Biology Ch 3.6-3.12

Triglyceride series of three ester linkages are

monoglyceride, diglyceride, and triglyceride (reference slide 47 to see the different molecules)

Polyunsaturated fatty acids have how many of what kind of bonds?

more than one double bond

Transport proteins

move substances between cells and across cell membranes

Lipids are soluble in __ solvents, and ____ in water

nonpolar; insoluble

Monounsaturated fatty acids have how many of what kind of bonds?

one double bond

What joins amino acids?

peptide bonds

Nucleotides are joined by

phosphodiester linkages, a type of covalent bond

What contain molecules similar to cholesterol?

plant cell membranes

Tertiary structure of a polypeptide chain

the overall shape assumed by each individual polypeptide chain; determined by factors involving interactions among R groups of the same polypeptide chain, including: - weak interactions (hydrogen bonds, ionic bonds, and hydrophobic interactions) - strong covalent bonds (disulfide bridges between sulfhydryl groups of two cysteines)

Primary structure of a polypeptide chain

the sequence of amino acids joined by peptide bonds; always represented in a simple, linear, "beads-on-a-string" form

Why are triacylglycerols important?

they are a form of reserve fuel/energy storage

What are carotenoids?

they are the orange and yellow pigments in plants that are insoluble in water (they have an oily consistency); they play a role in photosynthesis; consist of 5-carbon hydrocarbon monomers (AKA isoprene units)

Describe saturated fatty acids

they contain the max possible number of hydrogen atoms; found in animal fat and solid vegetable shortening (a kind of fat used in cooking)

Triglycerides (triacylglycerols) are formed by a series of

three covalent ester linkages

The most abundant lipids in living organisms are

triacylglycerols (or fats)

What determines a protein's conformation?

the amino acid sequence

When fatty acids are artificially hydrogenated...

the double bonds can become rearranged, resulting in a trans configuration

What do molecular chaperones do?

- Make the folding process more efficient - Prevent partially folded proteins from becoming inappropriately aggregated

An enzyme's shape allows it to

catalyze a specific chemical reaction

Enzymes

catalyze specific chemical reactions

What determines what a cell looks like and how it functions?

characteristic forms, distributions, and amounts of protein ex: proteins in muscle help it contract

What is a dipeptide?

2 amino acids joined by a peptide bond

Secondary structure of a polypeptide chain

2 common types of secondary structure (both may occur in the same chain): 1) alpha-helix (helical coil) 2) beta-pleated sheet

DNA contains 4 nitrogenous bases

2 double ring purines: adenine (A) and guanine (G) 2 single ring pyrimidines: cytosine (C) and thymine (T)

How many different amino acids are there that form proteins?

20

Quaternary structure of a polypeptide

3-D structure resulting from two or more polypeptide chains interacting in specific ways to form a biologically active molecule ex: hemoglobin, a globular protein consisting of 4 polypeptide chains; collagen, a fibrous protein with 3 polypeptide chains

Nucleotides important in energy transfers

Adenosine triphosphate (ATP)- major importance as the primary energy currency of all cells; composed of adenine, ribose, and three phosphates Guanosine triphosphate (GTP)- nucleotide that contains the base guanine; can transfer energy by transferring a phosphate group and also has a role in cell signaling Nicotinamide adenine dinucleotide (NAD+ or NADH)- Primary in oxidation and reduction reactions in cells; can exist in an oxidized form (NAD+) that is converted to a reduced form (NADH) when it accepts electrons

Why are steroids important?

cholesterol and some hormones

Deoxyribonucleic acid (DNA) vs Ribonucleic acid (RNA)

DNA: makes up hereditary material of the cell (genes) and contains instructions for making proteins and RNA RNA: participates in the process in which amino acids are linked to form polypeptides

Examples of steroids:

cholesterol, bile salts, reproductive hormones, cortisol, and other hormones

A protein hormone's shape allows it to

combine with receptors on its target cell

Why are phospholipids important?

components of membranes

Regulatory proteins

control the activities of proteins, genes, cells, and tissues

Ester linkage

covalent linkage formed by the reaction of a carboxyl group and a hydroxyl group, with the removal of the equivalent of a water molecule; the linkage includes an oxygen atom bonded to a carbonyl group; linkage in triacylglycerols

Protective proteins

defend against foreign invaders

Biological activity can be disrupted by

a change in amino acid sequence that results in protein conformation changes ex: sickle cell anemia; alteration of the hemoglobin affects the red blood cells, changing them to the crescent or sickle shapes that characterize this disease

Amino acids combine by

a condensation reaction between the carboxyl carbon and the amino nitrogen of another amino acid

What is a peptide bond?

a covalent carbon to nitrogen bond between two linking amino acids

What is a polypeptide?

a long chain of amino acids

What is a fatty acid?

