Molecular Biology: DNA and Genetic Code

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Questions and Answers

What defines a gene in DNA?

A random sequence of nucleotides

A group of amino acids

A specific segment of DNA that provides instructions for a protein (correct)

A specific segment of RNA

What are the four nitrogenous bases that compose DNA?

Adenine, Uracil, Cytosine, Guanine

Cytosine, Thymine, Uricil, Guanine

Adenine, Thymine, Uracil, Threonine

Adenine, Thymine, Guanine, Cytosine (correct)

How does the genetic code relate to amino acids?

Each amino acid has a corresponding single nucleotide

Each nucleotide directly codes for a single amino acid

A codon can code for multiple different amino acids

A codon of three nucleotides codes for a specific amino acid (correct)

What is the correct sequence in the central dogma of molecular biology?

DNA to RNA to Protein Signup and view all the answers

What role do alleles play in inheritance?

They are responsible for variations in traits among individuals Signup and view all the answers

What occurs during the process of transcription?

The DNA sequence is copied into messenger RNA (mRNA) Signup and view all the answers

What is a codon?

A sequence of three nucleotides in mRNA Signup and view all the answers

Which of the following statements about protein synthesis is correct?

Proteins are assembled based on the sequence of codons in mRNA Signup and view all the answers

What is the primary consequence of nondisjunction during meiosis?

Aneuploidy Signup and view all the answers

What does monosomy refer to in chromosomal terms?

Having one copy of a chromosome Signup and view all the answers

Which of the following conditions results from trisomy 21?

Down syndrome Signup and view all the answers

Which condition is characterized by females having three X chromosomes?

Triple-X syndrome Signup and view all the answers

What typically occurs in aneuploidy?

There is a gain or loss of one or more chromosomes Signup and view all the answers

In which inheritance pattern do both alleles express equally in the phenotype?

Codominance Signup and view all the answers

Which syndrome is associated with males having an extra Y chromosome?

Jacob syndrome Signup and view all the answers

What is the outcome when incomplete dominance occurs?

A blended phenotype results Signup and view all the answers

Individuals with Klinefelter syndrome are typically characterized by which chromosomal configuration?

XXY Signup and view all the answers

Which of the following is NOT a common outcome of aneuploidy?

Compatibility with life Signup and view all the answers

What is the first step of protein synthesis?

Transcription Signup and view all the answers

Where does transcription occur in eukaryotic cells?

In the nucleus Signup and view all the answers

What role does RNA polymerase play in protein synthesis?

Transcribing DNA into mRNA Signup and view all the answers

What is the consequence of errors in DNA replication or protein synthesis?

Potential diseases and mutations Signup and view all the answers

What do transfer RNA (tRNA) molecules do during translation?

Bring amino acids to the ribosome Signup and view all the answers

What happens to the polypeptide chain after it is formed?

It folds into a functional protein Signup and view all the answers

What aspect of molecular biology does the central dogma describe?

DNA to RNA to protein Signup and view all the answers

What genetic condition can result from nondisjunction during meiosis?

Down syndrome Signup and view all the answers

What do nucleoside reverse transcriptase inhibitors (NRTIs) do?

Interfere with viral DNA replication Signup and view all the answers

What characteristic determines the default developmental pathway in humans?

Male development requires activation of specific genetic pathways. Signup and view all the answers

Why are X-linked recessive disorders more common in males than in females?

Males have only one X chromosome. Signup and view all the answers

Which of the following conditions is associated with Turner syndrome?

Shorter stature and infertility in females. Signup and view all the answers

What occurs as a result of nondisjunction during meiosis?

Variations in the number of sex chromosomes. Signup and view all the answers

Which genetic principle did Gregor Mendel discover concerning the expression of dominant and recessive traits?

Law of Segregation. Signup and view all the answers

Which condition is characterized by individuals with three X chromosomes?

Triple-X females. Signup and view all the answers

What is a common result of Klinefelter syndrome?

Males with an extra X chromosome resulting in sterility. Signup and view all the answers

What are the main traits studied by Mendel using pea plants?

Flower color and pod shape. Signup and view all the answers

What happens to OY zygotes lacking an X chromosome?

They are nonviable. Signup and view all the answers

Which disorder is characterized by males having an extra Y chromosome?

Jacob syndrome. Signup and view all the answers

What occurs during prophase I of meiosis that enhances genetic diversity?

Crossing over Signup and view all the answers

Which process results in the unique combination of genes carried by gametes?

Independent assortment and crossing over Signup and view all the answers

What term describes the physical expression of alleles in an individual?

Phenotype Signup and view all the answers

What is the role of random fertilization in genetic diversity?

It creates countless genetic combinations in the zygote. Signup and view all the answers

Which statement correctly describes dominant alleles?

They are always expressed regardless of the other allele. Signup and view all the answers

How are alleles classified based on their expression in an individual?

Dominant and recessive Signup and view all the answers

What defines a homozygous individual?

Having two identical alleles for a trait Signup and view all the answers

Study Notes

Nucleotide Sequences Within DNA

Genes are specific segments of DNA that provide instructions for building proteins.
Proteins perform various functions in organisms, contributing to traits.
DNA has four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C).
Nucleotide sequence acts as a code, dictating the order of amino acids in proteins.

The Genetic Code

The genetic code relates the nucleotide sequence in DNA to the amino acid sequence in a protein.
Codons (three nucleotides) in mRNA translate into specific amino acids.
The order of codons in mRNA determines the order of amino acids in a protein.

The Central Dogma

The central dogma describes the flow of genetic information: DNA replicates to create identical DNA molecules; DNA transcribes into messenger RNA (mRNA); and mRNA translates amino acid sequences for protein formation

Inheritance

Offspring inherit a combination of genes from their parents, carried on chromosomes.
Each gene, defined by its nucleotide sequence, contributes to offspring traits.

Variations in Traits

Variations in traits among individuals arise due to different versions of a gene, called alleles.
Alleles can interact, affecting trait expression (dominant vs. recessive).

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Description

This quiz explores key concepts in molecular biology, focusing on nucleotide sequences, the genetic code, central dogma, and inheritance. Test your understanding of how DNA sequences translate into proteins and the mechanisms of genetic information flow.