Chapter 8: DNA Replication, Binary Fission and Mitosis

What is the main purpose of mitosis?

To make exact copies of somatic cells for growth, maintenance, repair, and asexual reproduction.

What are the main differences between asexual and sexual reproduction?

Asexual reproduction involves one parent and produces exact copies, while sexual reproduction involves two parents and results in genetically diverse offspring.

What is the ploidy level of somatic cells in humans?

Somatic cells are diploid (2n), meaning they have 23 pairs of chromosomes.

What phases comprise the cell cycle?

Interphase and Mitosis.

What occurs during interphase?

Cell growth, organelle duplication, and DNA replication.

What is the G1 phase in the cell cycle?

The phase where the cell grows and synthesizes organelles.

What is the S phase?

The phase in which DNA is replicated.

What is the role of helicase in DNA replication?

Helicase unwinds the double-stranded DNA.

What enzyme adds RNA primers during DNA replication?

Primase.

How does DNA polymerase III function during replication?

It reads the template strand from 3' to 5' and synthesizes the complementary strand.

What are Okazaki fragments?

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

What is the role of ligase in DNA replication?

Ligase creates covalent bonds between adjacent DNA segments.

What is the function of RNA primers in DNA replication?

They provide a starting point for DNA polymerase to initiate synthesis.

How many chromosomes do humans have?

Humans have 46 chromosomes, arranged in 23 pairs.

What occurs in prophase during mitosis?

Chromatin condenses into chromosomes, and spindle fibers begin to form.

What happens during metaphase?

Sister chromatids line up along the metaphase plate.

Define anaphase in mitosis.

Sister chromatids are separated and move to opposite ends of the cell.

What takes place during telophase?

Chromosomes reach the poles, nuclear envelope reforms, and chromatin uncoils.

What is cytokinesis?

The division of cytoplasm that results in two identical daughter cells.

What is binary fission?

A method of asexual reproduction in prokaryotes producing two identical cells.

What is the first step of binary fission in prokaryotes?

DNA replication where the single chromosome duplicates.

Define benign tumors.

Tumors that are slow-growing, harmless, and contained.

What is a malignant tumor?

A fast-growing tumor that invades other tissues.

List characteristics of cancer cells.

They lack a cell clock, divide without growth factors, and do not undergo apoptosis.

What is apoptosis?

Programmed cell death that eliminates excess and defective cells.

What is the role of proto-oncogenes?

Normal proteins that stimulate cell division.

What do tumor suppressor genes do?

They normally block cancer development by inhibiting cell division.

How can environmental factors influence cancer risk?

Environmental factors like diet, exercise, and sun exposure can reduce cancer risk.

How can regular exercise impact cancer risk?

It can help reduce the risk of developing cancer.

What should be avoided to reduce cancer risk?

Tobacco use and excessive exposure to UV radiation.

What is DNA proofreading?

The process by which DNA polymerase checks for errors during replication.

What does the term 'cleavage furrow' refer to?

The indentation that begins the process of cytokinesis in animal cells.