Unit 7

Question 1

What is a genome?

Answer 1

the complete complement of an organism’s genetic material, including the noncoding regions of DNA

Question 2

What are chromosomes?

Answer 2

discrete sections of the DNA molecule that carry a specific assemblage of genes

Question 3

Section of a chromosome that codes for a specific protein

Answer 3

gene

Question 4

Chromosome that are inherited from different parents that carry the same assemblage of genes

Answer 4

homogulous chromosomes

Question 5

What is chromatin?

Answer 5

loosely arranged DNA that is accessible to cellular machinery for protein construction

Question 6

Chromosomes that consist of DNA that is bound to proteins and inaccessible to cellular machinery; used to move chromosomes within the cell and inactivate genes

Answer 6

condensed chromosome

Question 7

What determines the length of a chromosome?

Answer 7

the number of coding and non-coding regions on the chromosome, this varies siginificantly between chromosomes

Question 8

Consists of a single copy of each gene, when condensed, the chromosome is constricted near the middle at the centromere

Answer 8

pre-replication chromosome

Question 9

Region of highly condensed DNA; genes here are inaccessible for replication

Answer 9

centromere

Question 10

Consists of two copies of each gene distrubuted across two chromatids

Answer 10

post-replication chromosome

Question 11

Each consists of an “arm” and a “leg” that are connected at the centromere; are attached to eachother by cohesion proteins

Answer 11

chromatid

Question 12

What is the cell cycle?

Answer 12

natural process of cell growth and replication

Question 13

Phase in which DNA and organelles are replicated in preparation for division

Answer 13

interphase

Question 14

Cell growth and organelle replication

Answer 14

G1 phase

Question 15

DNA replication/synthesis

Answer 15

S phase

Question 16

Cell growth and replication

Answer 16

G2 phase

Question 17

Division of the nucleus; equitable distribution of DNA between two daughter nuclei

Answer 17

mitosis

Question 18

Division of the cell

Answer 18

cytokenesis

Question 19

Initial phase of mitosis

Answer 19

prophase

Question 20

What occurs during prophase?

Answer 20

chromatin fibers condense to form tightly packaged chromosomes, nuclear envelope fragments and dissolves, mitotic spindle begins to form, the centrioles are duplicated in the G phases of interphase, so each cell in mitosis has 2

Question 21

What is the second phase of mitosis?

Answer 21

metaphase

Question 22

What occurs during metaphase?

Answer 22

centrioles have completely migrated to opposite poles of the cell, mitotic spindle is complete, each chromosome is attached to both centrioles, chromosomes have migrated to the center of the cell

Question 23

What is the third phase of mitosis?

Answer 23

anaphase

Question 24

What occurs during anaphase?

Answer 24

cohesion proteins are cleared, and sister chromatids become independent. liberated chromatids become true chromosomes and migrate to opposite poles of the cell toward centrioles

Question 25

What is the final stage of mitosis?

Answer 25

telophase

Question 26

What occurs during telophase?

Answer 26

microtubules detach from chromosomes, nuclear envelope reforms around chromosomes, chromosomes unwind and return to chromatin format

Question 27

What is cytokenesis?

Answer 27

division of the cell

Question 28

Why is the cell cycle closely regulated?

Answer 28

to avoid aberrant and uncontrolled growth of tissues; consists of a series of cyclically available molecules and distinct checkpoints

Question 29

What are checkpoints?

Answer 29

discrete times in the cell cycle where specific criteria must be met before the cell continues to grow and divide

Question 30

cells assess the replication of organelles and cytosol organelles; for mammilian cells, if it passes this checkpoint, it will likely pass the rest

Answer 30

G1 checkpoint

Question 31

cells assess the replication of all organelles, proteins, and DNA

Answer 31

G2 checkpoint

Question 32

Occurs during metaphase; cells assess the position of chromosomes along the metaphase plate

Answer 32

M checkpoint

Question 33

What happens to the cells that do not pass?

Answer 33

move into arrested development of G0

Question 34

Cells will not divide if the cell density is too ___.

Answer 34

high

Question 35

In which stage of the cell cycle is DNA replicated?

Answer 35

S phase

Question 36

In which stage of mitosis do the chromosomes align at the center of the cell?

Answer 36

metaphase

Question 37

In which stage of mitosis does the nuclear envelope dissolve?

Answer 37

prophase

Question 38

In which stage of mitosis do sister chromatids migrate to opposite poles of the cell?

Answer 38

anaphase