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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

Chloroplasts t
Chloroplasts (t)



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