Ch 9 Book Terms

Question 1

S Phase

Answer 1

The restricted part of the eukaryotic cell cycle during which synthesis of DNA occurs.

Question 2

Checkpoint

Answer 2

A biochemical control mechanism that prevents the cell from progressing from one stage to the next unless specific goals and requirements have been met.

Question 3

Catenate

Answer 3

To link together two circular molecules, as in a chain.

Question 4

Topoisomerases

Answer 4

An enzyme that changes the number of times the two strands in a closed DNA molecule cross each other. It does this by cutting the DNA, passing DNA through the break, and resealing the DNA.

Question 5

Doubling Time

Answer 5

The period (usually measured in minutes) that it takes for a bacterial cell to reproduce.

Question 6

Multiforked Chromosome

Answer 6

A bacterial chromosome that has more than one set of replication forks, because a second initiation has occurred before the first cycle of replication has been completed.

Question 7

Septum

Answer 7

The structure that forms in the center of a dividing bacterium, providing the site at which the daughter bacteria will separate. The same term is used to describe the cell wall that forms between plant cells at the end of mitosis.

Question 8

Minicells

Answer 8

An anucleate bacterial (Escherichia coli) cell produced by a division that generates a cytoplasm without a nucleus.

Question 9

Z-ring

Answer 9

“See Septal Ring”

A complex of several proteins coded by fts genes of Escherichia coli that forms at the midpoint of the cell. It gives rise to the septum at cell division. The first of the proteins to be incorporated is FtsZ, which gave rise to the original name of the Z-ring.

Question 10

Septal Ring

Answer 10

A complex of several proteins coded by fts genes of Escherichia coli that forms at the midpoint of the cell. It gives rise to the septum at cell division. The first of the proteins to be incorporated is FtsZ, which gave rise to the original name of the Z-ring.

Question 11

Site-specific Recombination

Answer 11

Recombination that occurs between two specific sequences, as in phage integration/excision or resolution of cointegrate structures during transposition.

Question 12

Growth Factor Receptor

Answer 12

Recruits the exchange factor SOS to the cell membrane to activate the RAS protein as part of the signal transduction pathway that ultimately cases the cell to begin replication and growth.

Question 13

Signal Transduction Pathway

Answer 13

The process by which a stimulus or cellular state is sensed by and transmitted to pathways within the cell.

Question 14

Proto-oncogenes

Answer 14

Genes that code for elements of the signal transduction pathway that when altered may cause cancer.

Question 15

Epidermal Growth Factor (EGF)

Answer 15

Peptide hormone that binds to EGFR in a lock-and-key type mechanism.

Question 16

Epidermal Growth Factor Receptor (EGFR)

Answer 16

A member of the erbB family of receptors that binds Epidermal Growth Factor (EGF).

Question 17

Dominant Gain-of-Function Mutation

Answer 17

A type of mutation in which the altered product possesses a new molecular function or pattern of gene expression.

Question 18

Cyclin-Dependent Kinases (CDKs)

Answer 18

Serine-threonine protein kinases that are synthesized in an inactive form and activated by binding a cyclin protein subunit.

Question 19

Cyclins

Answer 19

Cell cycle–dependent proteins that have no intrinsic enzymatic activity but when bound to an inactive cyclin-dependent kinase can activate it.

Question 20

Tumor Suppressor

Answer 20

A class of proteins that guard the cell cycle, ensuring that the cell size and absence of DNA damage criteria are met. These
proteins act as brakes on the cell cycle, preventing the cell from progressing from G1 to S.

Question 21

Apoptosis (Programmed Cell Death (PCD))

Answer 21

Programmed cell death triggered by a cellular stimulus through a signal transduction pathway.

Question 22

Restriction Point

Answer 22

The point in G1 of the cell cycle when the cell becomes committed to S phase.