Cells: Surface Area, Volume, and Division

• Cells: Stability and Change Answer Sheet

Cell A Problem Solving

• Cell A is shaped like a cube with a length of 5 cm.
• The surface area for Cell A is calculated as length x width x number of sides.
• The surface area of Cell A is 5x5x6=150 cm².
• The volume of Cell A is calculated as length x width x height.
• The volume of Cell A is 5x5x5=125 cm³.
• The surface area-to-volume ratio for Cell A is surface area : volume.
• The surface area-to-volume ratio for Cell A is 150:125= 6:5 or 6/5 or 1.2

Cell Division

• Organisms aren't made of just one cell because most organisms undergo mitosis to create more cells.
• Complex organisms need more than one cell to function properly.
• Cells divide instead of enlarging, which allows an organism to grow.
• Cell division replaces or repairs cells that are not functioning properly.
• When cells divide it allows more efficient transportation of materials and helps in reproduction.
• If a cell grows too large, it cannot efficiently transfer nutrients across the cell membrane into the nucleus.
• More surface area in relation to its volume makes it easier to maintain homeostasis.
• Skin cells undergo mitosis quicker than liver cells due to their shorter cell cycle and lifespan.
• Skin cells are more prone to damage and need to be replaced more often than liver cells.

Cell Cycle Stages

• Interphase stands as the stage where cells remain for the longest amount of time.
• During Gap 1 (G₁), cells grow, carry out normal functions, and replicate their organelles.
• During Synthesis (S), DNA is replicated.
• During Gap 2 (G₂), additional growth occurs.
• Mitosis is the process of cell division that results in two daughter cells genetically identical to the original parent cell.
• Mitosis is used for cell development, cell growth, cell replacement, and cell reproduction.
• The phases of Mitosis include prophase, metaphase, anaphase, and telophase.
• Cytokinesis is the process at the end of mitosis that divides the cytoplasm.

Mitosis Stages

• The stages of mitosis happen in this order: Prophase, Metaphase, Anaphase, and Telophase (PMAT).
• During prophase, chromosomes condense inside the nucleus.
• The nuclear membrane breaks down, centrioles begin to move to opposite sides (poles), and spindle fibers form during prophase.
• During metaphase, spindle fibers attach to the centromere of each chromosome.
• During metaphase, chromosomes line up along the middle or equator.
• During anaphase, chromatids move away to the opposite sides (poles) of the cell.
• Cytokinesis may begin during anaphase.
• During telophase, nuclear membranes of two new daughter cells start to form.
• During telophase, chromosomes uncoil and spindle fibers fall apart.

Normal vs. Cancerous Cells

• Cancer is defined as uncontrolled cellular growth.
• Cancer is invasive and will harm the organism if allowed to go unchecked.
• Cancer cells result in disorganized clumps of cells called tumors.
• Cancer cells divide more quickly than normal cells and do not perform normal cell functions.
• Cancerous cell groups should have a lower percentage of cells in interphase than noncancerous cells.
• Cancer cells undergo mitosis more often.
• Cancer cells have a higher rate of cell division, and they have a lower response to inhibiting factors.

Cell Theory

• All living organisms are made of cells.
• All existing cells are produced by other living cells.
• The cell is the most basic unit of life.

Key Terms

• DNA is a molecule that stores genetic information in all organisms.
• A chromosome is a long continuous thread of DNA that consists of numerous genes and regulatory information.
• A eukaryote is an organism with complex cells or a single cell with a complex structure.
• Eukaryotic cells contain a nucleus.
• A prokaryote is a single-celled organism that does not have a nucleus or other specialized organelles.
• Cell Differentiation constitutes the processes by which unspecialized cells develop into their mature form and function.
• Stem Cells divide for long periods of time while remaining undifferentiated.
• Genes constitute a segment of DNA that codes for a specific protein molecule.

Binary Fission vs. Mitosis

• Binary fission occurs in prokaryotic cells where as Mitosis occurs in Eukaryotic cells.
• Binary fission involves cellular chromosomes and mitosis involves a nucleus containing DNA.
• Both binary fission and Mitosis are forms of cellular reproduction.
• Binary fission is a form of asexual reproduction, where as mitosis involves differentiation into specialized cells.
• During both binary fission and Mitosis, chromosomes are copied and seperated.
• Both binary fission and Mitosis involves cells dividing the cytoplasm (cytokinesis).

Stem Cells

• The capacity to differentiate makes stem cells important to multicellular organisms.