Introduction to DNA and Cellular Structure
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Questions and Answers

What is the primary function of ribosomes in a cell?

  • Cell division
  • Protein synthesis (correct)
  • DNA replication
  • Energy production

Which component is NOT a part of the nucleus?

  • Cytoplasm (correct)
  • Chromatin network
  • Nucleolus
  • Nuclear membrane

What are nucleotides composed of?

  • A nitrogenous base, a sugar molecule, and a fatty acid
  • A nitrogenous base, an enzyme, and a sugar molecule
  • A phosphate group, a sugar molecule, and a nitrogenous base (correct)
  • A phosphate group, an amino acid, and a sugar molecule

Which part of the nucleus is responsible for producing ribosomes?

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

How many types of nucleic acids are found in the human body?

<p>Two (D)</p> Signup and view all the answers

Which nitrogenous bases are found in DNA?

<p>Adenine, Thymine, Guanine, Cytosine (A)</p> Signup and view all the answers

What is the primary function of DNA?

<p>To carry the genetic code for protein synthesis (B)</p> Signup and view all the answers

Where is nuclear DNA predominantly located within a cell?

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

Who proposed the 3-D double helix model of DNA structure?

<p>James Watson and Francis Crick (D)</p> Signup and view all the answers

What type of DNA is found outside the nucleus?

<p>Extra-nuclear DNA, which includes mitochondrial and chloroplastic DNA (A)</p> Signup and view all the answers

What are amino acids considered in the context of proteins?

<p>The monomers of proteins (C)</p> Signup and view all the answers

What determines the type of protein that is formed during protein synthesis?

<p>The sequence of amino acids (A)</p> Signup and view all the answers

What is the first stage of protein synthesis called?

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

What is a codon?

<p>A three-nucleotide sequence on mRNA (A)</p> Signup and view all the answers

Where does transcription occur in the cell?

<p>In the nucleus (D)</p> Signup and view all the answers

What is the role of the anti-codon in protein synthesis?

<p>To pair with the codon on mRNA (D)</p> Signup and view all the answers

How many different amino acids are involved in protein synthesis?

<p>20 (B)</p> Signup and view all the answers

What type of bond links amino acids together during protein synthesis?

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

What serves as a template for building a new DNA strand during replication?

<p>The original DNA strands (B)</p> Signup and view all the answers

What is a result of errors occurring during DNA replication?

<p>Changes in the nitrogenous base sequence (A)</p> Signup and view all the answers

How many types of chromosomes does each new daughter cell produced after mitosis contain?

<p>The same number and type as the original cell (A)</p> Signup and view all the answers

What does a DNA profile consist of?

<p>Lines of different lengths and thicknesses (C)</p> Signup and view all the answers

During DNA replication, which nitrogenous bases pair together?

<p>A with T and C with G (B)</p> Signup and view all the answers

What is a direct consequence of a nitrogenous base being added or deleted during replication?

<p>Alteration in the order of bases in the new DNA molecule (D)</p> Signup and view all the answers

What distinguishes the DNA profile of individuals, excluding identical twins?

<p>It is unique to each individual (B)</p> Signup and view all the answers

What is a key role of DNA replication during cell division?

<p>To ensure each daughter cell receives a complete set of chromosomes (A)</p> Signup and view all the answers

What happens to the hydrogen bonds between nitrogenous bases during DNA transcription?

<p>They break, allowing the DNA to unwind. (B)</p> Signup and view all the answers

What role does the mRNA play after being synthesized in the nucleus?

<p>It exits the nucleus into the cytoplasm for translation. (A)</p> Signup and view all the answers

In the context of translation, what is the function of tRNA?

<p>To carry specific amino acids to the ribosome. (B)</p> Signup and view all the answers

What are complementary sequences of three nitrogenous bases on mRNA called?

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

How are amino acids linked together during protein synthesis?

<p>By peptide bonds. (D)</p> Signup and view all the answers

What signifies the beginning of the translation process?

<p>The attachment of mRNA to the ribosome. (B)</p> Signup and view all the answers

What does the anti-codon on tRNA correspond to during translation?

<p>The codon on mRNA. (C)</p> Signup and view all the answers

Which of the following statements accurately describes the process of DNA transcription?

<p>Only one strand of DNA is used as a template for mRNA synthesis. (C)</p> Signup and view all the answers

What is the main function of DNA in the human body?

<p>Storing genetic information (A)</p> Signup and view all the answers

Which stage of protein synthesis involves the formation of mRNA?

<p>Transcription (D)</p> Signup and view all the answers

Where is DNA primarily located within a cell?

