Inside the Cell

 Centriole  Chloroplast  Chromatin  Chromosome  Cilia  Cytoplasm  Endoplasmic reticulum  Eukaryote  Flagella  Golgi body  Lysosome  metabolism  Microfilament  Microtubule  Mitochondria  Nucleoli  Nucleus  Organ  Prokaryote  Ribosome  Symbiosis  System  Tissue  vacuole

 Cells are:  Three-dimensional  Shaped like spheres, cubes, or bricks.  One-celled (unicellular) organisms may be either prokaryotes or eukaryotes.  Bacteria are prokaryotes. Primitive cells (0:46)

 Many-celled organisms that evolved from unicellular organisms.  Almost all carry out basic functions.  Ex: Not all tree cells perform photosynthesis, only those with chlorophyll.  Specialized cells like blood cells are dependent upon one another. Parts of an animal cell (4:55)

 A group of cells that have the same structure and function is called a tissue.  Examples of cells that make up tissues include:  Skin cells (0:37) Skin cells (0:37)  Muscle cells (0:49) Muscle cells (0:49)  Bone cells (0:13) Bone cells (0:13)  Nerve cells (1:12) Nerve cells (1:12)  Blood cells (1:16) Blood cells (1:16) Cell Review (1:57)

 Cells work together to form tissues.  Tissues work together to form organs.  An organ is a structure composed of many different tissues that work together to perform a particular function.  Your heart is an example of an organ.  A group of organs working together form a system.  Systems working together form an organism Organs (1:01)

 Cytoplasm, found in the cell, is composed of 70% water, 30% proteins, fats, carbohydrates, nucleic acids, and ions.  The exact composition varies from cell to cell because of chemical changes.  The sum of all the chemical changes is called metabolism.  Cytoplasm has three main functions: energy, storage, and manufacturing. Cytoplasm (1:30)

 Almost all living cells contain organelles that are surrounded by a membrane.  There are two types of cells:  Eukaryote: Cells that contain a nucleus.  Example: Almost all cells in the living world.  Prokaryote: Cells without a membrane or nucleus.  Example: bacteria Comparing prokarytoic and eukaryotic cells (0:30)

 Nucleus Nucleus  Nucleolus Nucleolus  Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER)  Centriole Centriole  Centrosome Centrosome  Golgi Apparatus Golgi  C ytoskeleton ytoskeleton  Cytosol Cytosol  Mitochondrion Mitochondrion  Secretory Vesicle Secretory Vesicle  Lysosome Lysosome  Peroxisome Peroxisome  Vacuole Vacuole  Ribosome Click on picture for interactive cell models Includes animal, plant, bacteria and prokaryote cells courtesy: cellsalive.com

 The nucleus is the control center of the cell.  It has a double membrane with a dense mass of material called chromatin.  The chromatin is made up of individual chromosomes.  Chromosomes are made of proteins and DNA.  By coding for RNA, DNA controls the activities within the cell. Nucleus: Draw me!

 DNA stays in the nucleus but RNA can move from out of the nucleus into the cytoplasm.  Some RNA acts like a messenger for DNA. It delivers instructions for making proteins at the ribosomes.  Before a cell reproduces, it’s chromosomes are copied so that the new cell has the same genes.  Large molecules that pass in and out of the nucleus do so through pores in the membrane.  Smaller particles can go through the membrane itself or through membrane proteins.  Nucleoli are chromosome parts that are copies of the DNA that codes for the RNA present in ribosomes.

 Some plastids can be found in plants and algae. Some store lipids and starches and some have pigments (color).  The most common one is the chloroplast which contains chlorophyll and other pigments needed for photosynthesis. photosynthesis. Plant cell vs. animal cell (6:05)

 Lysosomes are vesicles formed by the Golgi body.  Lysosmes fuse with vesicles containing food and release enzymes to break the food down.  They also digest worn out cell parts.  The rest of the cell is protected from the enzymes by the lysosome’s membrane.

 Sometimes cells produce substances that they don’t need right away.  Vacuoles are fluid- filled, membrane-bound structures that store these substances for later use.  Many freshwater protists have contractile vacuoles used to remove excess water.

 Proteins in a cell manufacture long, thin structures that give shape and support to the cell.  Microfilaments are mad of actin and myosin (proteins) that assist in cell movement as well as structure.  Microtubules provide structures that can help certain organelles like mitochondria move through the cytoplasm. Actin and Microtubules (0:39)

 In cells of animals, some fungi and algae, two pairs of centrioles play a role in cell division.  Cilia and flagella are flexible projections that extend outward from the cell, while still surrounded by the cell membrane. They are used to move the cell around its environment.  They are also found in your lungs where the cells don’t move, but the cilia move mucus up and out of your lungs. Centrioles, Cilia and Flagella (0:40)

 Prokaryotes were the first cells. So where did eukaryotes come from?  Symbiotic Theory states that sometime during evolution, prokaryotic cells became symbiotic partners of other cells which led to eukaryotes.  Evidence for this is that mitochondria and chloroplasts ( which are not in the nucleus) contain their own DNA, RNA and ribosomes.  It’s thought that these organelles are what remains of once free-living prokaryotes.  Mitochondria: An Example of Evolutionary Symbiosis (02:34)