DNA and RNA Chemical Structure
45 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a primary structural feature of tRNA?

  • It is composed of a double helix structure.
  • It has a cloverleaf appearance due to its folding. (correct)
  • It contains thymine as one of its bases.
  • It is synthesized in the cytoplasm.

What percentage of total RNA in a cell is made up of ribosomal RNA (rRNA)?

  • 65%
  • 50%
  • 90%
  • 80% (correct)

What is a key role of small nuclear RNA (SnRNA) in eukaryotic cells?

  • Replication of DNA strands.
  • Formation of ribosomes.
  • Involvement in mRNA processing and gene regulation. (correct)
  • Translation of mRNA.

Which of the following statements correctly describes the differences between RNA and DNA?

<p>RNA does not follow Chargaff's rules due to its single-stranded nature. (C)</p> Signup and view all the answers

What distinguishes ribosomal RNA (rRNA) from other types of RNA?

<p>It forms complex structures with proteins to create ribosomes. (A)</p> Signup and view all the answers

What is the primary factor that determines the melting temperature of DNA?

<p>The number of hydrogen bonds between base pairs (D)</p> Signup and view all the answers

During denaturation, which of the following events occurs?

<p>DNA strands separate due to heat or chemical exposure (D)</p> Signup and view all the answers

Which of the following accurately describes a key difference between prokaryotic and eukaryotic DNA?

<p>Eukaryotic DNA is associated with histones, while prokaryotic DNA is not (C)</p> Signup and view all the answers

What is the primary role of ribonucleic acid (RNA) within the cell?

<p>Playing a key role in protein synthesis (A)</p> Signup and view all the answers

Which type of RNA carries the genetic code from DNA to the ribosome?

<p>Messenger RNA (mRNA) (B)</p> Signup and view all the answers

What is the process of renaturation in nucleic acids?

<p>The reassociation of complementary DNA strands after denaturation (A)</p> Signup and view all the answers

Which of the following statements about the structure of RNA is accurate?

<p>RNA can have varied secondary structures due to base pairing (A)</p> Signup and view all the answers

What type of bond links nucleotides together in a nucleic acid chain?

<p>Phosphodiester bonds (B)</p> Signup and view all the answers

What is the main difference between prokaryotic and eukaryotic DNA regarding structure?

<p>Prokaryotic DNA is naked, while eukaryotic DNA is associated with histone proteins. (A)</p> Signup and view all the answers

Which of the following accurately describes messenger RNA (mRNA) in eukaryotic organisms?

<p>It is monocistronic and contains information from one gene. (A)</p> Signup and view all the answers

What is the primary function of transfer RNA (tRNA)?

<p>To read the code on mRNA and transfer specific amino acids to the ribosome. (B)</p> Signup and view all the answers

How do prokaryotic and eukaryotic mRNA differ in terms of their coding capacity?

<p>Prokaryotic mRNA is polycistronic, carrying information from more than one gene. (B)</p> Signup and view all the answers

Which of the following statements about RNA structure is true?

<p>The pentose sugar in RNA is ribose, and it includes uracil instead of thymine. (C)</p> Signup and view all the answers

What role does ribosomal RNA (rRNA) play in protein synthesis?

<p>It forms the structural and functional component of ribosomes. (A)</p> Signup and view all the answers

What is the highest level of structure that RNA can achieve?

<p>Tertiary: motifs and 3D folding. (B)</p> Signup and view all the answers

What is a distinguishing feature of prokaryotic DNA concerning plasmids?

<p>Plasmids are present. (A)</p> Signup and view all the answers

What is NOT a function of histone H1?

<p>Promotes transcription of genes (C)</p> Signup and view all the answers

Which statement accurately describes euchromatin?

<p>It constitutes the majority of the human genome (C)</p> Signup and view all the answers

Which histone modification is NOT part of the histone code's function?

<p>Proteolysis (A)</p> Signup and view all the answers

What type of chromatin is always condensed and generally inactive?

