Biomolecules and Cell Biology Practice Flashcards

Flashcards testing knowledge on biomolecules (carbohydrates, proteins, lipids, nucleic acids), inorganic compounds, and tissue analysis.

What percentage of total energy in the human body is provided by the breakdown of carbohydrates?

About $60\%$ of total energy is provided by carbohydrate breakdown.

What is the antiketogenic role of glucose?

Glucose prevents the incomplete oxidation of fats and the formation of ketonic bodies in the blood.

What are the basic physical and chemical characteristics of amino acids, and how many are found in nature?

Amino acids are colourless, crystalline solids that are soluble in water and insoluble in organic solvents. They contain at least one acidic carboxylic group ($-\text{COOH}$) and one basic amino group ($-\text{NH}_2$). There are $20$ amino acids present in nature.

What is the simplest amino acid?

Glycine.

How is a peptide bond formed between amino acids?

A peptide bond ($-\text{CO-NH}-$) is formed when the $\alpha$-carboxyl group ($-\text{COOH}$) of one amino acid joins with the $\alpha$-amino group ($-\text{NH}_2$) of another amino acid, eliminating a molecule of water.

What are the physiological functions of $\text{Na}^+$, $\text{Ca}^{++}$, and $\text{Mg}^{++}$ in the body?

$\text{Na}^+$ is involved in nerve impulse transmission, $\text{Ca}^{++}$ functions in muscle contraction and blood clotting, and $\text{Mg}^{++}$ acts as a co-factor.

Which inorganic ions function as buffers in the body?

$\text{PO}_4^{3-}$, $\text{SO}_4^{2-}$, and $\text{HCO}_3^-$ act as buffers.

What are the exact elemental abundance percentages of oxygen in the Earth's crust and the human body, as well as silicon in the Earth's crust?

Oxygen is the most abundant element in both the human body ($65.0\%$) and the Earth's crust ($46.6\%$). Silicon is the second most abundant element in the Earth's crust at $27.7\%$.

How are monosaccharides categorized by carbon number ($n$) using the general formula $(\text{CH}_2\text{O})_n$?

$n=3$ is a triose (e.g., glyceraldehyde); $n=4$ is a tetrose (e.g., erythrose); $n=5$ is a pentose (e.g., ribose); and $n=6$ is a hexose (e.g., glucose, fructose).

What are the monomer basic units, polymers, and linkage bonds for the four major biomolecules?

Carbohydrates: Monosaccharide $\rightarrow$ Polysaccharide (Glycosidic bond); Proteins: Amino acid $\rightarrow$ Polypeptide/Protein (Peptide bond); Lipids: Fatty acids and glycerol $\rightarrow$ Triglyceride (Ester bond; lipids are not true polymers); Nucleic acids: Nucleotide $\rightarrow$ DNA/RNA (Phosphodiester bond).

What monosaccharides make up the disaccharides sucrose, maltose, and lactose?

Sucrose = Glucose + Fructose; Maltose = Glucose + Glucose; Lactose = Glucose + Galactose.

Which sugars are classified as reducing sugars, and which is classified as a non-reducing sugar?

Reducing sugars include glucose, fructose, maltose, and lactose. Sucrose is a non-reducing sugar.

How do starch and glycogen differ in terms of origin, structure, and storage location?

Starch is a plant storage carbohydrate composed of $\alpha$-glucose formatted as linear amylose and branched amylopectin. Glycogen is a highly branched animal reserve carbohydrate made of $\alpha$-glucose, stored in the liver and skeletal muscles.

What are the structural units and functions of cellulose and chitin?

Cellulose is made of $\beta$-glucose and forms plant cell walls (humans lack cellulase to digest it). Chitin is composed of N-acetylglucosamine units and provides structural support in fungal cell walls and arthropod exoskeletons.

What are the stages involved in ash analysis of living tissue?

Living wet tissue loses water to yield dry tissue weight. When dry tissue is burned, organic compounds are consumed, leaving behind inorganic ash.