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Ch. 3 The Cellular Level of Organization
Martini - Fundamentals of Anatomy and Physiology 12th Edition
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
All textbooksMartini, Nath, Bartholomew 12th EditionCh. 3 The Cellular Level of OrganizationProblem 21
Chapter 3, Problem 21

How many amino acids are coded in the DNA segment:
CTC–ATA–CGA–TTC–AAG–TTA?
(a) 18
(b) 9
(c) 6
(d) 3

Verified step by step guidance
1
Understand that each amino acid is coded by a sequence of three nucleotides called a codon in the DNA or mRNA sequence.
Count the number of nucleotide triplets (codons) in the given DNA segment: CTC–ATA–CGA–TTC–AAG–TTA.
Since each codon corresponds to one amino acid, the total number of amino acids coded is equal to the number of codons.
Verify that the DNA segment is properly divided into codons of three nucleotides each, ensuring no incomplete codons are present.
Conclude that the number of amino acids coded is the total count of these codons.

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Key Concepts

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

DNA Codons and Amino Acid Coding

DNA sequences are read in groups of three nucleotides called codons, each of which corresponds to a specific amino acid during protein synthesis. Understanding that each codon codes for one amino acid is essential to determine how many amino acids a DNA segment encodes.
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Amino Acid Oxidation 2

Reading Frame and Codon Counting

The reading frame refers to how nucleotides are grouped into codons starting from a specific nucleotide. Counting the total number of codons in a DNA segment involves dividing the total number of nucleotides by three, which directly gives the number of amino acids coded.
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Types of Mutations

Transcription and Translation Basics

DNA is first transcribed into mRNA, which is then translated into a chain of amino acids forming a protein. Although the question focuses on DNA, knowing that the DNA codons correspond to mRNA codons helps in understanding the process of amino acid coding.
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3) Termination of Transcription
Related Practice
Textbook Question

If a cell lacked ribosomes, it would not be able to

(a) Move

(b) Synthesize proteins

(c) Produce DNA

(d) Metabolize sugar

(e) Divide

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Textbook Question

When a cell is placed in a(n)___solution, the cell will lose water through osmosis. This process results in the___ of red blood cells

(a) hypotonic; crenation

(b) hypertonic; crenation

(c) isotonic; hemolysis

(d) hypotonic; hemolysis

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Textbook Question

List, in sequence, the phases of the interphase stage of the cell life cycle, and briefly describe what happens in each.

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Textbook Question

The sodium–potassium exchange pump

(a) Is an example of facilitated diffusion

(b) Does not require the input of cellular energy in the form of ATP

(c) Moves the sodium and potassium ions along their concentration gradients

(d) Is composed of a carrier protein located in the plasma membrane

(e) Is not necessary for the maintenance of homeostasis

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Textbook Question

Microvilli are found

(a) Mostly in muscle cells

(b) On the inside of plasma membranes

(c) In large numbers on cells that secrete hormones

(d) In cells that are actively engaged in absorption

(e) Only on cells lining the reproductive tract

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Textbook Question

Suppose that a DNA segment has the following nucleotide sequence:

CTC–ATA–CGA–TTC–AAG–TTA.

Which nucleotide sequences would a complementary mRNA strand have?

(a) GAG–UAU–GAU–AAC–UUG–AAU

(b) GAG–TAT–GCT–AAG–TTC–AAT

(c) GAG–UAU–GCU–AAG–UUC–AAU

(d) GUG–UAU–GGA–UUG–AAC–GGU

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