microbiology exam 1 information

atomic number

number of protons

atomic weight

mass of protons and neutrons

98% C,H,O,N, 1% S,P and 1% other elements

what elements and percentages in living things

atoms of elements do not all have the same number of neutrons, these are called isotopes

do all atoms of the same element always have the same number of neutrons

atoms of an elements  always have the same number of protons, the atomic number defines an element

do atoms of the same element always have the same number of protons

atoms or molecules with an unequal number of protons and electrons are called ions; cations are positive, anions are negative

what do we call atoms or molecules with an unequal number of protons and electrons

table salt dissociates in water to ions

what happens to table salt added to water

spheres of hydration

surrounding layer of water molecules that form around an ion or molecule when it's dissolved in water

covalent bond

sharing of electrons

nonpolar covalent bond

electrons are shared equally, elements of about the same electronegativity

polar covalent bond

unequal sharing of electrons

much of the chemistry of life is dominated by weak interactions )hydrogen bonds, hydrophobic interactions, vanDer Aaals.  But many weak interactions may form a stable interaction

if hydrogen bonds are weak, why are they important

aicidic

low pH

neutral

pH of 7

basic

high pH

pH4 is 10 times more acidic than pH 5

what does it mean to say “the pH scale is a log scale”

sugars

monosaccharides and disaccharides are sometimes called …

carbohydrates

polysaccharides are often called …

glucose

cellulose glycogen, pectin, and dextran are all polymers of …

the differences are dependent on degree of branching, the carbon atom involved in branching, and orientation of the bonds

how can the same building block make different polysaccharides

there are 20 different amino acids.  the different side chains may be polar, nonpolar, basic, acidic, and special cases (Proline and cysteine)

how many different side chains are available in the amino acids found in proteins

ONLY L-isomer amino acids are found in all proteins of all organisms.

D-isomer amino acids are found in nature: bacterial capsules, cells walls and peptide–like antibiotics

where are the L and D isomers found

it would be too slows as too few reactions would occur without high temp or strong chemicals

what would happen to metabolism without enzymes

enzymes

work by lowering the energy of activation

they bind due to complementarity of structures (fit together)

how do enzymes bind

substrate diffuses into active site (remember heat is molecular motion)

how does substrate enter the active site

product diffuses out of active site (remember heat is molecular motion)

why does product leave the active site

deoxyribose in DNA and ribose in RNA

where are deoxyribose and ribose sugars found

purines

adenine and guanine

pyrimidines

cytosine, thymine (DNA), uracil (RNA)

antiparallel

5’ to 3’ and 3’ to 5’ sequence

ys

is there energy in all covalent bonds

the are unstable; easily made and broken.  this is what you need for a “currency”

why are the covalent bonds found in ATP used as the “universal energy currency” 

an argument for the unity of all life (bacteria, plants, animals, fungi) is that all use the same energy currency: ATP

what’s so special about ATP that all cellular life (bacteria, fungi, protozoans, plants & animals) uses the same energy currency

true

atp is a nucleotide (true/false)

(remember opposites attract and likes repel?)  the negative charges repel one another, so strain the covalent bonds, making them more easily made and broken

how to explain the unstable “High energy bonds”

double bonds in fatty acids put a “kink” or “bend” in the otherwise straight molecule

what effect does a double bond have on a fatty acid chain

hydrophilic heads

water loving

hydrophobic tails

water hating

cholesterol

stiffens & stabilizes the phospholipid bilayers in Eukaryotic cell membranes 

phospholipids

all biological membranes are composed of …

sterols

all eukaryotes have …

bacteria

what does not have sterols, except Mycoplasma

Mycoplasma

a tiny bacteria with no cell wall

steroid

four ringed molecules

steroids

human sex hormones are …

OH-

sterols have an … group

different

animals, fungi and plants have … sterols

metabolism

sum of all the chemical reactions of a cell

anabolism and catabolism

two aspects of metabolism

chemical energy, in the form of ATP and reducing power

what links the two aspects of metabolism

catabolism

molecules are broken down through metabolic processes to release the energy stored in their chemical bonds

anabolism

metabolic processes in which the energy derived from catabolism is used to build large organic molecules from smaller ones

electron transfer, oxidation and reduction reactions

what are both aspects of metabolism involved in (3)

oxidation

chemical reaction in which an atom, ion or molecule loses one of more electrons

reduction

chemical reaction in which an atom, ion or molecule gains one or more electrons

together

oxidation and reduction reactions always occur (together / seperately)

redox reaction

the combination of an oxidation reaction and a reduction reaction are jointly referred to as a …

loses

when a substance is oxidized, it (gains / loses) electrons

gains

when a substance is reduced, it (gains / loses) electrons

combustion

uncontrolled oxidation

enzymes

proteins (few RNA) that act as catalysts for metabolic reactions, making the reaction go faster

true

enzymes are specific for reactions (true / false)

in all living organisms

where are enzymes found

hundreds of types which are constantly being manufactured and replaced

how many enzymes do most cells contain

enzyme - substrate complex

enzyme + substrate

specificity determined by three dimensional shape, “form determines function”

why are enzymes specific for substrate, type of reaction they catalyze and product produced

inhibited

if shape of enzyme changes, the activity is …

active site

shape of enzyme provides distinctive site called the …

diffusion

how does substrate enter the active site

diffusion

why does product leave the site

speeds up reaction by increasing diffusion; high enough temp can break bonds and change shape

how does temp affect enzyme reaction rate

can break hydrogen bonds and change shape

how can pH affect enzyme rate reactions

lower number of substrate, product, and enzyme molecules means a lower level of activity

how can the concentration of the substrate, product and enzyme affect the enzyme reaction rate

competitive or allosteric

how can inhibitors affect the enzyme reaction rate

competitive and non competitive (allosteric)

two categories of enzyme inhibitors

pathways

the series of chemical reactions in which metabolic reactions occur

true

each step in the metabolic pathway is mediated or facilitated by a specific enzyme (true / false)

yes

are pathways regulated (yes / no)

intermediates

steps in between initial substrate and final product of pathways

microbes are fierce competitors   microbes are masters of regulation.  a tiny bit more efficient, and they out grow the competition

is the regulation of metabolism (for example, this pathway model) important

at the cellular level and is not the same as breathing

in metabolism, where does respiration occur

ventilation

respiration at the macroscopic level

aerobic respiration, anaerobic respiration, and facultatively anaerobic respiration

cellular respiration describes catabolic processes and is divided into …

aerobic respiration

metabolism that uses oxygen

anaerobic respiration

metabolism that does not use oxygen (uses nitrate or sulfate as electron acceptor)

facultatively anaerobic respiration

metabolism that can use oxygen but can also occur without it

glycolysis, krebs cycle, electron transport chain and chemiosmosis

respiration (3)

glycolysis and formation of fermentation end products

fermentation (2)

glycolysis

10 steps, means “sugar splitting”

two

glycolysis has a net gain of … ATP

two

glycolysis has a production of … reduced electron carriers (NADH)

two

glycolysis produces … pyruvates per glucose

yes

does glycolysis generate precursor molecules for other pathways (yes / no)

generates reduced electron carrier (NADH)

transition step between glycolysis and krebs cycle

krebs / citric acid cycle

carbon is completely oxidized to CO2; electrons transferred to coenzyme carriers that take them to electron transport chain

two`

how many ATP are generated from the krebs / citric acid cycle

electron transport chain

accepts electrons from coenzyme carriers; passes them in a series of redox reactions; and pumps protons (H+) across a membrane

at the membrane

where do electron transport chain and chemiosmosis occur

ATP synthase

what captures energy of proton gradient for ATP synthesis