Genetic Material and DNA Structure
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Questions and Answers

What defines a gene?

  • A molecule composed only of purines.
  • A complete chromosome in an unreplicated state.
  • A sequence of nucleotides that is not expressed.
  • A section of DNA that specifies the sequence of amino acids in a protein. (correct)

Which pair of nitrogenous bases is a complementary base pair?

  • Guanine and Thymine
  • Adenine and Cytosine
  • Adenine and Thymine (correct)
  • Thymine and Guanine

What is a chromatid?

  • The complete set of DNA in a cell.
  • A single nucleotide unit of DNA.
  • A DNA sequence without any histone proteins.
  • A chromosome in its unreplicated form consisting of one double helix. (correct)

Which best describes chromatin?

<p>A compact structure of DNA and proteins within the nucleus. (A)</p> Signup and view all the answers

How long is the smallest DNA molecule when stretched?

<p>14 millimeters long. (C)</p> Signup and view all the answers

What does the term kilobase (kb) refer to in DNA?

<p>One thousand DNA bases (B)</p> Signup and view all the answers

What is the primary function of a gene?

<p>To provide instructions for producing proteins (A)</p> Signup and view all the answers

What characteristic must genetic material have to construct an entire organism?

<p>It must provide the blueprint for inherited traits (D)</p> Signup and view all the answers

Which direction do the two strands of DNA run in relation to each other?

<p>One strand runs 3' to 5' while the other runs 5' to 3' (B)</p> Signup and view all the answers

What are the strong attachments formed between deoxyribose sugars and phosphates in DNA called?

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

During reproduction, what must occur with genetic material?

<p>It must be passed from parents to offspring (D)</p> Signup and view all the answers

What is the maximum size a human gene can reach?

<p>2 million bases (B)</p> Signup and view all the answers

How are variations within a species described?

<p>Significant phenotypic variability (C)</p> Signup and view all the answers

What is the primary function of scaffold proteins?

<p>They guide DNA strands. (B)</p> Signup and view all the answers

Which structure is formed by DNA coiling around histones?

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

What type of DNA is primarily inherited maternally?

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

Which of the following is NOT a significance of mirror repeats in DNA?

<p>Coding for protein synthesis (D)</p> Signup and view all the answers

What is the composition of a nucleosome?

<p>8 histones and 147 nucleotides of DNA (A)</p> Signup and view all the answers

What role do hairpins play in DNA function?

<p>Aid in gene regulation (C)</p> Signup and view all the answers

Which of the following describes genomic DNA?

<p>Is spread across multiple chromosomes (A)</p> Signup and view all the answers

Which statement about mitochondrial DNA is true?

<p>It is a double-stranded circular molecule. (D)</p> Signup and view all the answers

What is the most common and well-known form of DNA?

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

Which feature indicates that the two strands of DNA are oriented in opposite directions?

<p>They are antiparallel. (B)</p> Signup and view all the answers

What type of DNA is associated with sequences containing alternating purines and pyrimidines?

<p>Z-DNA (D)</p> Signup and view all the answers

Which structural feature of DNA involves the specific pairing of bases?

<p>Complementary base pairs (B)</p> Signup and view all the answers

What distinguishes A-DNA from B-DNA in terms of structure?

<p>A-DNA is more hydrated than B-DNA. (C)</p> Signup and view all the answers

What role does the hairpin structure play in DNA?

<p>Gene regulation and DNA-protein interactions (A)</p> Signup and view all the answers

What characteristic feature do hydrogen bonds provide in the DNA structure?

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

Which of the following DNA forms is typically not observed under normal physiological conditions?

<p>Z-DNA (B)</p> Signup and view all the answers

What significant conclusion did Alfred Hershey and Martha Chase reach about DNA?

<p>DNA can be passed from one bacterial type to another. (A)</p> Signup and view all the answers

Which statement correctly identifies a characteristic of a virus's structure?

<p>Viruses consist of a protein head surrounding DNA. (B)</p> Signup and view all the answers

According to Francis Crick, what roles must genetic material fulfill?

<p>It must replicate and control cell development. (C)</p> Signup and view all the answers

What significant role did Friedrich Miescher play in genetics?

<p>He identified DNA as a nucleic acid. (B)</p> Signup and view all the answers

Which biochemist showed that DNA has equal amounts of ATCG bases?

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

What is the main role of mRNA in cells?

<p>To carry genetic information from the nucleus to ribosomes (C)</p> Signup and view all the answers

Who was the first to identify the link between inherited diseases and proteins?

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

Which type of RNA is involved in protein synthesis by transferring amino acids?

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

What was the main contribution of Oswald Avery and his colleagues?

