CELLS Chapter 7 CELL THEORY All living things

CELLS Chapter 7

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

MICROSCOPES Compound light microscope – allows light to pass through a specimen and uses two lenses to form an image �Magnifies to 1000 x �Stains or dyes are used to show specific features �Fluorescent dies are used to tag molecules produced by cells

MICROSCOPES Electron microscopes – use beams of electrons that are focused by magnetic fields – can be used to see objects one billionth of a meter Transmission electron microscopes – thin slices , electrons pass through the specimen 2 D image Scanning electron microscopes – a pencil-like beam is scanned over the surface – makes a 3 D image SEM images

PROKARYOTES AND EUKARYOTES All cells have a cell membrane - a thin flexible barrier surrounding the cell Not all cells have a nucleus – a large membraneenclosed structure that contains genetic material in the form of DNA and controls many of the cells activities Prokaryotes - do not have a nucleus Typically smaller and more simple Eukaryotes = have a nucleus Typically larger and more complex Can be unicellular or multicellular

7. 2 CELL STRUCTURE – EUKARYOTIC CELLS The cytoplasm is the fluid portion of the cell outside the nucleus. Many cellular structures act as if they are specialized organs. These structures are known as organelles, literally “little organs. ”

THE CELL AS A FACTORY The eukaryotic cell is much like a living version of a modern factory. The specialized machines and assembly lines of the factory can be compared to the different organelles of the cell. Cells, like factories, follow instructions and produce products.

THE NUCLEUS The nucleus = the control center of the cell � It contains most of the cell’s DNA, the instructions for making proteins and other important molecules Nuclear envelope = surrounds the nucleus � contains pores (holes) that allow material to go in and out of the nucleus Chromosomes – carry the cell’s genetic information (DNA) � Found in the nucleus Nucleolus – a small dense region in the nucleus � Ribosomes are assembled here

ORGANELLES THAT STORE, CLEAN UP, AND SUPPORT Vacuoles –large saclike structures with membranes Store water, salt, proteins, and carbohydrates In plants there is often 1 vacuole filled with liquid Also found in unicellular organisms and animals for storing and moving materials

ORGANELLES THAT STORE, CLEAN UP, AND SUPPORT Lysosomes – small organelles filled with enzymes Break down lipids (fats) , carbohydrates, and proteins Help break down “old” organelles - removes “junk” from the cell Found in animal cells and some plant cells

ORGANELLES THAT STORE, CLEAN UP, AND SUPPORT Cytoskeleton – a network of protein filaments that give cells shape and internal organization Helps maintain cell shape and involved in movement Microfilaments – form a framework that supports the cell and help them move Microtubules – hollow structures made of proteins called tubulins and are involved in maintaining cell shape and in cell division Also form cilia and flagella Centrioles – located near the nucleus and organize cell division in animals (made of tubulins)

ORGANELLES THAT BUILD PROTEIN Ribosomes – the “protein factory” - where proteins are assembled small particles of RNA and protein found throughout the cytoplasm in all cells. produce proteins by following coded instructions that come from DNA. Each ribosome is like a small machine in a factory, turning out proteins on orders that come from its DNA “boss. ”

ORGANELLES THAT BUILD PROTEIN Endoplasmic reticulum (ER) – an internal membrane system where lipids are assembled and proteins and other materials are exported from the cell. Rough endoplasmic reticulum (rough ER) – the ER where protein synthesis occurs ribosomes on its surface Proteins made in the rough ER can be exported out of the cell or transported to other locations in the cell Smooth endoplasmic reticulum (smooth ER) – the ER where no ribosomes are found Contains enzymes to do tasks like making membrane lipids or detoxification of drugs

ORGANELLES THAT BUILD PROTEIN Golgi Apparatus - modifies, sorts and packages proteins and other materials from the ER for storage in the cell or transport out of the cell. Looks like a stack of flattened membranes “Ships” proteins to their final destination

ORGANELLES THAT CAPTURE AND RELEASE ENERGY Chloroplasts – capture the energy from sunlight and convert it into food (photosynthesis) Found in plants and some other organisms “solar power plants”

ORGANELLES THAT CAPTURE AND RELEASE ENERGY Mitochondria – “The POWER HOUSE” convert the chemical energy stored in food into compounds easier for the cell to use In humans, you inherit most of your mitochondria from your mom Contain small DNA molecules which suggest they may have been descended from independent microorganisms.

