Molecular Biology & DNA

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Nucleotides are held together by two types of bonds: phosphodiester bonds and hydrogen bonds. Education Portal describes phosphodiester bonds as bonds that link nucleotides into linear chains. According to Cambridge Physics, hydrogen bonds act as a bridge that connects two parallel rows of nucleotides. This connection aids in the formation of DNA's distinctive double-helix structure.

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  • Why Did Mendel Choose Peas for His Experiments?

    Q: Why Did Mendel Choose Peas for His Experiments?

    A: Gregor Mendel, a monk and teacher from Central Europe, chose common garden peas, or Pisum sativum, for his experiments in genetics because peas are easily grown in numbers large enough to be useful for his experiments and their reproduction can be altered. Pollen could be transferred from one pea flower to another with a paintbrush.
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  • What Happens During Protein Synthesis?

    Q: What Happens During Protein Synthesis?

    A: Protein synthesis is the process of converting the DNA sequence to a sequence of amino acids to form a specific protein. It involves three main steps: transcription of mRNA from the DNA sequence, initiation of the translation of the mRNA sequence to an amino acid sequence and elongation of the protein chain as the mRNA codes for additional amino acids to be added to the growing chain.
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  • What Is a Codon and Where Is It Found?

    Q: What Is a Codon and Where Is It Found?

    A: A codon is a sequence of three nucleotides in DNA or RNA that either codes for a particular amino acid or tells the cellular machinery to start or stop using the code. A group of codons starts with the initiation codon. It then has codons in sequence that gives instructions on the amino acids to use to build a protein, and it then has a stop codon to signal when the protein assembly is complete. Normally, there is one initiation codon and three stop codons, and most amino acids are represented by more than one codon.
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  • What Organelle Contains Chemicals That Help Digest Food?

    Q: What Organelle Contains Chemicals That Help Digest Food?

    A: The lysosomes contain chemicals that help digest food and worn-out cell parts. These organelles are located in the cytoplasm, a gel-like substance inside the cell membrane.
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  • What Is the Hardy-Weinberg Principle?

    Q: What Is the Hardy-Weinberg Principle?

    A: The Hardy-Weinberg principle states that the genetic variation in a population stays constant over generations in the absence of disruptive factors. The concept predicts that when mating occurs randomly in a vast population, the allele and genotype frequencies remain consistent because they are in equilibrium.
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  • Why Is DNA Called the Blueprint of Life?

    Q: Why Is DNA Called the Blueprint of Life?

    A: Just as blueprints direct the building of a house, DNA molecules contain the genetic instructions used in the development and functioning of a living organism. The DNA of eukaryotic organisms such as plants and animals is organized into linear chromosomes and stored within the nucleus of every cell.
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  • What Is the LacZ Gene?

    Q: What Is the LacZ Gene?

    A: The lacZ gene is a gene present in E. coli that encodes the protein beta-galactosidase. Beta-galactosidase is an enzyme that is essential for the breakdown of lactose as it cleaves a bond between the two carbon rings in lactose to produce glucose and galactose.
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  • What Are the Functions of Glycoproteins?

    Q: What Are the Functions of Glycoproteins?

    A: Glycoproteins provide many functions: they give structural support to cells, help to form connective tissues and facilitate digestion by producing secretions and mucous in the gastrointestinal tract. Glycoproteins are handy cell components and are found in many places within cells.
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  • What Is the Relationship Between Chromosomes, DNA and Genes?

    Q: What Is the Relationship Between Chromosomes, DNA and Genes?

    A: Chromosomes are paired long chains within a cell nucleus that are composed of genes (about 20,000 genes per chromosome pair), which are made up of the chemical substance called DNA. Genes on the chromosomes are made of segments of DNA which contain chemically coded messages resulting in the characteristics of an organism — including humans.
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  • What Makes up the Sides of the Ladder of a DNA Molecule?

    Q: What Makes up the Sides of the Ladder of a DNA Molecule?

