Microbiology week 1- Chapter 2

3, 7, isomers, deoxyribose

1 of the major classes of organic molecules CARBOHYDRATES - Carbohydrates are compounds consisting of atoms of carbon, hydrogen, and oxygen, with hydrogen and oxygen in a 2:1 ratio Monosaccharides contain from _____ to ____ carbon atoms - ___________ are two molecules with the same chemical formula but different structures and properties-for example glucose (C6H12O6) and fructose (C6H12O6) - Monosaccharides may form disaccharides and polysaccharides by dehydration synthesis Functions - Ex: a type of sugar, ______________, is a building block of deoxyribonucleic acid (DNA - Cell walls - Simple carbs are used to synthesize amino acids fats or fat like substances

salt

A ___________→ A substance that dissolves in water to cations and anions, neither of which is H+ or OH-

Acid

- A substance that dissociates into 1 or more hydrogen ions and 1 or more negative ions (anions) - Known as a proton donor

atom, protons, neutrons, electrons

- An ___________ is the smallest unit of a chemical element that exhibits the properties of that element - Atoms consist of a nucleus, which contains ____________ , ____________, and electrons which move around the nucleus - Atoms contain an equal number of protons and _____________ making each atom neutral

compound

- Atoms achieve the full complement of electrons in their outermost energy shells by combining to form molecules, which are made up of atoms of 1 or more elements - A molecule that contains at least 2 different kinds of atoms such as H2O is called a ________________

chemical bonds

- Molecules hold together because the valence electrons of the combining atoms form attractive forces called __________________ _______________ between the atomic nuclei - An attractive force between atoms forming a molecule

ten, 7, neutral

- The amount of H+ in a solution is expressed by the pH scale which ranges from 0 to 14 - A solution with a pH of 1 has ____________ times more hydrogen ions than a solution of pH 2 and has 100 times more hydrogen ions than a solution of pH 3 - Acidic solutions contain more H than OH and have a pH lower than ______ - If a solution has more OH than H, it is alkaline Water has a pH of 7→ it is ____________→ H=OH

antigen antibody, cations, anions

- The weaker ionic bonds formed in aqueous (water) solutions are important in biochemical reactions in microbes and other organisms - Ex: weaker ionic bonds assume a role in certain ____________ _______________ reactions , reactions in which molecules produced by the immune system (antibodies) combine with foreign substances (antigens) to combat infection - In general, an atom whose outer electron shell is less than half filled will lose electrons and form positively charged ions called ___________________ - Ex: Potassium (K+), Calcium ion (Ca+), sodium ion (Na) - When an atom's outer electron shell is more than half-filled, the atom will gain electrons and form negatively charged ions, called ______________ Ex iodide, chloride, sulfide

Covalent bonds

- ____________ ______________: A chemical bond formed by 2 atoms sharing 1 or more pairs of electrons - These bonds are stronger and far more common in organisms than ionic bonds - In a hydrogen molecule, H2 two hydrogen atoms share a pair of electrons. Each hydrogen atom has its own electron plus one electron from other atom - Atoms that share only 1 pair of electrons form a single covalent bond - Expressed by a single line between the atoms (H------H) Atoms that share two pairs of electrons form a double covalent bond expressed by two singly lines (=) - A Triple covalent bond is expressed as 3 single lines The principles of covalent bonding that apply to atoms of the same element also apply to atoms of different elements - Each outer electron of the carbon atom orbits both the carbon nucleus and a hydrogen nucleus. Each hydrogen electron orbits both its own nucleus and the carbon nucleus - Elements such as hydrogen and carbon, whose outer electron shells are half-filled, form covalent bonds quite easily

Isotopes

A form of a chemical element in which the number of neutrons in the nucleus is different from the other forms of that element - EX: Oxygen has 8 protons. If one atom of oxygen has 8 neutrons, one has 9 neutrons and one has 10 neutrons - Therefore 3 isotopes composing a natural sample of oxygen have atomic masses of 16, 17, and 18

