Chemistry for Bioscience Flashcards
1
Q
Subatomic Particles
A
Protons - 1 mass unit
Neutrons - 1 mass unit
Electrons - low mass
2
Q
Common chemical elements in out body
A
oxygen, nitrogen, carbon, calcium, hydrogen phosphorous
Potassium, cl, S, Mg, Na
all req for life
3
Q
Element
A
an element is a pure substance consisting only of atoms that all have the same numbers of protons in their nuclei.
4
Q
isotope
A
Isotopes are two or more types of atoms that have the same atomic number and position in the periodic table, and that differ in nucleon numbers due to different numbers of neutrons in their nuclei.
5
Q
Ionic bonds
A
6
Q
Covalent bonds
A
Non-metals
Strong bonds sharing electrons
one electron is donated by each atom to make the pair of electrons
Sharing one pair = single covalent bond
7
Q
Hydrogen bonds
A
Weak polar bonds between adjacent molecules based on electrical attractions
Involve attractions between S+ and S-
Hydrogen bonds between H2o molecules cause surface tensions
8
Q
Polar and non-polar covalent bonds
A
non-polar covalent bonds - equal sharing of electrons between atoms, equal pull on electrons
polar covalent bonds - unequal sharing if electrons because one atom has a disproportionately strong pull on electrons
Form polar molecules like water
9
Q
States of matter
A
Solid - constant volume and shape
Liquid - constant volume but changes shape
Gas - changes volume and shape
10
Q
Chemical reactions
A
Reactants Products Metabolism Energy Work Kinetic Energy Potential energy Chemical energy
11
Q
Metabolism
A
all of the reactions are occurring at one time
all the physical and chemical processes in the body that convert or use energy, such as: Breathing. Circulating blood.
12
Q
Work
A
Movement of an object of change in matter
13
Q
Types of chemical reactions
A
- Decomposition
- Synthesis
- Exchange
- Reversible
14
Q
Enzymes
A
Biochemical reactions in cells, do not occur spontaneously.
Protein catalysts
Lower the activation energy of reactions
15
Q
nutrients
A
ORGANIC
essential molecules from food
16
Q
metabolites
A
Molecules made or broken down in body - ORGANIC
17
Q
Inorganic compounds
A
Co2, O2, h2o, inorganic acids, bases, salt
18
Q
Organic compounds
A
Molecules containing C, H, carbohydrates, proteins, lipids, nucleic acids
19
Q
Properties of water
A
Accounts for up to 2/3 of body weight
Produces solutions = uniform mixtures of two or more substances
A solution consists of a solvent, or liquid, and solutes
Solutes are the dissolved substances
20
Q
Properties of aqueous solutions
A
Water is polar
inorganic compounds split into smaller molecules via dissociation
21
Q
ionization
A
Disassociation into ions
E.g NaCl + aq = Na+ and Cl-
22
Q
Hydrophobic
A
hates water
23
Q
Hydrophillic
A
Loves water
24
Q
pH
A
Negative logarithm of hydrogen ion concentration of a solution in mol/L
Neutral pH balance of H+ & OH-
25
Acid
proton donor
Solute adds H+ solution
Strong acids dissociate completely in solution
26
Base
Proton acceptor Solute removes H+ from solution
| Strong bases dissociates completely in solution
27
Weak acids/ bases
Fails to dissociate completely
| help to balance the pH
28
Salt
Solute that dissociates into cations and anions other than H+ and OH-
29
Carbohydrates
Organic molecules
contain H, C and usually covalently bonded
Contains functional groups that determine their chem
Includes carbohydrates, lipids, proteins and nucleic acid
30
Lipids
Mainly hydrophobic molecule --> fats, oils + waxes
most carbon and hydrogen atoms
Include
fatty acid, eicosanoids, glycerides, steroids, phospholipids and glycolipids
31
Fatty Acid
Saturated and unsaturated compartments