<p>They confirmed DNA as the transforming principle. (B)</p> Signup and view all the answers

What distinguishes monocistronic mRNA from polycistronic mRNA?

<p>Monocistronic mRNA codes for a single protein (D)</p> Signup and view all the answers

How did Frederick Griffith contribute to the understanding of DNA?

<p>He demonstrated that DNA could transform bacteria. (B)</p> Signup and view all the answers

What was the function of the polysaccharide capsule in Type S bacteria?

<p>To enhance the bacterial infection ability. (D)</p> Signup and view all the answers

Which type of unusual base is found in RNA and has a role in the structure?

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

What is the characteristic feature of the ribose sugar in RNA?

<p>Presence of a 2'-OH group (A)</p> Signup and view all the answers

Which biochemist provided evidence that DNA could be bombarded to deduce its structure?

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

In which part of the cell is rRNA synthesized?

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

What did Phoebus Levene contribute to the understanding of nucleic acids?

<p>He identified the sugar components of nucleic acids. (A)</p> Signup and view all the answers

How do RNA molecules generally exist in terms of structure?

<p>As single-stranded only (A)</p> Signup and view all the answers

What does the double helix structure of DNA symbolize in biology?

<p>The foundational concept of heredity. (A)</p> Signup and view all the answers

What is a common secondary structure formed by RNA?

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

What did Rosalind Franklin significantly contribute to genetics?

<p>She provided crucial X-ray diffraction images. (D)</p> Signup and view all the answers

What did the research findings of Watson, Crick, and Wilkins ultimately lead to?

<p>The confirmation of DNA's structure and its biological role. (A)</p> Signup and view all the answers

Flashcards

Nucleotide

The basic building block of DNA, composed of a sugar, a phosphate group, and a nitrogenous base.

Gene

A segment of DNA that contains the instructions for building a specific protein.

Complementary Base Pairing

The specific pairing of nitrogenous bases (A with T, and C with G) in DNA.

Chromatid

A single strand of duplicated DNA, formed during cell division, part of a chromosome.

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Chromatin

A complex of DNA and proteins that packages and organizes DNA within the cell nucleus.

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Kilobase (kb)

A unit of measurement representing one thousand DNA bases.

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Megabase (mb)

A unit of measurement representing one million DNA bases.

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Gene

A fundamental unit of heredity containing DNA instructions for producing proteins.

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Polynucleotide Chains

Long chains of nucleotides joined together by phosphodiester bonds.

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Phosphodiester Bonds

Strong bonds that link deoxyribose sugars and phosphates in DNA.

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Sugar-phosphate backbone

The repeating pattern of sugar and phosphate molecules forming the structural framework of DNA.

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Antiparallelism

The opposing orientation of the two DNA strands in a double helix (5' to 3' and 3' to 5').

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Characteristics of Genetic Material

Genetic material must contain information, be passed to offspring and replicated accurately within organisms and must allow for variability.

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DNA

Deoxyribonucleic acid; the molecule that carries genetic information in most living organisms.

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Hershey-Chase experiment

Experiment that proved DNA, not protein, is the genetic material.

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Griffith's experiment

Experiment showing a substance (later identified as DNA) from one type of bacteria could transform another type.

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Transforming principle

The substance responsible for the genetic transformation observed in Griffith's experiment.

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Type S bacteria

Type of pneumonia-causing bacteria with a smooth capsule.

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Type R bacteria

Type of pneumonia-causing bacteria lacking a capsule.

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Double helix

The structure of DNA, a twisted ladder shape.

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Nucleic acid

Biopolymer consisting of nucleotides.

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Base pairs

Two nucleotides forming a pair in DNA.

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Watson and Crick

Scientists who determined the 3D structure of DNA.

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Rosalind Franklin

Scientist whose research with X-ray diffraction contributed to determining the structure of DNA.

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Deoxyribose

Sugar component of DNA.

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Erwin Chargaff

Scientist who discovered the base pairing rules in DNA.

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Friedrich Miescher

Scientist who isolated nuclein, a substance later identified as DNA.

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Genetic material

The substance that carries the genetic instructions for an organism.

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Scaffold proteins

Proteins that form frameworks guiding DNA strands, influencing genetic processes.

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Histones

Proteins that DNA coils around, forming nucleosomes, influencing gene regulation.

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Nucleosome

DNA wrapped around histone proteins forming a repeating bead-like structure.

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Mirror repeats

DNA sequences that are identical but reversed, playing a role in DNA replication and gene regulation.

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Hairpin loop

A DNA sequence that folds back on itself, frequently involved in gene regulation.

