Cell Organelles and their Functions

Chapter 4 Section 2

1. Cell Membrane

Structure• A phospholipid bi-

layer around the cell that contains proteins and other markers

Function• Separates the cell from

its environment• Secretes materials out of

the cell• A selectively (semi)

permeable membrane that recognizes friendly and enemy objects and allows some materials to enter

2. Mitochondria

Structure• Large organelles that

contain their own DNA• Has a bilayer

membrane: a smooth outer membrane and very folded inner membrane (cristae)

2. Mitochondria2. MitochondriaFunctionFunction

• Releases energy in “food” into a form Releases energy in “food” into a form the cell can use which is called ATP the cell can use which is called ATP (cellular respiration) ATP is the currency (cellular respiration) ATP is the currency of energy that cells useof energy that cells use

• Parts of the body that use a lot of Parts of the body that use a lot of energy will have a lot of mitochondria energy will have a lot of mitochondria (muscle cells)(muscle cells)

• Because the mitochondria has its own Because the mitochondria has its own DNA, it can reproduce itself.DNA, it can reproduce itself.

3. Ribosomes

Structure • Each cell has 1000’s

of ribosomes which are little spheres

• A ribosome contains a protein connected to some RNA. Ribosomes don’t have membranes

Function• Protein Synthesis

• What is the function of What is the function of nucleic acids?nucleic acids?

4. Endoplasmic Reticulum ER

Structure

• A membrane system of folded sacs and tunnels

• When it is covered with lots of ribosomes= rough ER

• When it lacks ribosomes= smooth ER

4. Endoplasmic Reticulum 4. Endoplasmic Reticulum ERER

FunctionFunction

• The place where the ribosomes The place where the ribosomes assembles their proteinsassembles their proteins

• Intercellular highways: Intercellular highways: where where materials can move from one part materials can move from one part of the cell to another. of the cell to another.

5. Golgi ApparatusStructure

• A system of flattened sacs & membranes that emerge from the ER

Function• Modifies the

proteins made in the ER so they can be put into packages and exported from the cell

6. Vesicles

Structure • Little sacs that emerge

from the Golgi apparatus

Function• The transport

passage of materials within the cell

7. LysosomesStructure

• A sac of very strong enzymes in a double membrane

• Common in animal, fungi and protist cells, but are rare in plant cells

Function• Used to digest food

molecules and invaders of the cell

• Sometime used to “self destruct” cells suicide sacs

8. Nuclear Membrane or nuclear envelope

Structure• A double membrane

• Has holes called nuclear pores

Function• Holds the DNA safe

inside the cell• Controls what enters

and leaves the nucleus

9. Nucleolus

Structure• A spherical body in

the nucleus

Function• Makes the ribosomes

10. Chromatin

Structure• A fine strand of DNA

coiled around proteins

Function• Contains all the

information for making proteins

• Is the inherited information that is given to the offspring during reproduction

11. Chromosomes11. Chromosomes

StructureStructure • Chromatin that is Chromatin that is

coiled up tightly coiled up tightly during cell divisionduring cell division

FunctionFunction• Same as chromatin Same as chromatin

except that it is coiled except that it is coiled up tightly so that it can up tightly so that it can be separated cleanly be separated cleanly into the two daughter into the two daughter cellscells

12. Microfilaments

Structure• Long threads of

protein called actin

Function• Used when the cell

moves and when a muscle cell contracts

13. Microtubules

Structure • Long, slender tubes

of protein

Function• Gives structure to

the cell so it doesn’t collapse on itself

• During cell division, microtubules are used to pull apart the chromosomes into the new daughter cells

14. Cilia

StructureStructure• Short, “hair-like” Short, “hair-like”

structures that structures that emerge from the cell emerge from the cell membranemembrane

• A cell may have A cell may have 1000’s1000’s

FunctionFunction• The cilia beat in unison or The cilia beat in unison or

in waves. Cilia are used to in waves. Cilia are used to move cells move cells – e.g. parameciume.g. paramecium

• Cilia move mucus or fluids Cilia move mucus or fluids – e.g. over the cells of human e.g. over the cells of human

trachea and lungstrachea and lungs– Female reproductive Female reproductive

systemsystem

15. Flagellum

Structure• A long “whip-like”

structure that emerges from the cell membrane

• A cell has only 1-2 flagella

Function • Whip back and forth

to move a cell through fluid (e.g. sperm or Euglena)

16. Cell Wall

Structure• A rigid covering of:

– Cellulose in plants

Function• Gives the cell an

internal structure so it doesn’t collapse on itself

What does an animal cell have to not collapse?

17. Vacuoles

Structure • An empty sac is

usually large in plants

Function • Contains one of

these materials:• Water, enzymes,

food particles, or waste

18. Plastids(chloroplast)

Structure• Have a double

membrane and their own DNA

• Some plastids have thylakoids which contain pigments

• Thylakoids look like stacks of pancakes

Function• A chloroplast

contains thylakoids which absorb solar energy. Then converts it into converts it into chemical energy. chemical energy. “makes food”“makes food”

19. Centrioles

Structure • Pair of small

cylindrical bodies located near the nucleus

Function• Function in cell

division