1.3 Cell Structures

1. 1.3 Cell Structures Essential tasks of the cell All living cells must: • Obtain food + energy • Convert energy from an external source to a usable form • Build + maintain mculs that make up cell structures • Carry out chemical reactions • Eliminate wastes • Reproduce • Keep records of how to build structures

2. Two Basic Cell Types • Prokaryotic Cells Eukaryotic Cells • No nucleus; nucleoid Nucleus • Smaller Larger • Simple internal structure More complex internal structure • No membrane-bound Membrane bound Organelles organelles Ex. Bacteria Ex. Plants, animal, fungi

3. Cell Structures • All cells have: • Cell membrane • Cytoplasm • Cytoskeleton Eukaryotic cells have nucleus and other organelles!

4. The Cell Membrane http://www.cellsalive.com/cells/membrane.htm http://en.wikipedia.org/wiki/Cell_membrane McGraw-Hill Ryerson Biology 11 The Cell Membrane : • Is composed of lipids (molecules that store energy) and proteins. • Is the outermost covering of animal cells, which gives the cells • their definite shape. • Is a semi-permeable barrier which allows only certain molecules • to pass through. • Contains proteins that act as pumps, enzymes, etc. • Has the ability to connect one cell to an adjacent cell.

5. The Cell Membrane pt. 2 The “Gatekeeper”’s Function: The cell membrane surrounds the protoplasm of a cell and separates the content of the cell from the outside environment. It provides the shape of the cell and attaches certain cells together to form tissues. The cell membrane determines what enters and exits the cell based on what the cell needs to survive. The membrane surrounds the entire cell which allows nothing to get into the cell without passing through the membrane first. The cell membrane was discovered by Karl Wilhelm von Nageli in 1855

11. Chromosomes • Description: -an organized structure of DNA and protein that is found in cells. -The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000[1] nucleotides in a long chain • Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. • Function: • Chromosomes function is to control all the activities of a living cell. Chromosomes are essential for the process of cell division and are responsible for the replication, division and creation of daughter cells, that contain correct sequences of DNA and proteins. • Structure: • A molecule of DNA is a very long, coiled structure that contains many identifiable subunits known as genes. • In prokaryotes, or cells without a nucleus, the chromosome is merely a circle of DNA. In eukaryotes, or cells with a distinct nucleus, chromosomes are much more complex in structure.Facts: • Chromosomes were discovered in 1842 by Karl Wilhelm von Ngeil. http://en.wikipedia.org/wiki/Chromosome

12. Chromatin • Description • is the combination of DNA and other proteins that make up chromosomes. • chromatin is organized in seven progressive levels of organizational complexity, which coils the DNA into more and more compact forms through combination of proteins. • It is found inside the nuclear envelope of eukaryotic cells. • Function • The functions of chromatin are to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis, and to control gene expression and DNA replication. • Structure • The structure of chromatin is determined and stabilized through the interaction of the DNA with DNA-binding proteins. • Facts • Chromatin was discovered by Walter Flemming in 1879. http://en.wikipedia.org/wiki/Chromatin

16. Membrane Bound Organelles • Mitachondrion • Endoplasmic reticulum • Peroxisome • Lysosome • Golgi apparatus • Vacuole • Vesicle Non-membrane bound organelles: ribosome cilia flagella

17. General Information The mitochondrion of a cell works like a power plant. It produces adenosine triphosphate (ATP) which the cell uses for energy. It works a bit like our brain's pituitary gland, as it controls cell growth, and cell death. Depending on the organism and type of cell, there can be various amounts of mitochondria. Mitochondria also contain DNA.(deoxyribonucleic acid)

18. Cutaway Diagram of a Mitochondrion The outer membrane acts as the “skin” of the organelle, with the inner membrane acting as a second layer of “skin.” The matrix is the space inside the inner membrane. Cristae is the space formed by the infoldings of the inner membrane. There is intermembrane space between the outer and inner membranes.