hydrogen , hydroxide

Acid-Base Balance: The concept of pH - An organism must maintain a fairly constant balance of acids and bases to remain healthy - Ex if a particular acid or base concentration is too high or too low, enzymes change in shape and no longer effectively promote chemical reactions in a cell - In water acids dissociate into _______________ ions (H+) and anions - In water Bases dissociate into ______________ ions (OH-) and cations - The more hydrogen ions that are free in a solution, the more acidic it is - The more hydroxide ions that are free in a solution, the more basic or alkaline it is - Chemical reactions in living systems are very sensitive to even small changes in the pH of their environments - Any deviation from a cell's narrow band of normal H+ and OH- concentrations can dramatically modify the cell's functions

ionic, covalent

Atoms form bonds in 1 of two ways - By gaining or losing electrons from their outer shell - By sharing electrons on outer shell - When atoms GAIN OR LOSE outer electrons , the chemical bond is called an _______________ bond - When outer electrons are SHARED, the bond is called a ______________ bond Bonds range from highly ionic to highly covalent

oxygen, nitrogen, weak, negative, positive,

Hydrogen bonds - Another chemical bond of special importance to all organisms is the hydrogen bond - Bond between a hydrogen atom covalently bonded to ____________or __________ and other covalently bonded oxygen or nitrogen atom - Such bonds are ____________ and do not bind atoms into molecules, However they serve as bridges between different molecules or between various portions of the same molecule - When hydrogen combines with atoms of oxygen or nitrogen, the relatively large nucleus of these larger oxygen or atoms has more protons and attracts the hydrogen electron more strongly than does the small hydrogen nucleus - In a molecule of water all the electrons tend to be closer to the oxygen nucleus than to the hydrogen nuclei. As a result the oxygen portion of the molecule has a slightly ________________ charge and the hydrogen portion of the molecule has a slightly _______________ charge - When the positively charged end of one molecule is attracted to the negatively charged end of another molecule has a slightly negative charge and the hydrogen portion of the molecule has a slightly positive charge - When the positively charged end of one molecule is attracted to the negatively charged end of another molecule, a hydrogen bond is formed - This attraction can also occur between hydrogen and other atoms of the same molecule, especially in large molecules, but oxygen and nitrogen are the elements most frequently involved in hydrogen bonding Hydrogen bonds are considerably weaker than either ionic or covalent bonds - Hydrogen bonds are formed and broken relatively easily This property accounts for the temporary bonding that occurs between certain atoms of large and complex molecules such as proteins and nucleic acid

carbon, hydrogen, ionically, water

Inorganic compounds - A small molecule that does not contain ___________ and _______________ - Usually small and structurally simple; _______________ bonded - Include water, molecular oxygen, carbon dioxide, many salts, acids and base

negative, positive

Ionic bonds - Atoms are electrically neutral when the number of positive charges (protons) equals the number of negative charges (electrons). But when an isolated atom gains or loses electrons this balance is upset - If an atom GAINS ELECTRONS it acquires an overall _____________ charge - If an atom LOSES ELECTRONS it acquires an overall ________________ charge

ionization

When inorganic salts such as sodium chloride are dissolved in water, they undergo __________________ or dissociation ( they break apart into ions)

ion, +1, -1, ionic bonding

Ionic bonds - Such negatively or positively charged atom (or group of atoms) is called ________ ( A negatively or positively charged atom or group of atoms) Example: Sodium has 11 protons and 11 electrons, with one electron in its outer electron shell - Sodium tends to lose the single outer electron; it is an electron donor - When sodium donates an electron to another atom it is left with 11 protons and only 10 electrons and so it has an overall charge of ___________ - Chlorine has 17 electrons, seven of them in the outer electron shell. Chlorine tends to pick up an electron that has been lost by another atom - It is an Electron acceptor By accepting an electron, chlorine totals 18 electrons making it negative by __________ - The opposite charges of the sodium ion Na+ and chloride ion Cl- attract each other and a molecule is formed. This is an example of ionic bonding - _____________ ____________→ A chemical bond formed when atoms gain or lose electrons in the outer energy levels

