The Cell Theory The theory has three main parts summarized as: All living things are made up of one or more cells The cell is the functional unit of life All living cells come from pre-existing cells
The cell as a factory: The parts of a cell can be compared to the workers and jobs in a factory Each department in a factory has specific jobs that need to be done or else the factory becomes less efficient and eventually shut down. The same idea is true for the cell, if one of its components stops working efficiently then the cell or the organism could die.
Cell Membrane: The “gate keeper” or “bouncer” of the cell Decides which materials enter, which ones stay and which ones leave a cell. Keeps the good ones in and bad ones out. Every cell has a cellular membrane (including both animal and plant cells). It is a thin flexible covering surrounding all cells. Made up of primarily proteins and fats
Nucleus The “Boss” With few exceptions all plant and animal cells possess a nucleus (plural form is nuclei). Dark mass usually seen in the middle of the cell contain the DNA or genes for the cell which are the instructions for all the activities of the cell
Nuclear Envelope The membrane that encloses the contents of the nucleus. “the Boss’ office” It has pores in it for larger materials to pass in and out.
Nucleolus A visible darker staining region inside the nucleus. nucleolus It is where RNA and ribosomes are made.
Cytoplasm The rest of the cell material that is inside the cell membrane but outside the nucleus Organelles and vacuoles are considered part of the cytoplasm
Cell Organelles Like your body which has organs to perform the necessary functions for life, similarly cells have organelles which perform the necessary function of particular cells. Many organelles are bound by their own membrane The proportion of the different organelles inside a particular cell depends on the function of the cell. For example a cell that produces a lot of hormones will have a large amount of golgi apparatus which is the organelle responsible for packaging the products of a cell.
Ribosomes The “workers” that put together the products of the cell. The location of protein synthesis Made from RNA from the nucleolus Some are free in the cytoplasm and others are embedded in the endoplasmic reticulum (ER). The proteins produced by free ribosomes in cytoplasm are generally used within the cell
Endoplasmic Reticulum The “assembly line” for 1) Rough endoplasmic reticulum the products of the cell It consists of membranous channels that wind through the cytoplasm There are two types of 2) Smooth endoplasmic reticulum endoplasmic reticulum:
Rough Endoplasmic Reticulum: AKA “rough ER” The ER that has ribosomes embedded in it. Manufactures proteins for other cells and also phospholipids for the cell membrane Assists in the movement of molecules towards the cell membrane
Smooth Endoplasmic Reticulum Aka : Smooth ER Lack ribosomes Manufactures steroids Example: testicle cells which produce testosterone have abundant amounts of smooth ER.
Golgi ApparatusMay looks similar to smooth ER, but it is a set of about 7 or 8 flattened saccules between ER and the cell membrane “Packages, processes and labels” the products from the ER Makes concentrated packages of proteins Puts carbohydrate chains (labels) on the packages of proteins so that specific cells recognize them once they are released in the blood.
Vesicle “storage containers” Double membrane bound sacs carrying different products and substances from one part of the cell to another. Also carry food, waste products, digestive enzymes.
Lysosomes “Janitors or quality control” Vesicle-like structures that contain enzymes used for digestion of molecules in the cells. Example: to digest unwanted cells (dying cells) and cell parts that are defective Think of them as the quality control or health board, that can shut down the cell at any time.
Mitochondrion Plural form “mitochondria” “The Generator” or “power house” of the cell Give the cell the energy it needs by a series of chemical reactions called cellular respiration Fluid filled, with a complex internal membrane The inner fluid is called the matrix The inner membrane which folded in the matrix is called the cristae.
Vacuole “Storage Containers” Vacuoles serve a variety of functions, including storing nutrients, wastes and water. Irregular shape They are usually much larger in plant cells than in animal cells. Example: in the plant cell they take up almost the entire cell.
Centriol “Traffic Cop” Organizes organelles and chromosomes during cell reproduction
Plant cells vs Animal cells There are some structures that plant cells possess that animal cells do not. Including: Cell wall Chloroplasts Also, plant cells have larger vacuoles (that sometimes appear to take up the entire cell). Plant cell do not have a centriol!
Cell Wall The cell wall provides and maintains the shape of these cells and serves as a protective barrier. Has large pores that allow many molecules to enter.
Chloroplasts Chloroplasts are specialized organelles found in all higher plant cells. These organelles contain the plant cells chlorophyll, hence provide the green color. The place where photosynthesis takes place. They have a double outer membrane. Within the stroma are other membrane structures - including the thylakoids and grana where photosynthesis takes place.
Vacuoles in Plant cells Help the cell wall keep its shape Stand up, close eyes Pretend you are a plant that has not been watered for a week…what would you look like Now your mother waters the plant…what does it look like now.