19. Summary = The mitochondria of a cell keep it going. Without mitochondria, cells would not live. Mitochondria are complicated, essential organelles.

20. Endoplasmic Reticulum (ER) There are two types: Rough and Smooth. They are named so because one type has ribosomes attached to it (Rough) and the other does not (Smooth). Both made of a series of membranes, the Rough ER looks like many flattened cavities surrounding the nucleus of a cell, and the Smooth ER appears to be many small tubes. The Smooth is outside of the Rough. The interior of the ER is called the lumen. The Rough ER has a variety of jobs, often depending on what type of cell it is in. It creates membranes and secretory proteins. It is what aids in the creation of insulin in the pancreatic cells, and antibodies in leukocytes. The Smooth ER creates lipids and metabolizes carbohydrates. It receives proteins from the ER and moves them to other places. In liver cells, it makes enzymes that helps remove toxins. In the brain it synthesizes hormones. The shape and placement of the ER allows transportation of membranes and such to be easier because it is in the middle of the cell and has a large surface area. The Endoplasmic Reticulum is essentially a shipping department, because it ‘packages’ and transports important proteins. http://biology.about.com/library/weekly/aa041300a.htm

21. Peroxisomes Characteristics: -Spherical shape, surrounded by lipids and proteins, lipid plasma bilayer membrane, and crystalline core. Functions: -Peroxisomes help get rid of toxins within the cell. – - In plants they also assist in the process of Photosynthesis. Peroxisomes also are a big part of the cell metabolism process. They also help with breaking down fats and fatty acids. The Peroxisomes also help with the breakdown of alcohols in the cell, much like a small version of the liver but for a cell. . • Sources: • http://en.academic.ru/pictures/enwiki/80/Peroxisome.jpg • http://www.wisegeek.com.what-is-a-peroxisome.htm • http://micro.magnet.fsu.edu/cells/peroxisomes/images/peroxisomesfigure1.jpg

22. Peroxisomes • The structure also helps with the metabolism process in the way that it can easily take in lipids and proteins and start the breakdown into energy that the sell uses • Extra Info: • -Peroxisomes have the ability to break into another peroxisome if the cell needs another, much like DNA Structure Functions: The structure of the Peroxisomes give them the ability to breakdown toxins and convert them into by products like hydrogen peroxide or just oxygen and water. .

23. The vacuole is a storage bubble found in cells. It is a space within a cell that is empty of cytoplasm, lined with a membrane, and filled with fluid.Plant vacuoles serve as a “cellular trashbag” for all sorts of compounds and ions (such as salt, mineral nutrients, heavy metals and organic compounds) that would be toxic if they were in the cytoplasm. Plant vacuoles accumulate enough dissolved compounds to give the plant and cell a low enough osmotic potential to absorb water through osmosis. In conjunction with the cell wall, the vacuole functions to provide turgor for plant cells. The vacuole can also store protein or carbohydrates.

24. The vacuole stores food or any variety of nutrients a cell might need to survive, and stores waste products so the rest of the cell is protected from contamination. It is responsible for maintaining the shape and structure of the cell. The vacuole also performs functions such as storage, ingestion, digestion, excretion, and expulsion of excess water.The vacuole is formed by the fusion of multiple membrane vesicles and are effectively formed larger forms of these. This organelle has no basic shape or size. Its structure varies according to the needs of the cell. The vacuoles nickname is “the control center”. It was found between the late 1600’s/early 1700’s, by Anton van Leeuwenhoek.

25. Ribosome

26. Description Ribosome's are made from complexes of RNAs and proteins. It is divided into two subunits. One subunit is larger than the other.

27. Function The ribosome makes proteins from all amino acids. The ribosome reads the information in the RNA and uses it to create proteins. This process is known as translation. The smaller subunit binds to the mRNA while the larger subunit binds to the tRNA and the amino acids. The ribosome finishes reading a mRNA and then the two subunits split apart.