| Double covalent bonds causes a sharp bend in the molecule
32
Proteins
Most abundant + important organic compounds
Contains C, H, O and N
20 amino acids are monomers that combine to form proteins (polymers)
33
Functions of proteins
1. Support - structural proteins
2. Movement - contractile proteins
3. Transport - Transport (carrier) proteins
4. Buffering - regulation of pH
5. Metabolic regulation - enzymes
6. Coordination and control - hormones
7. Defense - antibodies
34
Linking two amino acids
requires dehydration synthesis amino groups of one amino acid and carboxyl group of another amino acid
Forms peptide links --> resulting molecule is a peptide
Polypeptide = lots
OH of COOH and H of NH2 come together and release water, creates Oprah can not help
35
Nucleic Acids
```
Large organic molecules found in the nucleus
Stores and processes information
* deoxyribonucleic acid (DNA)
- determines inherited characteristics
- controls enzyme production
- controls metabolism
* ribonucleic acid (RNA)
- controls intermediate steps in protein synthesis
```
36
Structure of nucleic acids
DNA + RNA consists of long chains or nucleotides (monomers) which contains
1. pentose sugar (deoxyribose or ribose)
2. Phosphate group
3. Nitrogenous base (A, G, T, C, or U)
37
DNA + RNA
DNA consists of a pair of nucleotide chains called complementary strands
Hydrogen bonds between opposing nitrogenous bases hold the strands together
form a twisting double helix
RNA consists of a single chain of nucleotides
- messenger RNA (mRNA)
- transfer RNA (+RNA)
- ribosomol RNA (rRNA)
38
Complementary base pairs of DNA
Adenine (A) bonds to Thymine (T)
| Cytosine (C) bonds to Guanine (G)
39
Complementary Base Pairs of RNA
Uracil (U) replaces Thymine (T)
40
Adenosine Monophosphate
Nucleotide that contains one phosphate group (AMP)
41
Adenosine diphosphate
2 phosphate groups (ADP)
42
Adenosine triphosphate
High energy compound containing 3 phosphate groups
43
Structure of ATP
ATP is formed by attaching two phosphate groups to the nucleotide adenosine monophosphate.
Connected by high-energy bonds
Quick energy by removing one phosphate group from ATP, forming ADP (
ADP can later be reconverted to ATP, and the cycle repeated.
44
pH
A measure of acidity or alkalinity of a solution
pH of body fluids depends on dissolved
Acids
Bases
Salts
pH of body fluids is altered by addition of acids or bases
pH of blood plasma maintained between 7.35–7.45
Buffering
Kidneys and lungs involved in excreting acid products
45
Salt
An ionic compound consisting of a cation other than hydrogen and an anion other than a hydroxide ion
46
Buffer
A substance that tends to oppose changes in the pH of a solution by removing or replacing hydrogen ions; in body fluids, buffers maintain blood pH within normal limits (7.35-7.45)
47
water
Makes up 99 percent of fluid volume outside cells
Extracellular fluid (ECF)
Essential ingredient of cytosol inside cells
Intracellular fluid (ICF)
All cellular operations rely on water
As diffusion medium for gases, nutrients, and wastes
48
Volumes, solute concentrations, and pH of ECF and ICF
Stabilised by three interrelated processes
Fluid balance
Electrolyte balance
Acid-base balance
49
Fluid balance
```
Daily balance between
Amount of water gained
Amount of water lost to environment
Involves regulating content and distribution of body water in ECF and ICF
Digestive system
Primary source of water gains
Urinary system
Primary route of water loss
```
50
osmosis
Movement of water molecules from an area of high concentration to one of low concentration through a semi-permeable membrane.
