Biology Chapter 12 Assessment Flashcards

Questions and Answers

The process by which one strain of bacterium is apparently changed into another strain is called _____.

transformation

What are bacteriophages?

viruses

Who used radioactive markers in experiments to show DNA was the genetic material in cells?

Alfred Hershey and Martha Chase

Before DNA could definitively be shown to be the genetic material in cells, scientists had to show that it could _____.

carry and make copies of information Signup and view all the answers

What was the conclusion of Frederick Griffith's experiments?

the 'transforming principle' Signup and view all the answers

What key factor allowed Hershey and Chase to show that DNA alone carried the genetic information of bacteriophage?

DNA doesn't contain sulfur and proteins don't contain phosphorous Signup and view all the answers

Describe the location in which the bacterial DNA withstood conditions that killed the bacteria. What happened to the DNA during the rest of the experiment?

The DNA blew up Signup and view all the answers

How did Avery and his team control variables in their experiment to ensure that only DNA caused the effect?

they used a variety of enzymes Signup and view all the answers

What does a nucleotide contain?

A five carbon sugar, a nitrogenous base, and a phosphate group Signup and view all the answers

According to Chargaff's rule of base pairing, A = ? and C = ?.

T; G Signup and view all the answers

What do the bonds that hold two strands of DNA together come from?

weak hydrogen bonds between nitrogenous bases Signup and view all the answers

Describe the components and structure of a DNA nucleotide.

DNA contains nucleotides and four nitrogenous bases Signup and view all the answers

Explain how Chargaff's rule of base pairing helped Watson and Crick model DNA.

The bases are held together by hydrogen bonds Signup and view all the answers

What important clue from Rosalind Franklin's work helped Watson and Crick develop a model of DNA?

the helix pictured in the X-ray Signup and view all the answers

Why is it significant that two strands of DNA are anti-parallel?

It allows the nitrogenous bases on both strands to meet at the center to ensure the parallel double helix Signup and view all the answers

How did Watson and Crick's model of DNA molecule explain base pairing?

It showed that only adenine could pair with thymine and only guanine could pair with cytosine Signup and view all the answers

How did Rosalind Franklin's x-ray pattern help Watson and Crick determine how bases are paired?

They were to be equidistant to each other and they would have to act the same between the two chains Signup and view all the answers

In prokaryotes, DNA molecules are located in the _____.

cytoplasm Signup and view all the answers

In eukaryotes, nearly all the DNA is found in the _____.

nucleus Signup and view all the answers

The main enzyme involved in linking individual nucleotides into DNA molecules is _____.

DNA polymerase Signup and view all the answers

What is meant by the term base pairing? How is base pairing involved in DNA replication?

Hydrogen bonds form between the certain base pairs. Base pairing ensures that the complementary strands that are produced are identical to the original Signup and view all the answers

Describe the appearance of DNA in typical prokaryotic cells.

Circular Signup and view all the answers

Explain the process of replication. When a DNA molecule is replicated, how do the new molecules compare to the original molecule?

The DNA separates into two strands and builds complementary strands according to base pairing. Each strand has one of the original and one of the copies. Signup and view all the answers

Is photocopying a document similar to DNA replication? Explain.

Yes, because the copier takes the original photo, converts it to 'computer language', and then converts it back to a copy. Signup and view all the answers

Describe similarities and differences between DNA replication in prokaryotic cells and in eukaryotic cells.

In eukaryotic cells there's only one replication site as opposed to prokaryotic cells; they both replicate. Signup and view all the answers

Knowing that ozone is a molecule that is very effective at absorbing ultraviolet light from the sun and evidence indicates that human activities have contributed to the destruction of ozone in the atmosphere, what question could you ask about the effect of removing it from the atmosphere?

(answers may vary) Signup and view all the answers

What does a gene consist of?

a start codon, the genetic information, and an end codon Signup and view all the answers

During replication, which sequence of nucleotides would bond with the DNA sequence TATGA?

ATACT Signup and view all the answers

Who is responsible for the discovery of bacterial transformation?

Griffith Signup and view all the answers

Which of the following options does not describe the structure of DNA?

Contains the adenine-guanine patterns Signup and view all the answers

What did Hershey and Chase's work show?

DNA is the genetic material not proteins Signup and view all the answers

The two 'backbones' of the DNA molecule consist of _____.

a sugar-phosphate backbone Signup and view all the answers

In eukaryotic chromosomes, DNA is tightly coiled around proteins called _____.

histones Signup and view all the answers

When prokaryotic cells copy their DNA, replication begins at _____.

One point on the DNA molecule Signup and view all the answers

Compared to eukaryotic cells, prokaryotic cells contain how much DNA?

about 1000th Signup and view all the answers

How does a eukaryotic cell keep such large amounts of DNA in the small volume of the cell nucleus?

coiling Signup and view all the answers

Study Notes

Transformation and Genetic Material

Transformation is the process that changes one bacterium strain into another.
Bacteriophages are viruses that infect bacteria.
Alfred Hershey and Martha Chase demonstrated that DNA is the genetic material in cells using radioactive markers.
DNA must carry and replicate information to be recognized as genetic material.

Key Experiments and Findings

Frederick Griffith's experiments led to the discovery of the "transforming principle."
Hershey and Chase concluded that DNA alone carries genetic information in bacteriophages due to the absence of sulfur in DNA and absence of phosphorus in proteins.
Avery and his team controlled variables using various enzymes to isolate the effect of DNA.

DNA Structure and Composition

A nucleotide consists of a five-carbon sugar, a nitrogenous base, and a phosphate group.
Chargaff's rule states that adenine pairs with thymine (A=T) and cytosine pairs with guanine (C=G).
DNA strands are held together by weak hydrogen bonds between nitrogenous bases.
DNA nucleotides are composed of four different nitrogenous bases.

Watson and Crick Model

The anti-parallel structure of DNA allows nitrogenous bases from both strands to pair correctly in the double helix.
Watson and Crick's model explained base pairing behavior of DNA.
Rosalind Franklin's X-ray diffraction image showed a helical structure which guided the DNA model development.

DNA in Prokaryotes vs. Eukaryotes

In prokaryotes, DNA exists in the cytoplasm as a circular molecule.
In eukaryotes, most DNA is located in the nucleus and tightly coiled around histones.
DNA replication initiation occurs at a single point in prokaryotes, whereas eukaryotes have multiple sites.

DNA Replication Process

During DNA replication, the molecule separates into two strands, each serving as a template for new complementary strands.
Each newly synthesized strand contains one original and one new nucleotide strand.
Base pairing during replication ensures the production of identical complementary strands.
DNA polymerase is the main enzyme that links nucleotides during DNA synthesis.

Additional Concepts

Genes consist of a start codon, genetic information, and an end codon.
Similarities exist in DNA replication processes between prokaryotic and eukaryotic cells, though differences in replication initiation sites are notable.
The effect of ozone depletion, which absorbs ultraviolet light, poses questions regarding environmental impacts due to human activities.
Prokaryotic cells contain approximately one-thousandth of the DNA found in eukaryotic cells.

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Description

Test your knowledge of key concepts from Biology Chapter 12 with these flashcards. This assessment covers transformation in bacteria, the role of bacteriophages, and crucial experiments by Alfred Hershey and Martha Chase. Perfect for reviewing essential topics before your exam!