Biology Chapter 6: Chromosomes and Cell Division

What is the difference between normal cells and cancer cells?

Normal cells divide until they bump up against other cells or tissues, at which point they stop dividing, but cancer cells ignore the signal to stop dividing and continue to divide, piling on top of one another.

What is the difference between prokaryotic chromosomes and eukaryotic chromosomes?

Prokaryotic cells have a single circular chromosomes attached to the cell membrane, while eukaryotic cells contain free-floating linear chromosomes within a nucleus.

What is a telomere?

A section of non-coding repetitive DNA that serves as a protective cap at the tip of every chromosome.

Why are cancers dangerous?

As a malignant tumor develops in a patient, it grows larger, taking up more and more space, pressing up against neighboring cells and tissues. A growing tumor can impinge on other cells and tissues, disrupting function and even causing death.

What is metastasis?

Cancer cells don not stick together like normal cells, therefore they can spread very quickly to other parts of the body.

Before a cell divides, what happens to the cell's chromosomes?

They are duplicated.

Describe Binary Fission in Prokaryotes

1. An exactly copy of the cells DNA is created 2. Cell elongates and begins to pinch into two. 3. Two daughter cells are formed.

Which of the stages of the eukaryotic cell cycle occur during interphase?

1. Gap 1 2. DNA Synthesis 3. Gap 2

What are the 5 stages of the eukaryotic cell cycle and what occurs at each stage?

1. Gap 1: The cells primary growth phase. Normal cellular function (making proteins, getting rid of waste, etc), takes place. 2. DNA Synthesis: The cell begins preparation for division. Every chromosome creates an exact duplication of itself in a process called replication. 3. Gap 2: second period of growth and preparation for cell division. 4. Mitosis: The parent cell's nucleus with its duplicated chromosomes, divides. 5. Cytokinesis: The cytoplasm is divided into two daughter cells, each of which has a complete set of the parent cell's DNA and other cellular structures.

Explain unwinding and rebuilding as used in the DNA replication process. What is the result of the DNA unwinding and rebuilding process?

1. Unwinding: The coiled, double-stranded DNA molecules unwinds into two separate strands 2. Rebuilding: Enzymes connect a nucleotide with the appropriate base to the growing new strand, as the base bonds with the exposed, complementary base. The result: Each of the single strands becomes a double strand, each identical to the cell's original DNA molecule.

What happens to eukaryotic chromosomes with each cell division?

They are shortened

What enzymes are used in the DNA replication process?

Unwinding and Rebuilding

Why is DNA replication a semi-conservative process?

DNA replication is a semi-conservative process because half of each of the two new molecules come from the original molecule.

How do telomeres partially solve the shortening problem?

Every time a cell divides the telomere gets shorter. After a critical number of cell divisions (about 50 in humans) functional DNA is lost which means almost certain death for the cell. However, as the telomeres act as a "buffer" so it takes the critical number of cell divisions before function DNA is lost, without telomeres the function DNA would be lost in the first division.

Why must a cell's DNA be replicated for cell division to occur?

If the DNA is not replicated, each daughter cell would only get 1/2 of the necessary DNA needed. By duplicating the DNA the daughter cell gets DNA identical to the parent cell.

Are telomeres used in binary fission in prokaryotes?

NO

What are the characteristics of cancer?

No contact inhibition and continued division