4.3

Question 1

DNA helicase (function)

Answer 1

unzips DNA helix

Question 2

DNA polymerase (function)

Answer 2

moves along separated strands and produces complementary strands

Question 3

DNA ligase (function)

Answer 3

fills in the gaps between Okazaki fragments on lagging strand

Question 4

1 parental DNA molecule makes ___ new daughter DNA molecules

this process is called ___

Answer 4

2

semiconservative replication

Question 5

DNA helicase…

Answer 5

opens the DNA helix, exposing the nitrogenous bases

Question 6

DNA polymerase…

Answer 6

reads nitrogenous bases and matches them w/ complementary free nucleotides

Question 7

DNA ligase…

Answer 7

joins the newly synthesized segments of DNA

Question 8

which molecule usually detects and corrects errors in DNA replication?

Answer 8

DNA polymerase

Question 9

exposure to chemicals and radiation may lead to changes in DNA structure called ___

Answer 9

mutations

Question 10

G1 phase (def)

Answer 10

interval b/n cell division and DNA replication

cell synthesizes proteins, grows, and carries out is preordained tasks for the body

cell accumulates the materials needed to replicate its DNA in the next phase

Question 11

how accurate is DNA replication?

Answer 11

the few errors made by DNA polymerase are usually corrected by DNA polymerase or other repair enzymes

Question 12

describe events that occur during the synthesis (S) phase of the cell cycle

Answer 12

a cell makes a duplicate copy of its centrioles and all of its nuclear DNA

Question 13

what occurs during the G2 phase of the cell cycle?

Answer 13

cell synthesizes enzymes that control cell division and also checks and repairs the newly copied DNA

Question 14

during the cell cycle, G1, S, and G2 collectively make up the phase known as what?

Answer 14

interphase

Question 15

S phase (def)

Answer 15

period of synthesis during which a cell makes a duplicate copy of its centrioles and all of its nuclear DNA

Question 16

which phase is the period of time during which cells are in a non-dividing phase outside of the cell cycle? The length of this period is variable and for some cells it may last days, years, or the rest of one’s life

Answer 16

G0

Question 17

which phase is a short period fo time of growth and preparation for mitosis? During that time, the cell produces enzymes that control cell division, and also checks and repair the newly copied DNA

Answer 17

G2

Question 18

indicate which events occur during prophase of mitosis

Answer 18

chromosomes condense
spindle fibers grow from the centrioles
nuclear envelope disappears
centrioles are pushed apart (migrate to opposite poles of cell)

Question 19

during metaphase, the spindle fibers form a lemon-shaped array called the ___ spindle

Answer 19

mitotic

Question 20

what is true of the G0 phase of the cell cycle?

Answer 20

an inability to stop cycling and enter G0 is characteristic of cancer cells

the duration of this phase is variable (for some cells it may last days, years, or the rest of one’s life

during this phase cells leave the cell cycle for a “rest” and cease to divide

Question 21

what occurs during anaphase?

Answer 21

daughter chromosomes migrate to opposite ends of cell

Question 22

the new nuclear envelop forms, new nucleoli appear, and the mitotic spindle vanishes during which phase of mitosis?

Answer 22

telophase

Question 23

during the mitotic phase called ___, chromosomes condense, the nuclear envelop disappears, spindle fibers grow, and centrioles migrate to the poles of the cell

Answer 23

prophase

Question 24

G0 phase

Answer 24

period fo time during which cells are in a non-dividing phase outside of the cell cycle

length of this period is variable and for some cells it may last days, years, or the rest of one’s life

Question 25

cytokinesis is the division of the cell's ___ to form 2 cells

Answer 25

cytoplasm

Question 26

statements that describe telophase

Answer 26

chromatids cluster on each side of the cell nuclear envelop reappears

Question 27

cells (start/stop) dividing when they snugly contact neighboring cells or when growth factors are withdrawn

Answer 27

stop

Question 28

what events occur during prophase of mitosis?

Answer 28

chromosomes condense nuclear envelope disappears centrioles are pushed apart spindle fibers grow from the centrioles

Question 29

cell division is stimulated by ___ and suppressed by ___

Answer 29

growth factors contact inhibition

Question 30

what is a cleavage furrow?

Answer 30

an indentation between the future cells that forms as cytokinesis progresses

Question 31

cyclins and Cdks are families of proteins that help regulate which of the following?

Answer 31

the cell cycle

Question 32

the division of the cytoplasm to form 2 cells is called ___

Answer 32

cytokinesis

Question 33

when do cells divide?

Answer 33

1) when neighboring cells die, opening up space in a tissue to be occupied by new cells 2) when they have replicated their DNA, so they can give each daughter cell a duplicate set of genes 3) when they grow large enough to have enough cytoplasm to distribute to their 2 daughter cells 4) when they are stimulated by growth factors 5) when they receive adequate supply of nutrients

Question 34

contact inhibition

Answer 34

when cells snugly contact neighboring cells --> cell stops dividing

Question 35

at 3 specific checkpoints during the cell cycle, a cyclin binds to a Cdk and activates a series of reactions that allow the cell to move on to the next phase. When in the cell cycle do these checkpoints occur?

Answer 35

During the G1 phase between the S and G2 phases at the end of metaphase

Question 36

cyclins and Cdks are families of proteins that help regulate ___

Answer 36

the cell cycle