Key Vocabulary Nucleus Nucleolus Cell Wall Mitochondria Chloroplast Eukaryote Prokaryote

Cell Biology Fall 2013

Cells Cell – Definition-The basic structural unit of living things. Cell Theory – 3 parts All living things are composed of one or more cells. Cells are the basic structural unit of all living things. Cells can only arise from pre-existing cells.

Homeostasis: Definition-Maintaining the cell’s delicate balance of internal conditions. pH, water, ions, O2 level, temperature, etc. Cell membrane responsible for maintaining homeostasis of cell.

Two Basic Cell Types Prokaryotes: Eukaryotes: No nucleus. No membrane-bound organelles. Cell-wall. Small in size. Bacteria. Eukaryotes: Have a nucleus -> where DNA is Have membrane-bound organelles. Some have cell wall (plants) and some don’t (animals). Large size. Plant and animal cells.

Prokaryotes

Eukaryotes

Which is bigger?

Basic Structures 1) Cell Membrane- Definition-Thin, flexible barrier around the cell that separates the cell from its environment. Selectively Permeable – allows some substances to pass through membrane but not others.

Cell Membrane Structure Phospholipid Bilayer – double layer of phospholipids surrounding cell. Phospholipid = lipid with phosphate group attached Phosphate head = hydrophilic. Faces inside and outside of cell (toward water). Fatty acid tail = hydrophobic. Faces inside middle of membrane.

Transport Proteins – form channels through membrane Transport Proteins – form channels through membrane. -Some open all the time. Others open and close as needed (requires energy). **Extra credit explain additional parts of the cell membrane

Fluid Mosaic Model Phospholipids and proteins are not locked in place. They are fluid and can float around in cell membrane.

Cell Membrane

Nucleus Contains DNA Surrounded by membrane called nuclear envelope. Holes in nuclear envelope -> nuclear pores. Nucleolus – area in nucleus where ribosomes are made.

Cytoplasm Cytoplasm: Definition-the semi-fluid environment inside the cell. Contains organelles  “little organs”

End of Cells Part One

Exit Slip Get out a new half sheet of paper. What are the two basic types of cells? What is the cell membrane made from? Where is DNA found in the cell? The fluid and organelles are called what?

Second Chance What is in the Cytoplasm? Phospholipids are the building blocks of what cell feature? What are the two basic cell types? The Nucleus contains what that is important in genetics?

Organelles Ribosomes – Definition- Where proteins are made. Two Types: -Free-Floating Ribosomes – make proteins for inside cell. -Attached to Endoplasmic Reticulum – make proteins that get shipped outside cell.

Endoplasmic Reticulum – folded series of membranes connected to nucleus. -Folds increase surface area -> more space -Two types of ER: Rough ER – has ribosomes on it. Proteins get made and sent to Golgi Apparatus. Smooth ER – No ribosomes. Where complex sugars and lipids are made.

Ribosomes and Endoplasmic Reticulum

Golgi Apparatus – modifies proteins, then re- packages them in a membrane = vesicle The vesicle then carries the protein out of the cell. Vacuoles – store nutrients and water. Lysosomes – contains enzymes that digest viruses, bacteria and worn-out cell parts. Centrioles – a group of microtubules that function in cell division. Mitochondria – convert sugar into usable energy known as ATP.

Golgi Apparatus

Cytoskeleton Supports organelles and helps them move around inside cell. Consists of proteins called microtubules (thick) and microfilaments (thin). Cell Movement Cilia: short, hairlike projections that move in a wavelike motion. Move particles down throat, up trachea, etc. Flagella: long projections that move back and forth. Only some cells have flagella (sperm, some bacteria, etc.)

Cytoskeleton

Animal Cell

Cell Membrane Lab Materials: bubble solution, straw ring, paper clip, rubber band Problem: How can you get a pencil through the ring without popping the bubble? (2 ways) How does this relate to the cell membrane?

Plant Cells Similar to animal cells plus 4 other features. Cell Wall: protects the cell and provides structural support. -Made out of cellulose. -Allows molecules to pass through, but it is non- selective. Chloroplasts: organelles that capture light energy and convert it to food (sugar). -Chloroplasts contain a green pigment called chlorophyll, which traps sunlight. Very Large Vacuole: stores water during long dry spells. Square or Rectangular Shape

Plant Cell

Cellular Transport How do substances (nutrients, O2, CO2, water, etc.) get in and out of cell? Five ways: Simple Diffusion Osmosis Facilitated Diffusion Active Transport Endocytosis/Exocytosis

Diffusion Definition-The net movement of molecules from high concentration to low concentration. -Passive process – does not require energy. -Concentration Gradient – the difference in concentration from one area to another. -Molecules move with the concentration gradient (high to low conc.)

-Molecules will continue to flow until two areas are equal AKA Dynamic Equilibrium -Substances that are small and lipid soluble can diffuse directly across phospholipid bilayer (no transport protein required). ex) O2, CO2, Lipids

Diffusion A B

Osmosis Diffusion of water only. Passive, no energy Directly across membrane. Cells are subject to osmosis because they have water inside and outside of cell. The different amounts of the water on either side lead to different situations.

Hypotonic: water moves into the cell Isotonic: water in = water out Hypertonic = water leaves the cell

Hyper- Hypo- Isotonic

Facilitated Diffusion Just like simple diffusion, except a protein channel is required. Passive – no energy required. Goes with conc gradient (high to low).

Active transport -Requires energy -Goes against the conc gradient (low->High) Endocytosis/exocytosis -large scale active transport -uses energy ENdo=Large molecules ENtering EXo=Large molecules EXiting