DNA, RNA, pentose, phosphate, nitrogen, pyrimidines, purines, hydrogen,

Nucleic acids - Nucleic acids→ ___________ and ___________-- are macromolecules consisting of repeating nucleotides - A nucleotide is composed of a ___________ , a ______________ group, and a _________________ -containing base. - A nucleoside is composed of a pentose and a nitrogen-containing base - A DNA nucleotide consists of deoxyribose (a pentose) and one of the following nitrogen-containing bases: thymine or cytosine (_____________) or adenine or guanine (______________) - DNA consists of two strands of nucleotides wound in a double helix. The strands are held together by ___________ bonds between purine and pyrimidine nucleotides: AT and GC Genes consist of sequences of nucleotides - An RNA nucleotide consists of ribose (a pentose) and one of the following nitrogen containing bases: cytosine, guanine, adenine, or uracil

insolubility, glycerol, fatty acid, saturated

One of the major classes or organic molecules LIPIDS - Lipids are a diverse group of compounds distinguished by their ______________ in water - Simple lipids consist of a molecule of _____________ and 3 molecules of ___________ ________ - A ______________ lipid has no double bonds between carbon atoms in the fatty acids; an unsaturated lipid has 1 or more double bonds. Saturated lipids have higher melting points than unsaturated lipids - Phospholipids are complex lipids consisting of glycerol, two fatty acids, and a phosphate group - Steroids have carbon ring structures; sterols have a functional hydroxyl group Function - to form plasma membranes that enclose cells - plasma membrane supports the cell and allows nutrients and wastes to pass in and out

covalently, chains

Organic compounds - A molecule that contains carbon and hydrogen - Carbon atoms form up four bonds with other atoms - Organic compounds are mostly or entirely _________________ bonded always contain carbon and hydrogen and typically are structurally complex - Carbon is a unique element because it has 4 electrons in its outer shell and 4 unfilled spaces. It can combine with a variety of atoms - Carbon ______________ form the basis of many organic compounds in living cells, including sugars, amino acids, and vitamins - Held together by covalent bonds - Some organic molecules such as polysaccharides, proteins, and nucleic acids, are very large and usually contain thousands of atoms Called Macromolecules

buffer

Organisms take in nutrients, carry out chemical reactions, excrete wastes which causes its pH to fluctuate - For this reason organisms possess natural pH buffers ______________ →A substance that tends to stabilize the pH of a solution - In the lab buffers are used to prevent the bacteria from dying - Most organisms grow best in environments with a pH value between 6.5 and 8.8 - - Fungi are best able to survive acidic conditions while prokaryotes called cyanobacteria tend to do well in alkaline habitats

20, sequence, helices, polypeptide,

Proteins -Amino acids are the building blocks of proteins - Amino acids consist of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur - _______ amino acids occur naturally in proteins - By linking amino acids, peptide bonds (formed by dehydration synthesis) allow the formation of polypeptide chains - Proteins have 4 levels of structure: primary (____________of amino acids), secondary (______________ or pleated), tertiary (overall 3 dimensional structure of a ______________) and quaternary (two or more polypeptide chains - Conjugated proteins consist of amino acids combined with inorganic or other organic compounds

Valence

The __________________ (The combining capacity of an atom or molecule) is the number of extra or missing electrons in its outermost electron shell - Ex: Hydrogen has a valence of 1 ( one unfilled space, or one extra electron) Oxygen has a valence of 2( 2 unfilled spaces), carbon has a valence of 4 ( four unfilled spaces, or 4 extra electrons, magnesium has a valence of 2(two extra electrons)

react, stable, unstable

The number of electrons in the outermost shell determines an atom's tendency to ______________ with other atoms - An atom can give up, accept, or share electrons with other atoms to fill the outermost shell - When its outer shell is filled the atom is chemically ________________ or inert (it doesn't tend to react with other atoms) - When an atom's outer electron shell is only partially filled, the atom is chemically ______________ - These unstable atoms react with other atoms, depending in part, on the degree to which the outer energy levels are filled

Atomic mass

Total number of protons and neutrons

Base

_________: A substance that dissociates into one or more hydroxide ions (OH2) and one or more positive ions - They can accept or combine with protons and one or more positive ions ( cations) Sodium hydroxide (NaOH) is a base because it dissociates to release OH-, which has a strong attraction for protons and is among the most important proton acceptors

Electron shells, 2, 8, 8

____________ _____________→ A region of an atom where electrons orbit the nucleus, corresponding to an energy level Shells are layered outward from the nucleus, and each shell can hold a characteristic maximum number of electrons- - ______ electrons in the innermost shell - _____ electrons in the second shell - _____ electrons in the third If it is the atoms outermost (valence shell) The fourth, fifth, and sixth electron shells can accommodate 18 electrons

Atomic number

number of protons in the nucleus