Cells • 2 Basic Types: • Prokaryotes • • Cell and • The

The 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells are produced from other cells. Two Basic Cell Types: Prokaryotic vs. Eukaryotic Cells Two Basic Types

• Remember….cells are the basic unit of for ALL living things.

• There are two basic types of cells: 1. Prokaryotic cells – found in 2. Eukaryotic cells – found in , fungi, and Characteristics Shared

• Perform the same basic functions • Surrounded by plasma membrane to control what enters and leaves the cell • “Filled” with cytoplasm • Contain ribosomes to make • Contain DNA to give the general instructions for the cell’s life What Makes Eukaryotic Cells Different? • Much larger • Much more complex

• Contain a true nucleus to house the genetic material (DNA) • Linear DNA packaged into chromatin found inside the nucleus • Contains specialized in the cytoplasm called organelles to carry out various functions • Not all have a cell wall

Eukaryotic Cells What Makes Prokaryotic Cells Different?

• Much smaller • Less complex

• No true nucleus • Circular DNA that is found in the cytoplasm • No organelles found in the cytoplasm • Surrounded by a cell wall Prokaryotic Cell What does size have to do with it? • Prokaryotic cells are much smaller than eukaryotic cells. Why? – Smaller surface area to volume allows to easily and quickly reach inner parts of the cell. – Eukaryotic cells are larger and can not pass nutrients as quickly. They require specialized organelles to: • carry out • provide • transport chemicals throughout the cell

Prokaryotic Cell

http://www.cellsalive.com/ cells/bactcell.htm#top

Cell Organelles

Review

• No organelles in prokaryotic cells • Both plants and animals are eukaryotic cells! Cell Cell Organelles Found in Plant and Animal Cells • Cell Membrane • Nucleus • Nucleolus • Mitochondria • Endoplasmic reticulum • Ribosomes • Golgi apparatus • (small in animals; large in plants) • Lysosomes The Cell Membrane • Location: Around the outside of the cell • Function: Controls what substances enter and leave the cell • Aka: “plasma membrane” Nucleus • Location: In the cytoplasm • Function: Directs all of the cell’s activities; stores the chromatin • Aka: “control center”

Nucleolus • Location: In the nucleus • Function: Makes ribosomes • Aka: “little nucleus” Mitochondria

• Location: In the cytoplasm • Function: Produces energy • Aka: “Powerhouse” or “Mighty Mitochondria” Ribosomes • Location: In the cytoplasm and on the rough ER • Function: Makes protein • Aka: “Protein packs” Endoplasmic Reticulum (ER) • Location: In the cytoplasm around the nucleus • Function: Modifies materials needed in the cell • Aka: “Fashion designers”

Smooth ER (no ribosomes)

Rough ER (has ribosomes) Golgi Apparatus • Location: In the cytoplasm • Function: Sorts and ships materials to the correct parts of the cell • Aka: “the post office” Vacuoles • Location: In the cytoplasm (large in plants; small in animals) • Function: Storage • Aka: “the closet”

Animal Cell Vaculole = small Plant Cell Vaculole = large Lysosome • Location: In the cytoplasm • Function: Destroys worn out cell parts • Aka: “the chamber:

Cilia / Flagella • (*animal cells only: not all cells have one of these) • Location: on the cell membrane • Function: help the cell move • AKA: the “motor”

Organelles Found in Only Plant Cells • Cell Wall • Chloroplast Cell Wall • Location: Around the cell membrane of plant cells • Function: Gives the cell shape and protection • Aka: “plant cell armor” Chloroplast • Location: In the cytoplasm • Function: : Makes sugar from sunlight (also takes in and gives off ) • Aka: “mean green sugar machine” See the Cell in Action! • http://www.youtube.com/watch?v=1Z9pqST72is

&feature=related (14 min.)

• Visit this link to see the cell in action, just click on the various organelles to get a better idea of how they work! http://www.johnkyrk.com/CellIndex.html http://www.cellsalive.com/cells/cell_model.htm

http://waynesword.palomar.edu/lmexer1a.htm Plant Cell • http://waynesword.palomar.edu/lmexer1a.htm Animal Cell Prokaryotic Cell

http://www.cellsalive.com/c ells/bactcell.htm#top http://waynesword.palomar.edu/lmexer1a.htm Plant Cell Name______• http://waynesword.palomar.edu/lmexer1a.htm Animal Cell Name______Prokaryotic Cell Name______

http://www.cellsalive.com/c ells/bactcell.htm#top Movement Through the Cell Membrane

http://programs.northlandcollege.edu/biology/bi ology1111/animations/passive1.swf

