Part II The parts of the cell Microtubules

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.