Libretexts. (2020, August 14). 3.4: The functions of carbohydrates in the body. Medicine LibreTexts. https://med.libretexts.org/Courses/American_Public_University/APUS%3A_An_Introduction_to_Nutrition_(Byerley)/APUS%3A_An_Introduction_to_Nutrition_1st_Edition/03%3A_Carbohydrates/3.04%3A_The_Functions_of_Carbohydrates_in_the_Body

They are essential food nutrients which we can find in fiber, starches and sugar, the human body uses them to form glucose (blood sugar) to give the body the energy it needs for proper function. A more complex group of carbohydrates can be found on fruits, whole grain foods and vegetables which are less likely to rise the sugar level on the blood.

-García, V. (2024). "Module 2. Principles of Cellular Biology"

-Cleveland Clinic. (February 20, 2025). “Carbohydrates”. https://my.clevelandclinic.org/health/articles/15416-carbohydrate

. Glucose is a monosaccharide and a primary energy source for the body. It’s classified as an aldose because it contains an aldehyde group, and it’s a hexose because it has six carbon atoms.

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APA

Universidad Autónoma de Puerto Alto (UAPA). (n.d.). Carbohidratos: Características químicas y clasificación. Recuperado de https://repositorio-uapa.cuaieed.unam.mx/repositorio/moodle/pluginfile.php/2564/mod_resource/content/4/UAPA-Carbohidratos-Caracteristicas-Quimicas-Clasificacion/index.html

• Starch: Used by plants to store energy

• Glycogen: Used by animals to store energy

• Cellulose: Used by plants to form walls around the cells

• Chitin: Used by some animals to form an external skeleton

Reference:

(2024). "1.10: Carbohydrates". LibreTexts Biology. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/01%3A_Introduction_to_Biology/1.10%3A_Carbohydrates

• Monosaccharides or simple sugars. (e.g., glucose, fructose, galactose)

• Disaccharides (e.g., sucrose, lactose, maltose)

Complex Carbohydrates:

• Oligosaccharides (e.g., raffinose, stachyose)

• Polysaccharides (e.g., starch, glycogen, cellulose)

Libretexts. (2024, March 25). 25.1: Classification of Carbohydrates. Chemistry LibreTexts. [https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/25%3A_Biomolecules-_Carbohydrates/25.01%3A_Classification_of_Carbohydrates](https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/25%3A_Biomolecules-_Carbohydrates/25.01%3A_Classification_of_Carbohydrates)

González-Torres, L., Téllez-Valencia, A., Sampedro, J. G., & Nájera, H. (2007). Las proteínas en la nutrición. Revista salud pública y nutrición, 8(2), 1-7.

Characteristics of Lipids:

• They are essential constituents of the diet because of their high energy value.

• Essential for the fat-soluble vitamins

• Occur naturally in living beings like plants, animals and microorganisms that form various components like cell membranes, hormones, and energy storage molecules.

• They exist in either liquid or non-crystalline solids at room temperature.

• In their solid state, lipids are colorless, odorless and tasteless.

References:

Sapkota. A. (2023, November 16). Lipids: Properties, Structure, Classification, Types, Functions . Microbe Notes. https://microbenotes.com/lipids/

Ajiboye.T. (2022, October 6). What are Lipids?. Very well health. What Are Lipids? Function, Benefits, and Risks

1. Acidic Proteins – Contain acidic amino acids and exist as anions. (Example: Blood group proteins)

2. Basic Proteins – Contain basic amino acids and exist as cations. (Example: Lysine, arginine-rich proteins)

2. Based on Constitution

2. Simple Proteins – Made up of only amino acids. (Example: Albumin, keratin)

3. Conjugated Proteins – Have a prosthetic group (a non-amino acid part). (Example: Hemoglobin with heme group, glycoproteins, lipoproteins)

3. Based on Shape

1.      Fibrous Proteins (Scleroproteins)

• Found in animals.

2. Insoluble in water.

3. Provide structural support. (Example: Collagen, keratin, elastin)

4. Globular Proteins

   • Soluble in water.

