Ch. 5 Bio

Key vocabulary terms from the lecture notes on the molecules of life, their structures, functions, and basic metabolism.

Carbohydrates

One of the four major classes of biological molecules; includes sugars and polysaccharides (e.g., starch, glycogen, cellulose) used for energy and structural roles.

Lipids

Hydrophobic molecules that do not form polymers; include fats, phospholipids, and steroids; primarily hydrocarbons and glycerol/fatty acids.

Proteins

Macromolecules made of amino acids; perform diverse functions such as enzymes, transport, structure, and signaling.

Nucleic acids

DNA and RNA; polymers of nucleotides that store, transmit, and express genetic information.

Monomer

A single building block that can join to form a polymer.

Polymer

A large molecule composed of many repeated monomer units.

Dehydration reaction

A chemical reaction that forms a bond between monomers with the loss of a water molecule.

Hydrolysis

A chemical reaction that breaks a bond by adding a water molecule.

Glycosidic bond

Covalent bond joining two sugar units in a disaccharide or polysaccharide.

Monosaccharide

The simplest sugar; basic unit of carbohydrates (e.g., glucose, fructose, galactose).

Disaccharide

Two monosaccharides linked by a glycosidic bond are formed from a dehydration reaction (e.g., maltose, sucrose, lactose).

Polysaccharide

Polymers of sugars; used for storage (starch, glycogen) or structure (cellulose, chitin).

Starch

Plant storage polysaccharide consisting of glucose units (amylose and amylopectin).

Amylose

simplest form of starch with little to no branching

Amylopectin

Slightly branched starch

Glycogen

Animal storage polysaccharide; highly branched glucose polymer stored mainly in liver and muscle cells.

Cellulose

Structural polysaccharide in plant cell walls; made of α- and β-glucose units linked.

Where does the alpha and Beta in glucose go below or above the structure?

alpha- below, and beta above

Aldose

Aldehyde sugar goes at the END of a structure with a carbonyl group

Ketose

Ketone sugar is found WITHIN a linear structure with a carbonyl group

Three carbon sugars are called ____ and what are the two and which is an aldose and ketose?

Trioses: Glyceraldehyde and Dihydroxyacetone; Glyceraldehyde is an aldose, while Dihydroxyacetone is a ketose.

Five carbon sugars are called _____ and what are the two and which is aldose and ketose?

Pentoses: Ribose and Ribulose; Ribose is an aldose, while Ribulose is a ketose.

Six carbon sugars are called _____ and what are the three and which are aldose and ketose?

Hexoses: Glucose, Galactose, and Fructose; Glucose and Galactose are aldoses, while Fructose is a ketose.

What’s the difference between Glucose and Galactose?

Glucose is formatted H—C—OH, and Galactose is formatted HO—-C—H. Even this small change can be an impact

What is the most common 5-carbon monosaccharide?

Ribose (backbone for RNA & DNA)

What is the most common 6-carbon monosaccharide?

glucose

Chitin

Structural polysaccharide in arthropod exoskeletons and fungal cell walls; polymer of N-acetylglucosamine.

Out of the four large biological molecules, what doesn’t form a polymer?

Lipids

Lipids

don’t form polymers, hydrophobic (since made of hydrocarbon) no affinity for water

3 most important biological lipids:

fats, phospholipids, and sterioids

Fat (Triglyceride)

Glycerol backbone with three fatty acids via ester linkages; main form of stored energy in animals.

Fatty acids

Hydrocarbon chains with a carboxyl group; vary in length and degree of saturation (sat vs. unsat).

Saturated fatty acids

Fatty acids with no double bonds; maximum hydrogen; typically solid at room temperature.

Unsaturated fatty acids

Fatty acids with one or more double bonds; kinked, typically liquid at room temperature.

Trans fats

Hydrogenated unsaturated fats with trans double bonds; often associated with negative health effects; unable to be digested

Hydrogenation

process of adding hydrogen, converting unsaturated fats to saturated

Dehydrogenation

taking out the hydrogens and forming double bonds

Phospholipid

Glycerol with two fatty acids and a phosphate head; amphipathic; forms lipid bilayers in membranes.

