Carbohydrates and Nucleic Acids Biochemistry

Flashcards covering carbohydrate classification, monosaccharides, disaccharides, polysaccharides, nucleic acid structure, central dogma, genetic mutations/disorders, and metabolic pathways.

Carbohydrates

The most abundant class of bioorganic molecules in nature.

Monosaccharide

A carbohydrate containing a single polyhydroxy aldehyde or polyhydroxy ketone unit that cannot be broken down into simpler units.

Disaccharide

A carbohydrate containing two monosaccharide units covalently bonded to each other; hydrolysis produces two monosaccharide units.

Oligosaccharide

A carbohydrate that produces several (typically 3-10) monosaccharide molecules upon complete hydrolysis.

Polysaccharide

A polymeric carbohydrate containing many (hundreds to thousands) monosaccharide units covalently bonded to each other.

Aldose

A monosaccharide that contains an aldehyde group.

Ketose

A monosaccharide that contains a ketone group.

D-Glyceraldehyde and Dihydroxyacetone

The simplest monosaccharides and important intermediates in the process of glycolysis.

D-Glucose

The most abundant monosaccharide in nature, also known as grape sugar, dextrose, or blood sugar; utilized as a primary source of energy.

Normal Blood Glucose Concentration

A value ranging from $70 - 100\,mg/dL$ in human blood.

D-Galactose

Also known as brain sugar, it is synthesized from glucose in the mammary glands and serves as a chemical marker for blood types.

D-Fructose

The most important ketohexose, also known as levulose or fruit sugar; it is the sweetest-tasting of all sugars.

D-Ribose

A pentose that is a known component of RNAs and energy-rich compounds such as ATPs.

Glycosidic bond

The covalent bond that joins two monosaccharides together to form a disaccharide.

Maltose

Commonly known as malt sugar, it is composed of glucose units and is produced when starch breaks down.

Cellobiose

A disaccharide containing two D-glucose units that cannot be digested by humans or fermented by yeast.

Lactose

Known as milk sugar, it is the major sugar found in milk and a common ingredient in infant formulas.

Sucrose

Common table sugar and the most abundant of all disaccharides; produced commercially from sugarcane and sugar beets.

Starch

A storage homopolysaccharide in plants containing glucose units; consists of amylose and amylopectin.

Amylose

A straight-chain glucose polymer that accounts for $15 - 20\%$ of starch.

Amylopectin

A branched glucose polymer that accounts for $80 - 85\%$ of starch.

Glycogen

Known as animal starch, it is the form of stored glucose in humans and animals, located primarily in liver and muscle cells.

Cellulose

The most abundant naturally occurring polysaccharide; it is a structural component of cell walls and is fibrous and water-insoluble.

Chitin

A structural polysaccharide similar to cellulose that provides rigidity to the exoskeletons of arthropods and fungal cell walls.

Stereoisomers

Isomers that have the same molecular and structural formulas but differ in the orientation of atoms in space.

Enantiomers

Stereoisomers that are nonsuperimposable mirror images of each other; often referred to as D and L forms.

Diastereomers

Stereoisomers that are not mirror images of each other.

Nucleotide

A three-subunit molecule consisting of a pentose sugar bonded to a phosphate group and a nitrogen-containing heterocyclic base.

Pyrimidine

A monocyclic nitrogenous base with a six-membered ring; derivatives include Thymine, Cytosine, and Uracil.

Purine

A bicyclic nitrogenous base with fused five- and six-membered rings; derivatives include Adenine and Guanine.

Primary Nucleic Acid Structure

The nucleotide sequence in which nucleotides are linked together in a nucleic acid.

B-form DNA

The most common structural form of DNA found under physiologic conditions.

Histone

The primary protein component of chromatin.

Nucleosome

A nucleoprotein formed when DNA wraps around a histone.

Central Dogma

The physiological framework involving replication (DNA to DNA), transcription (DNA to RNA), and translation (RNA to protein).

DNA Helicase

The enzyme responsible for unwinding the DNA double helix during replication.