51
Electrolyte balance
Electrolytes
- ions released though dissociation of inorganic compounds
- can conduct electrical current in solution
Electrolyte balance
- when gains and losses for every electrolyte are in balance
- primarily involves balancing rates of absorption across digestive tract with rates of loss at kidneys
52
acid-base balance
Precisely balances production and loss of hydrogen ions (H+)
Body generates acids during normal metabolism
Reduce pH
Kidneys
Secrete H+ into urine
Generate buffers that enter bloodstream
Lungs
Affect pH through elimination of carbon dioxide
53
Fluid Compartments
```
Osmotic concentrations of ICF and ECF
Identical
Osmosis across plasma membranes eliminates minor differences
Ion exchange
Between ICF and ECF occurs across selectively permeable plasma membranes by
Osmosis
Diffusion
Carrier-mediated transport
```
54
fluid compartments pt 2
```
Primary hormones that regulate fluid and electrolyte balance
Reduces water loss:
Antidiuretic hormone (ADH)
Aldosterone
Increases water loss
Natriuretic peptides (ANP and BNP)
```
55
water gains and water losses
are always equal
56
Acidosis
Acid-base balance
Physiological state resulting from abnormally low blood pH
Acidemia is when blood pH <7.35
57
alkalosis
Acid-base balance
Physiological state resulting from abnormally high blood pH
Alkalemia is when blood pH >7.45
58
Acidosis and alkalosis
Affect virtually all body systems
Particularly nervous and cardiovascular systems
Both are dangerous
But acidosis is more common
Because normal cellular activities generate acids
59
Acid-base balance
Control of pH
| Homeostatic process of great physiological and clinical significance
60
Types of acids in body
Fixed acids
Metabolic acids
Volatile acids
61
Fixed acids
- Acids that do not leave solution
- Once produced they remain in body fluids
- Until eliminated by kidneys
Sulfuric acid and phosphoric acid
* Most important fixed acids in body
* Generated during catabolism of
- Amino acids
- Phospholipids
- Nucleic acids
62
Metabolic acids
Participants in, or by-products of, cellular metabolism
* Pyruvic acid
* Lactic acid
* Ketone bodies
Metabolised rapidly under normal conditions
* Significant accumulations do not occur
63
Volatile acids
```
Can leave body by entering atmosphere at lungs
Carbonic acid (H2CO3) breaks down into carbon dioxide and water
CO2 diffuses from bloodstream into alveoli
```
64
Carbonic anhydrase
```
Enzyme that catalyzes formation of carbonic acid from carbon dioxide and water
Found in
Cytoplasm of red blood cells
Liver and kidney cells
Parietal cells of stomach
Many other cells
```
65
Co2 and pH
Most CO2 in solution converts to carbonic acid
Most carbonic acid dissociates into
Hydrogen ions (H+)
Bicarbonate ions (HCO3–)
Partial pressure of CO2 (PCO2)
The most important factor affecting blood pH
66
Pco2 and pH
```
inversely related
When CO2 levels rise
H+ and HCO3– are released
pH decreases
At alveoli
CO2 diffuses into atmosphere
H+ and HCO3– in alveolar capillaries decrease
Blood pH rises
```
67
Mechanisms of pH control
To maintain homeostasis, the body balances
| Gains and losses of hydrogen ions
68
Hydrogen ions (H+)
Gained
* At digestive tract
* Through cellular metabolic activities
Eliminated
* At kidneys
* At lungs
- Must be neutralised to avoid tissue damage
- Acids produced in normal metabolic activity
* Temporarily neutralised by buffers in body fluids
69
Strong acids and strong bases
Dissociate completely in solution
| Example: hydrochloric acid (HCl)
70
Weak acids and bases
Do not dissociate completely in solution
Some molecules remain intact
Weak acid releases fewer H+ than does a strong acid, and thus has less effect on pH of solution
71
Carbonic acid
- Weak acid
- In ECF at normal pH
* equilibrium state exists: H2CO3 ↔ H+ + HCO3–
72
Buffers
```
- Dissolved compounds that stabilize pH of solution
By adding or removing H+
- Weak acids
Can donate H+
- Weak bases
Can absorb H+
```
73
Buffer system
- Consists of a combination of
* A weak acid
* An anion released by its dissociation
- Anion functions as a weak base
- In solution, molecules of the weak acid exist in equilibrium with its dissociation products
74
Major buffer systems
1. Phosphate buffer system
2. Protein buffer systems
3. Carbonic acid-bicarbonate buffer system
75
Buffer system in body fluid
see sides
76
Phosphate buffer systems
- Consists of H2PO4– (a weak acid) and its anion
(HPO42–)
- Cells contain a weak base (Na2HPO4)
Provides additional HPO42– for this buffer system