Selectively-Permeable Membranes

• A selectively-permeable membrane will allow certain to pass through it, but not others. Partially permeable • Generally, small membrane particles can pass through…

…but large particles cannot Structure of the Plasma/Cell Membrane • Plasma Membranes consist of 2 types of molecules – and Diagram of a

Phospholipids have 2 regions:

• Polar head region: – attracts water molecules (hydrophilic) – Phosphorous group • Non-polar tail region: – nonpolar tails repel water molecules (hydrophobic). – Made of long carbon chains (fatty acids)

Phospholipid bilayer • Due to the hydrophobic and hydrophilic nature of the phospholipid, a double layer is formed where the heads protect the tails from the water. This is called the phospholipid bilayer. The bilayer is fluid, not a hard shell.

Proteins are Embedded Within the Bilayer • Proteins act as passageways for nonpolar (hydrophobic) molecules to pass through. • Without proteins embedded in the bilayer, essential molecules needed for communication, energy, etc., would not reach the interior of the cell.

• are attached to the proteins. – Allow for cell recognition and communication.

Proteins are Embedded Within the Bilayer (continued) • The model of the bilayer with embedded proteins is called the Fluid Mosaic Model.

TWO Types of Transport Through a Cell Membrane 1. Active Transport – the movement of molecules through a cell membrane using energy

2. Passive Transport – the movement of molecules through a cell membrane without the expenditure of energy 3 Types of Passive Transport

1. Diffusion - Movement of molecules from areas of high to low concentration 2. - Diffusion of water molecules from higher concentration of water to lower concentration of water 3. Facilitated Diffusion - Diffusion through pores or channel proteins DIFFUSION

• Molecules tend to move from areas where there is more of them to where there is less high concentration  low concentration – This is called moving WITH the concentration gradient.

• Diffusion continues until equilibrium is reached, or where molecules are equally distributed. – Some solutes will be able to move through when others will not. Diffusion (continued)

OSMOSIS

• Water passes through cell membranes rapidly. • Osmosis is a specialized form of diffusion that moves water molecules through membranes.

• – when more water molecules accumulate inside a cell, pressure increases. This pressure is called osmotic pressure. – when osmotic pressure is high inside the cell, water will want to leave the cell. OSMOSIS 3 Types of Solutions hypertonic solution -solute concentration is HIGHER in the solution than in the cell. • Water will move out of the cell- cell will shrivel hypotonic solution - solute concentration is LOWER in the solution than in the cell. • Water will move into the cell- cell will swell isotonic solution - EQUAL solute in the solution and in the cell. • Water will move in and out of the cell at equal rates.

FACILITATED DIFFUSION – some molecules cannot diffuse through on their own (membrane is impermeable to them), and will need assistance (facilitate). – Passive transport aided by proteins. Each are very specific to the size/shape/polarity of solute. -transport proteins -channel proteins *aquaporins- facilitated diffusion of water * channels- open and close in response to a (gated channels) Active Transport • Some molecules exist in low amounts on one side of a membrane and need to be moved to areas of high amounts • active transport- the use of energy to move molecules from LOW concentration to HIGH concentration (against or opposite the concentration gradient)

• Cell membranes have mechanisms to move these molecules against their concentration gradients: 1. ion/molecular pumps 2. endocytosis 3. exocytosis

Types of Active Transport

1. ion/molecular pumps -Molecules can be moved through the membrane by specific proteins embedded in the membrane -Na, K, Ca are transported in this manner -- pump is the major pump of animal cells -proton pump is main pump of plants, fungi, and bacteria

2. endocytosis- process of cells engulfing large particles by forming a vesicle around them -different names for different sizes of particles: pinocytosis (cell drinking) -occurs if the particles have been partially broken down into a liquid of tiny dissolved molecules

phagocytosis (cell eating) - If the particles are cell fragments or organic matter

3. exocytosis -process by which wastes or secretions () are brought to the cell membrane, packaged into vesicles and sent out of the cell – the reverse of endocytosis

Unicellular vs. Multicellular • Unicellular – single celled. • Include both prokaryotes and eukaryotes. • Maintain by growing, responding to the environment, transforming energy, and reproducing. • Multicellular organisms – many cells working together to create an . • Cells are specialized – different cell types play different roles. • Ex. Move, respond, communicate, substance production. • Cells communicate with one another to maintain homeostasis for the organism.

• The organization allows them to divide labor in order to maintain homeostasis.

Cellular communication • Cells in large organisms must communicate with one another in order to work together to maintain homeostasis! • Occurs via chemical signals that influence the behavior of the cells receiving the signals. • Receptors are often found on the outside of cells where they bind chemical signaling molecules and influence cellular activity.