Cell Biology
Chapter 4
Question
• How does the nucleus, ribosomes, ER.
Golgi apparatus and vesicles all work
together???
History of the Cell
• Cell theory
– 1. All living things made up of 1+ cells
– 2. Cells basic unit of structure & function
– Cells come from preexisting cells
Scientists contribution to cell
theory
•
•
•
•
•
Hooke
Leeuwenhoek
Schleiden
Schwann
Virchow
Cell shape, size, & function
• Cells have variety of shapes and sizes
to suit function
• Ex. Nerve cell, skin cell
Cell size
• Size of cell limited by surface area: volume
ratio
• As cell grows volume (amount of “stuff”
inside cell) increases faster then surface
area (area around the cell)
• Eventually volume increases more then
surface area and materials needed by cell
can’t get across surface of cell fast enough to
meet cell’s needs
• This is when they should divide
Calculate surface area
• Surface area = length squared x # sides
• Smaller cells exchange substances
more readily because higher surface
area: volume ratio
• Ex. Calculate volume and surface area
of cube 2 cm x 2 cm x 2 cm
Surface area
• SA = 2cm x 2 cm x 6 (number of sides)
Volume
• Volume = L x W X H
• 2cm x 2 cm x 2 cm
Surface area: volume
• SA = 2cm X 2 cm x 6 = 24 cm 2
• Volume= 2cm x 2 cm x 2 cm = 8 cm3
• SA: volume ratio = 24:8 (or 3:1)
• Now calculate this using a 5 cm cube
Ratio
• If the ratio is lower or numbers are
closer together- it harder for exchange
• Ex. 3:1 vs. 24:1
• Which will get things across the cell
quicker?
• The 24:1
Homework
• Calculate a surface area: volume ratio for a 5
cm cube.
• Calculate a surface area: volume ratio for a
10 cm cube.
• Which will bring things into the cell easier?
Why?
• The red blood cell is the smallest of human
cells, why is this an advantage?
Basic Parts of the cell
1.
2.
3.
4.
Plasma membrane
Cytoplasm
Nucleus
ribosomes
Phospholipid bilayer
membrane
1. Function- barrier, selectively permeable
2. Structure - bilayer fo phospholipids with
protein and carbohydrates
fluid mosaic model, because molecules
floating inside the cell membrane
Phospholipid bilayer cont…
• Phosphate - attracted to water, called
hydrophilic
• Lipids - not attracted to water, so
hydrophobic
• The phosphates are always toward the
water and the lipids toward each other
Proteins in the cell membrane
•
2 types
1. Peripheral
•
Usually have carbohydrate marker attached
to them, or used as a receptor for information
2. Integral
1. Protein embedded through the cell membrane
Used for transportation “secret passage way”
Cytoplasm
•
•
•
Jelly like material between nucleus
and plasma membrane
Includes fluid and all organelles
2 parts of cytoplasm
1. Cytosol - everything in cytoplasm except
organelles
2. organelles
Nucleus
• Within eukaryotic cell
• Contains DNA which regulates cells
functions
Ribosomes
• Small round nonmembranous structure
• Site of protein synthesis
• On RER (if it has one) and in cytoplasm
Two basic types of cells
1. Prokaryotic -
2. Eukaryotic
Cellular organization
• Unicellular
• Colonies
• multicellular
Cell organelles
• Functions
• Structures
• Use flash cards to study these
Plant vs. Animal cells
• 3 structures found in plants and NOT in
animal cells
– 1. Cell wall
– 2. Large central vacuole
– 3. Plastids
Cell Wall
• Outside cell membrane
• Made of cellulose
• Humans can’t digest cellulose but it
helps our dig. tract
• Secondary wall strong and can’t expand
– Ex. Wood on bark of tree
Central Vacuole
• Stores large amounts of water
• Contains enzymes, waste, etc..
• Formed by smaller vacuoles fusing
together
• Pushes organelles off to side
• When full, cells expand and plant
stands upright
• If not full - wilting
Plastids
•
•
Has own DNA (like mitochondria)
3 types
1. Chloroplasts - used to make nrg - green
pigment
2.chromoplasts - colorful pigments
•
(see when leaves change colors)
3. Amyloplasts - store starch (nrg source)
Prokaryotic vs. Eukaryotic
Cells
• Prokaryotic
–
–
–
–
No nucleus
No membranous organelles
Smaller
Have nucleoid (area where DNA is found)
• Eukaryotic
– Nucleus
– Membranous organelles
– Larger
Similarities
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•
•
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Cytoplasm
DNA
Cell membrane
Ribosomes