Unit 1- The Micro-Universe of the Cell

What are the four hypotheses that form the cell theory?

All living organisms are composed of one or more cells. Cells are the basic units of structure and function in all organisms. All cells are derived from preexisting cells. In a multicellular organism, the activity of the entire organism depends on the total activity of its independent cells.

Abiogenesis

The idea that life can develop from lifeless matter.

Biogenesis

The idea that life arises from life (one of the statements in the cell theory)

Resolution

The ability of the eye (or any other image-making instrument) to distinguish between separate objects that are close together.

Depth of Field

The vertical distance (the “thickness” of an object) that remains in focus at any one time while the specimen is being viewed

Prokaryotic Cells (Prokaryotes)

The smallest living cells and they have a relatively simple internal structure. DNA is in the nucleoid. The bacterium that causes strep throat is this term and all bacteria as well.

Eukaryotic Cells (Eukaryotes)

Cells that do contain a nucleus. DNA is in the nucleus. Plants, animals, fungi and protists are this term.

Organelle

Eukaryotes have a number of other specialized structures called this term. Each one is highly organized and has a specific function within the cell. The various organelles work together as a team to effectively carry out cell processes- the essential tasks of the cell.

Cell Membrane

A structure that separates the cell interior from the outside world and controls the movement of materials into and out of the cell.

Cytoplasm

A gel-like material consisting mostly of water that contains dissolved materials and creates the chemical environment in which the other cell structures work.

Nucleus

The command centre of the cell that contains the DNA blueprints for making proteins and is surrounded by a double membrane to protect the DNA from potentially damaging by products of biochemical reactions.

Nucleolus

A specialized area of chromatin inside the nucleus responsible for producing ribosomes.

Endoplasmic Reticulum (ER)

A system of flattened membrane-bound sacs and tubes continuous with the outer membrane of the nuclear envelope that has two types of membrane.

Rough ER

Studded with ribosomes and synthesizes proteins.

Smooth ER

Synthesizes phospholipids and packages macromolecules in vesicles for transport to other parts of the cell.

Ribosome

Tiny two-part structures found throughout the cytoplasm that help put together proteins.

Mitochondria

The cell uses a universal form of energy to run the processes within it. The powerhouse of the cell where organic molecules, usually carbohydrates, are broken down inside a double membrane to release and transport energy.

Chloroplast

The green chloroplast is one of a group of organelles in plant cells called plastids. All plastids contain stacked internal membrane sacs.

Vacuole

A large membrane-bound, fluid-filled sac for the temporary storage of food, water or waste products.

Vesicle

A small membrane-bound transport sac.

Golgi Apparatus

A stack of flattened membrane-bound sacs that receive vesicles from the ER, contain enzymes for modifying proteins and lipids, package finished products into vesicles for transport to the cell membrane (for secretion out of the cell) and within the cell as lysosomes.

Microtubules/Filaments

The rod-like tubes about 25nm in diameter, act like tracks along which organelles, such as vesicles and mitochondria, can move and stabilize the shape of cells with irregular contours, such as nerve cells. Microtubules also form the main structural component of centrioles, cilia and flagella.

Cilia

The short cylindrical projections (singular, cilium) and produce a wave-like motion. Propels food.

Lysosome

A membrane-bound vesicle filled with digestive enzymes that can break down worn-out cell components or materials brought into the cell.

Flagella

The long projections (singular, flagellum) and produce an undulating, whip-like motion.

Cell Wall

Around plant and fungal cells, and some single-celled eukaryotes, consists mostly of cellulose fibers and adds strength and rigidity to the cell. A plant cell requires a cell wall to carry on its life processes

Which structures are found in plant cells but not animal cells?

Plant cells possess several specialized structures not found in animal cells. The key structures include a rigid cell wall (composed of cellulose), specialized plastids (including green chloroplasts) and a large central vacuole.