Part II The parts of the cell

Microtubules Long slender protein tubes. Help support and give shape to the cell. Specialized microtubules, called spindle fibers, help with cell division.

Microfilaments Fine protein threads that help support and shape the cell wall. Lie just under the cell membrane. Help move cellular materials. Play a roll in cytoplasmic streaming.

Cilia & Flagella Extend out from the surface of the cell. Used to help move the cell. Cilia - hairlike extentions. Occur in large numbers.

Flagella - Whiplike, longer than cilia Occur singly or in pairs. Not all cells have these parts.

Nucleus Site where nucleic acids are made. Directs the cells activities. Surrounded by a double membrane called the Nuclear envelope. Nuclear pores are found in the nuclear envelope which allow nucleic acids to pass in and out.

Nucleus continued Filled with a protein rich substance called nucleoplasm. Nucleoplasm contains chromatin. Chromatin is a combination of DNA and proteins. Chromatin coils during cell division and forms chromosomes.

Nucleus continued again Chromosomes contain the genetic information of the cell. Most nuclei contain one spherical body called the nucleolus. The nucleolus makes ribosomes.

Plant Cells

Cell wall Rigid covering of a plant cell. Made of long chains of cellulose. Made hard by the chemicals pectin and lignin. Contains pores that allow of molecules to pass in and out of the cell. Wood is a plants cell wall.

Vacuoles Like lysosomes Store enzymes and waste products. Can take up to 90% of a mature plant cells volume.

Plastids Three kinds. Chloroplasts Chromoplasts Leucoplasts

Chloroplasts Contains a green pigment called chlorophyll. Converts sunlight to sugar.

Chromoplasts Produce pigments such as: xanthophyll and caroten. Give plants there cool colors. Convert light to sugar.

Leucoplasts Store food for plant. Starch, proteins, and lipids.