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Biology 12. Introduction to the Cell. Cells. Recall from grade 11: All living things....plants, animals, fungi, bacteria and protists ...share a number of characteristics They move, take in nutrients, excrete wastes, respire, reproduce, grow, respond to stimuli

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biology 12

Biology 12

Introduction to the Cell


Recall from grade 11:

  • All living things....plants, animals, fungi, bacteria and protists...share a number of characteristics
  • They move, take in nutrients, excrete wastes, respire, reproduce, grow, respond to stimuli
  • They are all made of 1 or more cells, containing DNA
the cell theory
The Cell Theory
  • All living organisms are made up of 1 or more cells
  • The cell is the basic unit of life
  • All cells come from the division of pre-existing cells
cell trivia
Cell Trivia
  • Average size of a cell?

0.001 cm = 0.1 mm = 10 um

    • Smallest cell?

0.3 um = a mycoplasm

    • Largest cell?

Some algae are 2-3 cm; egg of a chicken is 1 cell


Draw an ‘O’ on your page....

    • 40,000 red blood cells (rbc) in that circle
    • Make 2.5 million new rbc’s/second
  • Draw a 1 cm square on your arm...
    • 150,000 skin cells in that square
  • How many cells are in your body?
    • 50-100 trillion cells
prokaryote vs eukaryote
Prokaryote vs. Eukaryote
  • Bacteria cells
  • No nucleus (DNA loose in cytoplasm)
  • No membrane-bound organelles (have ribosomes)
  • Outer covering is chemically different
  • Animal, plant, fungus & protist cells
  • DNA always in the nucleus
  • Many membrane-bound organelles (nucleus, chloroplast, ER, Golgi apparatus, etc..)
  • Outer covering is chemically different
the b ig idea for this unit
The big idea for this unit
  • The cell is the basic unit of life
  • Living cells are composed of elements that form large, complex molecules
  • These molecules are arranged into the functional units of the cell called ORGANELLES
  • We can see how the cell operates by understanding how each organelle functions and how they work together.
let s see what you remember from good old grade 9
Let’s see what you remember from good old grade 9…..
  • Find a group of 3 or 4
  • Draw a cell (plant or animal) and label as many organelles as you can remember.
  • Describe the functions of the organelles you have drawn
  • Trade with another group and add to theirs if needed
cell structures

Cell Structures

(note: the letters beside the structure names refer to the cell diagrams.)

cell structures1
Cell Structures

For each of the cell structures, you need to know their…

  • Basic structure
  • Function(s)
  • How functions relate to other structures
  • Picture
  • Electro micrograph picture
cytoplasm x
  • Semifluid medium that contains all the organelles.
  • The “filler” of the cell.
cell membrane a
Cell Membrane (a)
  • Phospholipid bilayer
  • has proteins embedded in it
  • (More on this next week)
cell membrane a1
Cell Membrane (a)
  • Regulates materials that enter and leave cell
  • Recognition of foreign cells and materials
  • Allows cells to adhere (stick) to each other
  • Carries messages and info to other cells
  • Provides the cell with support, structure, shape, and strength
  • Responds to the environment (ex. touch)
cell wall b
Cell Wall (b)
  • Only in plant cells
  • Made of cellulose
  • Makes a strong “box” around outside of cell which provides structure and supports the cell shape
nucleus c
Nucleus (c)
  • The nucleus is a complex structure.
  • It is full of important structures, such as nucleoplasm, chromatin and the nucleolus
chromatin ch
Chromatin (ch)
  • Threads of DNA that are suspended in the nucleoplasm (a semi-fluid just like the cytoplasm).
  • When chromatin coils up it will form chromosomes.
nucleus c1
Nucleus (c)
  • 2 main functions
    • Contains DNA: DNA carries genetic information from one generation to the next
    • Control center of cell (it contains the “blueprints” for making proteins & dictates which proteins are produced in the cell – therefore controlling the chemical reactions of the cell and body)
nucleolus d
Nucleolus (d)



  • Located in the nucleus

(may be one or more)

