The Cell Cycle

Have you ever wondered… How do we go from one single cell to a baby?

Take a look at these two animations… B A http://www.youtube.com/watch?v=zrx7Xg0gkQ4 Which one represents how our cells grow?

Lets imagine our world if we were only ONE CELL and we GREW by just GETTING LARGER https://www.youtube.com/watch?v=yltlJEdSAHw

Ridiculous huh? What would be some disadvantages of this method of growth?

http://youtu.be/Q6ucKWIIFmg We once started off as one cell and now our body is made up of trillions of cells. While watching the video clip, answer the following… How did we developed so many cells in our body? What is the purpose of cell division? What would happen if our cells didn’t divide? Teachers: You can pause and ask the students what happens at each phase of the interphase after watching the video. Stop at 4:27

30 seconds Discuss with your neighbor… How did we developed so many cells in our body? What is the purpose of cell division? What would happen if our cells didn’t divide? By now, most of you should know that in order to make more cells our cells go through a process called cell division. The students should come to the conclusion that the cell divides to make new cells. If cells don’t divide, new cells can’t be made to replace old cells; some don’t divide (brain and nerve cells).

Why do our cells need to divide?

PURPOSES OF CELL DIVISION Growth- increase in size of the organism Occurs by dividing cells, not by increasing the size of the individual cells

PURPOSES OF CELL DIVISION Repair – needed because of worn out or injured cells Your skin cells are replaced every 28 days Your stomach every 7 days

PURPOSES OF CELL DIVISION 3. Reproduction (2 types) Asexual – one parent. Offspring identical to parent – made through Mitosis Sexual – combination of genetic material from two parents – made through Meiosis. Offspring different to parents

So our cell…it works like a clock At a certain time the cell “grows” and on the other times it divides. I can ….describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication and mitosis, and the importance of the cell cycle to the growth of organisms

Terms to know (Please write these on the next blank page in your journal.) Chromosome: Structure found in the nucleus of eukaryotic cells that contain the organism’s genetic material; made of chromatin.

Chromatin: strands of DNA found in the nucleus; makes up chromosomes when folded and thickened around proteins.

Chromatid: one of two strands of a chromosome that become visible during mitosis or meiosis.

Centromere: the region of the chromosome that holds the two sister chromatids together.

Vocabulary Mitosis – division of the nucleus. It is an asexual process since cells produced by mitosis are genetically identical to the parent cell Cytokinesis - division of the cytoplasm

Let’s build a Chromosome……….. When you have your chromosome built, explain the structures & functions of each part and where you find chromosomes to your table group.

Bell-Ringer Glue the Cell Cycle Notes on your next blank page! Grab ONE gluestick from the blue tub for your TABLE!!!

Cell Cycle (before cells divide)

Interphase The longest phase of cell cycle, cells prepare to divide 90% of the time cell is in interphase- Includes: G1, S, G2, Go

G1 Phase (Growth Phase 1) “Cell being a cell” Cell decides whether or not to divide Growth and development, cell increase in size Organelles are duplicated, proteins are made

S Phase: Synthesis/ DNA Replication Chromosomes copied, 2 sets of complete DNA

G2 Phase (Growth Phase 2) DNA replication is checked and repaired Cell prepares for mitosis (cell division), grows more Proteins organize themselves into spindle fibers

G0 Phase (Resting, Time Out) An extended G1, resting period Some cells staying G0 temporarily when cell division is not required Some cells will stay in G0 forever Ex: Nerve cells & Heart Muscle cells

Mitosis Nuclear division Includes: Prophase Metaphase Anaphase Telophase

Cytokinesis Result in two Identical daughter cells

Which phase of interphase involves cell growth and development? G1 phase S phase G2 phase G0 phase

Which part of interphase involves DNA replication (making copies)? G1 phase S phase G2 phase G0 phase

Which phase of the cell cycle is the LONGEST phase? Interphase Mitosis Cytokinesis

What happens to cells at G0 Phase? Cells continue to grow Cells stops dividing Cells grow uncontrolled

Where is the longest phase of cell cycle? Mitosis Cytokinesis Interphase

Check points-regulated by Cyclin Proteins

Lets take a look again at how bacteria grows….and how we grow http://www.youtube.com/watch?v=zrx7Xg0gkQ4 http://www.youtube.com/watch?v=0xvJ-NNuR6M

Bacteria growth: Binary Fission A type of asexual reproduction that involves the splitting of cells into two. Occurs in Bacteria. Cells makes copy of its DNA Cell divides into two