cells

Little Bit of Science History Hooke (1665) - used a primitive microscope observing cells for the first time and naming them “cells” Hooke’s drawing of cork cells Early compound microscope (2 lenses)

More History Van Leeuwenhoek - 1674 first to use a microscope to look at living cells in pond water and just about anywhere else even the plaque on his teeth! Spirogyra Vorticella

And Yet More History Schleiden and Schwann - 1839 Virchow - 1857 Schleiden stated that all plants are made up of cells. Schwann stated that all animals are made up of cells. Virchow - 1857 States that “every cell stems from another cell.”

All of that History Gave Rise to the Cell Theory All living things are made up of cells All cells come from preexisting cells Cells are the basic unit of structure and function in living things (take away the order of a cell and the organism will not survive)

Types of Cells Eukaryote Prokaryote

Prokaryotes ‘Before the Nucleus’ Archaebacteria and Eubacteria No nucleus, but all living things have DNA? Smallest type of cell (0.5-1.5 microns) No membrane bound organelles Unicellular / Simpler

Prokaryotes don’t have a nucleus ! DNA loosely organized close to the cell membrane

Prokaryotes don’t have organelles Organelle - specialized structures within a cell with a specific function, separated by a membrane. But they do have ribosomes, protein factories.

Eukaryotes True Nucleus Have a nucleus where DNA is protected away from the rest of the cell Have membrane-bound organelles Larger / more complex Found in plants, animals, fungi and protists Most multicellular but some uni- and others are colonial

Modern History The Endosymbiotic Theory Lynn Margulis Explanation as to how eukaryotic cells evolved. Margulis' original hypothesis proposed that aerobic bacteria (that require oxygen) were ingested by anaerobic bacteria (poisoned by oxygen), and may each have had a survival advantage as long as they continued their partnership.

Cell Parts and Functions Remember this?

Cell Membrane All cells have a cell membrane Boundary that allows selected materials to pass through Cell-to-cell recognition receptors made of glycoproteins Gatekeeper/Bouncer Phospholipid Bilayer

Cell Wall Found in plants, fungi, protists and bacteria Protective support for the organism Plants made up of CELLULOSE Porous allows H2O, CO2, and O2 through

Directs all cell activities Nucleus Directs all cell activities Contains and protects the DNA Includes: Nuclear Envelope Nuclear Pores Nucleolus Chromosomes/ Chromatin

Nuclear Envelope Lipid bilayer that protects the DNA from the cytoplasm Nuclear pores allow proteins and RNA to travel into the cytoplasm but prevent DNA from leaving Nuclear envelope is continuous with the endoplasmic reticulum

Nucleolus Made up of protein and RNA Site of ribosome synthesis Nucleus Made up of protein and RNA Site of ribosome synthesis

Cytoplasm (Cytosol) Jelly-like material that surrounds and encases the organelles Many chemical reactions occur in the cytoplasm Mostly made-up of water and enzymes

Plastids (plants only) Chloroplast Leucoplast Chromoplast Photosynthetic factory of the cell Storage of starch (polysaccharide) Contain pigments such as carotenoids Production of glucose using the energy of sunlight Cells of the potato are filled with leucoplasts Gives tomatoes their color

Ribosomes Mammalian cell can synthesize 20,000 ribosome subunits per minute Tiny protein factories, made in the nucleolus then moved into the cytoplasm or attached to the endoplasmic reticulum Made up of 2 subunits

Endoplasmic Reticulum 2 Types: Rough and Smooth Rough - ribosomes attached important in protein synthesis, packages new proteins and sends them to the Golgi apparatus Smooth - no ribosomes contains many enzymes that serve different functions; liver cells detoxifies drugs and breaks down glycogen, muscle cells involved in calcium release needed for muscle contraction

Mitochondria Powerhouse of the cell Site of cellular respiration Contain DNA can replicate independent of the cell Site of cellular respiration Convert chemical energy in food into usable cell energy (ATP)

Golgi Apparatus Flattened stack of pancakes Attaches carbohydrates Modifies, collects, packages and distributes molecules Attaches carbohydrates and lipids to proteins Flattened stack of pancakes

Lysosomes Primarily found in animal cells Small bubble-like Filled with enzymes necessary for digestion of unneeded cell parts Recycling center of the cell

Vacuoles / Vesicles Vesicles are small storage structures that can fuse with membranes to release materials Vacuole is very large, stores water and sugars for the plant

Cytoskeleton 2 Types: Microtubules Microfilaments Microtubules - hollow tubes, support, movement of organelles Framework made of proteins Microfilaments - long, thin fibers, support and movement of cytoplasm

Desmosomes Cell snaps - connect cells together and create cell junctions for materials to pass through

Centrosomes / Centrioles Centrosomes - area of the cell close to the nucleus where the centrioles are found Centrioles only found in animal cells, used to separate the chromosomes during cell division

Chromosomes DNA Tightly coiled chromatin (DNA when the cell is at rest) DNA takes the shape of a chromosome only during cell division