Questions and Answers
What best describes the structure of DNA?
A double helix consisting of two sugar-phosphate backbones with nucleobases oriented towards the interior.
How do nucleobases pair and bond in DNA?
Adenine pairs with thymine via two hydrogen bonds; cytosine pairs with guanine via three hydrogen bonds.
Doubled-stranded DNA consists of two antiparallel strands.
True
What is the smallest unit of an element that retains all properties of that element?
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What are the six most common elements found in all living organisms?
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How can atoms become more stable or less reactive?
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Match the following definitions to the terms:
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Match the description with the name of the chemical bond.
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What type of bond holds together adjacent amino acids in a protein?
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What level of protein structure do alpha helices and beta-pleated sheets represent?
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What defines the hydrogen ion concentration of a solution?
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In a solution of seawater, the ______ is the solvent, while the ______ is the solute.
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What would happen if a single bacterial cell were treated with a poison that inhibited all enzymes?
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Which of the following statements regarding enzymes is true? (Select all that apply)
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Study Notes
Structure of DNA
- DNA is a double helix with two sugar-phosphate backbones and nucleobases positioned inward.
- Adenine (A) pairs with Thymine (T) via two hydrogen bonds; Cytosine (C) pairs with Guanine (G) via three hydrogen bonds.
- DNA consists of two antiparallel strands: one in the 5' to 3' direction and the other in the 3' to 5' direction.
Basic Units of Matter
- An atom is the smallest unit of an element that retains its properties.
- The six most common elements in living organisms are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.
- Atoms are composed of negatively charged electrons, positively charged protons, and uncharged neutrons.
Atomic Stability and Bonding
- Atoms achieve stability by losing or gaining electrons for a full outer shell or by sharing electrons with other atoms.
- Chemical bonds include:
- Ionic Bonds: Attraction between positively and negatively charged ions through electron transfer.
- Covalent Bonds: Formation through shared electrons between two atoms.
- Hydrogen Bonds: Weak attractions between a positively charged hydrogen atom and a negatively charged atom.
Properties of Water
- Water is a polar molecule and forms hydrogen bonds, serving as an effective solvent for charged solutes.
- In seawater, water is the solvent and salt is the solute.
- Olive oil is least likely to dissolve in water due to its nonpolar nature.
pH and Buffers
- pH is defined by hydrogen ion concentration; as hydrogen ions increase, pH decreases.
- Buffers help maintain relatively constant pH by releasing or binding protons when acids or bases are added.
Carbohydrates
- Types of carbohydrates:
- Monosaccharide: Fructose
- Disaccharide: Lactose
- Polysaccharides: Cellulose, Starch, Glycogen, Chitin
- Important sources for energy: Glucose is commonly broken down in cells.
Proteins Structure
- Adjacent amino acids in proteins are linked by peptide bonds, crucial for maintaining primary structure.
- Secondary protein structures include alpha helices and beta-pleated sheets, characterized by specific folding patterns.
- Tertiary structure is stabilized by disulfide bonds.
Nucleic Acids
- Components of DNA and RNA include amino acids, phosphate groups, nucleobases, and deoxyribose.
- RNA contains nucleobases adenine (A), uracil (U), guanine (G), and cytosine (C).
Chemical Calculations
- Carbon has 4 valence electrons, necessitating 4 additional electrons to complete its outer shell for stability.
Biological Implications of Chemical Properties
- If a bacterial cell lacks buffers, pH fluctuations could disrupt enzyme function and molecular activities, potentially leading to cell death.
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Description
Test your knowledge of DNA structure and nucleobase pairing with these flashcards from Microbiology Chapter 2. Each card presents a question designed to reinforce your understanding of key concepts. Perfect for students looking to strengthen their grasp on the subject.
