Cell Division

What are the 2 reasons that cells divide? *
  1. DNA overload - nucleus cant keep up w/ demand of cell
  2. Exchange of materials - stuff goes in & stuff goes out
When a cell grows, does surface area or volume increase faster?

Volume

When does a cell divide?

When it reaches it max size & nucleus sends signal to start

What is growth? **

Producing new cells

What is differentiation? *

When cells become specialized

What is repair? *

Fixing tissue

What is the different between asexual & sexual reproduction?

Asexual: offspring produced by 1 parent

Sexual: offspring produced by 2 parents

Why are cells small? **
  1. Nucleus can only control so much
  2. Cell size depends on size of cell membrane

   • Membrane size must be large enough for all exchanges to happen, but cell volume must be low enough for efficient cell functioning

What is volume? *

Quantity of 2d space occupied by solid, liquid, or gas

What is a chromosome?

Strand of DNA

What is the centromere?

Where chromosomes attach

What happens in mitosis? **

Exact copy of DNA in “mother” cell must be distributed to each “daughter” cell

What cells does mitosis create?

Somatic/body cells (each & every cell except sperm & egg cells)

What happens in prophase? **
  1. Chromosomes condense
  2. Nuclear envelope dissapears
  3. Centrioles move to opposite poles
  4. Spindles start to form, growing out of centrioles towards chromosomes
What happens in metaphase? **
  1. Chromosomes line up on equator (metaphase plate) of cell
  2. Centrioles have migrated to opposite ends of cell
  3. Spindle fibers attach to centromeres
What happens in anaphase? **
  1. Chromosomes divide
  2. Spindle fibers shrink & chromosomes are pulled to opposite poles, towards centrioles
What happens in telophase? **
  1. Chromosomes are at poles of cell
  2. Spindle fibers disintegrate
  3. Chromatids spread out into chromatin
  4. Nuclear envelope re-forms around 2 sets of chromosomes
What are sister chromatids?

Copied DNA

What is cytokinesis?

Cytoplasm is divided into 2 separate cells

What is cytokinesis in plants?

Cell plate turns into cell wall

What is cytokinesis in animals? *
  1. Actin filaments
  2. Myosis - protein
How do cancer cells differ from other cells? *

Cancer cells dont respond to signals that regulate growth of most cells (cells divide uncontrollably)

What are cyclins? **
  1. Control timing of cell cycle (work w/ other enzymes)
  2. Cyclins bind to kinases to form mitosis promoting factors
What is cancer? **

Disorder in which body lose ability to control cell growth

What is a tumor? *

A mass of cells formed by cancer cells that divide uncontrollably

What is the difference between benign & malignant cancer?

Benign: good cancer - dont spread to other tissues

Malignant: bad cancer - spread to other tissues (metastasis)

What happens in G1? *

The cell grows (G0 cells do not divide, ex., brain cells, nerve cells in spinal cord)

What happens in S?

DNA is copied

What happens in G2?

Checks for errors (makes more organelles)

What happens in M?

Cell divides into 2 new cells

What are histones?

Little protein beads that the length of DNA is wound up onto