Cells The Basic Unit of Life

Organelles Special structures that perform specific functions in cells Cell Animations

Nucleus Has a double-layered porous (with pores - very tiny holes) membrane Contains DNA (deoxyribonucleic acid), DNA forms chromatin (long strands) and has instructions to assemble the necessary substances for building the cell and making it work Has a nucleolus, a dark structure that manufactures ribosomes

Cytoplasm The area outside the nucleus and inside the cell membrane. The cell membrane separates the cell contents from its surroundings. Jelly-like material Supports nucleus and other organelles

Ribosomes Structures that make protein Protein is used to make enzymes, muscle tissue, and other important structures

Endoplasmic Reticulum Series of canals Canals are used to transport materials to different parts of the cells Rough Endoplasmic reticulum has ribosomes attached

Mitochondria Transform energy for the cell

Golgi Bodies Package useful materials and secrete them to the outside of the cell for use elsewhere

Vacuoles Fluid-filled storehouses that contain water, food, wastes and other materials

Lysosomes Break down food and digest wastes and worn out cell parts

The Cell Cycle Cell division allows organisms to grow and develop When cells divide, they must have a complete nucleus, so all the instructions in the DNA are reproduced The process that makes this happen is MITOSIS

Before Mitosis Cells copy the chromatin so there are two sets of DNA The chromatin coils up to form double-stranded chromosomes, joined by a centromere Copy Figure 1.9 on page 17

Phases of Mitosis Remember PMAT Four major phases Results in two complete sets of DNA Prophase, Metaphase, Anaphase, Telophase

Prophase Chromosomes visible with a microscope Nuclear membrane disappears Spindle fibres form and stretch across the cell Spindle fibres attach to centromeres

Metaphase Spindle fibres pull chromosomes into a line across the middle of the cell

Anaphase Spindle fibres shorten Centromeres are pulled apart Chromosomes move to the opposite (ends) poles of the cell

Telophase Final phase of mitosis Spindle fibres disappear Nuclear membrane forms around each set of chromosomes Nucleolus appears Single stranded chromosomes uncoil into strands of chromatin The cell is ready to divide-cytokinesis

Cell Division After telophase Animal cells - the membrane pinches together and the cell divides Plant cells - a cell plate develops across the centre of the cell forming a new cell wall Two new cells- daughter cells Number of chromosmes in the nucleus of each cell is identical to the number in the original cell

Interphase Inter- between Cell growth, replication of DNA Prepares for mitosis Refer to the cell cycle pie graph on page 23 Mitosis is ____ h Rapid growth is ____ h Growth and DNA replication is ____h Growth and preparation for division is ____ h