What’s in the Nucleus? Genetic material Helix Found in the nucleus Contains the directions for making proteins Passed from one generation to the next DNA (deoxyribonucleic acid) Helix A coil that has a constant diameter

Double helix A coil made up of two strands, each of which is a helix DNA’s shape Complete yarn activity from genes to proteins activity 5

The Cell Cycle The cell cycle begins when the cell is formed and ends when the cell divides and forms new cells. It is the way multicellular organisms replace old cells that can no longer carry out life functions. It ensures that each new cell can perform the same function as the old cell it is replacing.

Interphase - the cell prepares for division G1 – the cell grows and does its job S – Chromosomes (DNA) are copied G2 – organelles and extra cytoplasm are replicated

Mitosis Forms two new nuclei – each with a complete set of chromosomes.

Prophase - chromosomes condense into rod-like structures called chromatids Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase – chromosomes line up at the middle of the cell Metaphase – chromosomes line up at the middle of the cell. Homologous chromosomes pair up Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase – the chromatids separate and move to opposite sides of the cell Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase – a nuclear membrane forms around each set of chromosomes and the chromosomes unwind Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Cytokinesis The process by which cells split their cytoplasm into two new daughter cells *In animal cells the cell membrane is drawn in and pinches into two *In plant cells a cell plate forms and becomes the cell wall

cytokinesis

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                              Cytokinesis                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                              Cytokinesis                                                             

Outline of the Cell Cycle Interphase Chromosomes (shape) G1 thread like- chromatin S G2 Mitosis rod like- chromatids Prophase Metaphase Anaphase Telophase Cytokinesis thread like- chromatin

Homologous Chromosome Chromosomes – made up of DNA and proteins humans have 46 chromosomes in each cell. Chromatin - chromosomes uncoiled and spread out in the nucleus (thread-like) Chromatid – chromosomes condensed into rod-like structures; chromatids occur in pairs in the shape of an X

A duplicated chromosome has two identical DNA strands, called chromatids that are held together at a region called the centromere.

Making Prokaryotic cells Are less complex than eukaryotic they have: Ribosomes, single circular DNA molecule No membrane enclosed organelles

Binary Fission Prokaryotic cell division is by “binary fission” which means “splitting into two parts” The cell splits into two separate parts Each part has one copy of the circular DNA (page 86 in textbook).

The cell cycle Flap-a-Doodle Label and add pictures under your flaps on the page. Pictures are not in order use pages 88-89 in textbook.

Events in the cell cycle   Chromosomes Other Interphase a copy is made; they are thread-like (chromatin) Prepares for division; grows; does its job; makes more organelles M I T O S I S Prophase Condenses into rod-like structures called chromatids Mitosis begins; nuclear membrane breaks apart; spindle fibers form; centrioles move to opposite ends of the cell Metaphase line up in the middle of the cell; homologous chromosomes pair up nuclear membrane disappears; spindle fibers attach at the centromere Anaphase Chromatids separate and move to opposite sides of the cell Telophase They uncoil becoming chromatin Mitosis is complete; cell plate forms in plant cells; nuclear membranes form Cytokinesis Thread-like (chromatin) Two new identical daughter cells have formed; in plant cells, cell plate becomes cell wall High light red areas on your chart.

The Cell Cycle All living things come from existing cells. Cells can divide again and again The three stages of the Cell Cycle: Interphase Mitosis Cytokinesis