CellsCellsChapter 2Chapter 2

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• Cell theory:Cell theory: Robert Hooke first looked Robert Hooke first looked at and described cells in 1665. The at and described cells in 1665. The word “cell” means “little room” in Latin.word “cell” means “little room” in Latin.

• Anton Leeuwenhoek first described Anton Leeuwenhoek first described protists, blood cells, and bacteria in the protists, blood cells, and bacteria in the later 1600s. later 1600s.

• We now know all living things are made We now know all living things are made of cells. Cell theory, written in the of cells. Cell theory, written in the 1800s, says three things: 1. All 1800s, says three things: 1. All organisms are made of one or more organisms are made of one or more cells.cells.

2.2. The cell is the basic unit of life.The cell is the basic unit of life.

3.3. All cells come from existing cells.All cells come from existing cells.

PARTS OF A CELL:PARTS OF A CELL:

CellCell membranemembrane-protective layer; acts as -protective layer; acts as barrier; controls what goes in and outbarrier; controls what goes in and out

CytoplasmCytoplasm-the fluid and it’s dissolved -the fluid and it’s dissolved contents inside the cellcontents inside the cell

OrganellesOrganelles: carry out various processes : carry out various processes within the cell; most have their own within the cell; most have their own membranes; some float in cytoplasmmembranes; some float in cytoplasm

NucleusNucleus:: Only present in Eukaryotic Only present in Eukaryotic (cells with nuclei) cells; contains the DNA (cells with nuclei) cells; contains the DNA in eukaryotic organisms (not bacteria)in eukaryotic organisms (not bacteria)

Eukaryotic Cells Eukaryotic Cells p. 56p. 56•Include plants and Include plants and animalsanimals

•All have a All have a nucleusnucleus--large organelle w/ large organelle w/ DNA; DNA directs the DNA; DNA directs the production of proteins; production of proteins; covered by two covered by two membranes; contains membranes; contains the the nucleolusnucleolus (where (where ribosomes are made)ribosomes are made)

Plant CellsPlant Cells•The main differences in plant and

animal cells is that plant cells have a cell wall (provides support) and chloroplasts (where photosynthesis takes place).

•Plants’ cell walls are made of cellulose, a complex sugar. This is why celery crunches when you bite it.

•Chloroplasts have their own membranes and DNA. They contain chlorophyll, which makes them green. This is also what traps the energy of sunlight.

All Eukaryotic Cells have All Eukaryotic Cells have these…these…• CellCell membranemembrane-contains proteins, lipids, -contains proteins, lipids, and phospholipids; lipids are fat and do not and phospholipids; lipids are fat and do not dissolve in water; protein passageways dissolve in water; protein passageways allow movement of materials in and out.allow movement of materials in and out.

• CytoskeletonCytoskeleton-keeps the cell’s membranes -keeps the cell’s membranes from collapsing and allows some to movefrom collapsing and allows some to move

• RibosomesRibosomes-make proteins; smallest -make proteins; smallest organelles; more than any other organelle organelles; more than any other organelle in a cell; some are attached to the rough in a cell; some are attached to the rough ER (prokaryotes have ribosomes too!)ER (prokaryotes have ribosomes too!)

•Endoplasmic Reticulum (ER):Endoplasmic Reticulum (ER): system system of folded membranes in which of folded membranes in which proteins, lipids and other materials proteins, lipids and other materials are made through chemical are made through chemical reactions. reactions. Rough ERRough ER makes proteins; makes proteins; smooth ERsmooth ER makes lipids and breaks makes lipids and breaks down toxins.down toxins.

•Mitochondria:Mitochondria: “powerhouse” of the “powerhouse” of the cell; sugar is broken down here to cell; sugar is broken down here to make energy (ATP) through cellular make energy (ATP) through cellular respiration; energy is found in respiration; energy is found in ATP ATP (adenosine triphosphate)(adenosine triphosphate)

Golgi Complex (apparatus)Golgi Complex (apparatus)

• Packages and distributes proteins; Packages and distributes proteins; looks like smooth ER but is farther looks like smooth ER but is farther from the nucleus; gets lipids and from the nucleus; gets lipids and proteins from the ER; modifies them proteins from the ER; modifies them to do different jobs then sends them to do different jobs then sends them out of the cell out of the cell

VESICLEVESICLE• Small sac that surrounds material to Small sac that surrounds material to

be moved in or out of a cell.be moved in or out of a cell.

REVIEW-write Q and A in REVIEW-write Q and A in Assignments SectionAssignments Section1.1. Explain how the mitochondria and Explain how the mitochondria and

chloroplast are related in a plant cell:chloroplast are related in a plant cell:2.2. Make a chart showing how a plant and Make a chart showing how a plant and

animal cell differ.animal cell differ.3.3. How do the Golgi complex and How do the Golgi complex and

endoplasmic reticulum work together?endoplasmic reticulum work together?4.4. How does smooth ER differ from rough How does smooth ER differ from rough

ER?ER?

Review-put in Assignments-Review-put in Assignments-write Q and Awrite Q and A1.1. Why do you think plants need a cell wall?Why do you think plants need a cell wall?

2.2. What is the function of the mitochondria?What is the function of the mitochondria?

3.3. Ribosomes make ____________but Ribosomes make ____________but ribosomes are made in the __________ribosomes are made in the __________

4.4. The rough ER is covered in ________. The rough ER is covered in ________.

5.5. The smooth ER makes __________.The smooth ER makes __________.

6.6. How are mitochondria and chloroplasts How are mitochondria and chloroplasts alike?alike?

7.7. (sect 3) What are the three advantages (sect 3) What are the three advantages to being multicellular?to being multicellular?

REVIEW-ASSIGNMENTS-WRITE OUTREVIEW-ASSIGNMENTS-WRITE OUT1.1. Compare and Contrast mitochondria and Compare and Contrast mitochondria and

chloroplasts.chloroplasts.

2.2. Explain the relationship between the Golgi Explain the relationship between the Golgi Complex and the ER.Complex and the ER.

3.3. What does the vacuole do?What does the vacuole do?

4.4. What does the lysosome do?What does the lysosome do?

5.5. What is the “powerhouse” of the cell?What is the “powerhouse” of the cell?

6.6. What is the difference in the rough ER and What is the difference in the rough ER and the smooth ER? (p. 59)the smooth ER? (p. 59)

7.7. What are the two main differences in a plant What are the two main differences in a plant and animal cell?and animal cell?

8.8. What is a lipid and how is it used in your What is a lipid and how is it used in your cells?cells?