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

Nucleus Structure 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 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 ER Function The place where the ribosomes assemble their proteins Intercellular highways (where materials can move from one part of the cell to another.

Golgi Apparatus Structure 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

Vesicles Structure Little sacs that emerge from the Golgi apparatus Function The transport passage of materials within the cell

General Storage Vacuoles 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

Chloroplasts Structure 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 convert it into chemical energy. “makes food”In the chloroplast, thylakoids absorb solar energy and convert it into chemical energy. “makes food”

Mitochondria Structure Large organelles that contain their own DNA Has a bilayer: a smooth outer membrane and very folded inner membrane (cristae)

Mitochondria Function 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

Microfilaments Structure 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

Structure 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)