Cell Growth and Division

Cell Growth and DivisionMs. HughesWhy Cells ReproduceMulticellular organisms grow larger by producing more cells.New cells are needed to keep organisms healthy and replace old worn out cells.3 main reasons for cells to reproduceCell SizeLarger cells require more nutrients than smaller cells.

Smaller cells are easier to maintain than larger cells.

Recall surface area-to-volume ratioCell maintenanceMore proteins are required to keep a larger cell up and running.

Smaller cells require less protiens.If a cell gets larger DNA cannot be copied quickly enough for that cell to continue dividing.

DNA limits a cells size.Making New CellsDaughter cells have a higher surface area-to-volume ratio than its parent does.

Because larger cells are more difficult to maintain, cells divide when they grow to a certain size.chromosomesDefine: Genes Chromosomes

Complete doodle definitions for these terms.Prokaryotic ChromosomesSingle circular molecule of DNAThousands of genes on this moleculeCondensed like a rubber band coiling back onto itself.Eukaryotic ChromosomesLinear chromosomesMuch more genes than prokaryotes.Eukaryotic DNA is packaged into highly condensed chromosome structures with the help of many proteinsDNA and chromosomes make up chromatin.Forms of chromatinHistones ( a protein) allow DNA to wrap around them like a spool of thread.Once DNA has wrapped around the histone this is now called a nucleosome.Nucleosomes line up together to form a chord.Packaging During Cell DivisionFor most of its life the cells DNA remains in this chord of nucleosomes.During cellular division the chord condenses even farther to ensure that the DNA is not damaged and is copied properly during cellular replication and division.Chromosome structureDefine and do a doodle def for

ChromosomeChromatidSister chromatidcentromerePreparing for cell divisionAll cells come from pre-existing cellsDNA is copied before cell is replicated and dividesAll newly-formed cells require DNA, so before a cell divides a copy of DNA is made for each daughter cellProkaryotesThe cell grows largerThe DNA strand is doubled like a rubber band.The cell is pinched in the middle like a balloon animal.EukaryotesEukaryotic cellular reproduction is much more complicated because they contain more DNA, organelles and are more complex themselves.ActivityRecap: how are these related???

ChromosomeChromatidDNAGenesHistonesnucleosomeHomeworkCreate a comic strip, rap or dance about chromosomes and their relationship to DNA and its packaging.MitosisMitosis is the division of a cells nucleus.

There are several steps that must be complete before this can happen however.Eukaryotic Cell CycleCell cycle: is a sequence of cellular growth and division during the life of a cell.

The life of a eukaryotic cell cycles through phases of growth, DNA replication, preparation for cell division, and division of the nucleus and cytoplasm.InterphaseComposed of three separate phases:

G1, S, and G2

During interphase the cell is not dividing.The cell is growing and preparing to divide.Some cells divide often and others do not.1, 2, 3 pair shareAssign 1, 2, 3 and paraphrase each step

1 G12 S3 G2Cell DivisionMitosis Cytokinesis

Complete doodle definitions for these words.ActivityRead aloud each of the steps for the stages of mitosis and create comic strip on the board.

Pages 230 - 231CytokinesisDuring cytokinesis, the cell membrane grows into the center of the cell and divides it into two daughter cells of equal size. Each daughter cell has about half of the parents cytoplasm and organelles. Animal cell vs. plant cell cytokinesis.

Cell plate formation page 232ActivityUsing yarn replicate the phases of mitosis on a piece of construction paper with the yarn as chromosomes.

You must also thoroughly explain what is happening in each of the four phases in your OWN words.

Draw, label and explain the other phases of the cell cycle on the back of your construction paper.Home WorkCompare each phase of the cell cycle to a part in the life cycle of a human.

Ex: interphase can be childhood with G1 as an infant. But you must explain why!!ControlsCell growth and division depend on protein signals and other environmental signals. Available nutrients Size of cellsEtc.

Checkpoints Doodle defs for the 3 checkpoints

G1 check point checks to make sure cell and organelles have grown to proper size.G2 check point Cell checks to make sure DNA is copied correctlyMitosis cell checks to make sure sister chromatids lined up correctly so that when they are pulled apart in anaphase each cell gets one chromosome.

CancerRead Page 235

Write a one page journal/diary entry as if you are someone suffering from cancer, a cancer researcher ,a doctor diagnosing someone with cancer, or have a close friend or family member suffering from cancer.ActivityCreate a memory game Write definitions for the check points and phases of the cell cycle on index cards.Write the actual term on another index cardPlace all cards facing down Match cards until all cards are matched.HomeworkCreate a board game in which the cell experiences the cell cycle.

All phases and check points must be covered.