Lecture 9 - Mitosis and Cancer

Flashcards covering the foundation of cell division, chromosome structure, DNA replication, the phases of mitosis, and the characteristics and treatments of cancer based on Lecture 9.

What are the three main steps of cell division identified in the lecture?

1. DNA replication. 2. Mitosis (division of the parent cell’s nucleus and chromosomes). 3. Cytokinesis (division into two daughter cells).

What are the three components of a nucleotide?

A nitrogenous base, a $5$-carbon sugar (ribose), and a phosphate molecule.

What are the complementary base pairs in DNA?

Adenine and Thymine; Guanine and Cytosine.

Define 'Chromatin'.

A linear strand of DNA wrapped around histones.

What is the function of histones?

They are proteins that keep DNA from getting tangled.

What does the term 'Genome' refer to?

The complete collection of an organism's genetic information.

What is a 'Karyotype'?

A pictorial arrangement of chromosomes.

What is the difference between haploid and diploid cells?

Haploid cells have a single copy of each chromosome (e.g., gametes like egg and sperm), while diploid cells have two copies (e.g., somatic cells).

What percentage of human DNA actually codes for proteins?

Only $1-2\%$.

What occurs during the G1 phase of the cell cycle?

The cell's primary growth phase where normal cellular functions like making proteins and waste removal occur.

What takes place during the S phase of interphase?

DNA synthesis, where every chromosome creates an exact duplicate of itself through replication.

What is the G0 phase?

A "resting" phase outside the cell cycle where cells can stay for days or years.

What is the function of the enzyme Helicase?

It unwinds DNA, separating it into two complementary strands.

What is the role of DNA Polymerase?

It creates the complementary strand by adding new DNA nucleotides to the template strand.

What structure holds sister chromatids together after replication?

The centromere.

Summarize the events of Prophase in mitosis.

Chromatin condenses into chromosomes, the nuclear membrane and nucleolus disappear, and mitotic spindles (microtubules) form.

What happens during Metaphase?

Centrosomes reach opposite poles and chromosomes line up on the metaphase plate.

What happens during Anaphase?

Sister chromatids are pulled apart by spindle fibers toward opposite ends of the cell.

How does cytokinesis differ in animal cells versus plant cells?

Animal cells form a cleavage furrow, while plant cells form a cell plate using membrane-lined vesicles containing cell wall precursors.

Define 'Cancer'.

Unregulated cell multiplication that invades nearby tissues or other parts of the body, destroying working tissues.

What does 'no contact inhibition' mean in the context of cancer?

Normal cells stop dividing when they bump into other cells, but cancer cells ignore this signal and continue to divide, piling on top of each other.

How do cancer cells interact with T-cells?

Cancer cells have membrane proteins that turn off T-cells, preventing the immune system from finding and killing them.

What is the difference between a benign and a malignant tumor?

Benign tumor cells do not spread from the tumor, whereas malignant tumor cells are invasive and spread to distant tissues via metastasis.

What are some ways chemotherapy drugs attack cancer cells?

They may prevent DNA replication, prevent transcription, inhibit microtubule formation, or alter mitochondrial DNA replication/transcription.

In cancer treatment, what is the difference between cryosurgery and hyperthermia?

Cryosurgery uses extreme cold to destroy cancerous tissue, while hyperthermia uses extreme heat.

How does Immunotherapy help treat cancer?

It uses drugs with protein inhibitors that prevent cancer proteins from binding with T-cell receptors, allowing T-cells to destroy the cancer cells.