<p>Constitutive heterochromatin (C)</p> Signup and view all the answers

What best describes the histone octamer's role in nucleosome formation?

<p>It acts as a core structure around which DNA wraps (D)</p> Signup and view all the answers

In which region is constitutive heterochromatin predominantly found?

<p>Near chromosomal centromeres and telomeres (C)</p> Signup and view all the answers

What is a characteristic of the N-terminal ends of histones?

<p>They can be modified by acetylation, methylation, or phosphorylation (A)</p> Signup and view all the answers

Which of the following best describes heterochromatin?

<p>It appears dark-staining and is typically gene-poor (A)</p> Signup and view all the answers

What characterizes facultative heterochromatin in comparison to euchromatin?

<p>It can switch between being condensed and actively transcribed. (A)</p> Signup and view all the answers

What is the composition of interphase chromatin?

<p>30-40% DNA, 50-60% protein, 1-10% RNA (A)</p> Signup and view all the answers

What type of chromosomes are referred to as 'S chromosomes'?

<p>Single stranded chromosomes present in non-dividing cells. (D)</p> Signup and view all the answers

Which term describes the condition of having multiple sets of chromosomes?

<p>Polyploidy (B)</p> Signup and view all the answers

How do d-chromosomes differ from S-chromosomes during cell division?

<p>D-chromosomes consist of chromatid pairs, whereas S-chromosomes do not. (D)</p> Signup and view all the answers

What structural feature allows d-chromosomes to be distinguished during the cell cycle?

<p>The presence of two joined chromatids at the centromere. (C)</p> Signup and view all the answers

What is the normal chromosomal configuration in human somatic cells?

<p>46 S chromosomes differentiated into autosomes and sex chromosomes. (C)</p> Signup and view all the answers

Which statement about transcriptional activity of facultative heterochromatin is correct?

<p>It can be transcriptionally active under certain conditions. (D)</p> Signup and view all the answers

Which statement correctly describes the function of histones in chromatin structure?

<p>Histones help compact DNA by wrapping around it to form nucleosomes. (A)</p> Signup and view all the answers

What characterizes euchromatin compared to heterochromatin?

<p>Euchromatin is loosely packed and often associated with active transcription. (B)</p> Signup and view all the answers

Which part of the chromosome structure is directly involved in the cohesion of sister chromatids?

<p>Centromere (C)</p> Signup and view all the answers

Which of these is NOT a role of chromatin modifications in gene expression regulation?

<p>Chromatin modifications are solely responsible for DNA replication. (C)</p> Signup and view all the answers

What is the primary reason for the negative charge of a nucleosome?

<p>The acidic nature of the linker DNA between nucleosomes. (A)</p> Signup and view all the answers

Which process explains the role of histones in regulating gene expression?

<p>Histones modify chromatin structure leading to transcriptional activation or repression. (C)</p> Signup and view all the answers

What is a critical step that occurs during the packaging of DNA into chromatin?

<p>Nucleosomes are formed by DNA wrapping around nucleoproteins. (D)</p> Signup and view all the answers

In the context of chromatin structure, what are the components of a nucleosome?

<p>A DNA double helix wrapped around an octamer of histones. (D)</p> Signup and view all the answers

Flashcards

Prokaryotic DNA

Circular DNA molecule, not associated with histone proteins, found free in the cell.

Eukaryotic DNA

Linear DNA molecules associated with histone proteins, enclosed within the nucleus.

mRNA (messenger RNA)

RNA that carries genetic information from DNA to ribosomes, specifying amino acid sequences.

Prokaryotic mRNA

mRNA carrying information from multiple genes.

Signup and view all the flashcards

Eukaryotic mRNA

mRNA carrying information from only one gene.

Signup and view all the flashcards

tRNA (transfer RNA)

RNA that carries amino acids to ribosomes during protein synthesis.

Signup and view all the flashcards

RNA structure

Single-stranded polymer of ribonucleotides with primary, secondary, and tertiary levels.

