Genetics: Alleles, DNA Structure, and Mutations

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Questions and Answers

What is a characteristic of a silent mutation?

It changes the amino acid sequence.

It leads to a different protein structure.

It does not alter the protein level. (correct)

It results in a loss of protein function.

Which type of point mutation results in a different amino acid being incorporated into a protein?

Transversion

Conservative mutation

Non-synonymous mutation (correct)

Silent mutation

Which of the following is NOT a type of point mutation?

Transition

Insertion

Deletion (correct)

Transversion

What distinguishes a conservative missense mutation from a non-conservative missense mutation?

Non-conservative mutations change protein structure significantly. Signup and view all the answers

Which of the following sequences represents a non-synonymous mutation?

TTC to TCC Signup and view all the answers

What is the mRNA codon generated by the DNA sequence TGC?

UGC Signup and view all the answers

Which mutation maintains the original amino acid sequence despite a change at the DNA level?

Silent mutation Signup and view all the answers

What is the specific type of mutation characterized by a base substitution that results in a different amino acid?

Point mutation Signup and view all the answers

In the context of point mutations, what is a transition?

A change from one purine to another purine. Signup and view all the answers

Which change in the DNA sequence would likely not disrupt the function of a protein?

A silent mutation Signup and view all the answers

What is the result of a non-synonymous (missense) point mutation at the DNA level?

The codon changes to encode a different amino acid Signup and view all the answers

What type of mutation is represented by the change from TGC to ATC in the genetic code?

Nonsense Mutation Signup and view all the answers

Which process is responsible for the introduction of new alleles through changes in DNA sequences caused by chemical reactions?

Spontaneous deamination Signup and view all the answers

Which codons represent the conservative and non-conservative mutations for the 49th codon?

Proline and Alanine Signup and view all the answers

In the context of the point mutations, which of the following codons would NOT be classified as silent?

AGG Signup and view all the answers

What role does DNA proofreading play during DNA replication?

It reduces the number of replication errors Signup and view all the answers

Which protein connects with actin filaments in the Z line?

Alpha-actinin-3 Signup and view all the answers

Which of the following codon changes is noted as resulting in the possibility of differing amino acids?

49th codon – proline or alanine Signup and view all the answers

What is the function of the SMARCAD1 gene as indicated in the content?

Acts as a chromatin remodeling factor Signup and view all the answers

What is a significant consequence of mutation by misalignment during DNA replication?

It results in duplications and deletions of DNA segments Signup and view all the answers

What is Adermatoglyphia associated with?

Absence of fingerprints Signup and view all the answers

How many cases of spontaneous chemical decay occur in mammalian cells per day?

20,000 Signup and view all the answers

Which process accurately describes genetic information flow from DNA to the final protein product?

DNA to mRNA to protein Signup and view all the answers

Which of the following mutations would lead to the production of a STOP codon?

A change from TGC to ATC Signup and view all the answers

What common errors occur during DNA replication per division?

100,000 errors Signup and view all the answers

Which amino acid is encoded by the codon ACG?

Threonine Signup and view all the answers

What is the outcome of mutations in proteins resulting from replication errors?

Alterations in protein function Signup and view all the answers

In genetic terms, what do you call a mutation that does not affect the amino acid sequence?

Silent Mutation Signup and view all the answers

Which of the following correctly identifies a type of mutation caused by deamination?

Point mutation Signup and view all the answers

What is the significance of identifying alleles such as AVI and PAV?

They are variants of the same gene with specific traits Signup and view all the answers

Study Notes

Where New Alleles and Genes Come From

Different versions of alleles noted:
- 49th codon - proline or alanine
- 262nd codon - alanine or valine
- 296th codon - valine or isoleucine
AVI & PAV alleles identified.
Genetic variation: Alanine (GCA) → Proline (CCA) at position 49.

The Structure of the Genetic Material

The structure of DNA is described, including:
- Nucleotide components (sugar, phosphate, bases)
- Sugar-phosphate backbone
- Purines (adenine, guanine) and pyrimidines (cytosine, thymine)
DNA replicates through complementary base pairing.

Mutation by Deamination

5-methylcytosine can be deaminated into thymine.
Deamination can lead to spontaneous mutations.
Results from a change in DNA base sequence.

Mutation by Misalignment

Mutations from misalignment in DNA replication can cause duplication and deletions
Change in DNA sequence occurs due to misalignment and improper pairing during replication.

Premutation

Mammalian cells experience 20,000 cases of spontaneous chemical decay per day.
DNA replication errors number approximately 100,000 per division.

DNA Repair

Polymerase adds an incorrect nucleotide to the new DNA strand.
Polymerase detects mispaired bases.
Polymerase uses 3′ to 5′ exonuclease activity to remove incorrect nucleotides.

Importance of Proofreading during Replication

Graphs illustrate the importance of proofreading during replication, showing survival rates of normal and deficient mice over time.
Deficiencies in proofreading mechanisms lead to increased mortality.

How Mutations Alter Protein Function

Shows flow of genetic information from DNA to mRNA to protein.
Amino acid changes due to mutations.
Example given - mutation in DNA sequence results in a change from valine to lysine and a change in the resulting protein's form and function.

The Genetic Code

Table shows the genetic code, with codons and their corresponding amino acids.
Different types of point mutations are given, such as:
- Transition (e.g., T-A → C-G)
- Transversions (e.g., T-A → G-C)

Point Mutation

Illustrates the molecular structure of amino acids like lysine and threonine.
Classifies mutations as no mutation (silent), transition, conservative/non-conservative missense, and nonsense.

Gene Duplication - Unequal Crossing Over

Shows how unequal crossing over can lead to gene duplication.
Gene duplication can create new genes through unequal crossing-over, leading to the creation of a new gene .
This can result in the development of new genes and functions, increasing the genome's complexity.

Gene Duplication- Retroposition or Retroduplication

Describes gene duplication through retroposition or retroduplication, explaining the process of reverse transcription of an RNA copy into DNA.
Describes a pathway for the creation of new genes.

New Genes from Scratch

Describes a new gene C220rf45 generated from non-coding DNA.
Shows DNA sequences in different species to illustrate different gene sequences and how new genes might develop.

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Description

Explore the origins of new alleles and genes, along with the structural components of DNA. This quiz covers genetic variation, mutations caused by deamination, and misalignment during DNA replication. Test your understanding of these fundamental concepts in genetics.