Cell Division

7th Grade Science Chapter 3 – Section 5

Cell Division and Growth

• A single cell _______ and then _______, forming two new cells.

• A single cell grows and divides producing ____ new cells.

• Then the two cells grow and divide forming ____and so on.

• The process of cell growth and division is _________ and it happens in __________.

Cell Division and the Cell Cycle

__________ - sequence of growth and division – a cell grows, prepares for division, and divides into 2 new cells.

- The two new cells are called _____________. - Each daughter cell begins the ___________ again.Three stages in the cell cycle: 1. _________ - cell grows

2. __________ - cell divides3. __________ - two new cells are formed

Stage 1. Interphase

• During _________, the cell grows, makes a copy of its DNA, and prepares to divide into two new cells.– During the first part of interphase, the cell _______

to its full size and produces structures that it needs– The next part of interphase, the cell makes an exact

copy of its _____ in its nucleus. This process is called ______________.

– The cell prepares itself for _________

Stage 2 - Mitosis

• __________ - one copy of the DNA is distributed to each of the two new daughter cells.

• There are four phases in the process of mitosis1. ________ 2. _________ 3. _________4. __________

Prophase, Metaphase, Anaphase

• Prophase - Chromatin in the ________ condense to form ___________. The thread-like chromatin move to opposite sides of the nucleus. The _______________ breaks down.

• Metaphase – The __________ line up across the center of the cell.

• Anaphase – The chromosomes separate and each ________ becomes a new chromosome. The new chromosomes move to opposite ends of the cell. The cell stretches out – ends are pulled apart.

Telophase

• During _________ a new ____________ forms around each new group of chromosomes.

Stage 3 – Cytokinesis______________ - the cytoplasm divides and

the organelles are distributed to each of the two new cells. Cytokinesis begins during _________.

Cytokinesis

• The __________ pinches into two new cells.• Each daughter cell gets about half of the

____________. • Each daughter cell has the same number of

____________as the parent cells• At the end of cytokinesis, ___________ begins

again.

Structure and Replication of DNA

• ______________ - ensures that each daughter cell will have the genetic information it needs to carry out its activities.

• Structure of DNA – twisted ladder, _________• Each rung of the ladder is made up of

_____________. There are four different bases - ____________, _____________, ____________, and ____________

DNA Replication

• _____________ begins when the two sides of the DNA strand ______and separate. The molecules of DNA separates between the two ___________________.

• Nitrogen bases that are floating in the ________ pair up with bases on each half of the DNA molecule.

• Adenine pairs with Thymine, Guanine pairs with cytosine.