BIOCHEM.

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Questions and Answers

What are enzymes primarily composed of?

Carbohydrates

Nucleic acids

Proteins (correct)

Lipids

At what temperature do enzymes in the body function best?

50°C

30°C

60°C

40°C (correct)

What term describes molecules that increase the activity of enzymes?

Activators (correct)

Inhibitors

Cofactors

Substrates

What is the role of the active site on an enzyme?

To bind to the substrate Signup and view all the answers

What are isozymes?

Enzymes with similar functions but different structures Signup and view all the answers

Which part of an enzyme is known as the apoenzyme?

Protein part Signup and view all the answers

How does an increase in substrate concentration affect enzyme activity?

Increases reaction rate Signup and view all the answers

What are zymogens?

Inactive precursors of enzymes Signup and view all the answers

What indicates a positive Biuret test for the presence of proteins?

Blue violet solution Signup and view all the answers

What gas is produced when catalase breaks down hydrogen peroxide?

Oxygen Signup and view all the answers

In the Benzidine test, what color indicates a positive result for dissolved oxygen?

Blue green Signup and view all the answers

What is the primary function of amylase in the digestive system?

Hydrolyzes starch Signup and view all the answers

What structure surrounds the glomerulus in the kidney?

Bowman's capsule Signup and view all the answers

What prevents protein material from passing through the membrane of the glomerulus?

Size of proteins Signup and view all the answers

What component of blood primarily drives the diffusion of fluid through the walls of the glomerulus?

Blood pressure Signup and view all the answers

Which pH is human enzymes, such as salivary amylase, most active?

pH 7 Signup and view all the answers

Which statement accurately describes nucleic acids?

They are polymers of mononucleotides. Signup and view all the answers

What is the primary role of deoxyribonucleic acid (DNA)?

Transfer of genetic information. Signup and view all the answers

What components are nucleotides made of?

Base, sugar, and phosphate. Signup and view all the answers

Which type of nucleic acid is primarily located in the cytoplasm?

Ribonucleic acid (RNA). Signup and view all the answers

Which property of nucleic acids is true?

They are readily soluble in hot water. Signup and view all the answers

Which enzyme specifically catalyzes the hydrolysis of RNA?

RNAase. Signup and view all the answers

What percentage of total cell weight do nucleic acids typically represent?

Less than 1%. Signup and view all the answers

Which of the following correctly defines a nucleoprotein?

A class of proteins that contain nucleic acids. Signup and view all the answers

How does the concentration of solutes in urine affect its density?

Higher solute concentration increases density. Signup and view all the answers

What is the typical pH range of normal urine?

4.0 to 8.0 Signup and view all the answers

Which dietary component is most likely to increase the acidity of urine?

Meats Signup and view all the answers

What color variation in urine indicates a high concentration of solutes?

Dark yellow Signup and view all the answers

What can cause urine to become alkaline?

Diet high in vegetables and fruits Signup and view all the answers

What is the main organ responsible for excretion in the body?

Kidney Signup and view all the answers

Which of the following urine characteristics could indicate a bacterial infection?

Offensive odor Signup and view all the answers

What is the primary component of urine?

Water Signup and view all the answers

What substances are primarily reabsorbed in the kidneys?

Water, glucose, and amino acids Signup and view all the answers

What is the daily excretion range of urine volume?

600 to 2500 ml Signup and view all the answers

What condition describes decreased urine flow?

Oliguria Signup and view all the answers

In normal urine composition, what is the expected presence of glucose?

0 g/ml Signup and view all the answers

What effect do diuretics like caffeine and alcohol have on urine output?

They increase urine flow Signup and view all the answers

What characterizes the condition of anuria?

Total lack of urine excretion Signup and view all the answers

What is the typical density range of urine?

1.003 to 1.030 g/ml Signup and view all the answers

What might cause polyuria?

High fluid intake and certain diuretics Signup and view all the answers

What condition is characterized by a decrease in urine flow?

Oliguria Signup and view all the answers

What is the range of urine density?

1.002-1.020 Signup and view all the answers

Which test indicates the presence of albumin in urine?

Exton's test Signup and view all the answers

How do enzymes facilitate chemical reactions?

Decreasing activation energy Signup and view all the answers

What do you call substances that increase the activity of an enzyme?

Activators Signup and view all the answers

Which term describes the unique fit between an enzyme and its substrate?

Specificity Signup and view all the answers

What is the typical pH range for human enzymes?

7 Signup and view all the answers

What is a positive reaction for the Biuret test?

Blue-violet solution Signup and view all the answers

Study Notes

Nucleic Acids

Nucleic acids are high molecular weight polymers built from nucleotides.
Nucleotides consist of a phosphate group, a sugar (ribose or deoxyribose), and a nitrogenous base (purine or pyrimidine).
Two major types of nucleic acids are DNA and RNA.
DNA is primarily responsible for storing genetic information.
RNA plays a crucial role in protein synthesis.

