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A DNA segment has base order AGC TTA TCG. Which copy exhibits a frameshift mutation through deletion?(1 point)

Responses

AGC TTA TAG
AGC TTA TAG

AGC TTT CG
AGC TTT CG

TTA TCG
TTA TCG

AGC TCG

9 answers

A frameshift mutation occurs when nucleotides are added or deleted from a DNA sequence, resulting in a shift in the reading frame of the genetic code. In this case, the original DNA segment is "AGC TTA TCG."

To identify which copy exhibits a frameshift mutation through deletion, we need to consider which option removes nucleotides and causes a shift in the reading frame.

Let's analyze the given options:

  1. AGC TTA TAG - This option replaces "TCG" with "TAG" (no frameshift, just a substitution).
  2. AGC TTT CG - This option deletes one "A" from "TTA" and "C" from "TCG" (frameshift).
  3. TTA TCG - This option removes "AGC" (frameshift).
  4. AGC TCG - This option deletes "TTA" (frameshift).

Based on this analysis, the option that demonstrates a frameshift mutation through deletion is AGC TTT CG.

A DNA segment has base order CCC ATA GCT. Which copy exhibits a deletion in the first codon triplet and then a substitution mutation?(1 point)
Responses

CCA TAA CT
CCA TAA CT

CCC TAG CT
CCC TAG CT

CCA ATA GCT
CCA ATA GCT

CCA TAG CT

To identify which copy exhibits a deletion in the first codon triplet followed by a substitution mutation, we need to analyze the original DNA segment and each of the provided options.

The original DNA segment is CCC ATA GCT. This segment has the following three codons:

  1. CCC
  2. ATA
  3. GCT

Analyzing the Options:

  1. CCA TAA CT - This option involves changing the first codon from "CCC" (to "CCA") and deleting the second codon "ATA" (producing a new sequence). This includes both a deletion and a substitution.
  2. CCC TAG CT - This option changes the second codon "ATA" to "TAG." This is a substitution only; the first codon remains the same (no deletion).
  3. CCA ATA GCT - This option changes the first codon "CCC" to "CCA," but does not involve a deletion in the first codon (no deletion).
  4. CCA TAG CT - This option changes the first codon "CCC" to "CCA" and changes "ATA" to "TAG," which constitutes a substitution as well and is not indicative of a deletion in the first codon.

Conclusion:

The option that exhibits a deletion in the first codon triplet and then a substitution mutation is CCA TAA CT.

Which type of mutation causes cystic fibrosis?(1 point)
Responses

insertion
insertion

deletion
deletion

substitution
substitution

silent

Cystic fibrosis is primarily caused by a deletion mutation in the CFTR gene, specifically the deletion of three nucleotides that leads to the loss of the amino acid phenylalanine at position 508 (commonly referred to as ΔF508).

Thus, the correct response is deletion.

Which statement about chromosomes is true?(1 point)
Responses

Chromosomes are found in sets of three.
Chromosomes are found in sets of three.

DNA contains chromosomes.
DNA contains chromosomes.

Chromosomes contain DNA.
Chromosomes contain DNA.

The same number of chromosomes appears in haploid and body cells.

The true statement about chromosomes is:

Chromosomes contain DNA.

This means that chromosomes are composed of DNA wrapped around proteins (histones) and are responsible for storing and organizing genetic information within the cell.

To clarify the other options:

  • Chromosomes are found in sets of three: This is incorrect; organisms typically have chromosomes in pairs (diploid) or single (haploid) sets.
  • DNA contains chromosomes: This is incorrect; it's the other way around—chromosomes are made of DNA.
  • The same number of chromosomes appears in haploid and body cells: This is incorrect; haploid cells (gametes) have half the number of chromosomes compared to diploid body cells.

Therefore, the correct answer is that Chromosomes contain DNA.

Which modification affects an organism’s expressed characteristics while leaving its DNA sequence unchanged?(1 point)
Responses

insertion mutation
insertion mutation

deletion mutation
deletion mutation

epigenetic change
epigenetic change

substitution mutation

The modification that affects an organism’s expressed characteristics while leaving its DNA sequence unchanged is an epigenetic change.

Epigenetic changes can alter gene expression through mechanisms such as DNA methylation or histone modification, without changing the underlying DNA sequence itself. This can lead to variations in traits and characteristics without altering the genetic code.

In contrast, insertion mutations, deletion mutations, and substitution mutations all involve changes to the DNA sequence itself.

Thus, the correct response is epigenetic change.