Chapter 12- The Cell Cycle

Rb protein

The serves as a gatekeeper that enforces the G1 checkpoint.

spindle apparatus

The is a structure that produces mechanical forces that:

Eukaryotic chromosomes

consist of DNA wrapped around globular histone proteins.

Cancer

is a general term for disease caused by cells that divide in an uncontrolled fashion, invade nearby tissues, and spread to other sites in the body.

Regulatory proteins

such as p53 are called tumor suppressors.

Serum

is the liquid portion of blood that remains after blood cells and cell fragments have been removed.

Growth factors

are polypeptides or small proteins that stimulate cell division.

Howard

and Pelc coined the term cell cycle to describe the orderly sequence of events that leads a eukaryotic cell through the duplication of its chromosomes to the time it divides.

Negative feedback

occurs when a process is slowed or shut down by one of its products.

genetic material

The process of copying the is separated, in time, from the partitioning of replicated chromosomes during M Phase.

telophase

During , the nuclear envelope re- forms around each set of chromosomes, and the chromosomes begin to decondense.

multicellular organisms

In , cells that keep dividing in this way may die or form a mass of cells called a tumor.

Centrosome

is a structure that contains a pair of centrioles.

sister chromatids

At the start of anaphase, the cohesins that hold together at 1e centromeres are cleaved by an enzyme.

MPF

The substance that initiates M- phase in oocytes is now called the M- phase- promoting factor, or .

Mitosis

begins with the events of prophase which is when chromosomes condense into compact structures.

MPF deactivation

illustrates two key concepts about regulatory systems in cells:

DNA copies

Each of the double- stranded in a replicated chromosome is called a chromatid.

Removal of the envelope

allows the cytoplasmic microtubules to attach to chromosomes at specialized structures called kinetochores.

Chromatid copies

that remain attached at their centromere are referred to as sister chromatids.

MPF

is a dimer consisting of a cyclin and a cyclin- dependent kinase.

The four cell-cycle checkpoints have the same purpose

They prevent the division of cells that are damaged or that have other problems

Chromosome

refers to these threadlike structures 

Gene

is a region of DNA in a chromosome that codes for a particular protein or ribonucleic acid (RNA). 

Chromatid

Each of the double-stranded DNA copies in a replicated chromosome is called a