1. Ch. 2:2 (pgs. 32-37) Cell Parts & Their Jobs
Unit 5: Inside the Cell
Ch. 2:2 (pgs ) Cell Parts & Their Jobs

2. Sizes & Shape of Cells How big/small are cells?
Vary (< ½ µm up to ~1 m)
smallest cells?
bacteria
largest cells?
eggs, nerve
Are cells 3-D or 2-D?
3-D
What shapes are cells?
many different
How big/small are cells? Vary in size Some < ½ µm (1 µm = 1/1000 mm or 1/1,000,000 m) some up to 1 m
What are some of the smallest cells? bacteria among the smallest
What are some of the largest cells? egg cells among the largest
Are cells 3-D or 2-D? 3-D
What shapes can cells be? spheres, cubes, or bricks
Can cells change shape? Many can change shape
What special features can cells have? Some have spikes, bulges, or other strange extensions

3. Why is there a limit to cell growth?
to keep surface area to volume ratio high
so diffusion can occur efficiently
Cells must constantly interact with their surrounding environment. important factor = rate of diffusion across membrane (must occur rapidly enough to supply the cell efficiently with needed materials & quickly remove wastes)
All areas of cell have to be served by part of the cell surface. As volume increase & membrane expands, volume increases more rapidly than surface area, so as cell gets bigger surface-to-volume ratio decreases.
If the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate increased volume. Cell must stop growing, or ideally, divide into smaller cells with higher surface area to volume ratios, otherwise it will cease to function.
WANT HIGH SA : Vol RATIO!!!

4. How can the surface area to volume ratio be increased?
cell division
if keep same overall volume, smaller cells have more surface area compared to one large cell
add folds or projections

5. 2 Main Types of Organisms
unicellular
How many cells?
one
How/where are cell processes carried out?
all by/in the one cell
examples?
bacteria, Amoeba, Paramecium, Euglena
multicellular
How many cells?
more than one
How/where are cell processes carried out?
cells specialize (÷ of labor)
examples?
human, tree,
zebra, bird,
fish, grass,
mushroom
Why can multicellular organisms be big if there is a limit to cell size? Multicellular organisms grow by making more cells, not increasing cell size
Why can multicellular organisms be big if cells need to be small?

6. Two Major Types of Cells
What are the two major types of cells?
prokaryotes
eukaryotes (YOU-karyote!)
similarities & differences?
Prokaryotes
*No nucleus
(single strand
of DNA)
*No mitosis
*No membrane-
bound organelles
Eukaryotes
*Nucleus
*Mitosis
*Membrane-bound organelles
both
*cell membrane
*cytoplasm
*ribosomes
*DNA
Similarities: Both have cell membrane & cytoplasm & DNA & ribosomes
Differences:
Prokaryotes No nucleus (DNA  single chromosome), so… does not undergo mitosis & no membrane-bound organelles contain ribosomes which synthesize proteins, but most metabolic functions take place in the cytoplasm
Eukaryotes (You – karyote!) Have a nucleus (DNA  multiple chromosomes), so… undergoes mitosis & has membrane-bound organelles

7. Two Major Types of Cells
examples?
prokaryotic
bacteria
eukaryotic
protists, fungi, plants, animals
Prokaryotes (pre/before nucleus)
Eukaryotes (true nucleus)
Vast majority of cells in living world are eukaryotic

8. Organization Within Eukaryotic Cells
Why might cells need to be organized?
not efficient to have all reactions happening in cytoplasm
How are they organized???
contained by cell membrane
have organelles
with membranes
do different jobs
cytoplasm
How are they organized???
Surrounded by cell membrane, organelles “floating” in cytoplasm
different structures have different functions Division of labor with organelles!
Many organelles are membrane-bound & are selectively permeable. Maintain separate environments in which particular sets of reactions can occur.

