Essential Questions:What is the cell theory? Why do cells have organelles? How do prokaryotes and eukaryotes differ?

Unit 3:Chapter 7: Cell Structure & Function

Georgia Standards:

•Analyze the nature of the relationships between structures and functions in living cells. •Explain the role of cell organelles for both prokaryotic and eukaryotic cells.

Warm-up: Are all cells alike? All living things are made up of cells.

Some organisms are composed of only one cell.

Other organisms are made up of many cells.

Answer the following questions in your binder:

1. What are the advantages of a one-celled organism?

2. What are the advantages of an organism that is made up of many cells?

The Cell Theory Anton van

Leeuwenhoek (lay-vuhn-hook) (early 1600’s) became one of the first people to use a microscope to study nature. – He was the first

person, for example, to see tiny living organisms in a drop of water.

Robert Hooke (1665) used one of the first light microscopes to look at thin slices of plant tissues, specifically cork.– They looked like tiny

chambers, so he called them “cells”

The Cell Theory

The cell theory states the following:

– All living things are composed of cells.

– Cells are the basic units of structure and function in living things.

– New cells are produced from existing cells.

Prokaryotes and Eukaryotes Prokaryotes

– Evolved first– smaller and simpler than

eukaryotes. – cell membranes – cytoplasm – NO nuclei– No membrane-bound

organelles

– Ex: All bacteria are prokaryotes

• Escherichia coli, which live in your intestines

• Staphylococcus aureus, which can cause skin infections.

Eukaryotes– Evolved from

prokaryotes– Large – Multicellular– Do contain nuclei– cell membrane– cytoplasm– specialized membrane-

bound organelles, that perform important cellular functions

– Ex: All plants, animals, and fungi, and protists.

Origin of Eukaryotic Cells The endosymbiotic theory proposes that eukaryotic

cells arose from living communities formed by prokaryotic organisms.

Evidence:– First, mitochondria and chloroplasts contain DNA similar to

bacterial DNA.

– Second, mitochondria and chloroplasts have ribosomes whose size and structure closely resemble those of bacteria.

– Third, like bacteria, mitochondria and chloroplasts reproduce by binary fission when the cells containing them divide by mitosis.

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Prokaryotic and Eukaryotic Cells

Flagella = Flagella are whiplike structures used for movement.

Peptidoglycan

Cell wall

Cell membrane

Ribosome

Flagellum DNA Pili

Section 19-1

The Structure of a Eubacterium

Go to Section:

Homework1. What three statements describe the cell theory?

2. What are the two main characteristics that distinguishes eukaryotes from prokaryotes?

3. What evidence supports the endosymbiotic theory?

4. If microscopes had not been invented, do you think the cell theory would have been developed? Explain your answer.

OR

Pg. 186 # 1-4

Basic Cell Structures (Organelles):

Organelles isolate cell activities

Organelles contribute to the specialization of eukaryotic cells

Cells Reproduce, manufacture and release energy, and maintain homeostasis

Basic Cell Structures

Despite differences in cell size and shape, certain structures are common to most cells.– Cell membrane– Cytoplasm

Cell Membrane = thin, flexible barrier around the cell. Maintains homeostasis

Cell Wall = support and protect cells, while allowing them to interact with their surroundings (Not in animal cells).

Nucleus = contains the cell’s genetic material (DNA) and controls the cell’s activities

Cytoplasm =inside the cell membrane—but not including the nucleus, contains many organelles.

Cell Wall• Found in many organisms,

including plants, algae, fungi, and nearly all prokaryotes.

• Animal cells, however, do not contain cell walls.

• The cell wall lies outside the cell membrane.

• Most cell walls allow water, oxygen, carbon dioxide, and other substances to pass through them.      

Made of carbohydrates (cellulose) and proteins

The main function of the cell wall is to provide support and protection for the cell.

Nucleus

The nucleus controls most cell processes and contains the hereditary information of DNA (deoxyribonucleic acid).

