Review of Cells

Essential Content

A. Development of the Cell Theory

1. Microscopes

2. Contribution of Scientists

B. Compare and Contrast Cell Types

1. Prokaryotes vs. Eukaryotes

2. Plant cells vs. Animal cells

C. Organelles: Roles and Functions

1. Storage, clean up, support

2. Building Proteins

3. Capture and Release Energy

4. Boundaries

D. Cell Membrane

1. Structure and Function of Phospholipids

2. Lipid Bilayer

E. Cellular Transport

1. Passive Transport

a. Diffusion, facilitated diffusion, osmosis

b. Hyper-, hypo-, isotonic solutions

2. Active Transport

a. Exocytosis

b. Endocytosis

c. Protein pumps

Objectives

A. Describe the scientific theory of cells (cell theory) and explain how the history of the discovery of the cell theory relates to the process of science.

• Compare and contrast the structure and function of various types of microscopes

B. Compare structures and describe related functions in different types of cells.

C. Identify role of organelles in cells

D. Identify the role lipids play in membrane structure and function.

E. Explain the role of the cell membrane in reference to passive and active transport.

Prokaryotes and Eukaryotes Cells come in an amazing variety of shapes and sizes, but all cells contain DNA. Also, all cells are surrounded by a thin flexible barrier called a cell membrane. There are two basic categories of cells based on whether they contain a nucleus. The nucleus (plural: nuclei) is a large membrane-enclosed structure that contains DNA.

Eukaryotes are cells that enclose their DNA in nuclei.

Prokaryotes are cells that do not enclose their DNA in nuclei.

Be able to describe what each structures functions for and WHO has it........

Cell Organization Eukaryotic cells contain a nucleus and many specialized structures.

Cytoplasm is the fluid portion of a cell.

Organelles are structures that have specialized functions in eukaryotic cells.

The nucleus contains DNA and controls the activity of a cell.

Organelles That Store, Clean Up, and Support These structures include:

vacuoles: membrane-enclosed saclike structures that store water, salts, and organic molecules

lysosomes: small organelles filled with enzymes that break down large molecules and organelles that are no longer useful the cytoskeleton: a network of protein filaments; it helps the cell maintain its shape and is involved in movement

centrioles: organelles made from tubulins; they help organize cell division in animal cells

Organelles That Build Proteins Three kinds of organelles work with the nucleus to make and distribute proteins:

ribosomes: small particles of RNA and protein found throughout the cytoplasm in all cells; they produce proteins by following coded instructions from DNA

the endoplasmic reticulum (ER): an internal membrane system where lipid components of the cell membrane are assembled, along with proteins and other materials

the Golgi apparatus: an organelle that appears as a stack of flattened membranes; it modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or release outside the cell

Organelles That Capture and Release Energy Two types of organelles act as power plants of the cells. Both types are surrounded by two membranes.

Chloroplasts capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis. Cells of plants and some other organisms contain chloroplasts, which contain chlorophyll.

Mitochondria are found in nearly all eukaryotic cells; they convert the chemical energy stored in food to a usable form.

Cellular Boundaries All cells are surrounded by a cell membrane. Many cells also have a cell wall. Both cell membranes and cell walls separate cells from the environment and provide support.

Cell walls support, shape, and protect the cell. Most prokaryotes and many eukaryotes have them. Animals do not have cell walls. Cell walls lie outside the cell membrane. Most cell walls allow materials to pass through them.

A cell membrane consists of a lipid bilayer, a strong but flexible barrier between the cell and its surroundings. The cell membrane regulates what enters and leaves the cell and also protects and supports the cell. Most biological membranes are selectively permeable, allowing some substances, but not others, to pass across them.

Passive Transport:

The movement of materials across the cell membrane without using cellular energy is called passive transport.

Diffusion is the process by which particles move from an area of high concentration to an area of lower concentration.

Facilitated diffusion is the process by which molecules that cannot directly diffuse across the membrane pass through special protein channels.

Osmosis is the facilitated diffusion of water through a selectively permeable membrane.

· Aquaporins are water channel proteins that allow water to pass through cell membranes.

· Two adjacent solutions are isotonic if they have the same concentrations of solute.

· Hypertonic solutions have a higher concentration of solute compared to another solution.

· Hypotonic solutions have a lower concentration of solute compared to another solution.

Osmotic pressure is the force caused by the net movement of water by osmosis.