• Hooke was the first person to see a cell under a microscope (1665). – He named the cork cells after the cells (rooms of his monastery).
The Cell Theory • All living things are made of cells. • Cells are the basic units of structure and function in living things. • New cells are produced from existing cells.
Types of Cells • All cells are surrounded by a membrane and carry biological information (DNA). • Cells are categorized based on whether or not they contain a nucleus. – (Nucleus [nuclei, pl]: a large membraneenclosed structure that contains the cells’ genetic material in the form of DNA.)
• Eukaryotes are cells that contain a nucleus. • Prokaryotes are cells that do not contain nuclei.
Eukaryotes • Karyon: greek – kernal or nucleus • Eu: greek – true • Where is genetic material contained? – In a membrane bound organelle (nucleus)
• Types of Organelles – Dozens of highly specialized structures and internal membranes
• Size – Many 2-1000µm in size
• How old – Evolved 1.5 billion years ago.
• Types of Organisms (examples) – Plants, animals, fungi, and protists
Prokaryotes • Karyon: greek – kernal or nucleus • Pro: greek – before • Where is genetic material contained? – Not in a nucleus
• Types of Organelles – None
• Size – Most 1-10µm in size
• How old – Evolved 3.5 billion years ago
• Types of Organisms (examples) – bacteria
Eukaryotic Cell Structure • Organelles: the specialized structures inside a cell. • Cytoplasm: the portion of the cell outside the nucleus. • Cell membrane: a lipid bilayer that surrounds all cells. • Cell wall: provides support and structure to plant, algae, fungi, and many prokaryotes. – Lies outside the cell membrane.
Nucleus
• The nucleus controls most cell processes and contains the hereditary information of DNA. • The nucleus is surrounded by a nuclear envelope that is composed of two membranes. – Proteins, RNA, and other molecules can move to and from the rest of the cell through nuclear pores.
• Chromatin is the material inside the nucleus. – It is DNA bound to proteins. – Chromatin condenses to form chromosomes during cell division.
• Nucleolus is where ribosomes begin to assemble.
Ribosomes • Ribosomes are small particles of RNA and protein found throughout the cytoplasm. • Proteins are assembled on ribosomes. • The nucleus gives coded instructions to the ribosomes, so they know what proteins to build.
Endoplasmic Reticulum (ER)
• An internal membrane system. • The ER assembles the lipids that go into building the cell membrane. • The ER also synthesizes proteins for export from the cell. • There are two types of ER. – Rough ER: has ribosomes on its surface. • Newly made proteins leave the ribosomes and the RER chemically modifies them.
– Smooth ER: doesn’t have ribosomes on its surface. • Enzymes on the SER synthesize membrane lipids and detoxify drugs. (Liver Cells have lots of SER.)
Golgi Apparatus • After proteins leave the RER, the Golgi apparatus modifies, sorts, and packages the proteins. • After the proteins are in the Golgi apparatus, they are ready to be – stored inside the cell – or secreted outside of the cell.
Lysosomes • Lysosomes are the cleanup crew of a cell. • Lysosomes are small, enzyme filled organelles. • They digest (breakdown) lipids, carbohydrates, and proteins that the rest of the cell can use. • They also break down organelles that are damaged or not used anylonger.
Vacuoles • A saclike structure that stores materials such as – Water – Salts – Proteins – Carbohydrates
• Plants have large central vacuoles filled with liquid. • Animals have smaller storage vacuoles.
Mitochondria • Mitochondria are organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use. • Mitochondria are made up of two membranes. • In humans, all of our mitochondria come from our moms. • Contain some DNA.
Chloroplast • Chloroplasts are organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis. • Chloroplasts are surrounded by two membranes. • Only plants and a few other organisms have chloroplasts. • Contain some DNA.
Cytoskeleton • A network of protein filaments that helps the cell to maintain its shape. • It also is involved in cellular movement.