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Genomic DNA

The complete set of DNA in an organism's genome, responsible for its traits

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Mitochondrial DNA (mtDNA)

Circular DNA located in mitochondria, inheriting maternally.

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Significance of DNA structures

DNA structures like mirror repeats and hairpins impact DNA replication, repair, gene regulation, and overall genetic information processing.

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DNA Forms

DNA exists in various structures, including B-DNA, A-DNA, and Z-DNA, each with distinct characteristics.

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B-DNA

The most common DNA structure, a right-handed double helix with specific base pairing (A-T and C-G).

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A-DNA

A right-handed DNA structure with a slightly different shape than B-DNA, forming under specific conditions.

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Z-DNA

A left-handed DNA structure found in alternating purine-pyrimidine sequences.

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Cruciform

A DNA structure formed by annealing of inverted DNA sequences.

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Antiparallel Strands

The two DNA strands run in opposite directions (3' to 5' and 5' to 3').

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Complementary Base Pairing

A-T and C-G pairings in DNA, crucial for DNA replication.

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mtDNA Differences

Mitochondrial DNA (mtDNA) doesn't undergo inheritance or recombination like nuclear DNA.

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mRNA function

Carries genetic instructions from DNA to ribosomes for protein synthesis.

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tRNA function

Transfers amino acids to ribosomes during protein synthesis.

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rRNA function

Combines with proteins to form ribosomes, crucial for protein synthesis.

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mRNA types

Monocistronic (one protein) in eukaryotes; polycistronic (many proteins) in prokaryotes.

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RNA Structure

Single stranded molecule with hydrogen base stacking, creating secondary structures like hairpins. Can have non-Watson-Crick binding.

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RNA Characteristics

RNA contains 2'-OH in ribose, unusual bases like inosine and pseudouridine.

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RNA discovery

Rich and Davies demonstrated RNA hybridization; Jacob and Monod introduced the concept of mRNA; Holley discovered tRNA structure.

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RNA location

mRNA moves to ribosomes for protein synthesis. tRNA and rRNA are found in ribosomes and cytoplasm, respectively.

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Study Notes

Genetic Material

  • DNA is the genetic material, not protein
  • DNA passed from type S bacteria to type R bacteria
  • DNA controls cell development and duplicates itself
  • DNA can be found with proteins in chromosomes
  • DNA replicates and transmits
  • Variability occurs
  • Genes are fundamental units of heredity
  • Genes are composed of DNA and provide instructions for producing proteins
  • Human genes vary in size, from a few hundred to over 2 million DNA bases

DNA Structure

  • DNA double helix is a symbol in modern biology
  • Structure is important for function
  • DNA is a polynucleotide chain of nucleotides
  • Nucleotides consist of a deoxyribose sugar, phosphate group, and nitrogenous base (A, T, C, or G)
  • Bases pair: A-T, C-G
  • Phosphodiester bonds link nucleotides
  • DNA strands are antiparallel (5' to 3' and 3' to 5')
  • DNA is measured in base pairs, kilobases, and megabases
  • DNA in a cell is 14 millimetres but it's 2 micrometers when packaged into chromosomes
  • DNA is packaged DNA is packaged into chromatin which coils around proteins called histones, forming nucleosomes.

DNA Configuration in the Nucleus

  • DNA within cells is 14 millimetres when stretched but 2 micrometers when packaged
  • DNA is packaged into chromatin fibre, which is wound around proteins called histones
  • Chromatin fibre is also known as "beads on a string"

Types of DNA

  • Genomic DNA / Nuclear DNA:
    • The genome of an organism
    • Located on 46 chromosomes
    • Controls traits
  • Mitochondrial DNA (mtDNA)
    • Located in mitochondria
    • Derived from circular bacterial genomes
    • Passed maternally, not in a nuclear fashion
    • Not subject to recombination
  • Different forms of DNA (B-DNA, A-DNA, Z-DNA)

RNA

  • RNA is a single-stranded polynucleotide chain
  • RNA is a single-stranded polynucleotide chain of ribonucleotides (ribose sugar, phosphate group, and nitrogenous base)
  • RNA is found in different forms:
    • mRNA: Carries information from nucleus to ribosomes, codes for amino acid sequence.
    • tRNA: Transfers molecules to growing polypeptide chains in proteins
    • rRNA: Synthesized in nucleolus. Combines with proteins to produce ribosomes; 80% of RNA occurs as rRNA

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M1. The Genetic Material PDF

Description

This quiz covers the fundamental concepts of genetic material and the structure of DNA. It explores the role of DNA in heredity, its composition, and its significance in biology. Test your knowledge on the double helix, nucleotides, and DNA replication.

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