place Animal Cells Only!

Cell Wall Rigid layer surrounding plasma membrane Made of cellulose Pores allow water, ions, & other molecules to pass Bacteria (peptidoglycan), some protists & fungi (chitin) also have cell walls Plant Cells Only!

Chloroplast Contain chlorophyll Site of photosynthesis Energy (sunlight)  food Contain own DNA & ribosomes Have a double membrane Plant Cells Only!

Any Questions??