Cell Structure

Cell Boundaries

- Plasma Membrane

Cell Boundaries- Plasma Membrane

Structure• A bi-lipid envelope

around the cell that contains proteins and other markers

Function• Separates the cell from

its environment• Secretes materials out

of the cell• Recognizes friendly and

enemy objects• A selectively permeable

membrane that allows some materials to enter

- Cell Wall

Structure• A rigid covering of:

– Cellulose in plants or peptido-glycan in bacteria or chitin in fungi

Function• Gives the cell an

internal structure so it doesn’t collapse on itself

Cell Control

• Nucleus– DNA

(2 Shapes)

Chromatin

Chromosomes– Nucleolus

NucleusStructure

• Surrounded by a double membrane called the nuclear envelope– Has holes called

nuclear pores

Function• Holds the DNA safe

inside the cell• Controls what enters

and leaves the nucleus

DNA as 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

DNA as Chromosomes

Structure • Chromatin that is

coiled up tightly during cell division

Function• Same as chromatid

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

Nucleolus

Structure• A spherical body in

the nucleus

Function• Makes the ribosomes

Protein Synthesis

- Ribosomes

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?

Assembly and Storage Organelles

• Endoplasmic reticulum

• Golgi Apparatus• Vacuoles• Lysosomes

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

Endoplasmic Reticulum Endoplasmic Reticulum ERER

FunctionFunction

• The place where the ribosomes assemble their proteins

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

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

VesiclesStructure

• Little sacs that emerge from the Golgi apparatus

Function• The transport

passage of materials within the cell

General StorageVacuoles

Structure • An empty sac is

usually large in plants

Function • Temporary storage

of water, enzymes, food particles, or waste

Lysosomes

Structure • A sac of very strong

digestive 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

Energy Transforming Organelles

• Chloroplast

• Mitochondria

ChloroplastsStructure

• Have a double membrane and their own DNA

• Contain the pigment chlorophyll

• Thylakoids look like stacks of pancakes

• Stroma fluid that surrounds the thylakoids ( sugary syrup)

Function• In the chloroplast,

thylakoids absorb solar energy and convert convert itit into into chemical energy. chemical energy. ““makes foodmakes food””

Mitochondria

Structure• Large organelles that

contain their own DNA• Has a bilayer: a smooth

outer membrane and very folded inner membrane (cristae)

MitochondriaFunction

• Releases energy in “food” into a form the cell can use which is called ATP– ATP is the currency of energy that cells use

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

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

Support and Locomotion

• Cytoskeleton: support structure/framework for the cell– Microtubules– Microfillaments

• Centrioles

• Cillia

• Flagella

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

MicrofilamentsStructure

• Long threads of protein called actin

Function• Used when the cell

moves and when a muscle cell contracts

Centrioles

Structure • Pair of small

cylindrical bodies located near the nucleus

Function• Function in cell

division

Cilia

CiliaStructureStructure

• Short, “hair-like” structures that emerge from the cell membrane

• A cell may have 1000’s

Function• The cilia beat in unison or

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

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

trachea and lungs

Flagella

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. Euglena)