Does an animal get larger because each cell increases in size or because it produces more of them?

Cell Growth  *As you might have guessed, living things grow by producing more cells.  *Every living thing has cells, but depending on shape and size depends on how many cells they have!

Why Cells Must Divide  In multi-celled organisms (like humans) cells specialize for specific functions.  Cells can only become certain sizes. If cells are too big, they cannot get oxygen and nutrients.  As you Grow you simply need more cells. (You are bigger than when you were a baby.)  When cells die, fall off, and injured your body need to replace and repair them with new cells.

Cell Cycle  The series of events that cells go through as they grow and divide.

interphase  G1 Phase- Cells increase in size.  S Phase- DNA replicates (copies) and Chromatin coils and become chromosomes.  G2 Phase- Organelles are produced and the cell gets ready for Mitosis.

interphase Animal Cell Plant Cell Photographs from:

Mitosis o Mitosis is the cell division of the NUCLEUS creating new cells from an original cell. o Contains 4 PHASES (PMAT) o P rophase o M etaphase o A naphase o T elophase

Mitosis produces identical offspring (2N---2N)

Prophase 1 st stage of mitosis Longest stage Nuclear membrane dissolves. Centrioles (or poles) appear and move to opposite end of the cell. Spindle fibers form between the poles. Sister Chromatids form.

Prophase Animal Cell Plant Cell Photographs from: Spindle fibers Centrioles

Metaphase 2 nd step in mitosis  Chromosomes line up SINGLE file along the equator (middle).

Metaphase Animal CellPlant Cell Photographs from:

Anaphase 3 rd step in mitosis Chromatids separate and are pulled towards the opposite poles

Anaphase Animal CellPlant Cell Photographs from:

Telophase 4 th step in mitosis  Nuclear membrane reforms  Spindle disappears  Cytokinesis begins

Telophase Animal Cell Plant Cell Photographs from:

Cytokinesis  The division of the cytoplasm  The result is two genetically complete daughter cells!

I P on a MAT C *Interphase: preparation between split Prophase Metaphase Anaphase Telophase *Cytokinesis: cells split MITOSIS

Cell Division Rap  v=I5uFuvkN97I

STARR Questions If a cat has 38 chromosomes in each of its body cells, how many chromosomes will be in each daughter cell after mitosis? F 11 G 19 H 38 J 76

The diagram shows cell division in which an error has occurred. Which of these statements is most accurate? A Cell A lacks the cytoplasm necessary to continue normal cell functions. B Cell B contains enough genetic material for the cell to reproduce itself. C Cell A is free of any mutation present in the genetic material of the parent cell. D Cell B lacks instructions for making the proteins necessary for cell metabolism. STARR questions

What stage is this?