Ch 7.2Cell

Structure

How is a cell organized?

- All Eukaryotic (Animal/Plant) cells

have 3 main parts:

- Nucleus

- Cytoplasm

- Cell Membrane

Organelles - Literally means “tiny organs”- Are membrane-bound compartments- Have specialized jobs in a cell- Can be compared to the machines in a factory

Nucleus

- Is the control center of a cell

- Contains a cell’s DNA- DNA in the form of chromatin- DNA bound to proteins

- Sends coded instructions for making proteins and other molecules

Nuclear Envelope- A two-layer membrane- Covers and protects the contents of the nucleus

Nuclear Pores- Small holes in the nuclear membrane- Allow molecules in and out of the nucleus

Nucleolus- Where ribosomes are assembled

Building Proteins

Ribosomes- Build proteins- Use instructions that come from DNA

Endoplasmic Reticulum (ER)

- Where lipids and proteins are assembled and transported

- Rough ER- Covered in ribosomes = “rough”- Synthesize proteins

- Smooth ER- No ribosomes = “smooth”- Synthesize lipids- Detoxify drugs

Golgi Apparatus

- Receives proteins from ER

- Give proteins an “address tag”

- Modifies, sorts, and packages proteins and other materials

- Sends proteins to final destination

Storing and Cleaning Up

Vacuoles and Vesicles- Vacuoles store water, salts,

proteins, and carbs- Vesicles store and move

materials between organelles

Lysosomes- Filled with enzymes- Breakdown lipids, carbs, and

proteins, and other organelles- Remove “junk” from cell

Providing Support and Structure

Cytoskeleton- Maintains cell shape

- Helps with cell movement

- Consists of Microfilaments and Microtubules

How do cells get their energy?

Chloroplasts

- Perform photosynthesis- Capture energy from sunlight and

convert it into food (sugars)

Mitochondria- Perform cellular respiration- Convert the chemical energy in food into cellular

energy (ATP)

Cell Wall

- Strong, supportive layer that surrounds plant cells

- Made of cellulose

- Also found in prokaryotes, but theirs is not made of cellulose

- Allow water, oxygen, carbon dioxide, and most nutrients to pass through

Cell Membrane- Regulates what enters and

leaves the cell

- Protects and supports the cell

- Is made of a double layer of lipids called a lipid bilayer

Lipids in the Membrane- Have regions that are hydrophilic

- “love” water

- Have regions that are hydrophobic- “fear” water

- Orient themselves so the hydrophilic parts face the water and the hydrophobic parts face away from it

- Make the membrane selectively permeable

- Some things can cross it, but others can’t

Fluid Mosaic Model- Proteins, carbohydrates and other molecules

are embedded in the lipid bilayer

- This makes the membrane look like a mosaic

- Since molecules can float and move in the membrane, it acts like a fluid

Differences Between Plant and Animal CellsPlant- Have cell walls- Have chloroplasts

Animal- No cell walls- No chloroplasts