Nucleic Acids and DNA Replication

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Questions and Answers

What is the primary function of DNA in an organism?

To act as an energy source

To transport oxygen

To store genetic information (correct)

To produce hormones

Which nitrogenous base pairs with adenine in DNA?

Guanine

Thymine (correct)

Uracil

Cytosine

What is the shape of a DNA molecule?

Linear strand

Triple helix

Single strand

Double helix (correct)

Which of the following correctly identifies the components of a nucleotide?

A phosphate group, a pentose sugar, and a nitrogenous base Signup and view all the answers

What type of sugar is found in RNA?

Ribose Signup and view all the answers

Which of the following statements about purines and pyrimidines is true?

Purines consist of adenine and guanine Signup and view all the answers

What was Erwin Chargaff's significant discovery regarding DNA?

The amount of guanine equals the amount of cytosine Signup and view all the answers

Which statement describes the directionality of DNA strands?

One strand runs 3' to 5' while the other runs 5' to 3' Signup and view all the answers

What was the main finding of the Hershey-Chase experiment?

DNA is the genetic material of life. Signup and view all the answers

Which radioisotope was used to track DNA in the Hershey-Chase experiment?

32P Signup and view all the answers

What role does helicase play in DNA replication?

It breaks the hydrogen bonds between base pairs. Signup and view all the answers

What is meant by the term 'semi-conservative' in the context of DNA replication?

Each new DNA molecule contains one original and one new strand. Signup and view all the answers

Which of the following enzymes is involved in adding nucleotides during DNA replication?

DNA polymerase III Signup and view all the answers

What happens to the viral DNA once it is injected into the host bacterial cell in the Hershey-Chase experiment?

It is expressed and used to produce new viruses. Signup and view all the answers

Which component of the viruses used in the Hershey-Chase experiment remains outside the bacterial cell after infection?

The protein capsid Signup and view all the answers

What is the primary purpose of single-stranded binding proteins during DNA replication?

To prevent the two DNA strands from re-annealing. Signup and view all the answers

What is the first step in the initiation of translation?

The small ribosomal subunit binds to the mRNA near the start codon. Signup and view all the answers

Which anticodon is carried by the first tRNA that binds during translation initiation?

UAC Signup and view all the answers

During the elongation phase of translation, what happens after a tRNA molecule binds to the A site?

A peptide bond is formed between the amino acids. Signup and view all the answers

What role does a release factor play during the termination of translation?

It binds to the A site to facilitate polypeptide release. Signup and view all the answers

What is the nature of the reaction that forms peptide bonds during translation?

Condensation reaction Signup and view all the answers

Which of the following best defines gene regulation?

Any measure used to promote or suppress gene expression. Signup and view all the answers

What effect do acetyl groups have on gene expression when added to histones?

They loosen DNA packing to promote gene expression. Signup and view all the answers

What is the outcome of methylation of genes?

Tighter DNA packing to suppress gene expression. Signup and view all the answers

What is the primary role of the promoter region during transcription?

It provides a binding site for transcription factors. Signup and view all the answers

What is the primary function of DNA polymerase III during DNA replication?

It copies DNA in the 5' to 3' direction. Signup and view all the answers

What differentiates small proteins from large proteins?

The number of amino acids in the chain. Signup and view all the answers

Which of the following statements about lagging strand synthesis is accurate?

It consists of short segments called Okazaki fragments. Signup and view all the answers

Which of the following statements accurately describes RNA polymerase II?

It synthesizes mRNA after transcription factors are in place. Signup and view all the answers

What role does DNA polymerase I play in DNA replication?

It replaces RNA primers with DNA. Signup and view all the answers

What component is added to the 5' end of the immature mRNA during processing?

A 5' cap of guanosine triphosphate Signup and view all the answers

Which of the following best describes the telomeres in regard to DNA replication?

They shorten slightly with each DNA replication cycle. Signup and view all the answers

Which of the following accurately describes the transcription process?

It results in the production of pre-mRNA. Signup and view all the answers

Which component is NOT part of the replisome during DNA replication?

Histones Signup and view all the answers

What does the term 'introns' refer to in the context of gene structure?

Noncoding DNA segments. Signup and view all the answers

What accurately describes the composition of chromatin?

It includes both DNA and proteins, particularly histones. Signup and view all the answers

Which base is not used in RNA, forming a crucial distinction from DNA?

