10 Minutes to Study for your Quiz

…if you are quiet.

Pop-Quiz (2/3/2010)Answer the following on a piece of paper (be sure to include your name, date, and

class)

1. What are the 4 Macromolecules2. Which Macromolecule carries an

organism’s genetic information?3. Where can this macromolecule be

located?4. During which phase of the cell cycle is

this molecule doubled?

Bellwork•There once was a man by the name of Bob,

homozygous dominant for white hair. He married a beautiful woman by the name of Sue who had black hair, which is a recessive trait. They had two beautiful children, Jack and Jane. One day a virus spread around the world killing almost everyone, leaving only Jack and Jane alive. These 2 were left to repopulate the planet.

What would be the new generation’s genotypic ratio?

DNA: Replication

DNA: Replication• DNA

Deoxyribonucleic acid, a chemical found in the nucleus of cells. DNA carries the instructions for making all the structures and materials the body needs to function.

DNA: Replication• DNA Structure

Nucleotides

Consist of a sugar, a phosphate, and a nitrogen base.

DNA: Replication• Chargaff’s Rule

%G=%C and %A=%T

The amount of guanine (G) is equal to cytosine (C) and the amount of adenine (A) is equal to thymine (T).

DNA: Replication• X-ray Diffraction

Using x-ray diffraction, Rosalind Franklin was able to obtain a clear visible representation that the structure of the DNA was a double helix.

DNA: Replication• Watson and Crick

Built a model of the double helix that conformed to Franklin’s research.

Two outside strands consist of alternating deoxyribose (sugar) and phosphate

Cytosine and guanine bases pair to each other by three hydrogen bonds

Thymine and adenine bases pair to each other by two hydrogen bonds

DNA: Replication• DNA Structure

DNA often is compared to a twisted ladder.

Rails of the ladder are represented by the alternating deoxyribose and phosphate.

The pairs of bases (cytosine–guanine or thymine–adenine)form the steps.

DNA: Replication• Orientation

On the top rail, the strand is said to be oriented 5′ to 3′.

The strand on the bottom runs in the opposite direction and is oriented 3′ to 5′.

DNA: Replication• Replication

Parent strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of the parent DNA and one strand of new DNA. This is called semi-conservative replication.

DNA: Replication• Unwinding

DNA helicase, an enzyme, is responsible for unwinding and unzipping the double helix.

RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand.

DNA: Replication• Base Pairing

DNA polymerase continues adding nucleotides to the chain by adding to the 3′ end of the new DNA strand.

DNA: Replication• Base Pairing

One strand is called the leading strand (3’ – 5’) and is elongated as the DNA unwinds.

The other strand of DNA, called the lagging strand (5’ – 3’), elongates away from the replication fork.

The lagging strand is synthesized discontinuously into small segments, called Okazaki fragments.

DNA: Replication

DNA: Replication• Joining

DNA polymerase removes the RNA primer and fills in the place with DNA nucleotides.

DNA ligase links the two sections.

Article

•Star important information•Write a 4-5sentance summary about the author’s purpose

•Is this narrative, informational, or argumentative writing? How do you know?

•Imagine you are the teacher grading this. What score would you give it? (1-10)

Summary• Watson and Crick were not the discoverers of DNA, but rather

the first scientists to formulate an accurate description of this molecule's complex, double-helical structure. Moreover, Watson and Crick's work was directly dependent on the research of numerous scientists before them, including Friedrich Miescher, Phoebus Levene, and Erwin Chargaff. Thanks to researchers such as these, we now know a great deal about genetic structure, and we continue to make great strides in understanding the human genome and the importance of DNA to life and health.