Cell Overview Cells are the basic unit of life. Cells are classified as prokaryotes or eukaryotes Cells Prokaryote Eukaryote

Prokaryotes Oldest cells – probably the first life on earth Very simple cells composed of 2 main parts Cell Membrane – the outer boundary of the cell Cytoplasm – jelly-like interior of the cell The name prokaryote comes from the Greek pros meaning “before” and karyon meaning “nut”, referring to the nucleus Most prokaryotes are single celled organisms Example: bacteria

Eukaryote More advanced cells Found in plants and animals Eukaryotic cells are composed of 4 main parts: Cell Membrane – the outer boundary of the cell Cytoplasm – jelly-like interior of the cell Nucleus – the control center of the cell which contains the cell’s genetic material (DNA) Organelles – structures that carry out cell functions Organisms can be single-celled or multicellular

Eukaryotes Plant cell Animal cell Examples: Single Celled – algae Multicellular - onion Examples: Single Celled: Amoeba, Protozoan Multicellular: Human

Eukaryotes Organelles – membrane-bound compartments within a cell Allow different internal environments within a single cell Allow many different chemical reactions to take place without disturbing each other Allow specialized functions Almost all Eukaryotic cells have the same basic set of organelles Some organelles are only found in plant cells, others are only found in animal cells

Cell (plasma) membrane Defines the boundary of the cell Regulates what comes in and goes out (selectively permeable) Composed of proteins and special lipids called phospholipids Outer side is hydrophilic Inner side is hydrophobic Molecules are fluid-like, not locked in place

Cytoplasm The entire region of the cell between the nucleus and the plasma membrane Consists of various organelles suspended in fluid Cytoskeleton is a network of fibers throughout the cytoplasm that give the cells shape

Nucleus Houses the cell’s DNA that directs all cellular activity DNA is attached to proteins in long fibers called chromatin Enclosed by a membrane (nuclear membrane) Contains nucleolus Nucleolus makes ribosomes

Chromatin & Chromosomes Most of the time, the DNA exists as a mass of very long, thin fibers called chromatin The instructions in the chromatin can be “read” so that the cell can produce proteins. When the cell is getting ready to divide, the chromatin condenses into compact chromosomes. Chromosomes are easier to move, but the instructions can’t be “read” to make proteins.

Ribosomes Ribosomes onstruct proteins Use instructions in the DNA to build proteins Ribosomes are found on the Endoplasmic Reticulum Make proteins for membranes and export outside the cell Ribosomes are also found suspended in the cytoplasm Make enzymes and proteins for use inside the cell

Endoplasmic Reticulum A network of membranes in the cytoplasm. Two types: rough ER and smooth ER Synthesize proteins (rough ER) Proteins can be secreted by the cell, or packaged and sent out of the cell to other cells Synthesize lipids (smooth ER) Example: hormones

Golgi Bodies Takes products from the ER and modifies, stores, and routes to next destination Enzymes in the golgi bodies refine and modify the ER products Example: fold proteins into their final shape

Lysosomes Contain digestive enzymes that can break down macromolecules such as proteins, nucleic acids, and polysaccarides Digest food to nourish the cell Help destroy harmful bacteria Recycle damaged organelles to make molecules available for construction of new ones.

Chloroplasts Photosynthetic organelles found in some plants and algae Convert light energy from the sun to the chemical energy stored in sugars and other organic compounds

Mitochondria Powerhouse of the cell Site of cellular respiration Releases energy from sugars and other organic molecules into an energy source the cell can use The energy that a cell uses is called ATP. We will learn about it in the next chapter.

Vacuoles Large membrane- bound sacs Store undigested nutrients or chemicals Many plants have a large central vacuole Vacuoles in flower petals may contain pigments

Cell Wall Protects the plant cell and maintains its shape Located outside the plasma membrane only plant cells and prokaryotes have cell walls Animal cells do not Made of cellulose

Cytoskeleton A network of fibers extending throughout the cytoplasm Microtubules – straight tubes of protein that give rigidity and shape to the cell. Organelles can move along microtubules Microfilaments – thin solid rods of protein that slide past each other to enable the cell to change shape Looks like an oozing movement (ex. Amoeba or white blood cells)

Centrioles Pair of tubular structures Important in cell division of animal cells and protists

Cilia & Flagella Flagella are long, thin, whip-like structures that enable some cells to move Wave in an S-shaped motion that propels the cell Cilia are short, hair-like structures that surround a cell Have a back and forth motion that moves the cell Can also be found on stationary cells in a multicellular organism Example: the cells lining your windpipe have cilia that move mucus out of your lungs

Multicellular Organisms Each organelle performs basically the same functions in all cell types Organelles vary in amount and properties by cell type. Allows cells to perform specialized functions All cells carry on the basic activities of life In a multicellular organism, each cell type also takes on specialized functions A group of cells with the same specialization works together to perform a function Tissues, organs, systems

R&C #1 p. 277 Explain why it is important for all cells to have a cell membrane. Why might it be beneficial?

#2 a. Prokaryotes Vs. Eukaryotes

#2 b. Plant Cells vs. Animal Cells

R&C #4 p. 277 What differences are likely to exist between single- celled organisms and the cell of a multicellular organism?

R&C #5 p. 277 Build a concept map using the following words: atoms, carbohydrates, cells, elements, lipids, nucleic acids, organic molecules, and organism.