Biology Chapter 2
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Has a positive charge, or defined amount of electricity. Protons and neutrons are in the nucleus, or core region, of an atom.
Zipping abou that nucleus are the negatively charged electrons. The positive charge of a proton and the negative charge of an electron balance each other; an atom that has the same number of electrons as protons has no net electrical charge.
All matter consists of different kinds of atoms called elements.
Atoms with the same number or protons but a differnet number of neutrons are isotopes.
Nested shells correspond to energy levels. They offer us an easy way to check for electron vacancies in various atoms.
The kind of electron=swapping between atoms is known as
Molecules with unvarying proportions of two or more elements are compounds.
Ex. A water molecule, for instance, always has one oxygen and two hydrogen atoms.
two or more molecules intermingle without bonding.
Ex. When you make a mixture by swirling water and sugar together.
Two atoms that are sharing a pair of electrons are connected by a covalent bond. A covalent bond is much stronger than an ionic bond.
When the negatively charged atoms is already taking part in a differnet covalent bond, the interaction between it and hte hydrogen atoms is called a hydrogen bond. Hydrogen bonds are individually weak, so they break easily. But they also for easily, and often.
That same polarity repels oils and other nonpolar molecules, which are hydrophobic substances.
Ex. Shake a bottle filled with water and salad oil, then set it on a table. They are seperate from water.
Measures the energy of their motion. (molecules)
When water temperature is below its boiling point, hydrogen bonds form as fast as they break. Energy input (heat) increases molecular motion so much that the hydrogen bonds stay broken, and molecules at the water's surface escape into air. Heat converts liquid water to a gas.
A dissolved substance is called a solute.
Means that Molecules resist separating.
At any instant in liquid water, some water molecules are split into hydrogen and hydroxide ions. Hydrogen ions are the basis of the pHscale.
- Lose hydrogen ions in solution. The ph of these solutions is less than 7.
- Ex. Lemon juice, gastric fluid, and coffee
- Aquire hydrogen ions. Ph have Ph greater than 7
- Ex. Egg white, baking soda, and seawater contain more OH- than H +
Is any compound that dissolves easily in water and releases ions other than H+ and OH-
- Most body fluids maintain a stable PH with buffers.
- Its a dynamic chemical partnership between a weak acid or base and its salt. These two related chemicals work in a equilibrium to counter slight shifts in pH.
Which are compounds with covalent bonds between carbon and hydrogen atoms.
- They and most other organic compounds have at least one functional group. An atom (other than hydrogen) or cluster of atoms bonded to carbon.
- A functional group is an atom or cluster of atoms that imparts
By which a cell builds, rearranges, or splits apart all organic compounds require energy and enzymes:proteins that make substances react much faster than they would on their own.
Enzymes split an -OH group from one molecule and an H atom from another. A covalent bond forms between the molecules at their exposed sites.
A type of cleavage reaction, is like condensation reversed. Enzymes split molecules, then attach an -OH group and a hydrogen atom to each of the exposed sites.
has a backbone of as many as thirty six carbonj atoms, and carboxyl group at one end, and hydrogen atoms at most or all of the remaining carbons.
Neutral fats, such as butter, lard, and vegetable oils. Each triglyceride has three fatty acids stretching out like flexible tails from a glycerol unit.
has a glycerol backbone, a hydrophilic head with a phosphate group, and two nonpolar fatty acid tails. Phospholipids are the principal component of cell membranes, which have two ayers of lipids.
are among the many lipids with no fatty acids. They differ in the number, position, and type of their functional groups, but all have a rigid backbone of four carbon rings.
have a long- chain fatty acids tightly packed and linked to long-chain alcohols or carbon rings. All have a firm condsistency; all repel water.
Is a small organic compound with an amino group, a carboxyl group, a hydrogen atom, and one or more atoms called its R group.
consists of many amino acids. Its carbon backbone contains nitrogen atoms in this regular pattern.
- At such times , polypeptide chains unwind and change shape in an event called denaturation.
- Ex. Albumin a protein in the white of an egg. When you cook eggs, the heat does not disrupt the covalent bonds of the albumins primary structure but, it does destroy the weaker hydrogen bonds that maintain the protein shape, and so the protein unfolds. When a translucent egg white turns opaque, we know the the albumin is denatures.
The nucleotide atp has a row of three phosphate groups attached to its sugar. Atp redily transfers the outermost of these phosphate groups to other moleules inside cells.
Enzyme helpers. Coenzymes move electrons and hydrogen from one reaction site to another.
DNA (deoxyribonucleic acid)
DNA is a polymer of four kinds of nucleotide monomers: adenine guanine, cytosine, and thymine.
Dna is one of the nucleic acids that store and retrieve heritable information in all cells. In all nucleic acids, a covalent bond joins the sugar of nucleotide monomer and the phosphate group of the next.
Like DNA, the rnas (ribonucleic acids) consist of four sugar =phosphate monomers-adenine, guanin, cytosine, and uracil (not thymine). Unlike DNA, most RNA's are single stranded.
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