a long, unbranched hydrocarbon chain with a carboxyl group (-COOH) at one end

Nucleotide

a monomer that is made up of three parts: 1) a 5-carbon sugar, either deoxyribose (in DNA) or ribose (in RNA) 2) one or more phosphate groups, which make the molecule acidic 3) a nitrogenous base, a ring compound that contains nitrogen

Alpha-helix

a region where a polypeptide chain forms a uniform helical coil; they are determined and maintained by the formation of hydrogen bonds between the hydrogen (amino group) and oxygen (carboxyl group); they are the basic structural unit of fibrous, elastic proteins (that make up wool hair, skin, and nails)

What is a nitrogenous base?

a ring compound that contains nitrogen; DNA double chain; may be either a double-ring purine or a single-ring pyrimidine

What is denaturation?

a structural change in a protein that results in a loss of its biological properties, occurs when a protein is heated, subjected to significant pH change, or treated with certain chemicals; structure becomes disordered and peptide chains unfold ex: frying an egg

What is glycerol?

a three-carbon alcohol with three hydroxyl groups

Sickle cell anemia

substitution of hydrophilic glutamic acid for hydrophobic valine; a single amino acid substitution

An amino acid with a carboxyl side chain is

acidic

What are essential amino acids?

amino acids that must be provided in the diet because the body cannot make it in sufficient quantities to meet nutritional needs; differs among species

What are phospholipids?

amphipathic lipids, with one hydrophilic head and one hydrophobic tail; head consists of glycerol molecule, phosphate group, and organic group; tail consists of 2 fatty acids

Amino acids consist of

an amino group (NH2), a carboxyl group (COOH), a side chain, and a hydrogen, all bonded to the alpha carbon each amino acid has a different "side chain" (="R group")

Define lipids

any of a group of organic compounds that are insoluble in water but soluble in nonpolar solvents

During digestion, triglycerides...

are hydrolyzed to produce fatty acids and glycerol

An amino acid side chain that accepts a hydrogen ion is

basic

Structure of a protein determines

biological activity; many proteins consist of two or more globular domains and each domain may have a different function (a domain is a stable structure that has a specific function)

What do lipid molecules mainly consist of?

carbon and hydrogen, with few oxygen-containing functional groups

A steroid consists of

carbon atoms arranged in four attached rings

Amino acids in solution at neutral pH are mainly

dipolar ions, meaning the posses a positive charge at one end and a negative charge at the opposite end; each carboxyl (COOH) donates a proton and becomes COO- and each amino group accepts a proton and becomes NH3+

In vivo (in the cell), proteins

do not always fold spontaneously into their correct shape; molecular chaperones mediate the folding of other protein molecules

Fats containing a high proportion of monounsaturated or polyunsaturated fatty acids tend to be liquid at room temperature because

each double bond produces a bend in the hydrocarbon chain that prevents it from aligning closely with an adjacent chain. This limits the number of van der Waals interactions between chains, permitting freer molecular motion.

Why are fats important?

energy storage

Biologically important groups of lipids include:

fats, phospholipids, carotenoids, steroids, waxes

Why are carotenoids important?

for pigments

Motile proteins

generate movement in cells and tissues

What do triacylglycerols consist of?

glycerol joined to three fatty acids

Misfolded proteins may play an important role in

human diseases, such as Alzheimer's and Huntington's disease

What are trans fats?

hydrogenated or partially hydrogenated cooking oils; unsaturated fatty acids converted to saturated fatty acids to make fat more solid at room temperature

Why are waxes important?

in plants- for cuticles in animals- beeswax both allow for waterproofing

Describe unsaturated fatty acids

include one or more pairs of carbon atoms joined by a double bond; tend to be liquid at room temperature (the same temperature fatty acids are solid at)

Most nucleic acids are

macromolecular polymers of nucleotides

Define proteins

macromolecules composed of amino acids; most versatile cell components

Nucleic acids

macromolecules that transmit hereditary information and determine what proteins a cell manufactures Two classes of nucleic acids are found in cells: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

β-pleated sheet

takes place between the backbones of different regions of a polypeptide chain that has turned back on itself; formation is strong and flexible but not elastic

Proteins have four levels of organization

primary structure: amino acid sequence secondary structure: results from hydrogen bonding involving the backbone tertiary structure: depends on interactions among side chains quaternary structure: results from interactions among polypeptides

Amino acids are grouped by

properties of their side chains; nonpolar side chains are hydrophobic and polar side chains are hydrophilic

Amino acids are the subunits of

proteins

What temperature are fatty acids solid and why?

room temperature because of van del Waals interactions

What is glucagon?

small polypeptide made up of 29 amino acids, represented in a linear, "beads-on-a-string" form; has an ionized amino group and ionized carboxyl group on each end

Trans configurations are solid at what temperature? What risk do they increase?

solid at room temperature and they increase the risk of cardiovascular disease

In vitro (outside a living cell), a polypeptide

spontaneously folds into its normal, functional conformation

Storage proteins

store nutrients

Structural proteins

strengthen and protect cells and tissues