Nucleic Acid Properties

Nucleic acids are large, acidic, chain-like molecules.
They are composed of phosphoric acid, sugar, and purine/pyrimidine bases.
Mononucleotides are the monomers of nucleic acids.
Nucleosides are composed of a base and a sugar.
Nucleic acids are insoluble in alcohol, slightly soluble in cold water, readily soluble in hot water and dilute alkalies.
They precipitate with HCL (hydrochloric acid) and excess acetic acid.
Enzymes facilitate nucleic acid hydrolysis.
Enzymes catalyze the hydrolysis of RNA specifically.
Nucleic acids possess high molecular weights, being among the largest known molecules.

Nucleic Acid Tests

Nucleoprotein Test: A positive result is a violet color, indicating the presence of proteins. The reagent is composed of hydrated copper sulfate, sodium hydroxide, and Rochelle salt.
Phosphate Test: A positive result is a yellow precipitate, indicating the presence of phosphates. The reagent consists of 10% HNO3 and 5% (NH4)2M004.
Ribose Test: A positive result is a green solution/precipitate, indicating the presence of ribose. The reagent is Bial's or Orcinol.
Purine Test: A positive result is a white precipitate, indicating the presence of purines. The reagent is 10% NH4OH and 5% AgNO3, forming a white precipitate.

DNA and RNA Differences

DNA stores and transmits genetic information.
RNA is involved in protein synthesis.
DNA contains deoxyribose sugar.
RNA contains ribose sugar.
DNA contains thymine.
RNA contains uracil.
DNA is typically a double helix.
RNA is typically a single-stranded structure.

DNA Structure

Watson and Crick described DNA's double helix structure.
Two polynucleotide chains are wrapped around a common axis to form a helix.
The chains are held together by hydrogen bonds between nitrogenous bases.
Each polynucleotide chain is composed of repeating nucleotides.
Each nucleotide comprises a pentose sugar, a phosphate group, and a nitrogenous base (thymine, adenine, guanine, cytosine).

Enzymes

Enzymes are biological catalysts that speed up chemical reactions.
They are proteins that are not altered during the reaction.
Enzymes function optimally at specific temperatures and pH values.
Enzyme activity can be affected by activators (increase activity) or inhibitors (interfere with activity).
Enzymes have an active site that binds to the substrate, forming an enzyme-substrate complex, creating product, and regenerating the enzyme.
Some enzymes consist of an apoenzyme(protein part) and a coenzyme (nonprotein part/often derived from vitamins).

Enzyme Tests

Catalase test: A positive test is evidenced by the production of oxygen when hydrogen peroxide is added to the enzyme extract. This oxygen supports combustion (glowing splint).
Amylase test: Amylase hydrolyzes starch, and a positive result is a noticeable change from a yellow/brown to colorless solution when performing the test. The absence of color indicates that the starch has been fully hydrolyzed to glucose.

Enzyme Specificity

Enzymes' high specificity arises from their protein nature.
Each enzyme's active site is tailored to bind only one, or a very limited set, of specific substrates.

Enzyme Naming Conventions

The newest naming system identifies substrates in enzyme names.
Names typically end in -ase.

Urine Formation and Properties

Blood is filtered through the kidneys by the renal arteries, forming glomeruli.
Filtered blood exits via renal veins.
Urine is formed in the nephrons, the functional units of the kidneys.
Waste and excess water are filtered out and then reabsorbed into the bloodstream.
Urine is then transported to the bladder.

Urine Composition

Urine is predominantly water (95%).
Urine contains dissolved waste products, including urea, salts, and electrolytes.
Urine composition is affected by dietary factors, fluid intake, and metabolic processes.

General Urine Characteristics & Testing

Normal urine: Straw- to amber-colored, clear, and has a slightly aromatic odor.
Urine pH: approximately 4.0-8.0.
Specific gravity: 1.003-1.030 g/mL. It measures the concentration of solutes in the urine.
Tests: various tests to identify specific compounds in urine (e.g., glucose, proteins, urea, uric acid).
Important clinical conditions often exhibit abnormal urine composition (e.g., diabetes).

Anuria (total lack of urine): Indicates severe kidney damage.
Oliguria (decreased urine output): Can result from various conditions.
Polyuria (excessive urine output): Can be due to excessive fluid intake or certain diseases.
Ketonuria (presence of ketone bodies in urine): Often associated with diabetes or starvation.
Positive urine tests for particular compounds can alert doctors to potentially serious underlying problems.

Additional Test Results for Chemical Components in Urine

A positive test for glucose in urine often indicates Diabetes Mellitus (DM). The reagent kit should have provided the instructions on how to use these kits properly. Specific kits should be used according to directions.
Albumin: Protein in urine can be indicative of abnormalities in the kidneys' filtering function. Various tests (e.g., Heller's test) can confirm the protein's presence.
Urea: a final product of protein metabolism in mammals, is the main end product of the urea cycle, and is then excreted in urine, so a urea test is important.
Uric Acid: A product of purine metabolism that may appear in the urine when certain metabolic conditions or diseases are present in the body.

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Description

This quiz explores the essential properties and functions of nucleic acids, including DNA and RNA. It covers the structure of nucleotides and their role in genetic information storage and protein synthesis. Test your knowledge about the unique characteristics that differentiate these vital biological molecules.