9. Eukaryotic Cell Organelles
*These can also be found in prokaryotic cells.
plant & animal cells
*cell (plasma) membrane
*cytoplasm
nucleus
nuclear membrane (envelope)
nucleolus
*ribosome
endoplasmic reticulum
golgi bodies (apparatus)
mitochondrion
cytoskeleton
vacuole
lysosome
plant cells
chloroplast
*cell wall
animal cells
*cilia & flagella
centrioles
Cilia
Flagella
*Cell membrane, cytoplasm, ribosomes, cell walls, & cilia/flagella can also be found in prokaryotic cells
Lysosome common in animals Uncommon in plants
Vacuole Few, large in plants Many, small in animals
Cilia & flagella Primarily in unicellular organisms (& some specialized cells of multicellular organisms)

10. Cell (Plasma) Membrane
Found in:
prokaryotic & eukaryotic cells
Functions:
boundary between cell & its environment
surrounds cell
acts as a gatekeeper
“selectively permeable”
Looks like:
fence w/ gates (around cell)
What does it mean that the cell (plasma) membrane is “selectively permeable”? It means that the membrane lets some things in/out & not others… & certain things are only let in/out at certain times. 10

11. Cytoplasm Found in: Functions: Looks like:
prokaryotic & eukaryotic cells
Functions:
organelles float in it
some chemical reactions happen in it
Looks like:
Jell-O
Gel-like substance filling much of cell (approx. 70% water)
Chemical reactions happen here (part of metabolism = sum of all chemical reactions & changes in cell)

12. Nuclear Membrane (Envelope)
Found in:
eukaryotic cells only
Functions:
boundary between nucleus & cytoplasm
acts as a gatekeeper
“selectively permeable”
Looks like:
fence w/ gates (around nucleus)
Nuclear membrane (envelope)—boundary btwn nucleus & cytoplasm; has double membrane w/ pores that let large molecules like RNA & proteins in/out
What does it mean that the nuclear membrane (envelope) is “selectively permeable”? It means that the membrane lets some things in/out & not others… & certain things are only let in/out at certain times.

13. Nucleus Found in: Functions: Looks like: eukaryotic cells only
“floats” in cytoplasm
Functions:
controls cell’s activities
contains DNA
Looks like:
an eyeball
Control Center for Cell

14. Chromatin & Chromosomes: Inside the Nucleus
Found in:
eukaryotic cells only
Functions:
genetic information
instructions for cell’s activities
chromatin looks like:
spaghetti
chromosomes look like: X
Chromatin (individual chromosomes) made of DNA & Protein (DNA = Genetic information)
Before cell divides, chromatin condenses into chromosomes (X-shapes) (which are copied before mitosis/cell division)

15. Nucleolus: Inside the Nucleus
Found in:
eukaryotic cells only
Functions:
Makes ribosomes/ RNA (ribonucleic acid)
Looks like:
iris (colored part) of eyeball
nucleus
can have more than one (plural = nucleoli)

16. Ribosome Found in: Functions: Looks like:
prokaryotic & eukaryotic cells
Functions:
synthesizes (makes) proteins from amino acids
Looks like:
pepper (dots)
Composed of RNA & protein
Thousands in cell (most common organelle in any cell, found in prokaryotic & eukaryotic cells)
Can be attached to (rough) endoplasmic reticulum or free in cytoplasm

17. Smooth Endoplasmic Reticulum (SER) & Rough Endoplasmic Reticulum (RER)
Found in:
eukaryotic cells only
Functions:
transports (mostly) proteins through cell
SER looks like:
bubble-letter “H”
RER looks like:
with pepper (dots)
ribosomes
Network of interconnected, flattened, tube-like membranes
Rough ER (RER) covered w/ ribosomes
Smooth ER (SER) Lacks ribosomes

18. Golgi Bodies (Apparatus)
Found in:
eukaryotic cells only
Functions:
packages, modifies & exports proteins within cell & out of cell
Looks like:
pancake stacks
often w/ drips of ends
Pancake stacks often w/ drips of ends (vesicles)
Stacks of flattened, slightly-curved, sac-shaped membranes; generally more disc-like & smaller than ER
Usually lies close to ER in order to receive proteins or other materials from ER

19. Why is the inner membrane highly folded?
Mitochondria
Mighty Mitochondria
Found in:
eukaryotic cells only
Functions:
“power house” of the cell
creates energy (ATP) through cellular respiration
Looks like:
hot dog w/ mustard
Why is the inner membrane highly folded? Allows greater surface area for making ATP (energy) during cellular respiration (more surface area = more energy that can be released)
Why is the inner membrane highly folded?