  • rRNA (ribosomal RNA) is made in the nucleolus
    • Then rRNA joins with proteins to make RIBOSOMES (g)
  • Thus, it is the site of ribosome synthesis
nuclear membrane e
Nuclear Membrane (e)
  • Surrounds the nucleus
  • Double membrane = 2 phospholipid bilayers
  • Nuclear Pores (f): openings that allow materials in and out
nuclear membrane e1
Nuclear Membrane (e)
  • It controls what materials enter and leave the nucleus
ribosomes g
Ribosomes (g)
  • Made of 2 components
    • Protein & rRNA (ribosomal RNA)
  • They are the site of protein synthesis (where proteins are made)
  • Exist as either free in cytoplasm

or bound to ER

ribosome g
Ribosome (g)
  • Bound ribosomes are attached to the ER (rough ER) & normally make proteins used in cell membrane or transported out of cell
  • Free ribosomes are suspended in the cytoplasm and usually make proteins used within the cell
  • In both cases, ribosomes are not usually loose but in clumps called polysomes
endoplasmic reticulum er h i
Endoplasmic Reticulum “ER” (h,i)
  • The phospholipid bilayers are in the shape of flattened membranous tubes or tunnels and extend throughout the cell
  • Rough ER (h) has ribosomes attached, smooth ER (i) does not
  • Rough ER is basically

an extension of the

nuclear membrane

endoplasmic reticulum
Endoplasmic Reticulum
  • 3 main functions:
    • Makes/ manufactures materials (proteins, lipids, carbohydrates etc.)
      • RER makes proteins (h)
      • SER makes lipids/ involved in carb metab. (i)
    • Begins to modify proteins
      • Ex. Adding a sugar chain to it (now called glycoprotein)
    • Transportation—moves materials from 1 part of the cell to another (ex. takes materials like proteins to Golgi Apparatus)
golgi apparatus j
Golgi Apparatus (j)
  • Series of phospholipid bilayer (membranes) that appear to be stacked on top of each other (like pancakes)
golgi apparatus j1
Golgi Apparatus (j)
  • Cis Face (side facing ER):
    • Processing = modifying materials such as those received from ER
      • Ex. joins things to the protein or lipid, changing them to their final form
    • Packaging = puts final product into a vesicle for export
  • Trans Face (side facing away from ER):
    • Ships material off to cytoplasm and cell membrane
vacuoles k
Vacuoles (k)
  • Phospholipid bilayer surrounding something (food, chemicals, fat, water, hormones, proteins)
  • Function: Stores materials and moves them from one place to another
  • Vesicle: a small vacuole! (L)
lysosomes m
Lysosomes (m)
  • Special type of vacuole/ vesicle that contain enzymes (break down materials)
    • Break down materials like food
    • Some enzymes break down invaders, cell debris, foreign material
peroxisomes n
Peroxisomes (n)
  • A special type of vacuole that contains enzymes which detoxify alcohols, metabolize fatty acids and other materials, breakdown peroxides
  • Often found attached to smooth ER
  • Large number of peroxisomes (and smooth ER) found in liver and kidney to detoxify materials
mitochondria o
Mitochondria (o)
  • Surrounded by 2 phospholipid bilayers

(double membrane)

  • Has its own DNA: can be independent and replicate itself


  • Makes energy for the cell (location where cellular respiration occurs to make ATP (ATP is the cell’s energy currency)
mitochondria o1
Mitochondria (o)

Consists of:

  • An outer membrane (p)
  • An inner membrane (q)that is highly folded (called cristae) (r)
  • The matrix (the inner

fluid-filled space) (s)

  • Only plant cells have plastids
  • Surrounded by a double membrane
  • Have their own DNA
  • Different types of plastids that contain different chemicals
    • Ex. Chloroplast (contains chlorophyll) (t)
    • Ex. Leucoplast, chromaplast
microtubules and microfilaments
Microtubules and Microfilaments
  • Long, thin rods made of protein
  • If protein makes a coil or thread structure = a microfilament
  • If protein is in a tube/ tunnel = microtubule
  • Give the cell shape and causes movement—can move whole cells (cilia & flagella) or things inside (centrioles & cytoskeleton)

Centrioles (w)

  • Only found in animal cells
  • Seen during cell division, when chromosomes pull apart.
    • Made of microtubules in a

specific arrangement