<p>Nucleus (D)</p> Signup and view all the answers

What component is essential for the process of DNA replication?

<p>Primers (D)</p> Signup and view all the answers

Which statement best describes the structure of RNA compared to DNA?

<p>RNA has a ribose sugar, while DNA has a deoxyribose sugar. (B)</p> Signup and view all the answers

What is the primary role of ribosomes in protein synthesis?

<p>To translate mRNA into amino acid sequences (B)</p> Signup and view all the answers

What is a consequence of errors during DNA replication?

<p>Mutations can occur in the DNA sequence (C)</p> Signup and view all the answers

Which of the following is NOT a stage in protein synthesis?

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

Flashcards

Ribosomes

Small, round organelles that are the site of protein synthesis. They can be found attached to the endoplasmic reticulum, free-floating in the cytoplasm, or inside other organelles like chloroplasts and mitochondria.

Nuclear membrane

A double membrane that encloses the nucleus. It contains small pores that allow substances to pass in and out of the nucleus.

Nucleoplasm

A jelly-like fluid found inside the nucleus that contains the nucleolus and chromatin network.

Nucleolus

A dark body inside the nucleoplasm that contains free nucleotide bases and produces ribosomes.

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Chromatin network

A network found in the nucleoplasm that contains DNA, which forms the chromosomes containing the genetic code.

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DNA

A molecule that carries genetic information

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Nucleotide

A building block of DNA, made of a phosphate group, sugar molecule, and nitrogenous base.

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Nuclear DNA

DNA found in the nucleus of a cell. This is where most of the DNA is stored

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Extra-nuclear DNA

DNA found outside the nucleus of a cell, in structures like mitochondria and chloroplasts

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Double Helix

The shape of DNA: two strands twisted together like a spiral staircase.

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What is DNA?

Deoxyribonucleic acid, a molecule that carries genetic information in all living organisms.

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Describe the structure of DNA.

It's a complex molecule composed of two long strands of nucleotides, twisted into a double helix shape.

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What is the role of DNA?

DNA stores genetic information, which determines an organism's traits and characteristics.

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Where is DNA found in a cell?

Located in the nucleus of eukaryotic cells, a membrane-bound organelle.

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What is RNA?

Ribonucleic acid, a molecule that plays a crucial role in protein synthesis.

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Describe the structure of RNA.

It's a single-stranded molecule, unlike DNA's double helix structure.

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What is the role of RNA?

RNA acts as a messenger, carrying genetic information from DNA to ribosomes, where proteins are synthesized.

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What is the cytoplasm?

The base substance of the cell that surrounds organelles. It's a watery environment for metabolic reactions.

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Transcription

The process of creating a messenger RNA (mRNA) copy from a DNA sequence.

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Codon

The sequence of three nitrogenous bases on mRNA that code for a specific amino acid.

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Translation

The process of translating the mRNA code into a protein.

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Transfer RNA (tRNA)

A type of RNA that carries a specific amino acid to the ribosome during protein synthesis.

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Anticodon

The sequence of three nitrogenous bases on tRNA that is complementary to the codon on mRNA.

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Peptide bond

The bond that forms between amino acids to create a protein.

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Where does protein synthesis begin?

The process of protein synthesis begins in the nucleus where specific DNA segments are transcribed into mRNA.

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Protein synthesis

The process of creating proteins by linking amino acids.

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Amino acids

The building blocks of proteins, there are 20 different types.

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Base triplet

A sequence of three nitrogenous bases on DNA that codes for a specific amino acid.

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DNA Replication

The process where a DNA molecule is copied to produce two identical DNA molecules.

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Semi-conservative Replication

Each new DNA molecule is composed of one original strand and one newly synthesized strand. This ensures that all genetic information is passed on accurately.

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Base Pairing in Replication

Free nucleotides, the building blocks of DNA, are added to the original DNA strand following the base pairing rules: A with T and C with G.

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Mutation

A change in the sequence of nitrogenous bases in DNA.

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Mitosis

The process of cell division that results in two identical daughter cells, each with a complete set of chromosomes.

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DNA Profiling

DNA profiling uses differences in individual DNA sequences to create unique patterns, used for identification in forensics and paternity testing.

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DNA Profile

A pattern of lines on an X-ray film representing the lengths of DNA fragments, unique to individuals (except identical twins).

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DNA Synthesis

The process of building a new DNA strand from a template strand by adding complementary nucleotides, following the base pairing rules.

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Study Notes

Introduction to DNA

  • DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are found in all living organisms
  • They are crucial for location, structure, and function, and their role in the human body, along with the process of replication, is explored.
  • Protein synthesis is a fundamental process for life, and this study examines how proteins are made using DNA and RNA.

