Ch 7.2
Cell 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
Lysosomes
- Vacuoles store water, salts,
proteins, and carbs
- Vesicles store and move
materials between organelles
- 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 Cells
Plant
Animal
- Have cell walls
- Have chloroplasts
- No cell walls
- No chloroplasts