Bio Exam 3: Cell Division: S-Phase and M-Phase (Ch. 8.4-8.6)

These flashcards cover key vocabulary concepts related to cell division and mitosis, including processes, enzymes, and important structures.

S-phase

The phase of the cell cycle in which DNA is replicated.

M-phase

The mitotic phase of the cell cycle where cell division takes place, producing two daughter cells.

Anti-parallel strands

Refers to the orientation of the two strands of DNA, running in opposite directions. There is a 5’ end and a 3’ end for each strand.

DNA polymerase

The enzyme responsible for adding new nucleotides to a growing DNA strand during replication.

Leading strand

The DNA strand that is synthesized continuously in the 5' to 3' direction during DNA replication.

Lagging strand

The DNA strand that is synthesized in short segments (Okazaki fragments) away from the replication fork.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during replication.

Semi-conservative replication

The process of DNA replication where each new DNA molecule consists of one original strand and one new strand.

Centromere

The region of a chromosome where sister chromatids are joined and where the kinetochore forms.

Cyclins

Proteins that regulate the cell cycle and ensure that cell division occurs at the appropriate time.

Cytokinesis

The final phase of cell division where the cytoplasm of a parental cell is divided into two daughter cells.

Kinetochore

A protein structure on the chromosome where the spindle fibers attach during cell division.

Histones

Proteins that DNA wraps around to form chromatin, helping to condense the DNA during cell division.

Microtubules

Cytoskeletal filaments involved in the movement of chromosomes during cell division. Form the mitotic spindle

Primase

An enzyme that synthesizes a short RNA primer to initiate DNA replication.

Topoisomerase

An enzyme that unwinds DNA ahead of the replication fork to relieve tension.

Single-stranded binding proteins

Proteins that stabilize unwound DNA strands during replication to prevent them from re-annealing.

Proofreading function

A mechanism by which DNA polymerase corrects errors in newly synthesized DNA.

Cancer

A disease characterized by rapid and uncontrolled cell division.

Chemotherapy

A cancer treatment using drugs to stop the growth of cancer cells by disrupting cell division.

Radiation treatment

A cancer treatment targeting tumors with radiation to damage cancer cells.

What does the 5' end of a DNA strand display?

A phosphate group.

What does the 3' end of a DNA strand display?

A hydroxyl (OH) group.

In what direction are DNA nucleotides added?

In the 5' to 3' direction.

What enzyme is responsible for the addition of the DNA nucleotides for the new strands?

DNA polymerase III

Helicase

An enzyme that unwinds the DNA double helix by breaking hydrogen bonds between base pairs, separating the two strands during DNA replication.

Replication fork

The Y-shaped region where the DNA double helix is unwound and separated into two single strands, providing templates for new DNA synthesis.

Sister chromatids

The two identical copies of a chromosome formed by DNA replication, joined together by a centromere.

What are the phases of M-phase?

1. Prophase: Chromatin condenses into visible chromosomes; mitotic spindle begins to form.
2. Metaphase: Chromosomes align along the metaphase plate in the center of the cell.
3. Anaphase: Sister chromatids separate and move to opposite poles of the cell.
4. Telophase: Chromosomes decondense; nuclear envelopes reform around the two sets of chromosomes.

Cleavage furrow

An indentation in the surface of an animal cell during cytokinesis, which eventually cleaves the cell into two daughter cells.

What is the end result of mitosis?

Two genetically identical daughter cells, each with a complete set of chromosomes.

What can mutations in the genes that code for cell cycle regulatory proteins lead to?

Uncontrolled cell division, which can result in diseases such as cancer.

What is the S-phase?

The phase of the cell cycle in which DNA is replicated.

What is the M-phase?

The mitotic phase of the cell cycle where cell division takes place, producing two daughter cells.

What does 'anti-parallel strands' refer to in DNA?

The orientation of the two strands of DNA, running in opposite directions. There is a 5’ end and a 3’ end for each strand.

What is the function of DNA polymerase?

The enzyme responsible for adding new nucleotides to a growing DNA strand during replication.

Describe the leading strand.

The DNA strand that is synthesized continuously in the 5' to 3' direction during DNA replication.

Describe the lagging strand.

The DNA strand that is synthesized in short segments (Okazaki fragments) away from the replication fork.

What are Okazaki fragments?

Short segments of DNA synthesized on the lagging strand during replication.

Explain semi-conservative replication.

The process of DNA replication where each new DNA molecule consists of one original strand and one new strand.

What is a centromere?

The region of a chromosome where sister chromatids are joined and where the kinetochore forms.

What is the role of cyclins?

Proteins that regulate the cell cycle and ensure that cell division occurs at the appropriate time.

What is cytokinesis?

The final phase of cell division where the cytoplasm of a parental cell is divided into two daughter cells.

What is a kinetochore?

A protein structure on the chromosome where the spindle fibers attach during cell division.

What are histones and what is their function?

Proteins that DNA wraps around to form chromatin, helping to condense the DNA during cell division.

What are microtubules and what is their role in cell division?

Cytoskeletal filaments involved in the movement of chromosomes during cell division. Form the mitotic spindle

What is the function of primase?

An enzyme that synthesizes a short RNA primer to initiate DNA replication.

What is the role of topoisomerase?

An enzyme that unwinds DNA ahead of the replication fork to relieve tension.

What is the function of single-stranded binding proteins?

Proteins that stabilize unwound DNA strands during replication to prevent them from re-annealing.

Explain the proofreading function.

A mechanism by which DNA polymerase corrects errors in newly synthesized DNA.

What is cancer?

A disease characterized by rapid and uncontrolled cell division.

How does chemotherapy work?

A cancer treatment using drugs to stop the growth of cancer cells by disrupting cell division.

How does radiation treatment work?

A cancer treatment targeting tumors with radiation to damage cancer cells.

What is the function of helicase?

An enzyme that unwinds the DNA double helix by breaking hydrogen bonds between base pairs, separating the two strands during DNA replication.

Define replication fork.

The Y-shaped region where the DNA double helix is unwound and separated into two single strands, providing templates for new DNA synthesis.

What are sister chromatids?

The two identical copies of a chromosome formed by DNA replication, joined together by a centromere.

What is a cleavage furrow?

An indentation in the surface of an animal cell during cytokinesis, which eventually cleaves the cell into two daughter cells.