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Recap. Biochemistry If you had to boil the previous unit down into four main ideas, what would they be?. Pre-Assessment. 1. What are the differences between a bacterial cell and one of your cells? 2. Rank these in order from smallest to largest: Organism, organelle, atom, cell

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  • Biochemistry

    • If you had to boil the previous unit down into four main ideas, what would they be?

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  • 1. What are the differences between a bacterial cell and one of your cells?

  • 2. Rank these in order from smallest to largest: Organism, organelle, atom, cell

  • 3. Name as many cell organelles as you know.

  • 4. How do things get in and out of a cell?

  • 5. The earliest cells that evolved were most similar to which: animal, plant, or bacteria cells?

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Chapter 7: Cell Structure and Function

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Section 7-1:Life is Cellular

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Two Categories of Cells:


  • Small and simple cells

  • Do NOT contain a nucleus

  • Do NOT contain membrane-bound organelles

  • NEVER multicellular

  • Examples: bacteria


  • Large and complex cells

  • Contain a nucleus

  • Contain membrane-bound organelles

  • Some multi-, some uni-

  • Examples: animals, plants, fungi, protists

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Prokaryote or Eukaryote?

  • Eukaryote (Paramecium, a protist)

200 µm long

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Prokaryote or Eukaryote?

  • Prokaryotes (Streptococcus bacteria)

Each = .7 µm (micrometers) diameter

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Prokaryote or Eukaryote?

  • Eukaryote (Homo sapiens dermis)

Each = 250 µm long

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Prokaryote or Eukaryote?

  • Prokaryotes (Spirillum bacteria)

Each = 30 µm long

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Prokaryote or Eukaryote?

  • Eukaryote (Onion Allium cepa root)

Each = 350 µm long

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Prokaryote or Eukaryote?

  • Eukaryote (Rat adrenal gland tissue)

Each = 350 µm long

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Categories of Cells

  • The first cells to evolve on earth most closely resembled modern-day prokaryotes.

  • Eukaryotes first evolved more than 1 billion years later.

    • Pro = Latin prefix meaning “forward”

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Section 7-2Cell Structures

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Cell Structures

  • FYI

    • Cell organelle = Specialized cell part with a specific function. “Little organ.”

  • What you must know about each cell organelle:

    • Its function

    • Its appearance and location in the cell

    • What kinds of cell have it (prokaryotes (bacteria) vs animals vs plants vs fungi vs protists)

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Cell Membrane

  • Thin, flexible barrier around the cell

  • Regulates what enters and exits the cell

  • Food & water pass into cell, wastes pass out

  • ALL cells have one

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Cell Wall

  • Found in plants, fungi, and bacteria but NOT animal cells

  • Lies outside the cell membrane

  • Made from fibers of carbohydrate (cellulose) and protein

  • Provides support and protection for cell, no regulation function like cell membrane

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  • The “goo” that the inside of the cell is filled with, and all the interior organelles

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  • Network of protein filaments called microtubules and microfilaments

  • Microtubules:

    • move organelles

      within the cell

    • help with cell

      movement (cilia/flagella)

  • Microfilaments:

    • help maintain cell


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Movement Organelles

  • Three modes of cell movement:

  • Cilia

    • Short hairlike microtubules

  • Flagella

    • Long whiplike microtubules

  • Pseudopods

    • Projections of cell cytoplasm

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  • stores genetic information (DNA) which controls most cell processes

    Parts of the nucleus:

    • Nucleolus – small dense region in the nucleus where ribosomes are assembled

    • Nuclear Membrane – forms the outside of the nucleus, has thousands of nuclear pores that allow materials to move in and out of nucleus

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  • small particle made of RNA and protein

  • location of protein synthesis (where proteins are polymerized by bonding amino acids together in a chain)

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Network of folded membranes

Smooth ER:

No ribosomes

Assembles cell membrane lipids

Rough ER:

Covered w/ ribosomes

Chemically modifies proteins

Receives protein from ribosomes, sends it to golgi when done

Endoplasmic Reticulum (ER)

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Golgi Apparatus

  • Stack of membranes

  • Packages and marks proteins and other molecules for their final destination elsewhere in the cell

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  • small sac filled with enzymes

  • breaks down unwanted materials into smaller molecules that the cell can reuse

  • Breaks down: waste, debris, damaged organelles, invading or consumed bacteria

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  • small or large sac

  • stores materials like water, salts, proteins, carbohydrates

  • also can transport substances within cells

  • very large in plant cells

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  • in plants, some protists, some bacteria

  • conducts photosynthesis: uses energy from sunlight to make the energy-rich food molecule glucose

  • has a green pigment called chlorophyll

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  • Plural: mitochondria

  • extracts energy from food molecules to “charge up” ATP

  • Energy used to power cell growth, movement, reproduction, survival

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Coordinated Action

  • Cell organelles work together to achieve the cell’s survival functions, such as:

    • Getting energy to live and do nearly everything else on this list

    • Maintaining the cell’s structure

    • Protect the cell

    • Making proteins

    • Building and repairing other organelles

    • Disposing of waste

    • Movement

    • Storing macromolecules produced

  • How many connections can YOU map out in a basic plant cell?

