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Cells

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Title: Cells


1
Cells
2
Discovery of the Cell
  • In 1665, Robert Hooke was one of the first people
    to see and identify cells.
  • He used a microscope to look at thin slices of
    cork. The cork was made of thousands of tiny
    chambers.
  • He called the chambers cells b/c they reminded
    him of a monasterys tiny rooms, called cells.

3
Robert Hooke
4
The Cell Theory
  • Proposed by 3 scientists in the mid-1800s
  • All living things are made of cells.
  • Cells are the basic unit of structure and
    function in living things.
  • New cells are produced from existing cells.
  • The cell theory applies to ALL living things!

5
Prokaryotes and Eukaryotes
  • Prokaryote
  • Do not have a nucleus
  • Small and simple
  • Bacteria are prokaryotic
  • Eukaryotes
  • Have a nucleus
  • Larger and complex
  • Cells of protists, fungi, plants, and animals are
    eukaryotic

6
Prokaryotes and Eukaryotes
  • Eukaryotic Cell
  • Prokaryotic Cell

7
Cell Structure
  • Eukaryotic cells are divided into two major parts
    the nucleus and the cytoplasm.
  • The cytoplasm is the portion of the cell outside
    the nucleus, but inside the cell membrane.

8
Cell Structure
  • Eukaryotic cells contain many structures, each
    with specialized functions. These specialized
    structures are called organelles.

9
Cell Structure - Nucleus
  • Contains almost all of the cells DNA the DNA
    contains genetic info and instructions for making
    proteins
  • Controls the cells processes/activities
  • The DNA exists as chromatin when the cell isnt
    dividing. Chromatin consists of DNA and protein.
  • Double membrane

10
Cell Structure - Nucleolus
  • Inside the nucleus is a structure called the
    nucleolus.
  • The nucleolus manufactures ribosomes.

11
Cell Structure - Ribosomes
  • Ribosomes are tiny organelles that manufacture
    proteins.
  • Ribosomes are located on rough endoplasmic
    reticulum and throughout the cytoplasm.

12
Cell Structure Endoplasmic Reticulum
  • ER transports substances throughout the cell.
  • Rough ER has ribosomes on it, so it produces
    proteins.
  • Smooth ER lacks ribosomes

13
Cell Structure Golgi Apparatus
  • Closely-stacked membranes
  • Modify, sort, and package proteins and other
    materials from the endoplasmic reticulum for
    storage in the cell, or secretion outside the
    cell.

14
Cell Structure - Lysosomes
  • Lysomes are small sacs filled with digestive
    enzymes.
  • These enzymes break down macromolecules into
    small molecules .
  • They also break down old, worn-out organelles.
    They clean up the cell.

15
Cell Structure - Vacuole
  • Large sac-like organelle in plant cells
  • Stores water, carbs, proteins, and salts
  • Is usually the largest organelle in plant cells

16
Cell Structure - Mitochondria
  • Convert the chemical energy stored in food into
    compounds that are more convenient for the cell
    to use.
  • Powerhouse of the cell
  • Double membrane

17
Cell Structure - Chloroplasts
  • Not found in animal or fungi cells
  • Capture energy from sunlight and convert it into
    chemical energy in a process called
    photosynthesis.
  • Double membrane

18
Cell Structure - Cytoskeleton
  • In all cells, the cytoskeleton maintains the
    shape of the cell
  • Cilia and flagella (extensions of the
    cytoskeleton) help some cells swim through water.

19
Cell Structure - Cytoskeleton
  • Cilia
  • Flagella
  • Numerous
  • Short and hair-like
  • Help unicellular organisms
  • Help multicellular organisms rid organs of dust
    and move mucous
  • Usually a cell only has one
  • Long and whip-like
  • Help unicellular organisms swim in liquids

20
Cell Structure cell membrane
  • Regulates what enters and leaves the cell
  • Double layer of phospholipids
  • Fluid mosaic model (not rigid)
  • Selectively permeable

21
Cell Structure Cell Wall
  • Not present on animal cells
  • Rigid made of cellulose and protein
  • Support and protect the cell

22
Plant vs. Animal Cells
  • Plant cells
  • Animal Cells
  • boxy
  • Often green
  • Contain chloroplasts, vacuole, and cell wall
  • Variety of shapes depending on function
  • May contain structures for movement (cilia and
    flagella)

23
Plant Cells
24
Animal Cells
25
Transport Across Cell Membrane
  • Passive transport requires no energy input from
    cell (Ex. Osmosis, diffusion, facilitated
    diffusion)
  • Active transport requires energy input to move
    molecules across the cell membrane

26
Moving Across the Cell Membrane(Passive)
  • Diffusion is the movement of particles (solutes)
    from an area of greater concentration to an area
    of lesser concentration.
  • When the concentration of solutes on both sides
    of the cell membrane is the same, equilibrium
    exists.
  • When equilibrium is reached, solute particles
    still continue to move across the membrane in
    both directions.

27
Moving Across the Cell Membrane
28
Moving Across the Cell Membrane
  • Osmosis is the diffusion of water across a
    membrane.

29
Hypotonic if concentration of dissolved
particles is lower outside of cell compared to
inside
  • Isotonic if concentration of dissolved particles
    is the same outside of cell compared to inside
  • Hypertonic if concentration of dissolved
    particles is higher outside of cell compared to
    inside

30
Moving Across the Cell Membrane
  • Osmotic Pressure
  • What would happen to a cell if it were placed in
    an isotonic solution?
  • What would happen to a cell if it were placed in
    a hypertonic solution?
  • What would happen to a cell if it were placed in
    a hypotonic solution?

31
Moving Across the Cell Membrane
32
Movement Across the Cell Membrane
  • During facilitated diffusion, molecules that
    cannot cross the cell membrane by themselves b/c
    they are too big, get help from protein channels
    in the membrane.
  • Uses transport protein

33
Endocytosis and Exocytosis
  • Endocytosis
  • Exocytosis

34
Movement Across the Cell Membrane
  • Sometimes, cells must move substances in the
    opposite direction of diffusion against the
    concentration gradient To move substances from a
    low concentration to a higher concentration
    requires energy. This requires active transport.
  • Uses transport protein

35
Cell Diversity
  • Unicellular Organisms
  • Multicellular Organisms
  • Made of only one cell
  • Made of many cells

36
Cell Diversity
  • Multicellular organisms are made of many, many
    specialized cells. In cell specialization, the
    cells of a multicellular organism develop in
    different ways to perform different tasks in the
    organism.

37
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38
Levels of Organization
  • In multicellular organisms, the levels of
    organization of the body are (from simplest to
    most complex)
  • Cells
  • Tissues - a group of similar cells that perform a
    particular function (ex nervous, connective,
    epithelial, and muscle)
  • Organs - a group of tissues working together to
    perform a specific function (ex heart, pelvis,
    uterus)
  • Organ systems group of organs working together
    to perform a specific function (ex
    cardiovascular system, reproductive system)
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