Signup and view all the flashcards

RNA function

Retrieves protein code and carries out processes for protein production.

Signup and view all the flashcards

snRNA Location

Small nuclear RNA (snRNA) is typically found in the nucleus of eukaryotic cells, where it plays a role in mRNA processing and gene regulation.

Signup and view all the flashcards

RNA vs. DNA: Strands

RNA is typically single-stranded, while DNA is double-stranded.

Signup and view all the flashcards

RNA vs. DNA: Bases

RNA uses uracil (U) instead of thymine (T) as one of its nitrogenous bases.

Signup and view all the flashcards

DNA

A double-stranded nucleic acid containing genetic information. It consists of two polynucleotide chains held together by hydrogen bonds between complementary base pairs: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).

Signup and view all the flashcards

RNA

A single-stranded nucleic acid that plays a vital role in protein synthesis. It consists of a ribose sugar backbone and four nitrogenous bases: adenine (A), guanine (G), cytosine (C), and uracil (U).

Signup and view all the flashcards

What's the primary difference between DNA and RNA?

DNA has deoxyribose sugar and thymine (T) as a base, while RNA has ribose sugar and uracil (U) as a base.

Signup and view all the flashcards

Nucleotide

The basic building block of nucleic acids. It is composed of a phosphate group, a pentose sugar (either deoxyribose or ribose), and a nitrogenous base.

Signup and view all the flashcards

Base pairing

The specific pairing of nitrogenous bases in DNA and RNA. Adenine pairs with thymine (or uracil) and guanine pairs with cytosine.

Signup and view all the flashcards

Phosphodiester bond

The chemical bond that links nucleotides together to form a polynucleotide chain. It forms between the 5' phosphate group of one nucleotide and the 3' hydroxyl group of the next nucleotide.

Signup and view all the flashcards

DNA duplex

The double-stranded structure of DNA, formed by two antiparallel polynucleotide chains held together by hydrogen bonds between complementary base pairs.

Signup and view all the flashcards

Tertiary structure of DNA

The 3-D shape of DNA. In its relaxed state, DNA exists as a double helix.

Signup and view all the flashcards

Histone Charge

Histones are positively charged proteins due to a high content of lysine and arginine amino acids, which are basic and carry a positive charge at physiological pH.

Signup and view all the flashcards

Nucleosome Core

A nucleosome core is a basic unit of DNA packaging in eukaryotes. It consists of eight histone proteins (two each of H2A, H2B, H3, and H4) around which DNA is wrapped twice.

Signup and view all the flashcards

Linker DNA

Linker DNA is the stretch of DNA between two nucleosomes. It's about 20-80 nucleotides long. Histone H1 binds to linker DNA, helping to keep DNA wrapped around the nucleosome.

Signup and view all the flashcards

Histone Modifications

Histones can be modified by adding or removing chemical groups like acetyl, methyl, or phosphate. These modifications form the 'histone code' and can affect gene expression by influencing how tightly DNA is wrapped around histones.

Signup and view all the flashcards

Chromatin Structure

Chromatin is the complex of DNA and proteins (mainly histones) that makes up eukaryotic chromosomes. It exists in two forms: euchromatin and heterochromatin.

Signup and view all the flashcards

Euchromatin

Euchromatin is the lightly packed form of chromatin that is rich in gene concentration. It is actively transcribed, meaning genes are being expressed and copied into RNA.

Signup and view all the flashcards

Heterochromatin

Heterochromatin is the tightly packed form of chromatin that is gene-poor and transcriptionally inactive. It is often found near centromeres and telomeres.

Signup and view all the flashcards

Constitutive Heterochromatin

Constitutive heterochromatin is a type of heterochromatin that is always condensed and inactive. It is found in regions near centromeres and at telomeres.

Signup and view all the flashcards

Chromosomes

Thread-like structures in the nucleus that carry genes (units of heredity).

