Chapter 2 lecture - The Chemistry of Life Flashcards
Define elements
The simplest form of matter to have unique chemical properties cannot be broken down by ordinary chemical means
How many naturally occurring elements are there?
91
Define atoms
The building blocks for each element
How many elements have a biological role?
24
What 6 elements make up 98.5% of our body weight?
Oxygen (O) Carbon (C) Hydrogen (H) Nitrogen (N) Calcium (Ca) Phosphorus (P
Lesser elements make up what percent of the body?
0.8%
Trace elements make up what percent of the body?
Less than 0.7%
Where and in what quantity are trace elements found in the body?
They’re required in minute amounts and are found as a part of enzymes
Give examples of lesser and trace elements
Lesser: K, S, Na, Cl, Fe, Mg
Trace: I, Co, Cu, Z, Cr, etc.
Define minerals
Inorganic elements extracted from soil by plants and passed to humans
What percent of our body weight is made up of minerals?
4%
What two minerals are most commonly found in the body? What are some other minerals in the body?
Mostly Ca and P (also Cl, Mg, K, Na, and S)
Define electrolytes in the context of minerals
Mineral salts needed for nerve and muscle function
What are the three components of atoms?
Protons, neutrons, and electrons
This is just a note to myself that this chapter does also cover the basics of protons, neutrons, and electrons, but those flashcards can be found in lab 2
Elements with an abnormal number of neutrons are called ____
Isotopes
Average of mass numbers of an element = ______
Atomic weight
True or false: most isotopes are stable. Why?
True; few will disintegrate and give off energy
Intense radiation can be ionizing, how does this affect the body?
Intense radiation can be ionizing (ejects electrons, destroys molecules) and can cause genetic mutations and cancer
Where are radioactive isotopes used in medicine? What are some other examples?
Used for radiation therapy and diagnostic procedures. This includes PET scans, using I-131 determine size and activity of the thyroid gland, Hida scans (Tc-99 technetium with a ½ life of 6 hours), Cobalt-60 for cancer
Other examples of radioactive isotopes include UV radiation, X-rays, alpha particles, beta particles, gamma rays
True or false: All elements have at least one radioisotope
True
True or false: X-rays and CT scans use radioactivity
False; they use very short electromagnetic waves.
Electron shells are also called ________
energy levels
In neutral atoms, number of electrons equals number of protons. Non-neutral atoms have a different number of electrons than normal; what are they called?
Ions (or electrolyte)
Define cations and anions
Anion—particle that gains electron(s) (net negative charge)
Cation—particle that loses electron(s) (net positive charge)
Ions with _____ charges are attracted to each other
a) opposite
b) same
a) opposite
Define electrolytes
Substances that ionize in water (acids, bases or salts)
Define salts
A compound (ex: NaCl) that can dissociate into water and contains cations (Na) and anions (Cl)
Define a molecule
Chemical particle composed of two or more atoms united by a chemical bond
Define a compound
Molecule composed of two or more different elements
Define molecular formula
Identifies constituent elements and how many atoms of each are present
Define structural formula
Identifies the location of each atom
What do chemical bonds do?
They hold atoms together within a molecule or attract one molecule to another
What are the three most important types of chemical bonds?
Ionic bonds, covalent bonds, and hydrogen bonds
Inert elements have a ____ outer shell
a) incomplete
b) full
b) full
Reactive elements have a ____ outer shell
a) incomplete
b) full
a) incomplete
Define ionic and covalent bonds
Ionic bonds: will transfer (gain/lose) electrons
Covalent bonds: will share electrons
Describe ionic bonds in detail (the attractions are between ____ and ____; electrons are shared or transferred; how easily are they broken)
Attractions between anions and cations
Electrons donated from one atom to another
Easily broken by water
____ compounds form crystals instead of individual molecules
Ionic
Define a single covalent bond
One pair of electrons is shared
What is the strongest type of bond?
Nonpolar bonds
In what type of bonds do electrons spend more time near oxygen?
