DNA, RNA, and Replication

AP Bio DNA, RNA, and Replication.

What was the main conclusion of Griffith's experiment?

The genetic material from the S cells must not be made of protein, as heat would have denatured it.

What did Avery's work reveal about genetic material?

Only DNA could transform the rough cells.

What was the purpose of the Hershey-Chase experiment?

To show that the genetic material was DNA, not protein, using bacteriophages.

What technique did Rosalind Franklin use to study DNA?

X-ray crystallography.

What did Erwin Chargaff discover?

He discovered complementary base pairs by calculating the amounts of adenine, guanine, cytosine, and thymine in DNA.

Who published the model of DNA in Nature in 1953?

James Watson and Francis Crick.

What are nucleic acids made of?

Elements C, H, O, N, and P; their monomer is nucleotides.

What are the two main types of nucleic acids?

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

What is the structure of DNA?

Nucleotides forming a double helix structure.

What are the components of a DNA nucleotide?

A 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogen base.

What are the nitrogen bases in DNA?

Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).

What is the difference between purines and pyrimidines?

Purines (A and G) have two fused rings, while pyrimidines (C and T) have a single ring.

What type of bonds connect the sugar and phosphate groups in DNA?

Phosphodiester

What is the significance of the 5' and 3' ends of DNA?

The 5' end has a phosphate group exposed, while the 3' end has an OH group on the sugar.

What is Chargaff's rule?

The amount of adenine equals the amount of thymine, and the amount of cytosine equals the amount of guanine.

What is the least organized form of DNA?

Double helix

What is the most organized form of DNA?

Chromosome, which is supercoiled DNA visible during cell division.

What are genes?

Short segments of DNA nucleotides that code for specific proteins or polypeptides.

What is the difference between prokaryotic and eukaryotic DNA?

Prokaryotic DNA is circular and found in the nucleoid region, while eukaryotic DNA is linear, found in the nucleus, and associated with histone proteins.

How does RNA differ from DNA?

RNA is single-stranded, has ribose sugar, contains uracil instead of thymine, and is found in both the nucleus and cytoplasm. DNA is double-stranded, has deoxyribose sugar, has thymine instead of uracil, and is found in only the nucleus.

What are the three types of RNA?

Messenger RNA (mRNA), Transfer RNA (tRNA), and Ribosomal RNA (rRNA).

What is the function of mRNA?

Carries the genetic code from the nucleus to the cytoplasm (ribosome).

What is the role of tRNA?

Brings amino acids needed for a protein to the ribosome.

What does rRNA do?

Part of the ribosomes; it reads the genetic code in mRNA and links amino acids together to assemble proteins.

What is the end result of DNA replication?

Two identical double helices.

Where does DNA replication occur in eukaryotes?

In the nucleus of the cell.

What is the purpose of DNA replication?

To ensure every cell has a complete set of genetic information.

What type of process is DNA replication?

Semiconservative.

What experiment did Meselson and Stahl conduct?

To determine if DNA replication was conservative, semiconservative, or dispersive.

What type of nitrogen did Meselson and Stahl use in their experiment?

Heavy nitrogen (15N)

What is the origin of replication?

A specific sequence of nucleotides where helicase attaches to start unzipping DNA.

What role do single strand binding (SSB) proteins play during replication?

They help hold the DNA open at the replication fork.

What is the function of topoisomerase in DNA replication?

To relieve strain ahead of the replication fork by breaking, swiveling, and rejoining DNA strands.

What are nucleoside triphosphates?

Nucleotides with two extra phosphates that provide energy for adding new nucleotides.

What is the role of DNA Polymerase III?

To bond new nucleotides to the DNA template.

In which direction can DNA polymerase add new nucleotides?

Only to the 3' end of the DNA template strand.

What are Okazaki fragments?

Short segments of DNA synthesized on the lagging strand during replication.

What is the function of primase in DNA replication?

To lay down a small strand of RNA nucleotides for DNA polymerase to start adding DNA bases.

How many RNA primers are needed on the leading strand?

One

What happens to RNA primers at the end of replication?

They are replaced with DNA nucleotides by DNA polymerase I.

What is the significance of telomeres in DNA replication?

They prevent the loss of vital genetic information at the ends of linear chromosomes.

What enzyme can extend telomeres?

Telomerase.

How often do errors occur during DNA replication?

About 1 in a billion nucleotides.

What is mismatch repair?

A process where DNA polymerase fixes errors in base pairing.

What is excision repair?

A process that involves removing an affected piece of DNA and replacing it with new corresponding nucleotides.

What is the rate of elongation in human cells during DNA replication?

About 50 nucleotides per second.

What is the role of DNA ligase in DNA replication?

To fuse Okazaki fragments together on the lagging strand.

Why is DNA replication more complex in eukaryotes than in prokaryotes?

Eukaryotes have multiple origins of replication and linear DNA, while prokaryotes typically have circular DNA.

What is the direction of growth for the new DNA strand during replication?

In the 5'-3' direction.

What happens to the 5' ends of linear DNA during replication?

They cannot be fully replicated, leading to shorter ends with each replication cycle.