Week 2: DNA Replication & Mitosis

During which phase of the cell cycle does DNA duplication, or replication, take place?

Interphase

During which phase of mitosis do the nuclear envelope and nucleoli disappear?

Prophase

During DNA replication, which nucleotide will bind to an A nucleotide in the original or parental DNA strand?

T

Which is representative of late prophase?

Attachment of chromatid pairs to spindle microtubules.

Which protein joins together the Okazaki fragments of DNA in the lagging strand?

DNA ligase

Which statement about DNA replication is FALSE? -The two strands of original or parental DNA are separated during DNA replication. -The lagging strand is made of a series of fragments that must be joined together to make a continuous strand. -DNA ligase adds nucleotides to the lagging strand. -Because the two strands of original or parental DNA run in opposite directions, the new strands must be made in different ways. -DNA polymerase III builds a new strand by adding DNA nucleotides one at a time.

DNA ligase adds nucleotides to the lagging strand.

Which of the following builds new strands of DNA?

DNA polymerase

Which of the following is least likely to result in a genetic mutation? -poor health -drugs -errors in DNA replication -radiation

poor health

During which of the following phases does DNA replication occur?

Synthesis Synthesis is part of interphase, and is completed well before the cell actually divides.

During which phase of mitosis do nuclear envelopes and the nucleoli reappear?

Telophase

In order for a cell to divide, all of its chromosomes must be duplicated in a process called DNA replication. During which phase of the cell cycle does DNA replication occur?

interphase

Which is representative of early prophase?

Chromosomes condense as sister chromatid pairs.

Select the correct activity occurring during anaphase.

Chromosomes move towards opposite poles of the cell.

The cell cycle is divided into two main parts: interphase and cell division. Interphase is the period in which the cell is performing normal functions and not actively engaged in cell division. Most of your body's cells spend a lot of their time in interphase. Before a cell can divide, what must occur during interphase?

Each chromatin fiber is duplicated in the nucleus.

Which of the following lists, in correct order, the phases of interphase?

G1, S, and G2

Which phrase below correctly describes metaphase?

Sister chromatids are aligned at the metaphase plate

Which statement best describes strand characteristics as it relates to DNA replication?

The leading strand is built continuously, and the lagging strand is built in pieces.

Match these prefixes, suffixes and roots to their meanings.

The prefix inter- means "within," "inside" or "between." The prefix endo- means "within." The prefix cyto- means "cell." The prefix exo- means "outside." The prefix centr- means "center."

In which stage of the cell cycle does a cell contain twice its normal number of chromosomes?

anaphase In anaphase, the chromatids are split apart. Each chromatid becomes a new, unreplicated chromosome, thus temporarily doubling the number of chromosomes in the cell until the end of cytokinesis.

When a double helix of DNA is replicated, two complete helices are formed. Together, these helices are called sister __________.

chromatids

During which of the following phases does chromatin condense and become chromosomes?

prophase

In which stage of the cell cycle does the cell condense chromatin into chromosomes?

prophase

Now that you have learned the correct order for the phases of mitosis, this activity will test your understanding of events that occur during each phase. Sort the following events into the phase of mitosis that they occur.

Prophase: -DNA condenses into chromosomes -Nuclear envelope breaks up -Mitotic spindle fibers form and attach to centromeres -Centrosomes move to opposite sides of the cell Metaphase: -Chromosomes align in the center of the cell Anaphase: -Chromosomes move along the spindle fibers -Sister chromatids separate into chromosomes Telophase: -Completion of cytokinesis -Chromosomes relax and nuclear envelopes form -Chromosomes reach the opposite ends of the cell

When does cytokinesis begin?

late anaphase In anaphase, the chromosomes split and migrate toward opposite poles of the cell. At the same time, the cell begins to "pinch" into two cells that will each contain half of the chromosomes.

Which of the following lists, in correct order, the phases of mitosis?

prophase, metaphase, anaphase, telophase

What is the purpose of the S phase of interphase?

to form sister chromatids that can be separated during mitosis

Drag and drop the term on the left to the best description occurring in subphases of interphase on the right. Answers may be used once.

1. Microtubule arrays around centrosomes. asters 2. DNA containing structures which condense during prophase. chromatin 3. These RNA structures disappear when chromosomes appear. nucleoli 4. These structures act as focal points for the appearance of the mitotic spindle. centrosomes 5. Structures containing DNA only visible during mitosis and first seen in prophase. chromosomes

Which of the following is true about genetic mutation? -It is defined as a change in a person's phenotype. -Mutations always have a negative impact. -It is a change in the DNA base sequence. -It is rarely passed on to other cells.

It is a change in the DNA base sequence.

During which phase of mitosis do the sister chromatids move apart?

Anaphase

What is the name of the process by which the cytoplasm divides in two?

Cytokinesis

Which is true regarding cytokinesis?

Cytokinesis usually begins in anaphase.

Which of the following statements about genes is not correct? -They are composed of DNA. -They are part of your chromosomes. -They are located in the nucleus. -Each single chromosome contains one single gene.

Each single chromosome contains one single gene.

During which phase of mitosis do sister chromatids line up at the center of the cell?

Metaphase

Match these vocabulary terms to their meanings.

The cellular material between the cell membrane and the nucleus is called cytoplasm. Exocytic transport vesicles send something outside of a cell. The button-like structure that holds homologous chromosomes together at their middles during cell division is called the centromere. The stage of the cellular lifecycle between divisions is called interphase. Endocytic transport vesicles bring something into a cell.

Each individual gene does which of the following?

carries the instructions for making a single polypeptide