Signup and view all the flashcards

Single Stranded Chromosome (S-chromosome)

The usual form of chromosome found in non-dividing cells. A long thread of double-stranded DNA coiled on itself.

Signup and view all the flashcards

Double Stranded Chromosome (d-chromosome)

A chromosome copied during cell division, consisting of two identical chromatids connected at a centromere.

Signup and view all the flashcards

Centromere

The central point of a d-chromosome where two chromatids are joined.

Signup and view all the flashcards

Autosomes vs. Sex Chromosomes

Autosomes: Chromosomes that determine most of a person's physical characteristics. Sex Chromosomes: Chromosomes that determine a person's sex (male or female).

Signup and view all the flashcards

Haploid vs. Diploid

Haploid: Having one set of chromosomes (found in germ cells). Diploid: Having two sets of chromosomes (found in somatic cells).

Signup and view all the flashcards

What is chromatin?

Chromatin is a complex of DNA, histone proteins, and other proteins found inside the nucleus of eukaryotic cells. It's essentially the organized form of DNA.

Signup and view all the flashcards

What are histones?

Histones are basic proteins that interact with DNA and help it condense and organize inside the cell.

Signup and view all the flashcards

What are nucleosomes?

Nucleosomes are the fundamental building blocks of chromatin. They consist of DNA wrapped around a core of eight histone proteins.

Signup and view all the flashcards

What is linker DNA?

Linker DNA is the short DNA segment that connects two nucleosomes together, forming the 'beads on a string' structure of chromatin.

Signup and view all the flashcards

What is a chromosome?

A chromosome is a highly condensed and organized structure formed from chromatin during cell division. It carries the genetic information of a cell.

Signup and view all the flashcards

What is karyotyping?

Karyotyping is a process of examining an individual's full set of chromosomes. It's used to diagnose genetic disorders.

Signup and view all the flashcards

What is the function of chromatin?

Chromatin plays a crucial role in DNA packaging, protecting DNA from damage, regulating gene expression, and facilitating DNA replication.

Signup and view all the flashcards

What is the purpose of histones?

Histones help to organize DNA, condense it into a manageable size, and regulate gene expression.

Signup and view all the flashcards

Study Notes

DNA and RNA Chemical Structure

  • Nucleic acids are the principle information molecules in cells, carrying all genetic codes.
  • Nucleic acids are linear polymers of nucleotides.
  • DNA and RNA are two types of nucleic acids.

Types of Nucleic Acids

  • Deoxyribonucleic Acid (DNA):
    • Pentose sugar is deoxyribose (lacks an oxygen atom at the 2' position).
    • Bases: Purines (Adenine, Guanine) and Pyrimidines (Cytosine, Thymine).
  • Ribonucleic Acid (RNA):
    • Pentose sugar is ribose.
    • Bases: Purines (Adenine, Guanine) and Pyrimidines (Cytosine, Uracil).

Base Pairing

  • DNA strands are antiparallel.
  • Bases pair via hydrogen bonds:
    • Adenine pairs with Thymine (2 hydrogen bonds).
    • Guanine pairs with Cytosine (3 hydrogen bonds).

Nucleotide Structure

  • Nucleotides are composed of a nitrogenous base, a pentose sugar, and one or more phosphate groups.
  • A nucleoside is a nitrogenous base and a sugar linked together.
  • A nucleotide is a nucleoside and a phosphate group.
  • Nucleotides polymerize to form nucleic acids.
  • Polynucleotide chains are synthesized in the 5' to 3' direction.

DNA Duplex

  • Two antiparallel DNA strands are interconnected by hydrogen bonds between purine and pyrimidine bases.

DNA Structure

  • DNA's double helix forms a right-handed helix.
  • A complete turn of the helix is 3.4 nm long.
  • The distance between adjacent bases is 0.34 nm.
  • A turn contains 10 base pairs.
  • The helix contains a major groove and a minor groove.

