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Cell Structure and Function

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Presentation on theme: "Cell Structure and Function"— Presentation transcript:

1 Cell Structure and Function
Chapter 7 Biology Miller • Levine

2 The Scientists… Robert Hooke (1665) Anton van Leeuwenhoek (1674)
Viewed cork under a microscope Called the chambers he saw “cells” Anton van Leeuwenhoek (1674) First to see living organisms in a drop of water

3 The Scientists… Matthias Schleiden (1838) Theodor Schwann (1839)
All plants are made of cells Theodor Schwann (1839) All animals are made of cells Rudolf Virchow (1855) All cells come from preexisting cells

4 The Cell Theory All living things are composed of cells
Cells are the basic units of structure and function in living things New cells are produced from existing cells

5 Unicellular vs. Multicellular
Unicellular – single-celled organism Multicellular – many-celled organism Cell specialization – cells are specialized to perform certain functions Cells → Tissues → Organs → Organ systems → Organism

6 Prokaryotes vs. Eukaryotes
Have a cell membrane & cytoplasm, but do not have a nucleus Ex. Bacteria such as E.coli Eukaryotes Have a nucleus, cell membrane, cytoplasm & organelles Ex. Plants, Animals, Fungi

7 Prokaryotes vs. Eukaryotes

8 Basic Cell Structures Cell membrane – thin, flexible barrier around the cell; protects the cell Present in all cells Selectively permeable Contains floating layers SS

9 The Fluid Mosaic Model Hydrophobic vs. Hydrophilic Hydro = water
Phobic = fear/hate Philic = love

10 material inside the cell membrane (not including the nucleus)
Cytoplasm – material inside the cell membrane (not including the nucleus) Prokaryotes & Eukaryotes

11 Cell Wall Found in many organisms, including plants, algae, fungi and nearly all prokaryotes Not found in animal cells Lies outside the cell membrane but is porous Main function is to provide support & protection for the cell

12 Nucleus Almost all eukaryotic cells, including plants and animals have a nucleus Prokaryotes do not have a nucleus Controls most cell process and contains the DNA

13 Nucleolus and Nuclear Envelope
Inside the nucleus Where ribosomes are made Nuclear Envelope: Double-membrane layer around the nucleus Allows material to move into and out of the nucleus

14 Nucleus

15 Cytoskeleton Found in all eukaryotic cells Not found in prokaryotes
A network of protein filaments that helps the cell maintain its shape It also is involved in cell movement

16 Microfilaments and Microtubules
made of actin, tough and flexible, functions for cell movement, assemble and disassemble the microtubules for cell movement made of tubulis, maintain cell shape, used in cell division with centrioles and build the projections of cilia and flagella

17 Ribosomes Found in all cells Main function is to make proteins
Can be found floating in the cytosol or attached to endoplasmic reticulum

18 Endoplasmic Reticulum (ER)
Found only in eukaryotic cells Where components of the cell membrane are assembled Two kinds: Smooth ER & Rough ER Smooth ER: no ribosomes; makes lipids Rough ER: has ribosomes; involved in making proteins

19 Endoplasmic Reticulum

20 Golgi Apparatus Found only in eukaryotic cells
Enzymes attach carbohydrates & lipids to proteins Send proteins to their final destination

21 Lysosomes Found in animal cells only
Break down lipids, carbohydrates & proteins from food into particles that can be used by the cell Also break down “dead” organelles

22 Vacuoles Not found in prokaryotes
Animal cells have small or no vacuoles Plant cells have a large central vacuole Store materials such as water, salts, proteins & carbohydrates

23 How endocytosis and exocytosis works in animal cells: Note the food Vacuole and Lysosomes

24 Chloroplasts They have their own DNA Found in all plant cells
Some prokaryotes have them, but most do not Use the energy from sunlight to make energy-rich food molecules (carbohydrates) during photosynthesis

25 Mitochondria converts stored energy to a usable form
double membrane with folds to increase surface area it also has its own DNA

26 Endosymbiotic Theory (CH 19)

27 Diffusion Molecules move from an area of high concentration to an area of low concentration Movement continues until equilibrium is reached Many substances move across the membrane by diffusion Does not require energy (passive transport)

28 Diffusion Rate of Diffusion is affected by: Temperature
concentration gradient Rate of Diffusion is affected by: Temperature Steepness of the gradient Size of Molecules

29 Facilitated Diffusion
Some molecules cannot cross the membrane without help Some of the proteins in the membrane form protein channels Materials still move from higher to lower concentrations No energy is required

30 Facilitated Diffusion
htlfacilitated diffusion (fast and specific but energy free)

31 Osmosis: A special name for a special Molecule!
The diffusion of water Isotonic – equal concentration Nothing happens (normal) Hypertonic – higher concentration Water moves out of the cell (shrivels) Hypotonic – lower concentration Water moves into the cell (pops at the extreme) No energy is required osmosis

32 Effects of Osmosis on Cells

33 Osmotic Pressure In pure water, an animal cell would burst
Plant cells are protected by their cell wall Some freshwater organism have special structures like contractile vacuoles to get rid of extra water

34 Active Transport: Working to go Uphill---Up the gradient.
Materials move from lower concentration to higher concentration Requires an input of energy Works kind of like a pump

35 Transport of Large Amounts Bulk Transport
Endocytosis – movement into the cell Phagocytosis – “cell eating” – solid particles Pinocytosis – “cell drinking” – particles dissolved in water Exocytosis – movement out of the cell

36 Phagocytosis

37 Pinocytosis animation

38 (homeo = same Stasis = state
Homeostasis and Cells (homeo = same Stasis = state SIngle and cells and Multicellular organisms - maintain a certain level of conditions in its environment Multicellular organisms divide and conquer tasks and jobs to maintain homeostasis. This takes communication!

39 Cell to cell communication:
cellular signals speed up or slow down cell activities receptors (1)in the cell membrane and (2) inside the cytoplasm carry electrical and chemical messages. review of phospholipid membrane and receptor visual

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