a single base deletion within the open reading frame of a gene’s dna sequence can result in ____________.

get a single base deletion within the open reading frame of a gene’s dna sequence can result in ____________. from EN Bilgi.

What kinds of gene variants are possible?: MedlinePlus Genetics

There are several types of genetic variants (or mutations). Learn more about the types of variants and how they affect gene function and health.

What kinds of gene variants are possible?

The DNA sequence of a gene can be altered in a number of ways. Gene variants (also known as mutations) can have varying effects ­­on health, depending on where they occur and whether they alter the function of essential proteins. Variant types include the following:

Substitution

This type of variant replaces one DNA building block (nucleotide) with another. Substitution variants can be further classified by the effect they have on the production of protein from the altered gene.

Missense:A missense variant  is a type of substitution in which the nucleotide change results in the replacement of one protein building block (amino acid) with another in the protein made from the gene. The amino acid change may alter the function of the protein.Nonsense: A nonsense variant  is another type of substitution. Instead of causing a change in one amino acid, however, the altered DNA sequence results in a stop signal that prematurely signals the cell to stop building a protein. This type of variant results in a shortened protein that may function improperly, be nonfunctional, or get broken down.Insertion

An insertion changes the DNA sequence by adding one or more nucleotides to the gene. As a result, the protein made from the gene may not function properly.

Deletion

A deletion changes the DNA sequence by removing at least one nucleotide in a gene. Small deletions remove one or a few nucleotides within a gene, while larger deletions can remove an entire gene or several neighboring genes. The deleted DNA may alter the function of the affected protein or proteins.

Deletion-Insertion

This variant occurs when a deletion and insertion happen at the same time in the same location in the gene. In a deletion-insertion variant, at least one nucleotide is removed and at least one nucleotide is inserted. However, the change must be complex enough to differ from a simple substitution. The resulting protein may not function properly. A deletion-insertion (delins) variant may also be known as an insertion-deletion (indel) variant.

Duplication

A duplication occurs when a stretch of one or more nucleotides in a gene is copied and repeated next to the original DNA sequence. This type of variant may alter the function of the protein made from the gene.

Inversion

An inversion changes more than one nucleotide in a gene by replacing the original sequence with the same sequence in reverse order.

Frameshift

A reading frame consists of groups of three nucleotides that each code for one amino acid. A frameshift variant occurs when there is an addition or loss of nucleotides that shifts the grouping and changes the code for all downstream amino acids. The resulting protein is usually nonfunctional. Insertions, deletions, and duplications can all be frameshift variants.

Repeat expansion

Some regions of DNA contain short sequences of nucleotides that are repeated a number of times in a row. For example, a trinucleotide repeat is made up of sequences of three nucleotides, and a tetranucleotide repeat is made up of sequences of four nucleotides. A repeat expansion is a variant that increases the number of times that the short DNA sequence is repeated. This type of variant can cause the resulting protein to function improperly.

For more information about the types of gene variants:

The National Human Genome Research Institute offers a Talking Glossary of Genetic Terms. This resource includes definitions, diagrams, and detailed audio descriptions of several of the gene variants listed above.

A brief explanation of different variants types is available from yourgenome.org, a service of the Wellcome Trust.

The Khan Academy has a video describing the different types of gene variants.

Topics in the Variants and Health chapter

What is a gene variant and how do variants occur?

How can gene variants affect health and development?

Do all gene variants affect health and development?

What kinds of gene variants are possible?

Can a change in the number of genes affect health and development?

Can changes in the number of chromosomes affect health and development?

Can changes in the structure of chromosomes affect health and development?

Can changes in noncoding DNA affect health and development?

Can changes in mitochondrial DNA affect health and development?

What are complex or multifactorial disorders?

What does it mean to have a genetic predisposition to a disease?

How are gene variants involved in evolution?

What information can statistics provide about a genetic condition?

How are genetic conditions and genes named?

Other chapters in Help Me Understand Genetics

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.

Source : medlineplus.gov

Frameshift Mutation

A frameshift mutation is a type of mutation involving the insertion or deletion of a nucleotide in which the number of deleted base pairs is not divisible by three.

​Frameshift Mutation

updated: May 15, 2022

Definition

00:00 00:04

A frameshift mutation in a gene refers to the insertion or deletion of nucleotide bases in numbers that are not multiples of three. This is important because a cell reads a gene’s code in groups of three bases when making a protein. Each of these “triplet codons” corresponds to one of 20 different amino acids used to build a protein. If a mutation disrupts this normal reading frame, then the entire gene sequence following the mutation will be incorrectly read. This can result in the addition of the wrong amino acids to the protein and/or the creation of a codon that stops the protein from growing longer.

Narration

00:00 01:19

A frameshift mutation is a particular type of mutation that involves either insertion or deletion of extra bases of DNA. Now, what's important here is the number three. The number of bases that are either added or subtracted can't be divisible by three. And that's important because the cell reads a gene in groups of three bases. Every group of three bases corresponds to one of the 20 different amino acids that are used by your body to make proteins. And keep in mind your body has a lot of proteins; everything from the material that makes up your skin, to the material that makes up your hair, to the digestive juices that help you digest that yummy lunch you just had. If a mutation disrupts one of those reading frames, so that the wrong amino acid is put in place, then the entire DNA sequence following the mutation will be disrupted or read incorrectly. Very often, what we see is a premature termination. Instead of the encoded protein being of a certain particular size, it'll end up being much shorter, and it won't be able to accomplish the role that's been set out for it.

