Download NOTES Organelle Structure and Function

Unit 2:The Cell
Section 3: Organelle Structure and Function
Mrs. McNamara
Biology

Organelle-cell part that performs a specific
function for the cell
◦ Most are surrounded by a membrane
◦ Each helps to maintain life of the cell
Parts of the Cell
Cell Membrane Model
Phospholipids and proteins move laterally (
side to side) for short distances.
 Proteins make a pattern on the surface known
as the fluid mosaic model.

CELL MEMBRANE or PLASMA
MEMBRANE
Mainly made of phospholipids and proteins.
 HYDROPHOBIC “tails” of phospholipids make
molecules line up as a LIPID bilayer (double
layer).

◦ POLAR head facing out and NON-POLAR tails
facing in.

Membranes are selectively permeable - they
allow certain molecules to pass through, but
keep others out.
◦ In plants and bacteria, this is within the cell wall.

Cytoplasm is the “gel-like material and
organelles” between the nucleus and cell
membrane.
NUCLEUS and NUCLEOLUS
NUCLEUS IS:
•Separated
from cytoplasm by nuclear membrane
(nuclear envelope).
• Nuclear pores allow molecules in and out.
•Serves as the COMMAND CENTER OF CELL; directs
cell’s activities.
•CONTAINS CELL’S GENETIC MATERIAL (DNA).
•Contains NUCLEOLUS (dark spot) which makes
RIBOSOMES which makes proteins.


DNA is scrunched up as chromosomes in
DIVIDING CELLS.
DNA is spread out as chromatin in NONDIVIDING CELLS.
CYTOSKELETON
Cell’s skeleton.
 Made of PROTEINS called microtubules and
microfilaments.
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FUNCTION: Give the cell shape, strength and the
ability to move.
Lysosome

Sac containing digestive enzymes.
FUNCTION:
 Digests: food particles, disease-causing bacteria and
viruses, and worn out or broken cell parts.
◦ Plays a role in apotosis “programmed cell death”.
 Cell suicide for the good of the organism.

Transports undigested material to cell membrane for
removal.
VACUOLE

Animal:
◦ Sac for storage, digestion, and waste removal.
◦ Contains water solution.

Plant:
◦ Large, central vacuole; stores water and nutrients
needed by cell.
◦ Help support the shape of the cell.

Huge in plant cells, small in animal cells, NOT
in prokaryotic cells.
CENTRIOLES
Made of PROTEINS called microtubules.
 Found only in animal cells.
 FUNCTION: aid in movement of chromosomes
during cell division.

CILIA and FLAGELLA
Made of PROTEINS called microtubules organized in a nine/two
arrangement that help with movement.
FUNCTION: external appendages from the cell membrane that
aid in locomotion (movement) of the cell.

RIBOSOMES
Can be free in the cytosol or bound to the
surface of Rough ER.
 MADE OF proteins and RNA
FUNCTION: make protein for use in the cell
(free) or for export (bound).

MITOCHONDRION (plural: MITOCHONDRIA)




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Surround by double membrane.
Contains its own DNA.
Called the powerhouse of cell.
Site of cellular respiration (use glucose to produce
cell energy, ATP).
Permeable outer membrane.
Folded inner membrane = cristae (increases surface
area for more chemical reactions).
GOLGI APPARATUS (BODY)
Looks like a stack of flattended sacs.
FUNCITON: Modify, sort, and package proteins and
lipids made by ER for transport out of cell. Enclose
digestive enzymes into membranes to form
lysosomes.

ENDOPLASMIC RETICULUM (ER)
ROUGH ER/SMOOTH ER
 Rough ER has ribosomes on its surface, while smooth
does not; continuous with nuclear envelope.

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FUNCION ROUGH ER: Internal delivery system of
the cell; makes, processes, and transports proteins to
be exported outside the cell.
FUNCTION SMOOTH ER (no ribosomes): produce
lipids, involved in carbohydrate metabolism, and
detoxification of drugs and poisons.
CHLOROPLASTS
Where photosynthesis takes place (produces
plant food (sugars) and oxygen gas.
 Contains green pigment, chlorophyll.
 Flattened membrane sacs called thylakoids
contain CHLOROPHYLL ; stacks of thylakoids
called grana. Gel like material around
thylakoids called stroma.
 FOUND ONLY IN plant CELLS.
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CELL WALL
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Found OUTSIDE the cell membrane in plant
cells and bacteria only.
Contains cellulose that provides support
(rigidity) and protection.
Bacteria have cell walls made of sugar and
proteins instead of cellulose.
PROKARYOTES


Bacteria are the most common prokaryotic
cell. They do not have a nucleus, but do
contain a single loop made of DNA.
Like all cells, bacteria are surrounded by a
cell membrane which contains the gel-like
cytoplasm of the cell.