BIO181 Exam 5 Study Guide - Chapter 14

Flashcards for reviewing Chapter 14 of BIO181 lecture notes, covering DNA and RNA structure, replication, and related concepts.

What are the key differences between DNA and RNA?

DNA contains deoxyribose sugar, uses thymine, and is double-stranded. RNA contains ribose sugar, uses uracil, and is typically single-stranded.

Describe the structure of DNA.

A double helix composed of two polynucleotide strands running antiparallel, with a sugar-phosphate backbone and nitrogenous bases (adenine, guanine, cytosine, and thymine) paired via hydrogen bonds.

What are the four nitrogenous bases in DNA and RNA?

DNA: Adenine (A), Guanine (G), Cytosine (C), Thymine (T). RNA: Adenine (A), Guanine (G), Cytosine (C), Uracil (U).

During which phase of the cell cycle is DNA replication completed?

S phase (Synthesis phase)

What is the primary goal of DNA replication?

To produce two identical copies of the original DNA molecule, ensuring each daughter cell receives a complete genome.

After replication, how many DNA molecules are present, and what are their compositions in terms of old and new strands?

Two DNA molecules; each is 50% old (template strand) and 50% new (newly synthesized strand).

How do bases pair in DNA, and how does this differ in RNA?

In DNA, Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). In RNA, Adenine (A) pairs with Uracil (U).

The process by which new molecules of DNA are formed is called what?

Replication

Strands of DNA are held together by hydrogen bonds between the what?

Nitrogenous bases

The sugar in RNA is what?

Ribose

The sugar in DNA is what?

Deoxyribose

Nucleotides come in four different forms; the are the parts of the nucleotides that can vary.

Nitrogenous bases

Describes the arrangement of the sides of the DNA molecule?

Antiparallel

If a DNA molecule is found to be composed of 40% thymine, what percentage of guanine would be expected?

10%

What molecule is found on RNA but not DNA?

Uracil

The ends of the linear chromosomes are maintained by what?

Telomeres

What enzyme covalently connects segments of DNA?

Ligase

How the leading and the lagging strands differ?

Leading strand is synthesized continuously, lagging strand is synthesized in fragments.

The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the basis of the finding that:

Radioactive DNA was found in the bacteria

If one strand of DNA has the nitrogen base sequence TAGCA, the sequence of bases on the other strand must be what?

ATCGT

What is meant by the description "antiparallel" regarding the strands that make up DNA?

The strands run in opposite directions (5' to 3' and 3' to 5').

What enzyme catalyzes the elongation of a DNA strand in the 5' 3' direction?

DNA polymerase

In eukaryotes, what is the DNA wrapped around?

Histones

What kinds of proteins are involved during the formation of the replication fork?

Helicases, single-strand binding proteins, topoisomerase.

What does the enzyme primase synthesize?

RNA primer