Radiobiology 4 MCQ

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Questions and Answers

Which of the following accurately describes the role of DNA in protein synthesis?

DNA produces enzymes that determine the structure of lipids.

DNA sequences dictate the arrangement of amino acids in proteins. (correct)

DNA is solely responsible for replicating genetic material.

DNA directly synthesizes proteins in the cytoplasm.

What is the consequence of a point mutation resulting in nonsense?

It does not affect the protein sequence.

It adds an amino acid causing longer proteins.

It leads to an incomplete protein due to premature termination. (correct)

It enhances the function of the protein.

Which of the following amino acids is coded for by the triplet CAA?

Leucine

Glutamine (correct)

Alanine

Valine

What role do enzymes play in biological reactions according to the provided content?

They catalyze reactions and determine cellular function. Signup and view all the answers

What is the primary role of DNA in living organisms?

It controls all the chemical changes in cells. Signup and view all the answers

Which of the following statements about deoxyribose is true?

It lacks one oxygen atom compared to ribose. Signup and view all the answers

Which of the following statements about mutations is false?

Silent mutations change the phenotype of an organism. Signup and view all the answers

Which of these is NOT one of the four common organic bases in DNA?

Uracil Signup and view all the answers

What defines a gene according to the provided information?

A segment of DNA coding for a protein. Signup and view all the answers

How is a nucleotide formed?

From deoxyribose, a phosphate group, and an organic base. Signup and view all the answers

In what way does an insertion mutation affect the reading frame?

It shifts the entire reading frame downstream. Signup and view all the answers

What type of molecule is DNA primarily categorized as?

A very large molecule made of nucleotides. Signup and view all the answers

Which pairing of nitrogenous bases is correct?

Cytosine pairs with Guanine. Signup and view all the answers

In what way can low-energy electrons affect DNA?

They can break a DNA strand by forming a transient molecular anion. Signup and view all the answers

Which type of mutation alters the DNA sequence by removing one or more bases?

Deletion mutation Signup and view all the answers

Which of the following is not a function attributed to DNA?

Directly participating in metabolic reactions. Signup and view all the answers

Why are some amino acids considered more radiosensitive than others?

Due to structural differences that affect stability. Signup and view all the answers

What are the components of a nucleotide?

A sugar, a phosphate group, and an organic base. Signup and view all the answers

What is a characteristic feature of ribose compared to deoxyribose?

It contains an extra oxygen atom. Signup and view all the answers

How do transient molecular anions relate to the stability of DNA?

They contribute to the degradation of DNA strands. Signup and view all the answers

What type of damage do low-energy electrons primarily cause within DNA?

Indirect clustered damage Signup and view all the answers

What is the mean free path range of low-energy electrons in nanometers?

0.1 to 10 nm Signup and view all the answers

Which type of bond is specifically formed between Adenine and Thymine in DNA?

Hydrogen bond Signup and view all the answers

Which component of DNA forms the backbone of its structure?

Sugar-phosphate chains Signup and view all the answers

Cytosine forms bonds with which nitrogenous base?

Guanine Signup and view all the answers

What type of radicals contribute mostly to radiation damage?

Hydroxyl radicals Signup and view all the answers

Which of the following represents a primary structural feature of double-stranded DNA?

Two intertwined strands Signup and view all the answers

Which functional groups allow Adenine and Thymine to pair effectively?

-NH and -OH groups Signup and view all the answers

Clustered damage within DNA primarily results from which particle?

Low-energy electrons Signup and view all the answers

Why do Adenine and Thymine specifically bond together?

They have a favorable spatial configuration for bonding. Signup and view all the answers

Study Notes

DNA Structure and Function

DNA stands for deoxyribose nucleic acid
DNA is a large molecule made of a long chain of subunits called nucleotides
Each nucleotide is composed of a sugar (deoxyribose), a phosphate group (-PO4), and an organic base
Ribose is a sugar similar to glucose but with only five carbon atoms
Deoxyribose is almost the same as ribose but lacks one oxygen atom
The most common organic bases are adenine (A), thymine (T), cytosine (C), and guanine (G)
Deoxyribose, phosphate, and a base combine to form a nucleotide
DNA is typically a double-stranded molecule
The sugar-phosphate chains are on the outside of the double helix and held together by chemical bonds between the bases
Adenine always pairs with Thymine, and Cytosine always pairs with Guanine

DNA Mutations

A mutation is a change in an organism's DNA
Mutations in germ cells (sperm and eggs) are passed on to offspring
Mutations in somatic (body) cells can be harmless or cause disease like cancer
Silent mutations don't affect the organism's phenotype
Chromosome mutations include deletion, duplication, inversion, insertion, and translocation
Point mutations are changes in a single nucleotide
- Nonsense mutations create a premature stop codon, shortening the protein
- Missense mutations change one amino acid to another, potentially affecting protein function
- Insertion mutations add one or more nucleotides
- Deletion mutations remove one or more nucleotides
These mutations alter the sequence of amino acids in a protein, which can lead to production of non-functional or faulty proteins

DNA and Enzymes

Proteins build cell structures and make enzymes
DNA controls which enzymes are made, and enzymes determine what reactions happen in the cell
DNA exerts control through the enzymes it codes for

Genes

A sequence of triplets in the DNA molecule may code for a complete protein.
Such a sequence forms a gene
A gene may contain thousands or more bases

Additional Information

In aqueous solutions, some amino acids (e.g., methionine, cystine) are more radiosensitive, compared to others (e.g., tyrosine, alanine)
The mean free path of the majority of LEEs (Low Energy Electrons) varies from 0.1 to 10 nm, potentially causing clustered damage within DNA

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Description

Test your knowledge on the structure and function of DNA, including its components such as nucleotides and the double helix formation. Additionally, explore the concept of DNA mutations, their types, and implications for organisms. This quiz is essential for understanding fundamental genetics.