Biochemistry (Unit 3)

Carbon and Carbon-bonding

• Very reactive - 4 valence electrons

• Each carbon can form 4 single covalent bonds

• Carbon forms extensive networks (carbon skeletons)→ forms large mlc

Functional groups

• A variety of functional groups added to carbon networks

  • Carbon sharing electrons with O, N, or other atoms in a particular region in organic compound

• Group of atoms linked by strong covalent bonds and tending to function in chemical rxns as single unit

5 functional groups

Hydroxyl, carboxyl, amino, methyl, and phosphate

Monomers and polymers

• Some organic macromolecules are called polymers and are made up of multiple copies of single units called monomers

  • Link together by covalent bonds to form large compounds - polymers through dehydration synthesis

  • Split into monomers by hydrolysis

Carbohydrates

• Composed of carbon, hydrogen, and oxygen (sugars)

• (CH2O)n - lots of -OH groups

  • most carbohydrates, hydrogen and oxygen are found in the same two-to-one relationships that they are in water

• Contains several hydroxyl groups - makes mlcs polar in nature

Monosaccharides

• Simple sugars - called glucose

  • 1 unit of sugar

• Pentose - 5 carbon atoms

  • ribose

  • deoxyribose

    • genetic - (RNA + DNA + ATP)

• Hexose - 6 carbon

  • glucose

  • fructose

  • galactose

    • nutritional

Disaccharides

• 2 unit sugars (2 monosaccharides joined tgt)

  • Sucrose - glucose + fructose

  • Maltose - glucose + glucose

  • Lactose - glucose + galactose

• all nutritional

Polysaccharides

• Many mono. linked tgt

  • a) Starch - storage, made by plants, amylose + amylopectin (nutritional)

  • b) Glycogen - storage, animal, human (nutritional)

  • c) Cellulose - structural, plants - made up of glucose subunits

Function of Carbs

• Used for energy: plant-based foods

• Polysaccharides (ex. starch), and various disaccharides and monosaccharides play a roles as a primary energy source - esp glucose

• Short chains of carbs can be used for glycocalyx that surrounds most animal cells

• Human body stores glucose as polysaccharide glycogen

• Pentose sugars important for ATP and nucleotides make up DNA and RNA

Lipids

• Have lots of (C-H), less oxygen, most are non-polar (hydrophobic)

• Few oxygen atoms lipids do contain are often at the edge of the molecules and part of functional groups

• Lipids form an emulsion - a mixture of solutions that do not mix well

  • due to the fats emulsifying, therefore, non-polar

Triglycerides (fats and oils)

• Triglycerides consist of a glycerol molecule covalently bonded to 3 fatty acids

• Glycerol - organic compound with 3 carbon atoms, while fatty acids have a long chain of hydrocarbons with an acidic carboxyl group on the end

• Each fatty acid is covalently bonded to one of the 3 oxygen atoms of the glycerol mlc through dehydration syn. - produce 3 mlc of water

Triglycerides (Sat vs. Unsat)

Only saturated fatty acids = saturated fat

One of the fatty acids is unsaturated = unsaturated fat

Saturated - No C=C, more hydrogen

• triglyceride w/ 3 saturated fatty acids

  • fats, solid, from animals

Unsaturated - at least one C=C, less H

• triglyceride w/ at least one unsaturated fatty acid

  • oils, from plants, liquid

Sat vs. Unsat. fats

Unsat. fats - called oils, in plants and liquid at room temp.

Sat. fats - get packed tightly (no bends in the fatty acid chains), solid at room temp and in animals

Triglyceride functions

• Major fuel source for the body

  • when glucose storages are low and fuel long - slow physical activities

• Dietry fats assits the absorption of non-polar fat-soluble vitamins (A, D, E, and K)

• Body fats protects and cushions the body’s bones and internal organs and acts as an insulation

• Fatty acids are components of glycolipids - sugar-fat compounds found in the cell membrane

Phospholipids

• Plasma membranes composed of a BILYAER of phospholipids

  • composed of glycerol covalently bound to 2 fatty acids and phosphate group

  • Has a region that attracts water (polar) - hydrophilic head where phosphate group is located

  • Has a hydrophobic tail - not attracted to water, where the fatty acid tail are located

Steroids

• 4 fused hydrogen rings and many have short hydrocarbon tail

• Aka sterols are considered lipids because they are hydrophobic

• Functions are hormones (testosterone and estradiol)

• IMPORTANT - CHLOESTEROL

What is the contribution of cholesterol in steriods?

• Synthesized by the liver and present in most animal-based foods

• Important component of bile acids, compounds that help emulsify dietary fats

• Building block of many hormones, signaling molecules that the body releases to regulate processes at distant sites

Protein

• Important to all tissues and organs

• A large, globular macromolecule made of 1 or more chains of amino acids

• Amino acid chains are called peptides.

  • Peptides twist + turn + bend into specific 3D shape (has 4 levels)

• Always have nitrogen, many have sulfur

• Amino acids - units that make up proteins

Peptide bonds

• Two amino acids positioned so that the carboxyl group of one is adjacent to the amino group of the other

  • joined by dehydration reaction

• Peptide bond forms between 2 amino acids

Protein structures

3-D are important for proper functioning

1. Primary structure - linear sequence of amino acids

2. Secondary structure - folding and coiling patterns resulting from hydrogen bonds between the R groups of amino aicds

3. Tertiary structure - produced by the folding of the already coiled and folded chain of amino acids

4. Quaternary structure - several polypeptides aka subnunits and the interaction of subunits create quaternary

Protein function

DNA

Deoxyribonucleic acid (DNA) - all nucleotides have deoxyribose as pentose sugars

• stores genetic information (cellular blueprint molecules)

• exists as two nucleic acids that coil around one another (double helix)

  • composed of 2 polymers and nucleotides (each a nucleic acid) formed with bonds between phosphate and sugar groups (sugar-phosphate backbone)

  • held by hydrogen bonds between nitrogen bases

RNA

Ribosenucelic acid (RNA) - all nucleotides have ribose as the pentose sugar

• involved in producing proteins

• exists as a single strand

Nucleicotides and nucleic acids

Nucleic acids (chains of nucleotides—phosphate grp, pentose sugar, nitrogen base) carry genetic blueprint of a cell and carry instructions for cell functioning

Adenosine triphopshate (ATP)

• Nucleotide composed of a ribose sugar, an adenine base, and three phosphate groups

• High energy compound - 2 covalent bonds linking its 3 phosphates store a significant amount of potential energy

• Energy released from breaking bonds help fuel body

• Breakdown of ATP → APD and AMP is reversible when AMP or ADP undergo phosphorylation