Revision of Cellular Structure

  • Cytoplasm is the watery substance in cells where organelles are suspended, allowing metabolic reactions to occur.
  • Ribosomes are organelles involved in protein synthesis, which can be found attached to the endoplasmic reticulum, freely floating in the cytoplasm, or in smaller numbers inside other organelles like chloroplasts and mitochondria.

Structure of Nucleic Acids

  • Nucleic acids are a type of organic compound.
  • The monomers that form DNA and RNA are nucleotides.

DNA - Deoxyribonucleic Acid

  • DNA is composed of nucleotides consisting of a phosphate group, a deoxyribose sugar molecule, and a nitrogenous base. The four nitrogenous bases are adenine, thymine, guanine, and cytosine.
  • It is a double helix structure where two strands are joined together and twisted spirally.
  • DNA carries the genetic code for protein synthesis, located in the nucleus with some extra-nuclear DNA in the mitochondria and chloroplasts.
  • Rosalind Franklin and her assistant Maurice Wilkins researched DNA structure using X-ray diffraction images. Watson and Crick developed a 3D double helix model of DNA in 1953.

Location of DNA

  • DNA is primarily found in the nucleus of a cell.
  • There is also extra-nuclear DNA, which exists in chloroplasts (in plant cells) and mitochondria.

Structure of DNA

  • DNA's structure is a double helix, formed by two strands of nucleotides.
  • The nucleotides are linked together by strong bonds between the phosphate and sugar molecules, and weak hydrogen bonds between the nitrogenous bases (A with T, and C with G).

The Role of DNA

  • DNA carries hereditary information in the form of genes.
  • Genes code for specific traits (physical characteristics and behaviour).
  • The functions of DNA include controlling cell function, regulating genes, and passing on hereditary characteristics.
  • Much of DNA does not code for anything and is known as non-coding DNA, whose significance is currently researched.

RNA - Ribonucleic Acid

  • RNA is also composed of nucleotides, comprised of phosphate, ribose sugar, and a nitrogenous base. The bases in RNA are adenine, uracil, guanine, and cytosine.
  • RNA is a single-stranded molecule, unlike DNA's double helix.
  • There are three types of RNA — messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). Each plays a critical role in protein synthesis.

Location of RNA

  • mRNA is formed in the nucleus and moves to the cytoplasm where it attaches to ribosomes
  • rRNA is found in the ribosomes
  • tRNA floats freely in the cytoplasm

Structure of RNA

  • RNA is a single-stranded molecule formed from nucleotides.
  • Similar to DNA, RNA nucleotides consist of ribose sugar and are linked together with phosphate groups and nitrogenous bases
  • The nucleotides are attached alternately, resulting in a chain.

Comparison Between DNA and RNA

  • DNA and RNA share similarities (both contain sugar alternating with phosphate, and the nitrogenous bases adenine, guanine, and cytosine).
  • However, they have key differences, including the type of sugar used (ribose in RNA, deoxyribose in DNA), the presence of thymine in DNA and uracil in RNA, and the structure (single-stranded RNA vs. double-stranded DNA).

DNA Replication

  • DNA replication is the process where DNA creates a duplicate copy of itself during interphase.
  • The process involves unwinding the double helix and breaking weak hydrogen bonds between the bases.
  • Free nucleotides pair with complementary bases on each template strand, creating two identical DNA molecules.
  • Errors during replication can lead to mutations, altering the base sequence.

DNA Profiling

  • DNA profiling produces a unique pattern of lines on X-ray film, unique to each individual, except identical twins.
  • This is a critical tool in forensic investigations and determining biological parentage. It can be used in establishing tissue type compatibility for organ transplants and identifying relatives.

Protein Synthesis

  • Proteins are made of amino acids.
  • Proteins are created through a process called protein synthesis.
  • Protein synthesis occurs in two stages: transcription (DNA code is copied into messenger RNA), and translation (mRNA code is used to make protein chains).

The Effect of Mutations on Protein Structure

  • A mutation is a change in the DNA sequence.
  • Mutations can result in changes in the amino acid sequence of the protein.
  • These changes can lead to different protein structures and functionality.

(Additional activities and diagrams referenced are shown within the source text)

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Description

This quiz covers key concepts of DNA and RNA, their functions and replication processes in organisms. Additionally, it revises cellular structures, including the cytoplasm and ribosomes, and explores the composition of nucleic acids. Test your knowledge on the molecular foundations of life and protein synthesis.

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