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Ch. 7 - Microbial Genetics
Bauman - Microbiology with Diseases by Taxonomy 6th Edition
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
All textbooksBauman 6th EditionCh. 7 - Microbial GeneticsProblem 1
Chapter 7, Problem 1

Which of the following is most likely the number of base pairs in a bacterial chromosome?


a. 4,000,000
b. 4000
c. 400
d. 40

Verified step by step guidance
1
Understand that bacterial chromosomes typically contain a single circular DNA molecule that carries the genetic information necessary for the cell's functions and reproduction.
Recall that bacterial genomes are generally much smaller than eukaryotic genomes but still contain thousands to millions of base pairs to encode essential genes.
Evaluate the options given: 40, 400, 4000, and 4,000,000 base pairs, and consider which size is consistent with known bacterial genome sizes.
Recognize that most bacterial chromosomes range from about 1 million to several million base pairs, making 4,000,000 a plausible number.
Conclude that the most likely number of base pairs in a bacterial chromosome among the options is the largest value, 4,000,000, because smaller numbers are too low to encode the necessary genetic information.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Bacterial Chromosome Size

Bacterial chromosomes typically consist of a single circular DNA molecule containing millions of base pairs. The size varies among species but generally ranges from about 1 million to 10 million base pairs, encoding thousands of genes necessary for bacterial survival and function.
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Base Pairs as a Unit of DNA Length

Base pairs (bp) measure the length of double-stranded DNA, representing the number of nucleotide pairs. This unit helps quantify genome size, with larger numbers indicating more genetic information. For bacteria, genome size is usually in the millions of base pairs.
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Comparison of Genome Sizes Across Organisms

Bacterial genomes are much smaller than eukaryotic genomes but larger than viral genomes. While viruses may have hundreds to thousands of base pairs, bacteria have millions, reflecting their complexity. Understanding this scale helps identify plausible genome sizes in multiple-choice questions.
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Related Practice
Textbook Question

On the accompanying figure, label:

DNA polymerase I, DNA polymerase III, helicase, lagging strand, leading strand, ligase, nucleotide (triphosphate), Okazaki fragment, primase, replication fork, RNA primer, and stabilizing proteins.

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Textbook Question

The three steps in RNA transcription are __________ , ___________ , and __________ .

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Textbook Question

How does the genotype of a bacterium determine its phenotype? Use the terms gene, mRNA, ribosome, and polypeptide in your answer.

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