28. Facts The ribosomes nickname is Protein Factories. Ribosomes were observed in the 1950’s by George Palade. The term "ribosome" was proposed in 1958 by Richard B. Roberts.

30. Cilia and Flagella Cilia Flagella • Hair like features used to push cell or particles located on the outside of cell • Many hair like structures beat to move the cell • Cilia means ‘eyelash’ in Latin • A tail like projection from the outside of a cell used for movement • Tail whips back and forth to push cell forward i.e. Sperm cells

31. Cilia and Flagella http://www.dnatube.com/video/363/Cilia-and-Flagella Website Information - http://www.dnatube.com/video/363/Cilia-and-Flagella

32. Structures Unique to …. Animal cells: • Centrioles Plant cells: • Cell wall • Plastids (chloroplast, amyloplast, chromoplast) • Crystals

34. Chloroplasts The chloroplast is surrounded by a double-layered composite membrane with an intermembrane space; further, it has reticulations, or many infoldings, filling the inner spaces. The chloroplast has its own DNA, which codes for redox proteins involved in electron transport in photosynthesis; this is termed the plastome. Chloroplast is one of the groups of organelles in plant cells called plastids. This gives green plants their color and transfers the energy in sunlight into stored energy in carbohydrates during photosynthesis. Chloroplast was first suggested by Mereschkowsky in 1905 after an observation by Schimper in 1883 that chloroplasts closely resemble cyanobacteria. URL: http://en.m.wikipedia.org/wiki/Chromoplast?wasRedirected=true  URL: http://en.m.wikipedia.org/wiki/Chloroplast?wasRedirected=true

35. Amyloplast They are responsible for the synthesis and storage of starch granules, through the polymerization of glucose. Amyloplasts also convert this starch back into sugar when the plant needs energy. Amyloplasts are non-pigmented organelles found in some plant cells. Large numbers of amyloplasts can be found in fruit and in underground storage tissues of some plants, such as in potato tubers. URL: http://en.m.wikipedia.org/wiki/Amyloplast?wasRedirected=true

36. Chromophlast Chromoplasts in the traditional sense are found in coloured organs of plants such as fruit and floral petals, to which they give their distinctive colors. This is always associated with a massive increase in the accumulation of carotenoid pigments. The conversion of chloroplasts to chromoplasts in ripening is a classic example. Chromoplasts are plastids responsible for pigment synthesis and storage. They, like all other plastids (including chloroplasts and leucoplasts), are organelles found in specific photosynthetic eukaryotic species. The term "chromoplast" is occasionally utilized to include any plastid that has pigment, mostly to emphasize the contrast with the various types of leucoplasts, which are those plastids that have no pigments. In this sense, chloroplasts are a specific type of chromoplast. Still, "chromoplast" is more often used to denote those plastids with pigments other than chlorophyll. URL: http://en.m.wikipedia.org/wiki/Chromoplast?wasRedirected=true

37. Cell Wall • Identifying Characteristics of the Cell Wall • - Tough, flexible but sometimes fairly rigid layer that surrounds some types of cells. • - Located outside the Cell Membrane. • - Provides structural support and protection. • - Acts as a filtering mechanism. • How the structure relates to the function • The structure of the Cell Wall relates to the function because the structure of the Cell Wall is rigid and tough to offer protection against any stress that may be present. The structure and the function also relate because the Cell Wall limits the entry of any toxic molecules. • The structure of the Cell Wall is the function, it serves as a wall.

38. Cell Wall’s Function • Determining Cell Shape • - the shape of a plant is determined by the cell wall, the cell wall is like a skeleton acting as the main supporting structure of a cell. • Strength • - provides strength to the cell, since the cell wall is also flexible • Controlling Turgor Pressure • - an important function of a cell is to maintain Turgor Pressure, Turgor Pressure is the pressure applied by the cell constituents on the cell wall. • Passage of Substances • - the cell wall allows the movement of small molecules like protein to go in and out. But limits the large more toxic molecules it will allow in. • Protection • - the cell wall is the first line of defense against attacks.