Almost all eukaryotic cells, including the plant and animal cells contain a nucleus.

Chromatin and Chromosomes 

The granular material visible within the nucleus is called chromatin.

It consists of DNA bound to protein.

Most of the time, chromatin is spread throughout the nucleus.

When a cell divides, however, chromatin condenses to form chromosomes (kroh-muh-sohms).

Nucleolus & Nuclear Envelope

 Most nuclei also contain a small, dense region known as the nucleolus (noo-klee-uh-lus).

The assembly of ribosomes begins. Ribosomes aid in the production of proteins within the cell.

The nucleus is surrounded by a double-membrane layer called the nuclear envelope.

Nuclear pores, which allow material to move into and out of the nucleus.

– The nucleus sends a steady stream of RNA and other information-carrying molecules to the rest of the cell through the nuclear pores.

• The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape and is involved in many forms of cell movement

• Microtubules• Microfilaments

Organelles in the Cytoplasm

Ribosomes - Proteins are assembled on ribosomes– small particles made

of RNA (ribonucleic acid) and protein.

Endoplasmic Reticulum – Transports

molecules in cell. – SER – smooth

endoplasmic reticulum has no ribosomes attached

– RER – rough endoplasmic reticulum has ribosomes attached

Organelles in the Cytoplasm Golgi Apparatus 

– Proteins produced by the rough endoplasmic reticulum move into a stack of membranes called the Golgi apparatus.

– Enzymes in the Golgi apparatus attach carbohydrates and lipids to proteins.

Lysosomes  (ly-suh-sohmz) are small organelles filled with enzymes. – break down lipids,

carbohydrates, and proteins from food

– help break down organelles that have outlived their usefulness

– removing debris that might otherwise accumulate and clutter up the cell

Organelles in the Cytoplasm

Cells often store materials such as water, salts, proteins, and carbohydrates in saclike structures known as vacuoles (vak-yoo-ohlz).

Many plant cells have a single large, central vacuole filled with liquid.

Vacuoles are also found in single-celled organisms and in animals.

Smaller vacuoles, especially those involved in transporting substances within the cell, are often also called vesicles.

Organelles in the Cytoplasm

The chloroplasts are found in plants and some bacteria and protists.

Animal and fungal cells do not contain chloroplasts.    

Chloroplasts use the energy from sunlight to make energy-rich food molecules in a process known as photosynthesis.

Mitochondria:

The mitochondria are organelles that release energy from stored food molecules.    

Mitochondria are found in nearly all eukaryotic cells, including those of plants and algae.

Mitochondria use energy from food to make high-energy compounds that the cell can use to power growth, development, and movement in a process called cellular respiration.

Animal Cell

Centrioles

NucleolusNucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrian

CellMembrane

Ribosome(free)

Ribosome(attached)

Animal Cells

Plant Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrian

Cell wall

CellMembrane

Chloroplast

Vacuole

Plant Cells

Classwork Assignments:

Construct a Venn diagram that compares and contrasts eukaryotes and prokaryotes.

Construct a Venn diagram that compares and contrasts the various organelles that exist in animal and plant cells.

Prokaryotes Eukaryotes

Cell membraneRibosomesCell wallcytoplasm

NucleusEndoplasmic reticulumGolgi apparatusLysosomesVacuolesMitochondriaCytoskeleton

Animal Cells Plant Cells

Lysosomes

Centrioles

Cell membraneCytoplasmRibosomesNucleusEndoplasmic reticulumGolgi apparatusVacuolesMitochondriaCytoskeleton

Cell Wall

Chloroplasts

Large central vacuole

Venn Diagrams

Agenda:

Go to www.cellsalive.com – Complete handout

Formative Assessment:

1. Describe the functions of the endoplasmic reticulum, Golgi apparatus, chloroplast, and mitochondrion.

2. What does the cell wall provide for a cell?

3. Describe the role of the nucleus in the cell.

4. What are two functions of the cytoskeleton?

5.Name two structures that all cells have.

6. How is a cell like a factory?