Biology Chapter: Nucleic Acids and Structures

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Questions and Answers

Which nitrogenous base is only found in RNA?

Uracil (correct)

Adenine

Cytosine

Thymine

What type of bond holds the two strands of DNA together?

Covalent bonds

Hydrogen bonds (correct)

Ionic bonds

Peptide bonds

What describes the structure of RNA?

Single chain of nucleotides (correct)

Circular arrangement of bases

Double helix of nucleotides

Linear chain with hydrogen bonds

Which of the following correctly describes the sugar-phosphate backbone of DNA?

Composed of phosphate and sugar molecules Signup and view all the answers

What is the role of the sequence of nitrogenous bases in nucleic acids?

Contains information for protein synthesis Signup and view all the answers

What role do buffers play in bodily fluids?

They stabilize pH by removing or replacing hydrogen ions. Signup and view all the answers

Which of the following is an example of a buffer system mentioned?

Carbonic acid and sodium bicarbonate Signup and view all the answers

What is true about organic compounds?

They typically consist of long chains of carbon linked by covalent bonds. Signup and view all the answers

Which of the following options best describes carbohydrates?

They contain C, H, and O, and include sugars and starches. Signup and view all the answers

What percentage of total body weight do sugars constitute?

1-5% Signup and view all the answers

What is the primary function of monosaccharides?

Energy source Signup and view all the answers

Which disaccharide is found in milk?

Lactose Signup and view all the answers

Which of the following is a function of polysaccharides?

Glucose storage Signup and view all the answers

What must happen to disaccharides before absorption?

They undergo hydrolysis Signup and view all the answers

Which lipid type acts as an energy source and provides physical protection?

Fatty acids Signup and view all the answers

What is a characteristic of lipids compared to carbohydrates?

Lower oxygen content Signup and view all the answers

Which example is a type of glyceride?

Triglycerides Signup and view all the answers

What is the role of eicosanoids in the body?

Chemical messengers Signup and view all the answers

What is required for glycerides to be used as an energy source?

They need to be broken down into fatty acids Signup and view all the answers

What distinguishes isomers in molecular structures?

Same molecular formula, different structures Signup and view all the answers

What is the primary function of enzymes in biochemical reactions?

Lower the activation energy needed for the reaction Signup and view all the answers

Which of the following best describes dehydration synthesis?

It involves removing water to form larger compounds Signup and view all the answers

How do decomposition reactions contribute to metabolism?

They break down compounds to release energy Signup and view all the answers

What role do metabolites play in the body?

They are substances synthesized or decomposed during reactions Signup and view all the answers

How are synthesis reactions characterized?

They assemble larger molecules from smaller units Signup and view all the answers

What is activation energy?

The minimum energy required to initiate a reaction Signup and view all the answers

What occurs during hydrolysis?

Compounds are broken down by adding water Signup and view all the answers

Why are metabolic pathways important?

They are series of interconnected reactions requiring specific enzymes Signup and view all the answers

What is a main consequence of defects affecting enzymes within metabolic pathways?

They can lead to the disruption of normal metabolic functions Signup and view all the answers

In the context of ionic compounds, what does losing an electron result in?

The formation of a positively charged ion Signup and view all the answers

What are eicosanoids, such as leukotrienes, primarily produced for?

To respond to injury or disease Signup and view all the answers

What type of lipid is lecithin?

Phospholipid Signup and view all the answers

What is the primary function of triglycerides in the body?

Energy storage Signup and view all the answers

What is a defining structural characteristic of steroids?

Four carbon rings Signup and view all the answers

What distinguishes monounsaturated fatty acids from saturated fatty acids?

Number of double bonds Signup and view all the answers

Phospholipids are critical for which of the following roles?

Forming cell membranes Signup and view all the answers

Which of the following statements is true regarding fatty acids?

Fatty acids can be classified based on the number of double bonds. Signup and view all the answers

What are the primary components of a triglyceride?

