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
(No Transcript)
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)