Forms of DNA

  • B-form:

    • Most common form in cells
    • Right-handed helix
    • Turn every 3.4 nm
    • 10 base pairs per turn
    • Contains a major and minor groove

  • A-form:

    • Less common than B-form
    • Right-handed helix
    • Turn every 2.82 nm
    • 11 base pairs per turn

  • Z-form:

    • Less common form
    • Left-handed helix
    • Turn every 4.56 nm
    • 12 base pairs per turn
    • Radical change of B-form, GC-rich DNA regions.
    • The sugar-base backbone forms a zig-zag shape.

  • Properties of B-DNA, A-DNA, and Z-DNA are summarized in a table.

Denaturation and Annealing of DNA

  • Denaturation is the loss of helical structure in DNA due to heat or chemicals.
    • AT regions denature first (2 H bonds).
    • GC regions denature last (3 H bonds).
  • Denaturation is reversible, and strands can re-anneal when cooled.
  • Melting temperature (Tm) is the temperature at which half of the DNA becomes single-stranded.

Hyperchromicity

  • Hyperchromicity (melting profile) is used to measure DNA denaturation.
  • Single-stranded (ss) DNA absorbs more UV light than double-stranded (ds) DNA at 260 nm.
  • The melting profile shows a change in absorption versus temperature.
  • A-T rich regions denature first.
  • G-C rich regions denature last.

Comparison between Prokaryotic and Eukaryotic DNA

  • Prokaryotic DNA:
    • Main chromosome is circular.
    • DNA is naked.
    • DNA is free within the cell.
    • No introns.
    • Plasmid is present.
  • Eukaryotic DNA:
    • Each chromosome is linear.
    • DNA is linked with histone proteins.
    • DNA is enclosed within the nucleus.
    • Introns are present.
    • Plasmid is absent.

RNA Structure

  • RNA is a single-stranded polynucleotide molecule.
  • It can have three levels of structure:
    • Primary: Nucleotide sequence.
    • Secondary: Hairpin loops (base pairing).
    • Tertiary: Motifs and 3D folding.

RNA Function

  • RNA retrieves protein code from DNA and carries out the needed processes to produce proteins.
  • RNA is found inside and outside the nucleus (e.g., nucleus, ribosome, mitochondria, cytoplasm).

Classes of RNA

  • Messenger RNA (mRNA):
    • Carries genetic information from DNA in the form of a series of 3-base codes (codons).
    • Synthesized in the nucleus during transcription and relocated to the cytoplasm.
  • Transfer RNA (tRNA):
    • Smallest of major RNA types.
    • Adapter to read mRNA code and deliver amino acids to ribosomes.
  • Ribosomal RNA (rRNA):
    • Major component of ribosomes, which are essential for protein synthesis.
  • Small RNAs: e.g., small nuclear RNA (snRNA), microRNA (miRNA).
    • Involved in mRNA processing and gene regulation.

RNA vs. DNA

  • Key differences in structure and function between RNA and DNA are summarized in tables. RNA and DNA also have different sugar molecules.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

DNA and RNA Chemical Structure PDF
Chromatin Structure & Human Chromosome PDF

Description

Explore the chemical structures of DNA and RNA through this quiz. Understand the components of nucleic acids, their types, and the essential base pairing mechanisms. Test your knowledge on how these fundamental molecules carry genetic information.

More Like This

DNA and RNA Structure Quiz
20 questions

DNA and RNA Structure Quiz

DR.MOATAZ avatar
DR.MOATAZ
Nucleic Acids: DNA and RNA Structure
30 questions

Nucleic Acids: DNA and RNA Structure

EventfulQuantum avatar
EventfulQuantum
Nucleic Acids: DNA & RNA Structure and Function
6 questions

Nucleic Acids: DNA & RNA Structure and Function

HilariousNiobium6572 avatar
HilariousNiobium6572
Nucleic Acids: DNA & RNA Structure
5 questions

Nucleic Acids: DNA & RNA Structure

UnrivaledHyperbola avatar
UnrivaledHyperbola
Use Quizgecko on...
Browser
Open
Browser
Browser