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7-1 Life is Cellular

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7-4 Diversity of Cellular Life

Pg.190-193

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THE DIVERSITY OF CELLULAR LIFE

• Single celled organisms are called unicellular organisms.

• Organisms made of many cells are called multicellular organisms.– Cells of a multicellular organism can develop

in different ways to perform different tasks. This process is called cell specialization.

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LEVELS OF ORGANIZATION

• In multicellular organisms, cells are the first level of organization.

• Similar cells are grouped into units called tissues.

• Many groups of tissues working together form an organ.

• A group of organs that work together to perform a particular function is called an organ system.

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cells

tissue

Organ system

organ

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Muscle CellMuscle Tissue

Organ

Organ System

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CORK CELLS

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THE CELL THEORY

• In 1838, German botanist Matthias Schleiden concluded that all plants were made of cells.

• In 1839, German biologist Theodor Schwann stated that all animals were made of cells.

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• In 1855, German physician Rudolf Virchow concluded that new cells could be produced only from the division of existing cells.

• These discoveries, confirmed by other biologist, are summarized in the cell theory.

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• CELL THEORY STATES…

1. All living things are composed of cells.

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

3. New cells are produced from existing cells.

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STOP & TWEET

• In the form of a text or tweet write the cell theory in 80 characters or less.

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PROKARYOTES and EUKARYOTES

• Cells fall into two categories, depending on whether they contain a nucleus.

1. Eukaryotes (YOUkaryotes)- means “true nut.” Eukaryotes contain a nucleus

2. Prokaryotes (Pro=Before)- means “before nut.” Prokaryotes do not contain a nucleus

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PROKARYOTIC CHARACTERISTICS

• Smaller than eukaryotic cells

• Genetic info is not in a nucleus.

• Some have a few internal membranes

• Less complex than eukaryotic cells

• They DO grow, reproduce, and respond to their environment.

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Some Prokaryotes move with:

1. Cilia – hair like structures

2. Flagella – whip like structure. (sperm)

• Examples: Bacteria

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EUKARYOTIC CHARACTERISTICS

• Larger than prokaryotes

• Contain many structures and internal membranes.

• Genetic info is contained in a nucleus.

• Some live alone. Others live in vast multicellular organisms.

• Examples: plants, animals, fungi, and protists.

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Compare and Contrast

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Prokaryotes Eukaryotes

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PARTS OF THE CELL

• The two main parts of the cell are: the nucleus and the cytoplasm.

• The cytoplasm is the portion of the cell that is outside the nucleus.

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THE NUCLEUS• The nucleus is the control center of the

cell.

• contains the cell’s DNA and the code for making proteins and other important molecules.

• is surrounded by a nuclear envelope composed of two membranes. The envelope is dotted with thousands of pores, which allow materials to enter and leave the cell.

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• Has a granular substance called chromatin.–Chromatin consists of DNA bound

to protein.

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• When a cell divides, the chromatin condenses to form chromosomes.

• These are the distinct structures that are passed from cell to cell…generation to generation.

• Deep inside the nucleus is the nucleolus which is where assembly of ribosomes begins.

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Topic Comparison

• Organelles– Nucleus– Nuclear Envelope– Nuclear pores– Nucleolus– Chromatin– Cytoplasm

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7-2 Eukaryotic Cell Structure

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RIBOSOMES

• Ribosomes make proteins. VERY IMPORTANT JOB!!

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• Ribosomes are small particles of RNA and protein found throughout the cytoplasm.

• Ribosomes produce proteins by following coded instructions that come from the nucleus.

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? QUESTION ?

• WHAT DO RIBOSOMES PRODUCE ?

• ANSWER: PROTEINS

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ENDOPLASMIC RETICULUM

• The endoplasmic reticulum is called the ER. It is the site where lipid components of the cell membrane are assembled, along with some proteins and other materials.

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• The portion of the ER involved in synthesis of proteins is called Rough ER.

• Rough ER = ribosomes found on the surface.

• Newly made proteins (membrane, lysosomal, and excreted) leave ribosomes and are inserted into the Rough ER, where they can be chemically modified.

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• There are other parts of the ER called Smooth ER because it does not have ribosomes.

• Smooth ER contains enzymes which synthesize lipids and are involved in the detoxification of drugs. (liver cells contain a lot of Smooth ER)

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? QUESTION ?

• WHAT IS THE ROLE OF THE ROUGH ER ?

• ANSWER: TO SYNTHESIZE PROTEINS

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GOLGI APPARATUS

• The Golgi Apparatus receives proteins from the Rough ER.

• The job of the Golgi Apparatus is to modify, sort, and package proteins for storage or secretion outside the cell. – The Golgi Apparatus is like a

customizing shop that puts on the final touches before proteins are shipped out.

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? QUESTION ?

• Explain what service in Sugarland would be synonymous with the golgi apparatus (golgi body) in the cell?

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LYSOSOMES

• Lysosomes are the clean up crew of the cell.

• They contain enzymes that break down and digest lipids, carbohydrates, and proteins.

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? QUESTION ?

• WHAT IS THE ROLE OF THE LYSOSOME ?

• ANSWER: CLEAN UP THE CELL AND GET RID OF WASTE MATERIALS.

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VACUOLES

• Vacuoles are structures that store materials such as water, salts, proteins, and carbohydrates.

• Plant cells have vacuoles. They help each cell maintain water pressure to hold up heavy structures such as leaves and flowers.

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• Some single-celled organisms have contractile vacuoles which regulates the water inside the cell.– Contractile vacuoles help cells

maintain Homeostasis (“internal balance”)

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Contractile Vacuole

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? QUESTION ?

• WHAT IS THE ROLE OF A VACUOLE ?

• ANSWER: THEY STORE MATERIALS AND HELP PLANTS MAINTAIN THEIR STRUCTURE.

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CELLS AND THEIR POWER

• Nearly all eukaryotic cells, including plants contain Mitochondria.

• Mitochondria are organelles that convert the chemical energy stored in food into compounds that are more convenient.

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• Be sure to thank your mother because almost all of your cells’ mitochondria came from her!!! They come from the cytoplasm of the ovum, or egg cell.

• In plants chloroplasts are the organelles that capture the energy from the sunlight and convert it into chemical energy in a process called photosynthesis.

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• In plants chloroplasts are the organelles that capture the energy from the sunlight and convert it into chemical energy in a process called photosynthesis.

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• Both chloroplasts and mitochondria are the only organelles that have small DNA molecules.

Scientists believe that these two organelles may have been descendants of ancient prokaryotes at one time.

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CYTOSKELETON

• The cytoskeleton is a network of protein filaments that help the cell maintain its shape.

• Microfilaments are threadlike structures and made of a protein called actin.

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• Microtubules are hollow structures that are made up of proteins called tubulins.

• In animal cells, microtubules help develop centrioles, which are located near the nucleus and help in cell division.

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CELL MEMBRANE

• The cell membrane regulates what enters and also leaves the cell AND also provides protection and support.

• The cell membrane is made up of a phospholipid bilayer.

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CELL WALL

• Many cells also produce a strong supporting layer around the membrane known as the cell wall.

• Cell walls are present in plants, algae, fungi, and many prokaryotes.

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

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CELL WALL

Cell Wall vs. Cell Membrane

Compare and contrast the cell wall and the cell membrane.

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