What is the main item that makes membranes?

phospholipids are the main components that make up cell membranes

Describe the phospholipid bilayer:

The heads are hydrophilic, polar, and charged, meaning they love water and are facing the water. However, the tails are hydrophobic, nonpolar, and uncharged, meaning they repel water and face inward, away from the water. These bilayers are spontaneously formed

Steroid

Lipids with a carbon skeleton and four fused carbon rings; include cholesterol and steroid hormones.

Cholesterol

A cholesterol steroid essential in animal membranes; it modulates membrane fluidity. directly proportional 

What functions can proteins be classified by?

enzyme, defense problems, storage proteins, transport proteins, structural proteins, motor proteins, hormonal proteins, and receptor proteins

Amino acid

Building block of proteins; contains amino group, carboxyl group, and a variable R group.

R group

The side chain of an amino acid that determines its properties (polarity, charge, size).

Peptide bond

Covalent bond linking amino acids in a polypeptide.

Polypeptides

Long chains of amino acids linked by peptide bonds form proteins.

What do peptides and proteins describe about a chain when replaced with polypeptides?

peptides are shorter chains of amino acids and proteins are longer chains of amino acids

Protein

Macromolecule formed by one or more polypeptides; functions include enzymes, transport, and structure.

3 most common ways proteins are depicted:

space-filling, ribbon model, and wire-frame model 

Primary structure

Linear sequence of amino acids in a protein linking from the amino end to the carboxyl end always

Secondary structure

Local folding into α-helixes and β-pleated sheets is held by hydrogen bonds along the backbone. Stabilized by hydrogen bonds holding the two secondary structures together 

random coli

everything that doesn’t fold up into a specific sheet

Tertiary structure

How alpha helices and beta sheets come together- Overall three-dimensional shape of a single polypeptide; stabilized by non-covalent interactions and disulfide bonds.

Disulfide bridges

strong covalent bonds that may reinforce protein structure

Quaternary structure

Association of two or more polypeptide chains/subunits into a functional protein.

Ex: collagen makes triple helices, but originally three separate chains of amino acids that involve non-covalent reactions

Nucleoside

Nitrogenous base attached to a sugar (nucleotide without the phosphate group).

Nucleotide (3 things it consists of)

Monomers of polynucleotides consiting of a nitrogenous base, pentose sugar, and phosphate group; has a phosphate group removed

Polynucleotide

A polymer made up of nucleotides linked by phosphodiester bonds, forming the structural basis of nucleic acids like DNA and RNA.

DNA

Deoxyribonucleic acid; double-stranded helix; stores genetic information; sugar is deoxyribose; backbones run in opposite direction from eachother (anti-parallel)

RNA

Ribonucleic acid; usually single-stranded; sugar is ribose; base uracil replaces thymine; shape differs

mRNA

messenger RNA carrying genetic code from DNA to ribosomes

tRNA

transfer RNA that brings amino acids to ribosomes during protein synthesis

rRNA

Ribosomal RNA that makes up the core of ribosomes and aids in protein synthesis.

Central Dogma

The process by which genetic information flows from DNA to RNA to proteins, outlining the steps of transcription and translation.

Protein folding spontaneous vs. chaperonins

The process by which proteins assume their functional three-dimensional shapes; spontaneous folding occurs without assistance, while chaperonins are protein complexes that assist in proper folding.

X-ray crystallography technique

used to determine the three-dimensional structure of molecules, particularly proteins and DNA, by analyzing the patterns produced when X-rays are diffracted through a crystallized sample.

Base pairing

A pairs with T (DNA) or U (RNA); G pairs with C; stabilized by hydrogen bonds.

double helix

The double helix is the structure of DNA, consisting of two intertwined strands that are held together by base pairing and twisted in a spiral shape.

RNA structures

single-stranded molecules that can fold into various shapes, allowing for diverse functions, including coding, decoding, regulation, and expression of genes.