What is the cell theory? What are the names of those who added to the cell theory? What did each contribute? Cell

 What do you know about the cell theory?  Get together with a partner and discuss this question.  Be ready to share what you have discussed!

Cell Theory  Robert Hooke (1665) ◦ first discovered and named “cells” ◦ looked at dead cells of a cork plant Cell

Cell Theory  Anton van Leeuwenhoek (1674) ◦ built microscopes to study ‘animalcules’ known today as microorganisms ◦ first to see living cells Cell

Cell Theory  Matthias Schleiden (1838) ◦ stated all plants are made of cells Cell

Cell Theory  Theodore Schwann (1839) ◦ studied human notochord ◦ concluded all animals are made of cells Cell

Cell Theory  Rudolph Virchow (1858) ◦ every cell comes from another cell like it. Cell

Cell Theory  modern Cell Theory ◦ All living things are composed of cells. ◦ Cells are the units of structure and function in living things. ◦ New cells are produced from pre-existing cells. Cell

Basic Cell Structure  Cells can come in 3 shapes 1. Sphere 2. Brick 3. Cube Cell

Cell Structure The smallest are bacteria cells The largest is the human egg Cell

 Cell Membrane ◦ Encloses cell ◦ Controls the movement of materials into and out of cell  Cytoplasm ◦ Jellylike substance that contains the molecular building blocks (proteins, nucleic acids, minerals, ions, organelles etc.)  Organelles ◦ Structures specialized to perform a distinct cell function

Cell Structure  Two types of organisms 1. Unicellular- ex. Bacteria, yeasts, Amoeba 2. Multicellular- some cells are specialized; evolved from unicellular cells Cell

Cell Structure  Two Types of Organisms  Prokaryote ◦ No nucleus ◦ No membrane organelles ◦ DNA is in Cytoplasm ◦ Single Celled Organisms (unicellular) Cell

Cell Structure  Two Types of Organisms  Eukaryote ◦ Have a nucleus ◦ Genetic Information is located in the nucleus ◦ Have membrane bound organelles ◦ Unicellular or multicellular

Evolution of eukaryotic cells Prokaryotes were the 1st to evolve, then eukaryotes Why??

 What are the major organelles of a cell?  What function or major role does each organelle play within a cell?

 List as many cell organelles that you can think of.  List the major function of each!

1. Cell membrane/Plasma membrane:  Boundary between cell and outside environment  Controls the passage of materials in and out of cell  Double layer of phospholipid (charge phosphate group, glycerol head, fatty acid tail)  Phosphate group and glycerol head are polar and hydrophilic  Fatty acid tail is nonpolar and hydrophobic  Very important properties for transport (we will come back to this very soon)

2. Cell Wall  In plants, algae, fungi, and most bacteria  Strong and rigid  Gives cell protection, support, and shape  Cell walls can adhere to each other for support

3. Nucleus  Storehouse for genetic information  Surrounded by a double layer nuclear envelope  Select molecules can cross this barrier  Also contains the nucleolus  place where ribosomes are made

 4. Cytoskeleton  In Eukaryotic cells  Network of proteins  Made-up by 3 types of fibers ◦ Microtubules ◦ Microfilaments ◦ Intermediate filaments

Cytoskeleton Microtubules  Stained green  Long, hollow tubes  Gives cell shape  The “track” for organelle movement  Used in cell division to pull DNA Intermediate Filaments  Give cell strength

Cytoskeleton Microfilaments  Smallest of the 3  Tiny threads that enable cell to divide  Important roles in muscle cells, as they allow muscles to contract and relax

5. Endoplasmic reticulum (ER)  Thin folded membranes (many creases and folds)  Interior is called the lumen  Many cell processes but mostly protein and lipid synthesis  Rough: ribosomes  Smooth: no ribosomes

6. Ribosomes  Stained red  Site of protein synthesis (transport to lumen if on ER)  Assembled in the nucleus and transported to cytoplasm or on ER  Link amino acids together

7. Golgi Apparatus  From the ER proteins move to the golgi  Here, proteins are sorted, modified, and packaged  Either stored or transported out of cell

8. Mitochondria  Supplies energy to the cell  Two membranes, folded and has a high surface area  Converts food to energy  Have their own DNA and ribosomes  Originally free living prokaryotes?

10. Lysosome  Contain enzymes  Defend cells from bacteria and viruses  Break down damaged or worn out cell parts  Do not know if they are in plant cells  Made in ER and are inactive  Activated and Packaged in Golgi  Bud from vesicles

11. Vacuole  Fluid-filled  Storage of materials needed by cell (water, food, ions, enzymes, etc)  Animals have several small vacuoles  Plants have one large one  largest structure in plant cells  holds fluid that strengthens and supports plant  also can hold toxins, waste, and pigments

12. Chloroplasts  Carry out photosynthesis  Stacked disc shaped structures called thylakoids contain the chlorophyll (light absorbing molecule)  Have own mitochondria and DNA  Free living prokaryote?

