essential questions: what is the cell theory? why do cells have organelles?
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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. Essential Questions: What is the cell theory? - PowerPoint PPT PresentationTRANSCRIPT
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?