1. Cell Structure and Function
Essential Question: How are cell structures adapted to their functions?

2. 7.1 Life is cellular
Robert Hooke discovered cells by using an early compound microscope to examine a cork screw. There appeared to be thousands of tiny empty chambers, which he named “cells” b/c they looked like the tiny rooms that monks lived in which were called cells?
What is 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 pre-existing cells

3. How do microscopes work?
Most microscopes use lenses to magnify the image of an object by focusing light or electrons
We usually use a compound microscope. 2 different lenses (ocular- what you look through, and objective, an adjustable magnification) are used to view an object.

4. Magnification is found by multiplying the objective lens power by the ocular lens power. Ex: 40x 10x= 400x
Light microscopes can magnify objects to about 1000x
Most cells are nearly transparent, but we use stains or dyes to visualize cells and their structures.
Fluorescent microscopy- fluorescent dyes are attached to specific molecules that can be used to identify the location movement of molecules around a cell.

5. Electron microscopes
Use beams of electrons that are focused by magnetic fields to view objects that are too small to be seen with a light microscope.
Types of electron microscopes:
Transmission: Can view cell structures and proteins. Samples are cut thin, so images appear 2-dimensional
Scanning: Scan the surface of cells. Images appear 3-D

7. How are prokaryotic and eukaryotic cells different?
All cells contain a cell membrane- a thin, flexible barrier on the outside of the cell.
Cells are categorized by the presence or absence of a nucleus:
Eukaryotic cells- contain a nucleus to enclose their DNA
Prokaryotic cells- DNA is NOT enclosed within a nucleus

8. 7.2 Cell Structure Organelle video
What is the role of the cell nucleus?
Both prokaryotic and eukaryotic cells contain cytoplasm- a gel-like substance that holds the cell together.
Organelles- the specialized structures that help the cell perform vital functions
The nucleus contains the cell’s genetic information, and with it, the coded instructions for making proteins and other important molecules

9. Nucleus
Surrounded by a “nuclear envelope.” Nuclear pores allow material to move in and out of the nucleus.
–like a manager
Nucleus is control center of the cell.
DNAchromosomeschromatinnuleolus
nucleus

10. What are the functions of vacuoles, lysosomes, and the cytoskeleton?
Vacuole- a sac-like membrane that stores water, salts, proteins, and carbohydrates. Also can store away harmful substances.
-like a storage closet
Lysosomes- break down lipids, carbs, and proteins into small molecules the cell can use. Recycle and clean up materials that have lost their use.
-like a janitor

11. Cytoskeleton- Maintains cell shape and is involved in movement and transfer of substances.
2 principal protein filaments that make up the cytoskeleton:
Microfilaments: Thread-like structures composed of the protein actin. Responsible for cytoplasmic movement
Microtubules: Larger (hollow) and much more rigid than microfilaments. Maintain cell shape and responsible for cell division.
Centrioles- made of microtubules, organize cell division
*Only found in animal cells

12. Organelles that build proteins
Proteins are assembled on ribosomes.
Ribosome-a small particle of RNA and protein
Endoplasmic reticulum (ER)- an internal membrane system where lipids and proteins are assembled and exported from the cell.
Rough ER-site of protein synthesis
Smooth ER- site of lipid synthesis
Proteins made on the rough ER include those that will be released, or secreted, from the cell as well as many menbrane proteins and proteins destined for lysosomes and other specialized locations.

13. Golgi apparatus -Appears as a stack of flattened membranes.
The Golgi apparatus modifies, sorts, and packages proteins and other materials from the ER for storage in the cell, or release from the cell

14. Energy in the cell
Chloroplast- capture energy from the sun and convert it into food that contains chemical energy via photosynthesis
*Only present in plant cells
Mitochondria- converts chemical energy stored in food into compounds easier for the cell to use
-like the powerhouse
*Present in both plant and animal cells

15. What is the function of the cell membrane?
Cell wall- Protect cell and support its structure. Porous, allowing for exchange of materials.
Like walls
*Found in plant cells and some prokaryotic cells
Cell membrane (lipid bilayer)- regulates what enters and leaves the cell. Also functions in support and protection.

16. Lipid structure- Hydrophobic (water-hating) head, hydrophilic (water-loving) tails. The heads cluster together, and the tails do the same. This creates the lipid bilayer.
Fluid mosaic model- describes the mobile embedding of proteins throughout the lipid bilayer. The proteins and other molecules float among the lipids
Selective permeability- membrane allows certain materials to pass, and others not to

17. 7.3 Cell Transport What is passive transport?
Passive transport- the movement of materials w/out using cellular energy
Diffusion- a type of passive transport in which particles move from an area of high  low concentration.

18. Facilitated diffusion- substance passes through a membrane with the aid of an intermediary or a facilitator
Osmosis- the diffusion of water through a selectively permeable membrane.
Water channels proteins that allow for movement through membrane= aquaporins.

19. Isotonic- [solution] = [solutes]
Isotonic- [solution] = [solutes] Water in and out of cell are = (normal)
Hypotonic- [solution] < [solutes] More water inside of cell (bursting)
Hypertonic- [solution] > [solutes] More water outside of cell (shriveled)

20. Endocytosis vs. Exocytosis
Osmotic pressure- pressure that must be applied to prevent osmotic movement across a selectively permeable membrane.
What is active transport?
The movement of materials against a concentration difference. It requires energy.
Endocytosis vs. Exocytosis
Endocytosis is the process of taking materials into the cell via enfoldings of pocketings in the membrane.
Exocytosis is when the membrane of the vacuole fuses w/ the cell membrane to force contents out of the cell.

21. 7.4 Homeostasis and Cells
How do individual cells maintain homeostasis?
To maintain homeostasis, unicellular organisms grow, respond to the environment, transform energy, and reproduce.
How do the cells of multicellular organisms work together to maintain homeostasis?
They become specialized for particular tasks and communicate w/ one another to maintain homeostasis.

22. Levels of Organization
Cell  tissue organ organ system organism
Tissue- a group of similar cells that work together to perform a particular function
Organ- Groups of tissues that work together to perform a particular function
Organ system- a group of organs that work together to perform a particular function

23. Cellular communication
Cells communicate via chemical signals.
To respond to a chemical signal a cell must have a receptor to which the signaling molecule can bind.
Chemical signals can cause important changes in cellular activity.