13. Centrosome and Centrioles  Centrosome is a small area in cytoplasm that produces microtubules  Has two small structures called centrioles  Cylinder shaped made of microtubules arranged in a circle  Used in cell division  Organize microtubules to form cilia and flagella

14. Flagella  Cell movement  Propels cell like a motor boat

15.Cilia  Cell movement  Small hair like structures  Crawl

Evolution of eukaryotic cells Endo-Symbiotic Theory: prokaryotes were once engulfed by other cells, giving rise to eukaryotes. 1. Ex. Mitochondria and Chloroplasts have their own DNA and RNA

Evolution of eukaryotic cells mitochondria are the result of endocytosis of aerobic bacteria chloroplasts are the result of endocytosis of photosynthetic bacteria Cell

What are the different states of concentration across a membrane? Cell

 Brainstorm the following with a partner:  How do cells transport substances in and out of the cell membrane?  Be prepared to share with the class.

Fluid Mosaic Model ◦ Cell membrane is fluid, not rigid ◦ Phospholipids can move side to side and slide past each other  membrane constantly moving ◦ 3 main molecules  proteins  carbohydrates  lipids  hydrophilic (water loving) heads  hydrophobic (water fearing) tails

Transport Cell

Transport  cell membrane ◦ allows for transport of materials into and out of cell Cell

 Allows some but not all materials to cross  Maintains homeostasis  Molecules cross in several ways: ◦ Small nonpolar cross easily ◦ Small polar cross with help of proteins ◦ Large cross with help of vesicles

 Passive:  Movement of molecules across a cell membrane without energy input from the cell ◦ Diffusion ◦ Osmosis ◦ Facilitated diffusion  Active:  Movement of molecules across a cell membrane by chemical energy ◦ Endocytosis ◦ Exocytosis ◦ Phagocytosis

Movement of molecules across a cell membrane without energy input!

diffusion ◦ movement of molecules in liquid or gas from a region of higher concentration to lower concentration

Diffusion Results In:  equilibrium ◦ state in which concentration is equal in all areas

osmosis ◦ movement of water from higher to lower concentration.

 osmosis ◦ Can be described in 3 ways: ◦ hypertonic ◦ Hypotonic ◦ Isotonic ◦ Note that we are speaking of solutions in comparison to each other, this requires a point of reference. ◦ Example: You may be taller than ___________

◦ hypertonic  concentration of solute is greater outside cell  Water is more concentrated inside the cell  Water diffuses out of the cell, causing it to shrivel ◦ hypotonic  concentration of solute is less outside cell  Water is more concentrated outside the cell  Water diffuses into the cell  Cell sells

 Isotonic ◦ Same concentration inside as outside of cell ◦ Water molecules move in and out of the cell in equal rates ◦ Cell size remains constant

 osmosis

Get with a partner and answer the following: Which is isotonic, hypertonic, hypotonic?

Tugor: the pressure within cells derived from osmotic pressure differences between the inside and outside of the cell causing rigidity.

 Osmosis  Complete the following table meaning of name concentration of solute (compared to cell) percent of water (compared to cell) water moves into/out of cell hyper hypo iso

 osmosis meaning of name concentration of solute (compared to cell) percent of water (compared to cell) water moves into/out of cell hypermorehigherlowerout of cell hypolesslowerhigherinto cell iso

 osmosis meaning of name concentration of solute (compared to cell) percent of water (compared to cell) water moves into/out of cell hypermorehigherlowerout of cell hypolesslowerhigherinto cell isosame both directions

 facilitated diffusion ◦ molecules move across membrane with help of transport proteins ◦ Still moving down the concentration gradient, no energy required

Movement of molecules across a cell membrane by chemical energy

 active transport ◦ uses energy to transport molecules against concentration gradient

 active transport ◦ uses energy to transport molecules against concentration gradient

 Done with the help of transport proteins, usually called pumps  Low concentration to high concentration!  Maintain Homeostasis

 Span the membrane  Change shape when bind to a molecule  Each protein has one or two target molecules  Uses chemical energy: ATP!

 endocytosis ◦ engulfing solid particles using the cell membrane

 endocytosis ◦ engulfing solid particles using the cell membrane 1. phagocytosis  endocytosis of solid material 2. Pinocytosis  Endocytosis of liquid material

Transport  exocytosis ◦ cell secretes large particles via membrane bound sacs Cell