20. Cytoskeleton Found in: Functions: Looks like: eukaryotic cells only
shape & support
move organelles
Looks like:
beams in a house
Made of microtubules & microfilaments (proteins)

21. Vacuole Found in: Functions: Looks like: eukaryotic cells only
large vacuoles in plant cells
small vacuoles in animals cells
Functions:
store water, food, waste
maintain turgor pressure in plants
keeps cells “plump” & prevents wilting
maintain osmotic balance
prevents cell from bursting
contractile vacuole
Looks like:
swimming pool
Central vacuole Maintains turgor pressure in plants (keeps cells “plump” & prevents wilting)
Contractile vacuole Pumps water out of many unicellular freshwater protists like Paramecium
Why would these organisms need to pump out water? To avoid cytolysis… Adaptation b/c lives in hypotonic freshwater environment (which causes water to move into cell)
Paramecium

23. Lysosome Found in: Functions: Looks like: eukaryotic cells only
Lysosome animation
Found in:
eukaryotic cells only
primarily in animal cells
Functions:
contains digestive enzymes:
to breakdown:
large food molecules
old, worn out cell parts
Looks like:
stomach (w/ enzymes)
Small, round vesicles formed from golgi bodies that contain digestive enzymes
mostly in animals cells b/c must break down large food particles into glucose before it can be used in cellular respiration…. Plants make their own glucose during p’syn….

24. Chloroplast Found in: Functions: Looks like: eukaryotic cells only
Chloroplast Cyclosis
Chloroplast
Found in:
eukaryotic cells only
plants (& some protists)
Functions:
photosynthesis
makes glucose & oxygen
Looks like:
green solar panels
Green, oval-shaped plastids w/ double-membrane that contain chlorophyll (green pigment)
Found in plants & some protists (like algae & Euglena)

25. Cell Wall Found in: Functions: Looks like: prokaryotes some eukaryotes
bacteria
some eukaryotes
plants
algae
fungi
Functions:
protection
support
Looks like:
wall, box
Outermost boundary of some cells (outside of the cell/plasma membrane)
made of cellulose or chitin (carbohydrates)

26. Cilia Found in: Functions: Looks like: eukaryotic cells movement
some animals
some protozoa
Functions:
movement
sometimes sensing the environment
Looks like:
fringes
Cilium = singular, cilia = plural
In animal & protozoa (like Paramecium) cells
made from microtubules
Shorter & more numerous than flagella
For motility (movement)… rowing, waving-like motion & in some cases, sensing the environment

27. Flagellum Found in: Functions: movement
many prokaryotic cells
bacteria
some eukaryotic cells
some animals
some protozoa
Functions:
movement
sometimes sensing the environment
Looks like:
tail, whip
flagellum = singular, flagella = plural
In bacteria, protozoa (like Euglena), some animal cells (& some plant sperm)
made from microtubules
Longer, but few in number than cilia
For motility (movement) using whip-like motion & in some cases, sensing the environment

28. Centrioles Found in: Functions: Looks like: eukaryotic cells only
animals cells only
Functions:
help in cell division (mitosis)
Looks like:
stacked logs
salt & pepper shakers
Paired, rod-like structures near nucleus
made of a cylindrical of microtubule pairs
play role in cell division (mitosis) by separating chromosome pairs

32. Extras ID eukaryotic animal cell organelles: Cell Part ID interactive:
Cell Part ID interactive:
Cell Organelles Game: