Cell Unit Notes

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¢  All living things are made up of cells

¢  Cells are the basic units of structure and function

in living things

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¢  Cells come in many different shapes and sizes

¢  The human eye can see things larger than 0.5

mm or 50o um

¢  In general, cells are much smaller than this and

so microscopy is critical for understanding the world on a cellular scale

¢  http://learn.genetics.utah.edu/content/begin/cells/

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¢  Prokaryotic cells are those that do not enclose

their DNA inside of a nucleus

¢  Generally small and simple

¢  Organisms with prokaryotic cells

are called prokaryotes.

¢  Bacteria are examples of

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¢  Eukaryote cells are those that do

enclose their DNA inside of a nucleus

¢  These cells are generally much

more complex with many internal structures

¢  Eukaryotes are very diverse.

Some are single celled (like yeast) and many others are multicellular like plants,

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¢  About 100 trillion, but most of them are bacteria

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¢  Cell Membrane – encloses the

cell. We will visit it later

¢  Cytoplasm – the area inside of

the membrane but outside of the nucleus. It contains many

different ___________ (specialized structures).

¢  Nucleus – generally the most

prominent organelle.

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¢ For an organism to grow, it’s cells could get

bigger, or the cells could divide..

¢ They divide when they reach a certain size.

¢ Cells must maximize their surface to volume

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¢  Process by which one cell divides into two

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¢  Cell Cycle - Cell growth and division.

—  Does this happen once you stop growing?

¢  Apoptosis – programmed cell

death

¢  Both normal and tightly

regulated processes

¢  If unregulated, problems

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¢ Cells divide only about 50 times

¢ Only stem cells and cancer cells

can divide endlessly

¢ This allows growth of the

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¢ Two main phases with

sub-phases:

—  Interphase - cell growth and

preparation for division

¢ G1, S, G2

—  Cell Division

¢ Mitosis- division of the nucleus and

DNA

¢ Prophase, Metaphase, Anaphase,

Telophase

¢ Cytokinesis - division of the rest of the

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¢  DNA needs to be exposed to give

information to the cell

¢  But, it needs to be tightly packaged to

be portable from parent cell to daughter cell

¢  Tightly packed DNA = chromosome

¢  Chromosomes are often shown already

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¢  Nearly all of your cells have 46 chromosomes. 23 from

your mom and 23 from your dad

¢  In preparing for cell division, each cell has 2 copies of

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¢ Normal cells will divide until they come into

contact with other cells.

¢ When cells make contact, they respond by not

growing.

¢ So, cell growth and division can be turned on

and off.

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Example of Contact Inhibition

C op yr ig h t Pea rs on Pr en ti ce Ha ll

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¢  Cancer is a disorder in which some of the body's own

cells lose the ability to control growth.

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¢  Cancer is uncontrolled, or unchecked growth and

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¢  They have internal growth signals

¢  They do not undergo

apoptosis

¢  Can build their own

blood supply (angiogenesis)

¢  They have No contact

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¢  1920-1951

¢  Died of Cervical Cancer

¢  Her cells are still used by scientists all

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¢  Single-celled

¢  Made of Prokaryotic Cells

—  No nucleus or other

organelles

¢  Other Features

—  Can have cell wall and/or capsule

for protection.

—  Can have Flagella for locomotion

—  Can have pili for communication

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¢  Can be single or multi-cellular

¢  Made of eukaryotic cells

—  Have a nucleus and other organelles

¢  Other Features

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¢  Can be single or multi-cellular

¢  Made of eukaryotic cells

¢  Other Features

In order for plants to maintain shape without a Skeleton, their cells:

—  Are surrounded by a cell wall

—  Contain a central vacuole

—  Contain chloroplasts (which

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¢  Can be single, but mostly multi-cellular

¢  Made of eukaryotic cells

¢  Other Features

—  Contain a cell wall

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¢  Only multi-cellular

¢  Made of eukaryotic cells

¢  Other features

—  Do not contain a cell wall

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¢  There are many different

cell types.

¢  Cells combine to form

tissues.

¢  Tissues combine to form

organs.

¢  Organs combine to form

Organelle Erythrocyte (Red Blood Cell) Macrophage (White Blood Cell) Hepatocyte Beta Cell Sperm

Cell Neuron Fibroblast

Nucleus 0 75 50 50 25 50 50 Ribosome 50 50 300 175 50 300 275

Endoplasmic

Reticulum 0 50 350 175 0 400 350

Golgi 0 75 100 400 0 350 300 Lysosome 30 350 75 50 100 150 25

Microtubules

(Cytoskeleton) 150 400 125 150 600 150 75

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¢  In addition to protection

and structure

¢  Membranes control what

goes in and out of cells or in and out of the

membrane bound

organelles inside of cells

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¢  Easily pass the lipid bilayer:

—  Gasses

¢  Can not pass the lipid bilayer:

—  Most biological molecules

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¢  Any substance will move DOWN its concentration

gradient (from an area of high concentration to an area of low concentration

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Passive Transport

• 

No energy required

Movement down (or

with) the

concentration

gradient

•  Diffusion

•  Osmosis

Animation 6.2

Active Transport

• 

Energy required

Movement up (or

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¢  Diffusion of water

across a plasma

membrane when an unequal

concentration of water exists

¢  Animation 6.2

•  If only water can cross this

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¢  We can compare the concentrations of solutes

between different solutions using these words:

—  Hypertonic –higher concentration of solutes

compared to another solution

—  Hypotonic –lower concentration of solutes

compared to another solution

—  Isotonic –equal concentrations in both

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¢  What happens if I place a cell into a hypertonic

solution?

¢  What happens if I place a cell into a hypotonic

solution?

ISOTONIC

SOLUTION HYPOTONIC SOLUTION HYPERTONIC SOLUTION

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¢  Remember the Mystery Solution??

¢  Water moves

—  Toward less water

—  Toward more solutes

¢  Solutes move

—  Toward more water

Q

9/25

1.  The _________ is the organelle where cell energy is made.

2.  The _________ is the control center of the cell.

3.  Which biomolecule is contained in the nucleus?

4.  The ribosome makes (carbohydrates / proteins).

5.  If the eye piece has a magnification of 10X and the

objective has a magnification of 15X, what is the total magnification?

6.  The diaphragm allows you to adjust the amount of

_________ that enters the microscope.

7.  Humans are an example of (eukaryotes / prokaryotes). anaphase, prophase, telophase, metaphase, cytokinesis

8.  Which stage of mitosis is first?

9.  During which phase does division of the

cytoplasm happen?

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¢  Prokaryotic cell

¢  Eukaryotic cell

¢  Cell Membrane

¢  Cytoplasm

¢  Nucleus

¢  Organelle

¢  Diffusion

¢  Osmosis

¢  Cell Division

¢  Cell Cycle

¢  Mitosis

¢  Cancer