One glycerol and three fatty acids Signup and view all the answers

What role do steroids like cholesterol play in the body?

Maintaining plasma membranes Signup and view all the answers

What distinguishes glycolipids from phospholipids?

Presence of a carbohydrate group Signup and view all the answers

What is the primary composition percentage of protein in the total body weight?

20% Signup and view all the answers

What is a unique property of polyunsaturated fatty acids?

More than one double bond Signup and view all the answers

What is the primary function of structural lipids in the body?

Building structural components Signup and view all the answers

How do lipids primarily differ from carbohydrates in terms of energy?

They provide more energy. Signup and view all the answers

Study Notes

Nitrogenous Bases

Purines are two-ring structures: Adenine and Guanine.
Pyrimidines are one-ring structures: Cytosine, Thymine (only in DNA), and Uracil (only in RNA).

Nucleic Acid Structure

Nucleotides join through dehydration synthesis, forming a sugar-phosphate backbone.
The sequence of nitrogenous bases encodes genetic information necessary for protein synthesis.

DNA Molecule Characteristics

Composed of nucleotide chains that form complementary strands.
Strands twist to create a double helix, resembling a spiral staircase.
Hydrogen bonds link complementary base pairs: Adenine with Thymine, Guanine with Cytosine.

RNA Molecule Features

Consists of a single chain of nucleotides.
Shape and functionality are dictated by nucleotide interactions.
Three types of RNA molecules are present for various functions.

Chemical Reactions

Decomposition reactions involve water (hydrolysis) to break down compounds.
Catabolism releases energy for growth, movement, and reproduction.
Synthesis reactions combine smaller molecules into larger ones, opposite to decomposition.

Activation Energy

The minimum energy needed to initiate a reaction is called activation energy.
Proteins, particularly enzymes, lower the activation energy required for metabolic reactions.

Metabolic Pathways

A series of interconnected enzymatic reactions form metabolic pathways essential for various physiological processes.
Birth defects can affect these enzymes, impacting metabolic functions.

Metabolites

Substances produced or altered by enzymes are called metabolites, which are essential for various biological functions.

Buffers

Buffers stabilize pH levels by either removing or replacing hydrogen ions to maintain homeostasis.
Examples include carbonic acid and sodium bicarbonate, crucial for normal physiological limits.

Organic Compounds

Composed mainly of Carbon (C), Hydrogen (H), and Oxygen (O), forming long chains connected by covalent bonds.
Functional groups define the properties and functionality of the organic molecules.

Carbohydrates

Composed of C, H, and O; energy resources are essential for survival.
Monosaccharides (e.g., glucose) serve as basic energy sources, while disaccharides (e.g., sucrose) must be broken down before absorption.
Polysaccharides (e.g., glycogen) serve as glucose storage, primarily within animal cells.

Lipids (Fats)

Composed mainly of C, H, and O, with less oxygen than carbohydrates.
Important types include fatty acids, glycerides, eicosanoids, and steroids.
Fatty acids can be saturated (no double bonds) or unsaturated (one or more double bonds).

Glycerides

Classified as monoglycerides (1 fatty acid), diglycerides (2 fatty acids), or triglycerides (3 fatty acids).
Lipid breakdown occurs via hydrolysis into fatty acids and glycerol.

Functions of Lipids

Serve as energy reserves, providing twice the energy of carbohydrates.
Structural lipids form cell membranes, allowing separation of cellular environments.
Eicosanoids act as chemical messengers during injury or disease responses.

Proteins

Comprise approximately 20% of body weight and contain carbon, hydrogen, nitrogen, and oxygen.
Essential for various biological functions, serving as structural components and enzymes.

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Description

Explore the essential components of nucleic acids, including the characteristics of DNA and RNA molecules. Understand the roles of nitrogenous bases, the formation of nucleotide chains, and the significance of chemical reactions in biological processes.