   • Play functional roles like enzymes, antibodies, and transport proteins. (Example: Hemoglobin, insulin, myoglobin) Proteins:

Structure, Classification, Functions with Videos and Examples. (2020, 26 noviembre). Toppr-guides. https://www.toppr.com/guides/biology/biomolecules/proteins/

Protein definitions. (s. f.). byjus.com. https://byjus.com/chemistry/protein-definition/#classification-of-proteins

Primary. - A specific linear sequence of a polypeptide chain. If a single amino acid position is changed, it forms a different protein

Secondary. - Two polypeptide chains bonded by a hydrogen molecule, known as an α-helix or β-pleated sheets

Tertiary. - Its the 3-dimensional shape acquired by the union of various secondary structures.

Quaternary. - A large complex of of polypeptide chains which combines all previous structures

Proteins: Structure and Functions. (s. f.). Byju´S. Recuperado 20 de febrero de 2025, de https://byjus.com/biology/proteins-structure-and-functions/

Quaternary Structure. (s. f.). Science Direct. Recuperado 20 de febrero de 2025, de https://www.sciencedirect.com/topics/chemistry/quaternary-structure

1. Help to maintain a proper pH: Proteins play a vital role when it comes to regulate the concentrations of acids and bases in body. Proteins such as hemoglobins bind acid, helping to maintain a balance.

2. Help to balance fluids: Proteins like albumin and globulin help to maintain water balance by attracting and retaining water. They also help to regulate blood flow.

3. Regulate immune cells production: proteins help form antibodies to fight infections and also send the necessary signals to "call" more antibodies.

4. Transporting Nutrients: Proteins transport a lot of substances throughout the bloodstream, it can be into cells, out of cells or within cells. They help balancing the nutrients in all the body.

Van De Walle Ms Rd, G. (2023, February 15). 9 important functions of protein in your body. Healthline. https://www.healthline.com/nutrition/functions-of-protein#TOC_TITLE_HDR_9

Both structures have a sugar phosphate backbone consisting of alternating sugars and phosphates.

produced by photosynthesis

store and produce energy.

Cannot be hydrolyzed (separated) into other sugars.

are named according to number of atoms (shape) and the orientation of the d-shape.

Processes:

When eaten, the body breaks down disaccharides, oligosaccharides and polysaccharides into monosaccharides so that they can be converted into glucose, the main carbohydrate functioning in our bodies. It is absorved into de bloodstream and further directed into the rest of the body.

Insulin and glucagon are the hormones that increase or decrease the glucose in the bloodstream by diverting it into the cells. These two hormones are produced by the pancreas in the islets of Langerhans 

Cleveland Clinic (2024, jan 17). Insulin. 2025, feb 20: https://my.clevelandclinic.org/health/body/22601-insulin 

Cleveland Clinic (2024, mar 8) Carbohydrates. 2025, feb 20: https://my.clevelandclinic.org/health/articles/15416-carbohydrates 

Cleveland Clinic (2025, jan 21) Glucagon. 2025, feb 20: https://my.clevelandclinic.org/health/articles/22283-glucagon 

Kumar Dhara, A., Kumar Nayak, A., Dilipkuman, P. (2021). Biological Macromolecules. Academic Press. 2025, feb 20: 

They are a four carbon ring structure, they are hydrophobic and they play essential roles in physiology. They are derived from the cholesterol which are the most abundant steroid in humans

1. Structural function: maintain fluidity and stability

2. Reduce redness and swelling (Inflammation)

3. Reduce the activity of the inmune system

4. Regulates metabolism, growth, reproduction

5. Bone health

6. Mood, cognition

Athletes and bodybuilders often use anabolic steroids to:

• Muscle growth

• Faster recovery

• Reduce fatigue

• Enhanced endurance

• Reduction in body fat

Libretexts. (2024, 23 noviembre). 3.6: Lipid molecules - steroids. Biology LibreTexts. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/General_Biology_(Boundless)/03%3A_Biological_Macromolecules/3.06%3A_Lipid_Molecules_-_Steroids

Website, N. (2024, 11 septiembre). Steroids. nhs.uk. https://www.nhs.uk/conditions/steroids/#:~:text=Steroids%20reduce%20redness%20and%20swelling,defence%20against%20illness%20and%20infection.

