Overview of Cells

• Prokaryotes vs Eukaryotes

• The Cell Organelles

• The Endosymbiotic Theory

• Archaea• Bacteria

Prokaryotic Cells

• Come in many different shapes and sizes .5 µm – 2 µm, up to 60 µm long

• Have large surface to volume ration – nutrients from outside can easily reach all parts of the cell

• Protists• Fungi• Animal Cells• Plant Cells

Eukaryotic Cells

• Like prokaryotic cells, eukaryotic cells come in many different shapes and sizes, but have the same basic set of organelles

• Multicellular organisms (fungi, plants and animals) have specialized eukaryotic cells that each perform a particular job and all work together for the benefit of the organism

Eukaryotic CellsCommon Organelles– Plasma membrane– Nucleus

Chromatin (DNA) Nucleolus Nuclear Envelope

– Ribosomes– Rough Endoplasmic

Reticulum (rough ER)– Smooth Endoplasmic

Reticulum (smooth ER)– Golgi Apparatus– Centrioles– Mitochondria– Cytoskeleton– Vesicles, Peroxisomes, Lysosomes, Small Vacuoles

Eukaryotic CellsOrganelles only found in Plants– All those in animal cells except

Centrioles– plus

Cell Wall Chloroplasts Large Vacuoles

– The cell wall and vacuoles help plant cells maintain a rigidshape (keep plant fromdrooping)

Organelles• Organelles are the parts within a cell that have specific functions• Prokaryotic cells (e.g. bacteria) are smaller and less complex

(fewer organelles) than eukaryotic cells.

Prokaryotic Cells– Plasma Membrane – Cytoplasm– Cell Wall– DNA (no nucleus)– Ribosomes

Eukaryotic Cells– Plasma Membrane– Cytoplasm– Nucleus

Chromatin (DNA) Nucleolus Nuclear Envelope

– Ribosomes– Vesicles, Peroxisomes, Lysosomes– Rough Endoplasmic Reticulum– Smooth Endoplasmic Reticulum– Golgi Apparatus– Centrioles– Mitochondria– Cytoskeleton

Plant Cells (eukaryotic)– Cell Wall– Chloroplasts– Vacuole

Polysaccharides

Organelles are made of:• Proteins – made of amino acids• Lipids – made of fatty acids• Carbohydrates - polysaccharides

made of sacharides (sugars)• Nucleic Acids (DNA and RNA)

– made of nucleotides

Nucleic Acids

LipidsProteins (Polypeptides)

Organelles

Components found in all cells

• Made of a Phospholipid Bilayer • Various proteins, lipids, and sugars float in membrane

• Semipermeable Small hydrophobic molecules pass easily through Contains pores that enable water and very small ions to pass through large molecules must pass through channel proteins

Plasma Membrane

Eukaryotic cells also membrane-bound internal organelles composed of lipid bilayer membranes

• Nuclear Envelope

• Golgi Apparatus

• Endoplasmic Reticulum (rough and smooth)

• Mitochondria

• Chloroplasts (in plants)

• Vesicles, Lysosomes, Peroxisomes & Vacuoles

Components found in all cellsPlasma Membrane

• The fluid that fills cells and surrounds the organelles• Consists of:

• Water (mostly)• Proteins (e.g. hormones and enzymes)• Small Molecules (e.g. ions)

Components found in all cellsCytoplasm

• Prokaryotic Cells• May be linear or circular• Contained in the nuclear region (nucleoid)• May also include short, circular plasmids

• Eukaryotic Cells • Longer (approx. 9 feet per cell in humans),

coiled around histone proteins to help pack it into the cell

• Always linear• Contained in the nucleus• Known as chromatin when relaxed and

chromosomes when condensed (supercoiled)

Components found in all cellsDNA

• Float freely in the cytoplasm of prokaryotic and eukaryotic cells

• Also coat the rough ER of eukaryotic cells

Components found in all cellsRibosomes

Components found in all cellsRibosomes• Build proteins using instructions encoded in DNA

• Build proteins using instructions encoded in DNA• Complex of protein and rRNA forming two subunits

Purple = ProteinsBlue = rRNA of small subunitGrey = rRNA of large subunit

Components found in all cellsRibosomes

• Nuclear Envelope double membrane nuclear pores allow RNA to exit

• Chromatin – “relaxed” DNA

• Nucleolus – where ribosomes are assembled

Nucleus

Components found only in Eukaryotic Cells