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Related

Mutation

Nonsense Mutation

Insertion

Deletion

Source : www.genome.gov

Week 8 PQs Flashcards

Study with Quizlet and memorize flashcards terms like How is DNA sequencing accomplished? A. A genomic sequence is broken into small fragments of a few hundred base pairs. B. Whole chromosomes are sequenced in one piece. C. Each gene is separated from the others and individually sequenced. D. The DNA is converted to RNA., How is the actual base sequence of DNA fragments determined? A. They are analyzed in a machine that determines the base sequence. B. They are analyzed in a powerful microscope. C. They are translated into proteins and the amino acid sequence is determined. D. They are carefully lined up with known sequences from other organisms., How is the order of DNA fragments determined to obtain the sequence of the entire genome? A. They are sorted by size using gel electrophoresis. B. The base sequences are aligned by matching short regions at the ends that overlap. C. They are converted into sentences that are then assembled. D. They are matched up to chromosomes prepared from the nucleus. and more.

Week 8 PQs

28 studiers in the last day

How is DNA sequencing accomplished?

A. A genomic sequence is broken into small fragments of a few hundred base pairs.

B. Whole chromosomes are sequenced in one piece.

C. Each gene is separated from the others and individually sequenced.

D. The DNA is converted to RNA.

Click card to see definition 👆

A

Click again to see term 👆

How is the actual base sequence of DNA fragments determined?

A. They are analyzed in a machine that determines the base sequence.

B. They are analyzed in a powerful microscope.

C. They are translated into proteins and the amino acid sequence is determined.

D. They are carefully lined up with known sequences from other organisms.

Click card to see definition 👆

A

Click again to see term 👆

1/68 Created by beckybelisle

Terms in this set (68)

How is DNA sequencing accomplished?

A. A genomic sequence is broken into small fragments of a few hundred base pairs.

B. Whole chromosomes are sequenced in one piece.

C. Each gene is separated from the others and individually sequenced.

D. The DNA is converted to RNA.

A

How is the actual base sequence of DNA fragments determined?

A. They are analyzed in a machine that determines the base sequence.

B. They are analyzed in a powerful microscope.

C. They are translated into proteins and the amino acid sequence is determined.

D. They are carefully lined up with known sequences from other organisms.

A

How is the order of DNA fragments determined to obtain the sequence of the entire genome?

A. They are sorted by size using gel electrophoresis.

B. The base sequences are aligned by matching short regions at the ends that overlap.

C. They are converted into sentences that are then assembled.

D. They are matched up to chromosomes prepared from the nucleus.

B

How do repeated sequences in the genome complicate assembly of fragments?

A. The repeated sequences may appear in many fragments.

B. Fragments from different regions of the chromosomes may appear identical if they contain the same repeated sequence.

C. Regions of sequence overlap may occur between fragments not actually adjacent in the genome.

D. All of these choices are correct.

D

To maintain the accuracy of the genome sequence, the DNA should not be cut into small pieces before sequencing.

T/F F

In DNA sequencing, the newly synthesized DNA strand that is complementary and anti-parallel to a template DNA strand is called a sequence read.

T/F T

Repeated DNA sequences represent a special challenge in genome sequence assembly. Which of the following would be harder to assemble correctly, assuming the number of copies of the repeat can be determined?

A. sequences containing repeats shorter than the DNA fragments to assemble

B. sequences containing repeats longer than the DNA fragments to assemble

B

Which one of the following steps comes FIRST in shotgun sequencing?

A. matching regions of overlap

B. breaking the DNA into small fragments

C. sequencing the DNA

D. reconstructing the long sequence of nucleotides

E. putting the sequences in the correct order

B

Which one of the following pairs of people has the exact same genome?

A. fraternal twins B. identical twins

C. mother and daughter

D. father and son B

Select the answer option that lists the levels of genetic information in order from smallest to largest.

A. DNA strand; gene; genome; chromosome

B. gene; DNA strand; chromosome; genome

C. gene; chromosome; DNA strand; genome

D. genome; gene; chromosome; DNA strand

E. DNA strand; chromosome; gene; genome

B

Sequencing reads can be aligned to a reference genome (i.e., human genome) to identify single nucleotide variants and potential mutations.

T/F T

How can researchers distinguish exons from introns in a segment of DNA?

A. Exons have a characteristic sequence.

B. Only exons contain three-base sequences that can code for amino acids.

C. Primers won't bind to introns.

D. The sequence of exons complements mRNA molecules in the cell.

D

Genome annotation includes all of the followings except:

A. locations of genes

B. conserved sequences

C. regulatory sequences

D. start codons E. none of these E

When an open reading frame (ORF) is identified, it may not actually correspond to the amino acid sequence of any polypeptide in the cell. Why not? (Select all that apply.)

A. The amino acid sequence may not match any known sequence.

B. The DNA may not be transcribed into RNA.

C. It may contain one or more stop codons in the middle.

D. The ORF could be due to chance.

BD

Which of the following are sequence motifs?

A. promoters

B. hairpin structures

C. coding region

D. open reading frame

E. All of these choices are correct

E

Which one of following statements explains why genome annotation is an ongoing, dynamic process in need of continued updating?

A. The functions and interactions of macromolecules are never the same.

B. Certain structures like hairpins are not predictable using older annotation techniques.

Source : quizlet.com