Topoisomerases

Enzymes that unwind DNA supercoils.

DNA Polymerase

The enzyme that copies DNA templates, working only in the $5' - 3'$ direction.

DNA Ligase

The enzyme that joins Okazaki fragments of the lagging strand together.

Okazaki Fragments

Short sections of DNA synthesized on the lagging strand which grows in the $3' - 5'$ direction.

rRNA (Ribosomal RNA)

RNA components of ribosomes that carry out the synthesis of proteins.

mRNA (Messenger RNA)

Intermediary RNA that carries genetic information from genes to a ribosome.

tRNA (Transfer RNA)

Adapter molecules that translate the mRNA sequence into a specific sequence of amino acids; smallest RNA with $75 - 90$ nucleotides.

Codon

A three-letter genetic "word" that contains information for protein synthesis; 3 of these are stop signals (UAG, UAA, UGA).

Start Codon

The initial sequence for protein synthesis, AUG, which codes for methionine.

A site (Aminoacyl site)

The site in a ribosome that holds the tRNA attached to the next amino acid in the sequence.

P site (Peptidyl site)

The site in a ribosome that holds the tRNA containing the growing protein chain.

E site (Exit site)

The position occupied by a tRNA after delivering its amino acid and just before exiting the ribosome.

Silent Mutation

A mutation where a base change occurs but the resulting protein still codes for the same amino acid.

Missense Mutation

A mutation where a change produces a different codon, resulting in a different amino acid.

Nonsense Mutation

A mutation where a base change produces a stop codon, prematurely ending protein synthesis.

Autosomal Recessive

A pattern of inheritance where both parents must carry the trait for it to be passed to the child.

Autosomal Dominant

A pattern of inheritance where only one parent needs an altered gene to pass the trait to the child.

Phenylketonuria (PKU)

A rare genetic condition caused by a mutation in the Phenylalanine Hydroxylase gene, leading to phenylalanine build-up and a musty odor.

Sickle-cell Anemia

An inherited blood disorder involving flawed hemoglobin that affects RBC shape and interferes with oxygen delivery.

Cystic Fibrosis

A genetic disorder affecting the lungs and digestive system, characterized by thick, sticky mucus and very salty sweat.

Marfan Syndrome

An autosomal dominant disorder of connective tissue resulting in long digits, optical defects, and cardiovascular issues.

Steinberg Sign

A clinical test for Marfan syndrome where the thumb tip extends beyond the palm when folded into a fist.

Down Syndrome

A genetic condition, most commonly Trisomy 21, where an individual has an extra chromosome 21.

XYY Syndrome

Also known as Supermale syndrome, a rare chromosomal disorder where a male has 47 chromosomes.

CIPA (Congenital Insensitivity to Pain with Anhidrosis)

An autosomal recessive disorder characterized by the inability to feel pain or temperature and thick, leathery skin on the palms.

Glycolysis

The metabolic pathway that converts glucose into two molecules of pyruvate.

Lactate Fermentation

The enzymatic anaerobic reduction of pyruvate to lactate; its sole purpose is to convert NADH to NAD+.

Ethanol Fermentation

The enzymatic anaerobic conversion of pyruvate to Ethanol and Carbon Dioxide using yeast.

Glycogenesis

The metabolic pathway by which glycogen is synthesized from glucose 6-phosphate.

Glycogenolysis

The metabolic pathway by which glucose 6-phosphate is produced from glycogen.

Gluconeogenesis

The metabolic pathway by which glucose is synthesized from non-carbohydrate materials such as pyruvate.

Cori Cycle

A cyclic process where glucose is converted to lactate in muscle, reconverted to glucose in the liver, and returned to the muscle.

Pentose Phosphate Pathway

A pathway where glucose is used to produce NADPH and ribose 5-phosphate.

Beta-Oxidation

A repetitive series of four reactions that degrades acyl CoA to acetyl CoA by removing two carbon atoms at a time.

Ketogenesis

The metabolic pathway by which ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone) are synthesized from acetyl CoA in liver mitochondria.