    A: A rigid chain of alternating deoxyribose sugars and phosphates makes up the sides of the DNA ladder. The rungs of the DNA ladder consist of four nitrogenous bases.
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  • What Class of Macromolecules Does DNA Belong To?

    Q: What Class of Macromolecules Does DNA Belong To?

    A: DNA, also known as deoxyribonucleic acid, belongs to a class of polymeric organic macromolecules called nucleic acids. The only other member of this class is ribonucleic acid, or RNA. Nucleic acids were first discovered in 1869 by the Swiss scientist Friedrich Miescher.
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  • What Is the Principle of Dominance?

    Q: What Is the Principle of Dominance?

    A: The principle of dominance is a genetic law that states that the offspring of individuals with contrasting traits will only express the dominant trait. The discovery was made by Gregor Mendel and thus, the law is also called "Mendel's Law."
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  • Are Freckles a Dominant or Recessive Trait?

    Q: Are Freckles a Dominant or Recessive Trait?

    A: Freckles are a dominant trait. Freckles come from genes and the sun and are most often seen on people with light-colored skin.
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  • How Does Molecular Size Affect Diffusion Rate?

    Q: How Does Molecular Size Affect Diffusion Rate?

    A: Diffusion rates are dependent on molecular sizes because larger molecules diffuse slower than smaller molecules. The sizes of the particles involved in the diffusion are important because they closely relate to the concepts of heat and energy in the context of diffusion. It takes more energy and heat to move a larger object than a smaller one, so larger particles require more heat from their surroundings.
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  • Why Must DNA Be Able to Make Copies of Itself?

    Q: Why Must DNA Be Able to Make Copies of Itself?

    A: The University of Illinois at Chicago explains that DNA must replicate itself so that during cell division, both daughter cells receive the same genetic information. DNA replication is necessary during the process by which somatic cells divide, called mitosis, as well as during meiosis, the process by which organisms produce gametes, or sex cells.
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  • What Is Spermatozoa?

    Q: What Is Spermatozoa?

    A: Spermatozoa, also referred to as sperm, are male reproductive cells. Sperm occur in several different forms, and are essential components for reproduction. Sperm vary slightly in physical composition, but have distinct body shapes, characterized by heads and long singular tails.
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  • What Is an Analogy for Mitochondria?

    Q: What Is an Analogy for Mitochondria?

    A: One common analogy for the mitochondria (singular mitochondrion) is a powerhouse, as mitochondria create energy for the cell. Mitochondria are sometimes called the furnace of the cell as well. Like a powerhouse or furnace, mitochondria take in basic fuel stuff and generate energy from it: a furnace generates heat energy, and a powerhouse generates electricity, whereas mitochondria generate ATP.
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  • What Is RNA Primase?

    Q: What Is RNA Primase?

    A: According to Scitable, RNA primase is an enzyme involved in the replication of DNA strands during cell division. It goes over a single DNA strand and creates RNA sequences called primers, which transcribe DNA into RNA. These short sequences of RNA are complementary to the DNA strand they were hovering over, and serve as a template for a new strand of DNA.
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  • How Many Different Kinds of Bases Can Be Found in DNA?

    Q: How Many Different Kinds of Bases Can Be Found in DNA?

    A: Human DNA contains a total of approximately 3 billion base pairs within the genome. These base pairs are contained within 23 chromosome pairs.
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  • What Is Chromatin Made Of?

    Q: What Is Chromatin Made Of?

    A: Chromatin is made of nucleic acids, such as DNA or RNA, and proteins. During cell division, chromatin condenses to form chromosomes. Eukaryotic and prokaryotic cells differ in where chromatin is housed. In eukaryotes, it is located in the nucleus and in prokaryotes, it is located in the nucleoid.
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  • What Happens During DNA Replication?

    Q: What Happens During DNA Replication?

    A: During DNA replication, two strands of DNA separate, and each separate strand forms a template to make a new strand. The replication process results in the formation of two identical molecules, containing one strand from the original piece of DNA and one newly synthesized strand.
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