W13 L2 - DNA structure

Flashcards based on lecture notes covering DNA structure, components, and related concepts.

What is DNA?

A truly magnificent molecule that contains all the information about an organism, from cell development to disease susceptibility and lifespan.

Where in the cell is DNA found?

In the nucleus, mitochondria, and chloroplasts.

What is the endosymbiotic theory explaining the origin of mitochondria and chloroplasts?

About 1.5 to 2 billion years ago, a eukaryotic cell engulfed a prokaryotic cell (bacterium) and formed a symbiotic relationship, eventually leading to the development of mitochondria and chloroplasts.

What is the basic structure of DNA?

DNA is made up of a sugar and phosphate backbone, held together by hydrogen bonds between nitrogenous bases.

What is the sugar component of DNA called?

Deoxyribose, a five-carbon sugar.

What is the significance of the hydrogen at the two prime position of deoxyribose?

It has a role in DNA's stability.

What are the four different bases in DNA?

Adenine (A), guanine (G), cytosine (C), and thymine (T).

Which bases are purines?

Adenine (A) and guanine (G).

Which bases are pyrimidines?

Cytosine (C) and thymine (T).

What is a phosphodiester bond?

Holds the sugars together in the DNA backbone.

What is a nucleotide?

Sugar, base, and at least one phosphate group.

What is a nucleoside?

Sugar and base; no phosphate.

Which component of DNA is charged?

Phosphate group.

What neutralizes the negative charges of the phosphate groups in DNA?

Magnesium and sometimes sodium ions.

What are the A, B, and Z conformations of DNA?

A, B, and Z conformations relate to slight conformational variations in the DNA structure in response to ionic conditions and other environmental factors.

How do the bases pair in DNA?

A pairs with T (two hydrogen bonds), and G pairs with C (three hydrogen bonds).

What is the 'complement' of a DNA strand?

The strand that complements the given DNA sequence, with A paired with T and G paired with C.

What is the 'reverse complement' of a DNA strand?

The complement strand written in the reverse direction (5' to 3').

How many base pairs do humans have?

About three times 10 to the power of nine base pairs (3,000,000,000 base pairs).

If you were to spread out the DNA from a single human cell, how long would it be?

Approximately two meters.