Cole, T. J., Short, K. L., & Hooper, S. B. (2019). The science of steroids. Seminars in Fetal & Neonatal Medicine, 24(3), 170–175. https://doi.org/10.1016/j.siny.2019.05.005

Mayo Clinic. (s.f.). Medicamentos para mejorar el rendimiento: Conoce los riesgos. Recuperado de https://www.mayoclinic.org/es/healthy-lifestyle/fitness/in-depth/performance-enhancing-drugs/art-20046134

Universidad Internacional de La Rioja. (2020). Uso de esteroides anabólicos: ventajas en el deporte y consecuencias para la salud. Recuperado de https://www.ui1.es/blog-ui1/uso-de-esteroides-anabolicos-ventajas-en-el-deporte-y-consecuencias-para-la-salud

HealthyChildren.org. (2024). Esteroides y potenciadores del rendimiento deportivo: por qué su uso es perjudicial. Recuperado de https://www.healthychildren.org/Spanish/ages-stages/teen/substance-abuse/Paginas/anabolic-steroids.aspx

Protein is required for the growth and maintenance of tissues. Your body’s protein needs are dependent upon your health and activity level.

Causes Biochemical Reactions

Enzymes are proteins that allow key chemical reactions to take place within your body.

Acts as a Messenger

Amino acid chains of various lengths form protein and peptides, which make up several of your body’s hormones and transmit information between your cells, tissues and organs.

Provides Structure

A class of proteins known as fibrous proteins provide various parts of your body with structure, strength and elasticity

Reference:

Van de Walle Ms Rd, G. (2023, 15 febrero). 9 Important Functions of Protein in Your Body. Healthline. https://www.healthline.com/nutrition/functions-of-protein#TOC_TITLE_HDR_5

They provide protection, principally at the plants which cover the leaves of plants. In humans they principally know the waxes as earwax that protects the skin on the ear canal. In animals waxes protect feathers, fur or exoskeletons from moisture or other environmental factors.

Creative Proteomics. (2021). Wax in Biochemistry: Properties, Functions, and Contrasts with Triglycerides - Creative Proteomics. Creative-Proteomics.com. https://www.creative-proteomics.com/resource/waxes-biochemistry-functions-contrasts.htm#:~:text=Waxes%3A%20Waxes%20are%20protective%20compounds,moisture%20and%20other%20environmental%20factors.

Thompson, T. E. (1999, July 26). Lipid | Definition, Structure, Examples, Functions, Types, & Facts. Encyclopedia Britannica. https://www.britannica.com/science/lipid/Waxes

Phospholipids are composed by 2 fatty acids, two alcohols and a phosphate group (Encyclopedia of Food Chemistry, 2019). It belongs to the complex lipids.

They are one of the main components of cell membranes, by constituting a lipid bilayer. The nature of the molecule allows for it, as one end is hydrophilic, and the other one is hydrophobic. 

Their function is to give structure to cell membranes, and given its hydrophilic and hydrophobic nature, it acts like a policeman that regulates the entry and exit of molecules, activating signaling substances and enzymes. Phospholipids give different lipid profiles in a way that cell types are differentiable.

Resources consulted

Creative Proteomics. (n.d.). Phospholipids: Structure, Functions, and Applications. https://www.creative-proteomics.com/resource/phospholipids-structure-functions-and-applications.htm#:~:text=Functions%20of%20Phospholipids&text=This%20arrangement%20provides%20structural%20integrity,membrane%20dynamics%20and%20cell%20movements.

The Editors of Encyclopaedia Britannica (2025). phospholipid. Encyclopedia Britannica. https://www.britannica.com/science/phospholipid

• Fructose can be found in fruits

• Glucose results from the digestion of other carbohydrates

When two monosaccharides bind together, they form a disaccharide. They provide the major source of energy to living cells.

• Table sugar: Formed when a fructose and a glucose monosaccharide bind together

Reference:

(2024). "1.10: Carbohydrates". LibreTexts Biology. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/01%3A_Introduction_to_Biology/1.10%3A_Carbohydrates

• Desoxyribonucleic Acid (DNA): All living species have DNA. it's a nucleic acid molecule with two strands. DNA is mostly present in the chromosomes of plant and animal cells’ nuclei. It’s found in mitochondria and chloroplasts as well. It’s found in circular and supercoiled chromosomes in prokaryotes’ cytoplasm and in eukaryotes with proteins such as histones and protamine. DNA is a polymer made of monomeric units called nucleotides. A nucleotide comprises a 5-carbon sugar, deoxyribose, a nitrogenous base and one or more phosphate groups. The building blocks for DNA synthesis contain three phosphate groups, two are lost during this process, so the DNA strand contains one phosphate group per nucleotide.

