AP Biology: Chapter 12 Guided Reading Assignment

Compare and contrast the role of cell division in unicellular and multicellular organisms

In a unicellular organism, cell division creates an entire new organism, but in multicellular organism, it creates offspring. Additionally in multicellular organisms. Cell division enables sexually producing organisms to develop from a single cell (zygote


A cells endowment of DNA, its genetic material


DNA molecules are packed into these, makes the replication and distribution of DNA manageable

Somatic Cells

And body cells except the reproductive cells each contain 46 chromosomes made up of 2 sets of 23


Reproductive cells, sperm and egg, have half as many chromosomes as somatic cells, they have one set of 23


What eukaryotic chromosomes are made of, complex DNA and associated protein molecules

Sister Chromatids

Each duplicated chromosome has 2 of these, the 2 chromatids, each containing an identical DNA molecule attached by adhesive proteins along their lengths


The narrow "waist" region where the 3 chromatids are most closely attached


The division of the nucleus


The division of the cytoplasm


The production cycle of gametes, yields nonidentical daughter cells that have only one set of chromosomes, thus half as many chromosomes as the parent cell

Mitotic Phase

Mitosis and eytokinesis, the shortest part of the cell cycle


Alternates with the mitotic phase, accounts for 90% of the cell cycle

G1 Phase

1st gap of interphase, cell grows by producing proteins and cytoplasmic organelles such as the mitochondria and chromosome copies

G2 Phase

2nd gap, grows more as it completes preparation for cell division

S Phase

Chromosomes are duplicated during this phase, continues growth

Mitotic Spindle

Begins to form in the cytoplasm during phrophase, this structure consists of fibers made of microtubules and associated proteins


Where assembly of spindle microtubules starts, a nonmembranous organelle that functions throughout the cell for organic the cells microtubules


A radical array of short microtubues, extends form each centrosome, the spindle includes the centrosomes, the spindle microtubules, and this


A structure of proteins associated with specific sections of chromosomal DNA at the centromere, each of the 2 sister chromatids has this

Describe the experiment concerning the movement of microtubules during mitosis and its result

During interphase, the centromere replicates to make 2 centromeres and they move apart inside of phrophase and prometaphase. Inside of metaphase, asters, short microtubules, form and extend from the centrosomes kinetochores of chromosomes and microtubules

Contrast cytokinesis in plant and animal cells

Inside of animal cells cytokinesis occurs by cleavage. Cleavage is first apparent because of cleavage furrow, which is a groove on the old metaphase plate

Discuss the hypothetical evolution of mitosis

Some unicellular eukaryotes have cell division mechanisms intermediate between binary fission and mitosis

What is the cell cycle control system and how do checkpoints play into this?

Cyclical operating set of molecules that trigger and coordinate key events in the cell cycle; point in the cycle where stop or go - ahead signals regulate the cycle

What is a cyclin and what does it activate?

Cyclin is a protein whose concentration fluctates cyclically (highest during mitosis)

What are CDK's

CDK is a cyclin dependent kinase, which is only active when it is attached to a cyclin

What does MPF stand for and what does it promote?

MPF stands for mitosis promoting factor. It promotes mitosis. Maturation promoting factor; triggers the cell to enter mitosis

What is growth factor?

A protein released by certain cells that stimulates other cells to divide

What is density-dependent inhibition?

Crowded cells stop dividing

What is anchorage dependence?

It's also an external factor. It is when cells divide when they are attached to a certain substance (to divide, cells must be attached to a substrate)


The process that is converts a normal cell into a cancer cell

Benign Tumor

A tumor that is caused by abnormal cells remaining in the original site, a lump

Malignant Tumor

It is a tumor that becomes invasive and can impair the functions of one or more organs


The spread of cancer cells to locations distant from their original site