CELLULAR BOUNDARIES Cell Wall – supports, shapes, and protects the cell Allow water, oxygen, carbon dioxide to pass through Found in prokaryotes and eukaryotes (NOT ANIMALS) Provides strength in plants (wood is made of mostly cell walls) Cell Membrane – controls what enters and leaves the cell and supports Made of a lipid bilayer (see the next slide)

CELLULAR BOUNDARIES The cell membrane is made of a double layered sheet with lipids and proteins The cell membrane is selectively permeable – some substances are allowed to pass and some are not.

PLANT VS ANIMAL CELLS PG 206

7. 3 CELL TRANSPORT Passive Transport = The movement of materials across the cell membrane without using cellular energy is called passive transport. Diffusion - The process by which particles move from an area of high concentration to an area of lower concentration

PASSIVE TRANSPORT CONT. Facilitated Diffusion – the process where molecules that cannot directly diffuse across the membrane pass through special protein channels Osmosis –the diffusion of water through a selectively permeable membrane Water moves across a membrane until equilibrium is reached

OSMOSIS Types of Solutions Isotonic = When the concentration is the same on both sides of the membrane Hypertonic = The more concentrated solution Hypotonic = The dilute solution Osmotic pressure = the net movement of water out of or into a cell exerts a force

ACTIVE TRANSPORT Active transport = the movement of materials against a concentration difference (requires energy

MOVEMENT OF LARGE MOLECULES

CHAPTER 9 –ENERGY AND EXERCISE (PG 265) Your body uses energy in the form of ATP Quick energy First few seconds (50 m of a race) – use ATP stored in cells Up to 90 seconds (200 -300 m) – lactic acid fermentation (make lactic acid – to get rid of it, you need oxygen = breathing hard) Long-term energy Over 90 seconds – cellular respiration glycogen (carbohydrate stores) are used up in 15 -20 minutes followed by other molecules including fats.

CHOOSE THE CORRECT ORGANELLE 1. 2. 3. 4. A. Nucleus B. Nuclear Membrane C. Nucleolus D. Golgi E. Smooth ER F. Rough ER

CHOOSE THE CORRECT LETTER 5. 9. 6. A. Vacuole B. Chloroplast C. Cytoplasm 7. D. Cell Wall 8. E. Cell Membrane F. Mitochondria 10.

MATCH THE STRUCTURE AND FUNCTION 11. Controls what enters and leaves the cell 12. Gives support to cells, found in plants 13. Contains genetic material in the form of DNA and controls many of the cells activities 14. Makes ribosomes 15. fluid portion of the cell outside the nucleus. 16. Controls what goes in and out of the nucleus A. Nucleus B. Nuclear Membrane C. Nucleolus D. Cytoplasm E. Cell Wall F. Cell Membrane

MATCH THE STRUCTURE AND FUNCTION 17. Storage 18. Breaks down “old junk” 19. “Protein factory” 20. Membrane that has ribosomes on it – makes proteins 21. Membrane that does not have ribosomes – makes lipids 22. modifies, sorts and packages proteins and other materials A. Ribosomes B. Smooth ER C. Rough ER D. Golgi Bodies E. Vacuole F. Lysosome

MATCH THE STRUCTURE TO THE FUNCTION 23. A cell with a nucleus 24. A cell without a nucleus 25. The “power house” 26. Structures in the nucleus made of DNA 27. Convert energy in sunlight to food A. Mitochondrion B. Chloroplast C. Chromosomes D. Prokaryote E. Eukaryote