DNA Packaging in Prokaryotes: Practice Quiz and Flashcards

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Questions and Answers

What is the purpose of gel electrophoresis in DNA sequencing?

To translate DNA into proteins

To separate DNA fragments based on their charge

To replicate DNA fragments

To separate DNA fragments based on their size (correct)

What is the main difference between the DNA arrangement in eukaryotes and prokaryotes?

The size of the genome

The type of DNA molecule

The number of chromosomes

The presence of a well-defined nucleus (correct)

What is the approximate number of genes in the human genome?

10,000

20,000 (correct)

40,000

30,000

What is the percentage of noncoding DNA in the human genome?

98% Signup and view all the answers

What is the purpose of supercoiling in prokaryotes?

To organize the DNA within the nucleoid Signup and view all the answers

What is unique about the marbled lungfish's genome?

It is the largest known genome Signup and view all the answers

What is the purine that always pairs with cytosine in DNA molecules?

Guanine Signup and view all the answers

Who determined the structure of DNA using Rosalind Franklin's X-ray crystallography image?

Watson and Crick Signup and view all the answers

What is the method of DNA sequencing developed by Fred Sanger?

Dideoxy chain termination method Signup and view all the answers

What is the difference between deoxynucleotides and dideoxynucleotides?

The absence of a free 3' OH group on the five-carbon sugar Signup and view all the answers

What is the purpose of using a predetermined ratio of deoxynucleotides to dideoxynucleotides in DNA sequencing?

To generate DNA fragments of different sizes Signup and view all the answers

Who was the person who contributed to the discovery of the shape of DNA but did not receive the Nobel Prize?

Rosalind Franklin Signup and view all the answers

What is the characteristic of the prokaryotic genome?

It consists of a single circular chromosome Signup and view all the answers

What is the function of histones in eukaryotes?

To wrap DNA into structures called nucleosomes Signup and view all the answers

What is the term for the tightly packaged region of eukaryotic chromosomes?

Heterochromatin Signup and view all the answers

What is the location of the prokaryotic chromosome?

In the cytoplasm Signup and view all the answers

What is the purpose of plasmids in prokaryotes?

To provide beneficial genes like antibiotic resistance Signup and view all the answers

What is the term for the less dense region of eukaryotic chromosomes?

Euchromatin Signup and view all the answers

What is the characteristic of euchromatin?

It contains DNA packaged around nucleosomes but not further compacted Signup and view all the answers

What is the term for the process in which one parental DNA strand acts as a template for new DNA synthesis?

Semi-conservative Signup and view all the answers

What is the result of Meselson and Stahl's experiment after one round of cell division?

DNA sediments halfway between the 15N and 14N levels Signup and view all the answers

What is the purpose of the Meselson and Stahl experiment?

To test the different models of DNA replication Signup and view all the answers

What is the difference between the 15N and 14N DNA in the Meselson and Stahl experiment?

15N DNA is heavier than 14N DNA Signup and view all the answers

What is the model of DNA replication supported by the Meselson and Stahl experiment?

Semi-conservative model Signup and view all the answers

Study Notes

DNA Structure and Replication

Complementary base pairing: Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C)
Predicting DNA strand sequence: knowing the sequence of the complementary strand allows us to predict the sequence of the original strand

DNA Structure Discovery

Rosalind Franklin's X-ray crystallography image of DNA led to Watson and Crick's discovery of the double helix structure in 1953
Watson and Crick won the Nobel Prize in 1962, but Rosalind Franklin had passed away by then, likely due to radiation poisoning

DNA Sequencing

Fred Sanger's dideoxy chain termination method is widely used for DNA sequencing, including the human genome sequencing project
Method uses chain terminators (dideoxynucleotides) that lack a free 3' OH group, preventing further DNA strand extension
Sanger's method generates DNA fragments of different sizes, which can be separated using gel electrophoresis

Gel Electrophoresis

Technique used to separate DNA fragments based on size
Nucleic acids are loaded into a gel matrix, and an electric current is applied to pull negatively charged molecules towards the positive electrode
Smaller molecules move faster through the gel, separating fragments by size

DNA Packaging in Cells

Prokaryotes (e.g., E. coli) have a single circular chromosome in the cytoplasm, condensed into the nucleoid
Plasmids are small loops of DNA outside the genomic chromosome, not essential for normal growth and function
Human genome consists of approximately 3.2 billion base pairs, with only 0.4% variation between individuals

DNA Arrangement in Prokaryotes and Eukaryotes

Prokaryotes have a single circular chromosome, wound tightly around itself (supercoiling)
Eukaryotes have linear DNA molecules wrapped around proteins (histones) to form nucleosomes, which are further compacted into fibers

DNA Replication

Three models of DNA replication were proposed: conservative, semi-conservative, and dispersive
Meselson and Stahl's experiment using E. coli grown in heavy nitrogen (15N) and 14N supported the semi-conservative replication model

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Description

Test your knowledge on how DNA is arranged in prokaryotic cells, particularly in prokaryotes like E. coli. Learn about the structure of the prokaryotic genome, supercoiling of DNA, and the presence of plasmids.

DNA Packaging in Prokaryotic Cells Quiz