• Ribonucleic Acids (RNA): RNA is a single-stranded nucleic acid found in a few viruses, such as retroviruses and viroids, as genetic material. The majority of RNA is located in the cytoplasm of cells. The nucleolus and nucleoplasm both contain it. Except for a few viruses that have double-stranded RNA, it is generally found as a single-stranded polynucleotide. The largest and most abundant RNA is rRNA. Between 60 and 80 percent of the total RNA in cells is rRNA, and it has a molecular weight of several million atomic mass units. The rRNA combines with proteins to form ribosomes, which are the sites for the synthesis of new protein molecules.

They are built based on a series of identical building blocks called nucleotides. Which consist of a nitrogen attached to a pentose (five carbon) sugar, which is in turn attached to a phosphate group. Each nucleic acid contains four or five possible nitrogen-containing bases such as: Adenine (A), Guanine (G), Cytosine (C), Thymine (T), and Uracil (U).

U.S. National Library of Medicine. (2019). The role of nucleic acids in cellular processes. PubMed. Retrieved from https://pubmed.ncbi.nlm.nih.gov/31652314/

Yale University. (n.d.). Nucleic acids: Catalysis, recognition, and role in biosynthesis. Retrieved from https://chemicalbiology.yale.edu/faculty/nucleic-acids-catalysis-recognition-and-role-biosynthesis#:~:text=While%20nucleic%20acids%20often%20serve,%2C%20transcriptional%20control%2C%20and%20translation.

GeeksforGeeks. (2021, 22 diciembre). Nucleic acids Definition, Structure, Properties, Types. GeeksforGeeks. https://www.geeksforgeeks.org/nucleic-acids-definition-structure-properties-types/

Energy reserve: Lipids are a source of energy that is stored in the body in the form of fat. They are a set of organic compounds found in adipose tissue and muscle cells. They contribute 9kcal per gram

Transport: The transport of lipids from the intestine to the site of use or to adipose tissue (storage) is carried out by the emulsification of lipids by bile acids and proteolipids, associations of specific proteins with triacylglycerides, cholesterol, phospholipids, etc.

Thermal protection from different temperatures

They are the basic components of larger lipid compounds

They serve as substrates for bioactive molecules

They are classified into 2: saturated and unsaturated

Saturated fatty acids are organic acids with a linear chain without double bonds in their hydrocarbon chain. We can find them in animal fats and vegetable oils.

Unsaturated fatty acids are acids that contain at least one double bond between their carbon atoms. They are more reactive than saturated fatty acids.

Function: 

Fatty acids have many functions in the body, including providing energy, building cell membranes, and signaling. 

Fatty acid. (2025, febrero 10). En Encyclopaedia Britannica. https://www.britannica.com/science/fatty-acid

Saturated fatty acid. (s.f.). ScienceDirect. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/saturated-fatty-acid

Unsaturated fatty acid. (s.f.). ScienceDirect. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/unsaturated-fatty-acid

The most common type of fat in the body. They come from foods, especially butter, oils, and other fats you eat. Triglycerides also come from extra calories. These are calories are necessary to eat but our body doesn't need right away.

They are made by a molecule of glicerol alcohol and 3 carbons

Energy reserve: Lipids are a source of energy that is stored in the body in the form of fat. They are a set of organic compounds found in adipose tissue and muscle cells. They contribute 9kcal per gram

Transport: The transport of lipids from the intestine to the site of use or to adipose tissue (storage) is carried out by the emulsification of lipids by bile acids and proteolipids, associations of specific proteins with triacylglycerides, cholesterol, phospholipids, etc.

Thermal protection from different temperatures

Nucleotide 

They consist in a nitrogenous base and a five carbon sugar (pentose) which is attached to a phosphate group.

Nucleoside

Nucleosides are similar to nucleotides in that they consist of a nitrogenous base and a five-carbon sugar. However, they do not have a phosphate group attached to the sugar.