Chapter 2 Flashcards
Ionic bond:
- bond between atoms formed by the transfer of 1 or more electrons.
- Atom that gains electron is called the anion and is the electron acceptor. Also, gains negative charge.
- Atom that loses the electron is called the cation and is the electron donor, also gains a positive charge.
ie) NaCl
Covalent bond:
- electrons are shared between 2 atoms.
ie) CH4 O2 N2 - polar covalent, unequal sharing of electrons. slightly negative polar region pulls the slightly positive region towards itself.
- non-polar covalent, equal electronegativity.
Hydrogen bond:
- Attraction between a hydrogen atom (already covalently linked to one atom) and another atom.
- weakest bond
- responsible for surface tension.
- intramolecular bonds, DNA double helix.
Three types of chemical reactions:
Synthesis reactions: - Anabolic - Smaller particles are bonded together to form larger, more complex molecules. ie) AA's join together to form proteins. Decomposition reactions: - Catabolic - Bonds are broken in larger molecules, resulting in smaller, less complex molecules. ie) Glycogen broken down to release glucose molecules. Exchange reactions: - Bonds are both made and broken (also called displacement reactions). - ATP transfers its phosphate group to form glucose-phosphate.
Carbohydrates:
Atoms: C:H:O in 1:2:1 ratio Monomer: Monosaccharides - simple sugars 3-7 C atoms ie) Hexose 6 sugars, pentose 5 sug. Polymer: Dissacharides - 2 monosaccharides bonded by dehydration synthesis (loss of water by hydroxyl from one monomer combining with H of other) - broken apart by hydrolysis (adding water, one monomer gains a hydroxyl the other a hydrogen) ie: sucrose, maltose, lactose. Polysaccharides - Long chains of sugars bonded by dehydration synthesis. ie: starch, glycogen, (cellulose).
Carbs are energy!
!
Lipids
- Atoms; C,O,H
- non polar covalent bonds
- not water soluble
# types:
1. Triglycerides: - 1 glycerol and 3 fatty acids
- most concentrated source of usable energy.
- found mainly beneath skin
where they insulate and protect.
2. steroids
3. lipids
Saturated vs unsaturated fats (triglycerides)
saturated ie: butter - no double bonds, all covalent single bonds unsaturated: - monounsaturated fatty acids ie: oil - has a single double bond
- polyunsaturated:
more than one double bond.
Phospholipids
- polar head
- 2 non-polar fatty acid hydrophilic tails
ie) plasma membrane, transport lipids throughout blood.
Steroids
- 4 interlocking hydrocarbon rings.
ie) cholesterol, stabilizing membrane.
Proteins
atoms: C:H:O:N Monomers: AA's Polymers; Polypeptides and proteins. - bonds are peptide bonds fromed by dehydration synthesis, broken down by hydrolysis. - 10 or more AA's is a polypeptide chain - 15 or more AA's is a protein - function of protein determined by AA's
Protein structural levels:
Primary structure:
- polypeptide chain
Secondary structure:
- a helixes and b pleated sheets
Tertiary structure:
- orientates itself to hide or expose unique r group
Quaternary structure:
- 2 or more polypeptide chains each with tertiary structures
ie) hemoglobin
ie) collagen, found in connective tissue, most abundant protein in body.
Fibrous and Globular Proteins
Fibrous proteins, also known as structural proteins, form
long strands. Some exhibit only secondary structure, but most have tertiary or even quaternary structure as well.
Globular proteins, also called functional proteins, are
compact, spherical proteins that have at least tertiary structure. Some also exhibit quaternary structure. The globular proteins are water-soluble, chemically active molecules, and they play crucial roles in virtually all biological processes. Some (antibodies) help to provide immunity, others (protein-based hormones) regulate growth and development, some are transport proteins, and still others (enzymes) are catalysts that oversee
just about every chemical reaction in the body
Enzymes:
- catalysts, lower AE
- have active sites that bind to specific substrates
central dogma
DNA exists in the nucleus as chromatin, carries instructions for protein production and genetic information.
These instructions are transcribed into mRNA in the nucleus.
mRNA then leaves the nucleus through nuclear pores and bring instructions to the ribosome. The polypeptide is formed as it is fed through the subunits and hooked onto AA’s delivered by tRNA. Therefore, mRNA is translated to a polypeptide chain