Cell Growth and Division

Chapter 10

Limits to Cell Growth

• What problems does growth cause for cells?

• The larger a cell becomes, the more demands the cell places on its DNA. In addition, the cell has trouble moving enough nutrients and wastes across the cell membrane.

Limits to Cell Growth

• The rate at which food, oxygen, water, and wastes are moved into and out of the cell is dependent on the surface area of the cell.

• The rate at which food, oxygen, and water are used and produced depends on the cell’s volume.

Surface Area to Volume Ratio

• As the length of cell increases, its volume increases faster than its surface area.

• The decrease in the cell’s ratio of surface area to volume makes it difficult for the cell to move needed material in and waste products out quickly enough for the cell to survive.

• Why?!

Division of the Cell

• Before it becomes too large, a growing cell divides, forming two “daughter” cells.

• The process by which a cell divides into two new daughter cells is called cell division.

Cell Division

• In eukaryotes, cell division occurs in two major stages: 1. Mitosis = Division of the cells nucleus

2. Cytokinesis = division of the cell cytoplasm

Genetic information is passed from one generation to the next on chromosomes.

Cell Division

• Before cell division, each chromosome is duplicated, or copied.

• Each chromosome consists of two identical “sister” chromatids.

• Each pair of chromatids is attached at an area called the centromere.

Cell Division

• When the cell divides, chromatids separate. Each new cell gets one chromatid.

The Cell Cycle

• The cell cycle is the series of events that cells go through as they grow and divide.

• Interphase is the period of growth that occurs between cell divisions.

During the Cell Cycle…

• A Cell grows

• Prepares for division

• Divides to form two daughter cells, each of which begins the cycle again.

Cell Cycle

• The cell cycle consists of four phases:

– G1 (First Gap Phase), or “Growth”

– S Phase, or “Synthesis”

– G2 (Second Gap Phase), or “Get Ready”

– M Phase or “Cell Division”

Events of the Cell Cycle

• During G1, the cell… – Increases in size

– Synthesize new proteins and organelles

• During the S phase… – Chromosomes are replicated

– DNA synthesis takes place

– Once a cell enters the S phase, it usually completes the rest of the cell cycle.

Events of the Cell Cycle…

• The G2 Phase… – Organelles and molecules required for cell

division are produced

– Once G2 is complete, the cell is ready to start the M phase (Mitosis first!)

Find your seats from last class! Warm Up 11/4/16

What are the four stages of Mitosis? What organelle does this take place in?

Mitosis – 4 phases

•P = Prophase

•M = Metaphase

•A = Anaphase

•T = Telophase

Steps of Cell Division

• Class Handout!

Cytokinesis

• During cytokinesis, the cytoplasm pinches in half.

• Each new cell has an identical set of duplicate chromosomes.

Cytokinesis in Plants

• What is the key difference between plant and animal cells?

• Plant Cells have a…

Cytokinesis in Plants

Plant Cells have a CELL WALL!

Cytokinesis in Plants

• In plants, a structure known as the cell plate forms midway between the divided nuclei.

• The cell plate gradually develops into a separate membrane.

• A cell wall then begins to appear in the cell plate.

Animal Cell

Plant Cell

Mitosis Lab!

→ Have your computer?!

- No computers - by Welsh’s office- Computers - by the door! :) PAIR UP!

→ Once you have your partner and desks arranged, ask Mr. McNish for the handout!

When you’re finished…

→ Turn in your lab up front! (Be sure your name is on it!)

→ Pick up a Mitosis Crossword!

Exit Ticket

On your Ticket:

What are 3 things you learned today?

What do you want to learn about cell division?

Happy Monday! → Warm Up

Why is it important for cells to have a natural limit to the frequency and amount of growth in their lifecycle? What are some of the potential issues arriving from unregulated growth/ division?

Example summary sentence: First written description of cancer is found in Egyptian writing.

Example summary sentence: Hippocrates is the first to use the term cancer.

Example summary sentence: Surgeons perform crude mastectomies using fire, acid and leather binding.

Example summary sentence: Surgeons began performing radical mastectomies.

Example summary sentence: High doses of radiation are used to treat tumors.

Example summary sentence: The National Cancer Institute is created.

Example summary sentence: Scientists began studying the use of chemicals (chemotherapy) as a

treatment for cancer.

Example summary sentence: Dr. Sydney Farber creates the Jimmy Fund, a cancer advocacy organization.

Mitosis Meiosis Myles Jerique

Tristan Mya

Olivier Josh

Daniel Kylie

Mirage Afra

Nikko Roz

Skylar Spencer

McKayla Kayla

Nathan Sage Adam Janiah

Ben Phillip

Megan Blake

Leina Brennan

Sarah Jemma

Ruby Sydney

Zane Declan

Jonathan Adia

Sasha Isabella

Lamont Charlie

Bianca Veronika

Exit Ticket

- What were the most relevant 2 - 3 portions of today’s class?- Which concepts do you need further clarification on?

Exit Ticket

What were the 2 - 3 most important concepts that you will take away from today’s class?

Which concepts do you need further clarification on?