Thymine Signup and view all the answers

Which of the following molecules is considered noncoding DNA?

Telomeres Signup and view all the answers

At which point does RNA polymerase II stop transcription?

When it encounters the stop codon. Signup and view all the answers

What primary function does the H1 protein serve in the organization of DNA?

It helps hold DNA to the nucleosome. Signup and view all the answers

What function does the poly-A tail serve for mRNA?

It stabilizes mRNA, protects it from digestion, and aids in routing. Signup and view all the answers

Which statement is true regarding tRNA?

tRNA is necessary for transporting amino acids to ribosomes during translation. Signup and view all the answers

Which of the following correctly describes the structure of ribosomes?

Ribosomes have three binding sites for tRNA during translation. Signup and view all the answers

What is the total number of amino acids that can be coded for by the genetic code?

20 Signup and view all the answers

What differentiates prokaryotic ribosomes from eukaryotic ribosomes?

The small and large subunits of prokaryotic ribosomes are different sizes than those of eukaryotes. Signup and view all the answers

Which of the following describes the codons in the genetic code?

There are more codons than amino acids due to the redundancy of the genetic code. Signup and view all the answers

During protein synthesis, what happens when ribosomes translate mRNA?

Ribosomes can synthesize proteins concurrently on the same mRNA strand. Signup and view all the answers

What role do spliceosomes play in RNA processing?

They remove introns from pre-mRNA transcripts. Signup and view all the answers

Study Notes

Nucleic Acids

DNA (deoxyribonucleic acid) contains genetic information for development and reproduction
RNA (ribonucleic acid) is also a nucleic acid
Nucleotides are the monomers of nucleic acids
Each nucleotide contains a pentose sugar, phosphate, and a nitrogenous base
DNA has deoxyribose sugar and bases A, G, C, and T
RNA has ribose sugar and bases A, G, C, and U
DNA forms a double helix
Bases in DNA pair up in complementary fashion: A with T, and C with G
Bonds between bases are hydrogen bonds
DNA strands run antiparallel (5' to 3' and 3' to 5')
RNA is typically single-stranded

DNA Replication

DNA replication is semi-conservative
Replication starts at a single origin, opening a replication bubble
Enzymes read the parent strand and construct a daughter strand
Replication continues bidirectionally
The process ensures each new DNA molecule has half of the original
Colored boxes represent enzymes, used in replication process.
Helicase breaks hydrogen bonds between bases
Single-stranded binding proteins prevent the strands from reconnecting
RNA primers are put in place by primase for DNA polymerase III attachment
DNA polymerase III copies DNA in 5' to 3' direction
Leading strand gets replicated continuously, lagging strand gets replicated in fragments (Okazaki fragments)
DNA polymerase I removes RNA primers and DNA ligase seals gaps
DNA Replication is a process where the DNA cell duplicates.

Gene Structure and Function

Genes are segments of DNA, with specific coding segments
Eukaryotic genes have exons (coding regions) and introns (non-coding regions)
Upstream from the start codon (in a gene) is the promoter region
Promoter region begins with TATA
Transcription factors bind to the promoter region

Gene Regulation

Gene regulation is the cell's controlled expression of genes.
Gene expression occurs before, during, and after transcription and translation
Enhancers enhance expression and promoter region is upstream of gene
Histones are proteins that DNA is associated with.
Acetylation of Histone proteins loosens the DNA structure, increasing expression.
Methylation of Histones proteins tightens the DNA structure, decreasing expression.

Transcription

Transcription is the first step in protein synthesis
RNA polymerase II binds to the promoter region
Breaks hydrogen bonds to transcribe the template strand of DNA to make mRNA.
mRNA molecules are made in the 5' to 3' direction
mRNA is called pre-mRNA initially and it needs processing before it can be translated

Translation

Ribosomes translate mRNA into proteins
tRNA brings amino acids to ribosomes
Anticodons of tRNA match codons on mRNA
Peptide bonds form between amino acids, creating a polypeptide
Translation happens at ribosomes in the cytoplasm
mRNA codons are read in triplets (three bases at a time)

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Description

Explore the essentials of nucleic acids, focusing on DNA and RNA structures, their monomeric units, and the intricate process of DNA replication. Understand the significance of nucleotide components, base pairing, and enzyme functions in genetic information transfer. This quiz is perfect for students looking to deepen their understanding of molecular biology.