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Cell Membrane –

Cell Wall –

Nucleus –

Ribosome –

ER –

Golgi Apparatus –

Lysosome –

Vacuole –

Chloroplast –

Mitochondrion –

border patrol

fence surrounding the city

city hall


trucking company

post office

recycling center

storage company


power plant

A Cell Is Like A City

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Plant Cell

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Animal Cell

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Comparing Cells

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Organelle DNA

  • Chloroplasts and mitochondria have prokaryote DNA that’s essential for their function.

  • Lynn Margulis – discovered endosymbiotic theory, found that mitochondria and chloroplasts are actually descendants of ancient prokaryotes

  • Endosymbiosis – eukaryotic cells were first formed from a symbiosis among several different prokaryotic organisms

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Section 7-3Movement Through the Membrane

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Cell Membrane

  • Made of phospholipids and proteins.

    • Its structure determines its functions

    • Phospholipid:

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Cell Membrane

  • Hydrophilic = Attracted to water (“Loves” water)

  • Hydrophobic = Repelled from water (“Fears” water)

    • Phospholipid’s phosphorus “head” = hydrophilic.

    • Fatty acid tails = hydrophobic.

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Cell Membrane

  • What do phospholipids do in water?

  • Form a lipid bilayer (also called phospholipid bilayer)

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Cell Membrane

  • Lipid bi-layer is flexible, but hydrophobic/hydrophilic action makes it tough because it never parts or splits on its own.

  • “Semi-permeable” or “selectively permeable” = allows some substances to pass through but not others

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  • Fluid mosaic model

  • Membrane proteins run through the lipid bi-layer:

    • Channel Proteins – help transport materials in & out of cell

    • Receptor Proteins – receive chemical signals from outside cell

    • Marker Proteins – stick off cell surface to act as identification tags so cells can recognize one another

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Cell Membrane

  • Because the cell membrane is a hydrophilic/hydrophobic phospholipid bilayer, with transport protein channels inserted periodically, it has four ways for substances to pass through.

    • Know how each way works, and be able to tell the difference between them

  • Three of these ways happen through diffusion…

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Diffusion Across the Membrane

  • Diffusion = molecules move from an area of high concentration to an area of low concentration

    • Happens automatically because molecules are constantly moving. Molecules or cell don’t choose or make it happen.

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Diffusion Across the Membrane

  • Simple diffusion = The diffusion of small, non-polar, hydrophobic molecules through the membrane bilayer

    • Requires no energy

    • Only small molecules do it because only they can fit in between the phospholipids. Only non-polar, hydrophobic molecules can do it because the hydrophobic fatty acid tails will reject and repel hydrophilic molecules

    • Examples: oxygen and carbon dioxide

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Facilitated Diffusion

  • Facilitated diffusion – molecules diffuse across the cell membrane through channel proteins

    • Requires no energy

    • Used to allow molecules to diffuse that can’t go through simple diffusion (too big or hydrophilic)


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  • Osmosis – simple diffusion of water across a membrane

    • Requires no energy

    • Will change the water levels in a container, or the shape of a cell


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Osmotic Pressure

  • Isotonic solutions = The solutions on either side of the membrane have the same concentration

    • Osmosis in isotonic solution… Water moves in and out equally

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Osmotic Pressure

  • When the solutions do not have the same concentration… more concentrated solutes = hypertonic, less concentrated solutes = hypotonic

    • Hyper = High, like “hyperactive”

    • Hypo = Low, like “hypothermia”

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Osmotic Pressure

  • In hypertonic solution (outside of cell has more solutes),

    water flows out, cell shrivels.

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Osmotic Pressure

  • In hypotonic solution (inside of cell has more solutes),

    water moves in, cell swells.

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Osmotic Pressure

  • Which of these blood samples was placed in which kind of solution? Hypertonic, hypotonic, isotonic?

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Active Transport

  • Active transport – molecules move against a concentration gradient, from an area of low concentration to high concentration

    • Cell spends ENERGY and uses a transport protein to force molecules to move against the direction of diffusion.

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Types of Transport

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Types of Transport

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