- Important in buffering pH of ICF and urine
77
Protein buffer systems
- Rely on amino acids
* Respond to pH changes by accepting or releasing H+
- Important in ECF and ICF
- If pH rises
* Carboxyl group of amino acid dissociates
* Releasing a hydrogen ion, acting as weak acid
* Carboxyl group becomes carboxylate ion
Carboxyl and amino groups in peptide bonds cannot function as buffers
Most buffering capacity of proteins is provided by R groups of amino acids
78
Protein buffer systems and pH
- At normal pH (7.35–7.45)
* Carboxyl groups of most amino acids have already given up their H+
- If pH decreases
* Carboxylate ion and amino group act as weak bases
* Accepting H+
* Forming carboxyl group and amino ion
79
The role of amino acid buffers in Protein Buffer Systems
Neutral pH - amino acid zwitterion
pH decreases - In an acidic medium, the amino acid acts as a base and absorbs H+
pH increases - In an alkaline medium, the amino acids acts as an acid and releases H+
80
Hemoglobin buffer systems
- CO2 in plasma rapidly diffuses into red blood cells
And is converted to carbonic acid
- As carbonic acid dissociates
* Bicarbonate ions diffuse into plasma
* In exchange for chloride ions (chloride shift)
* Hydrogen ions are buffered by hemoglobin molecules
- The only intracellular buffer system with an immediate effect on pH of ECF
- Helps prevent major changes in pH when plasma PCO2 is rising or falling
81
Carbonic acid-bicarbonate buffer system
- carbon dioxide
* Constantly generated by body cells
* Most is converted to carbonic acid
- This buffer system involves carbonic acid and its dissociation products
* H+ and bicarbonate ions
- Prevents changes in pH caused by metabolic acids and fixed acids in ECF
82
Limitations of carbonic acid-bicarbonate buffer system
- Cannot protect ECF from changes in pH that
result from increased or decreased levels of CO2
- Functions only when respiratory system and
respiratory control centers are working normally
- Ability to buffer acids is limited by availability of bicarbonate ions
83
Bicarbonate ion shortage is rare because
- fluids contain large reserve of sodium bicarbonate
* Called bicarbonate reserve
- Additional HCO3– can be generated by kidneys
84
The carbonic acid-bicarbonate buffer system
see lecture
85
Limitations of buffer systems
- Provide only temporary solution to acid-base imbalance
- Do not eliminate H+
- Supply of buffer molecules is limited
86
Regulation of acid-base balance
- To preserve homeostasis, captured H+ must be
* Permanently tied up in water molecules through CO2 removal at lungs
* Removed from body fluids by secretion at kidneys
- Requires balancing H+ gains and losses
- To maintain body pH within narrow limits, buffer systems coordinate with
* Respiratory mechanisms
* Renal mechanisms
87
Respiratory and renal mechanisms
- Support buffer systems by
Secreting or absorbing H+
Controlling excretion of acids and bases
Generating additional buffers
88
Respiratory compensation
Change in respiratory rate
* Helps stabilize pH of ECF
Occurs whenever body pH moves outside normal limits
Directly affects carbonic acid–bicarbonate buffer system
89
Respiratory compensation and pH
- Increasing or decreasing rate of respiration alters pH by lowering or raising PCO2
- When PCO2 rises
* pH falls
* Addition of CO2 drives buffer system to right
- When PCO2 falls
* pH rises
* Removal of CO2 drives buffer system to left
90
Renal compensation
- Change in rates of H+ and HCO3– secretion or reabsorption by kidneys
* In response to changes in plasma pH
- Body normally generates enough metabolic and fixed acids each day to add 100 mEq of H+ to ECF
- H+ are excreted in urine
- Kidneys assist lungs by eliminating any CO2 that
* Enters renal tubules during filtration
* Diffuses into tubular fluid en route to renal pelvis
91
Hydrogen ions
- Secreted into tubular fluid along
Proximal convoluted tubule (PCT)
Distal convoluted tubule (DCT)
Collecting system
92
Buffers in urins
- Required to eliminate large numbers of H+
- Glomerular filtration provides components of
* Carbonic acid–bicarbonate buffer system
* Phosphate buffer system
- Tubule cells of PCT
* Generate ammonia
* Ammonia buffer system
93
Disorders of Acid-Base Balance
* Serious and prolonged disturbances of acid-base balance can result in
- Disorders affecting circulating buffers, respiratory performance, or renal function
- Cardiovascular conditions such as heart failure or hypotension
- Conditions affecting CNS
* Neural damage or disease can affect reflexes essential to pH regulation
