Chapters 13 and 14 Test

What experiment did Frederick Griffith conduct in 1928 to study pneumonia-causing bacteria?

He injected mice with different strains of bacteria to determine how they produced pneumonia.

What was the key conclusion from Griffith's experiment regarding bacteria?

A factor from the heat-killed S strain transformed the R strain into disease-causing bacteria.

What is the significance of Oswald Avery's work in 1944?

Avery identified DNA as the transforming factor responsible for genetic information transmission.

What was the method used in the Hershey-Chase experiment?

They used radioactive isotopes to label DNA and protein to determine which was the genetic material.

What are Chargaff's Rules?

The percentage of adenine (A) equals thymine (T) and cytosine (C) equals guanine (G).

Who contributed to determining the helical structure of DNA using X-ray diffraction?

Rosalind Franklin.

What did Watson and Crick create regarding the structure of DNA?

They built the first accurate 3D model of DNA as a double helix.

What are the components of a DNA nucleotide?

5-carbon sugar (deoxyribose), phosphate group, and nitrogenous base (A, T, C, G).

How do Adenine and Thymine pair in DNA?

Adenine (A) pairs with Thymine (T).

What is the role of helicase in DNA replication?

Helicase breaks hydrogen bonds, forming a replication fork.

What is the direction of DNA strand synthesis during replication?

DNA strands are synthesized in the 5’ to 3’ direction.

What are Okazaki fragments?

Segments synthesized on the lagging strand during DNA replication.

What are the main differences between prokaryotic and eukaryotic DNA replication?

Prokaryotes have a single circular DNA molecule; eukaryotes have multiple replication forks across linear chromosomes.

What is the role of single-stranded binding proteins (SSBs) during DNA replication?

SSBs prevent reannealing of the DNA strands during replication.

What type of sugar is found in RNA?

Ribose sugar.

What are the four nitrogenous bases in RNA?

Adenine (A), Uracil (U), Cytosine (C), and Guanine (G).

What is the function of messenger RNA (mRNA)?

mRNA carries genetic information from DNA to ribosomes.

What occurs during the transcription process?

RNA polymerase synthesizes a complementary mRNA strand from the DNA template.

What is the start codon in mRNA?

The start codon is AUG, which codes for methionine.

What is the function of the lac operon in prokaryotes?

It controls gene expression, allowing transcription when lactose is present.

What is epigenetics?

Chemical modifications that affect gene expression without altering the DNA sequence.

What are point mutations?

Gene mutations that involve substitution, insertion, or deletion of nucleotides.

What is a frameshift mutation?

A mutation that shifts the reading frame, affecting downstream amino acids.

What can the effects of mutations be classified as?

Mutations can be neutral, harmful, or beneficial.

What are mutagens?

Chemical or physical agents that cause mutations, such as UV light or chemicals.

What is polyploidy?

A condition where organisms have extra sets of chromosomes; common in plants.

What major discovery did Oswald Avery make about the transforming factor?

Avery concluded that DNA was the substance responsible for transformation.

What was the result of injecting mice with heat-killed S strain bacteria?

Mice lived, indicating there was no disease-causing bacteria.

How did the Hershey-Chase experiment determine that DNA is the genetic material?

Radioactive phosphorus (32P) was found in bacteria, indicating DNA was transmitted.

What is ribosomal RNA (rRNA) responsible for?

It combines with proteins to form ribosomes.

What happens to the mRNA during the editing process after transcription?

Introns are removed, and exons are spliced together.

What do codons represent in the genetic code?

Codons are sequences of three mRNA nucleotides that code for specific amino acids.

What effect do transcription factors have in eukaryotic gene regulation?

They facilitate the assembly of the transcription machinery at the gene promoter.

What is the role of the TATA box in eukaryotic DNA?

It helps position RNA polymerase for proper transcription initiation.

What is the function of transfer RNA (tRNA)?

tRNA transfers amino acids to ribosomes during protein synthesis.

What signals the end of translation?

Stop codons signal the end of translation.

What do hydrogen bonds do in DNA?

Hydrogen bonds hold the base pairs together.

What is the difference between the leading strand and the lagging strand during DNA replication?

The leading strand is synthesized continuously, while the lagging strand is synthesized in segments.

What is the significance of proofreading during DNA replication?

DNA polymerase ensures the correct matching of nucleotides to prevent mutations.

What is transformation as it relates to Griffith's experiments?

Transformation is the process of a non-virulent strain acquiring virulence factors from a virulent strain.

What type of genetic material did the Hershey-Chase experiment show was inherited by offspring?

DNA was shown to be the genetic material inherited by the next generation.

How does the structure of RNA differ from DNA?

RNA is single-stranded, while DNA is double-stranded, and RNA contains uracil instead of thymine.