Cell Reproduction Chapter 8

Chromosomes Vs. Chromatin

Chromosomes

Chromatin

Think of it like Cookies !

Chromatin Chromosomes MAKES

Our cells are constantly needing to replace themselves. For example, when we get a paper cut or any kind of cut, those cells need to be replaced. Also, cells in your stomach lining constantly need to be replaced, and even bone marrow cells.

Cell Division: What is it?

The Cell Cycle is a sequence of separate periods of __________ & __________ The period where the cell grows in size, metabolizes, and spends a majority of its life is _______________ Also, during this period, the chromosomes are ___________ to prepare for cell division. Growth Division INTERPHASE duplicated

The period where the cell undergoes nuclear division and creates 2 daughter cells is called ____________ Each daughter cell contains a ____________ set of the parent cell’s chromosomes. MITOSIS Complete

Which phase of the cell cycle takes the longest? 75% of a cell’s life is spent in Interphase Copies its chromosomes

G2G2 S G1G1

“Checkpoints” = stop & go-ahead signals to regulate the cycle Regulatory molecules, usually enzymes (protein kinases)  To become active kinases need a cyclin to trigger them  Often called “Cdks” (cyclin-dependent kinases)

The first phase = ____________  This is the ________ phase (OF MITOSIS)  During this phase, chromatin coils to form visible _____________  Each chromosome is made up of ___ sister chromatids and are held together by a __________ *Remember: The chromosomes are duplicated in ____________ to prepare for cell division PROPHASE longest chromosomes 2 centromere Interphase

One Chromatid Duplicated Chromatid sister chromatids The TWO together are

 In addition, the ________ envelope starts to disappear and the __________ disintegrates.  In animal cells, ___________ migrate to opposite ends of the cell and ________ ________ begin to form.  In plant cells _______ _______ form without centrioles. nuclear nucleolus centrioles spindle fibers Spindle fibers

The Second Phase = _____________ The chromosomes begin to line up along the _________ of the cell The spindle fibers _______ to the centromeres. Each chromatid has its own spindle fiber attached METAPHASE Equator attach

The Third Phase = ____________  This marks the ___________ of sister chromatids.  The centromeres ______ and the ______ ___________ are pulled apart to opposite poles of the cell by shortening spindle fibers ANAPHASE separation split sister chromatids

The Fourth Phase = ______________ Here two distinct _________ cells start to form. In addition, the _____________ unwind, the spinder fibers ______ down, the _________ reappears, a new nuclear __________ forms, and a new double __________ begins to form between the two nuclei. TELOPHASE daughter chromosomes breaknucleolus envelope membrane

Cytokinesis  the division of ____________  Toward the end of telophase in animal cells, the plasma membrane _______ in along the equator  In plant cells, a ____ _________ forms around each cell and new cell ______ form on each side of the cell plate until separation is complete. cytoplasm pinches cell membrane wall

Can you identify any of the stages?

Now the cells are separated, they will continue in the cell cycle and enter __________ interphase