Polar bonds
Define polar and nonpolar bonds
Nonpolar bond: electrons shared equally (strongest bond)
Polar bond: electrons shared unequally (spend more time near oxygen)
_____ sharing of electrons produces polar molecules
Unequal
What is an example of an intermolecular hydrogen bond? An intramolecular hydrogen bond?
Intermolecular hydrogen bond between water molecules
Intramolecular hydrogen bonds helps protein folding; holds sides of DNA together
Define hydrogen bonds
Weak charge attraction between a slightly positive hydrogen and a slightly negative oxygen (or nitrogen)
Define mixtures
When elements/molecules/objects are physically blended but not chemically combined
What are body fluids?
Complex mixtures of chemicals
What percent of the body is made up of water? What factors determine this?
Water is 50% to 75% of body weight; this depends on age, sex, fat content, etc.
What two things give water the properties to support life? What are these properties?
Polar covalent bonds and a V-shaped molecule give water solvency, cohesion, adhesion, chemical reactivity, and thermal stability
Define solvency
The ability to dissolve other chemicals
Define hydrophilic and hydrophobic
Substances that dissolve (mix) with water are Hydrophilic
Substances that do not mix easily with water are Hydrophobic
What is the universal solvent?
Water
Metabolic reactions depend on ______ of water
solvency
Define adhesion versus cohesion
Adhesion—water adheres to other substances
Cohesion—water molecules cling to each other
Give an example of adhesion in the body
Water adheres to large membranes reducing friction around organs
Water adhering to large membranes is an example of _____
adhesion
Why is water so cohesive?
Its hydrogen bonds
What is surface film (think bugs walking on water) on the surface of water due to?
Surface film on surface of water is due to molecules being held together by surface tension
Which element’s thermal stability helps stabilize the internal temperature of the body?
Water’s
Define high heat capacity and explain why water’s heat capacity is so high
Something with a high heat capacity absorbs and releases large amounts of heat before changing temperature.
In water, hydrogen bonds inhibit temperature increases by inhibiting molecular motion.
What is an effective coolant?
Water
What is chemical reactivity?
The ability to participate in chemical reactions
Water ionizes into what two things?
H^+ and OH^−
What can water ionize?
Water ionizes many other chemicals (acids and salts)
Define acids
A substance that dissociates in solution to produce hydrogen ions (H+) and anions.
Define bases (also called alkalines)
A substance that dissociates in solution to yield cations and hydroxide ions (OH-).
Name two important bases (aka alkalines) in the body
Bicarbonate ion (HCO3–) and ammonia (NH3) are important bases in the body
Define salt
A substance that dissociates in solution producing cations and anions but not hydrogen ions or hydroxide ions.
Define the three pH categories
Acidic: pH 0–6.99
Basic: pH 7.01–14
Neutral: pH 7.00
Body fluids each have their own ____ range they must maintain.
pH
What can help prevent large changes in pH?
Buffers
Define energy
The capacity to do work [move something]
True or false: all body activities are forms of work
True
Define potential energy and give an example
Energy stored in an object, but not currently doing work (ex: water behind a dam waiting to be released)
Define chemical energy and free energy
Chemical energy—potential energy in molecular bonds
Free energy—potential energy available in a system to do useful work
Define kinetic energy and give an example
Energy of motion, doing work
Example: water flowing through a dam, generating electricity
Define heat
Kinetic energy of molecular motion
Define a chemical reaction
A process in which a covalent or ionic bond is formed or broken
Define chemical equation
Symbolizes the course of a chemical reaction (reactants into products)
What are the two classes of chemical reactions?
Decomposition and synthesis reactions
What are decomposition reactions?
A large molecule breaks down into two or more smaller ones (i.e. AB > A + B)
What are synthesis reactions?
Two or more small molecules combine to form a larger one (i.e. A + B > AB)
Define reversible reactions. When do they reach equilibrium?
Reactions that can go in either direction under different circumstances. They reach equilibrium when ratio of products to reactants is stable.
When do reactions occur?
When molecules collide with enough force and correct orientation
When do reaction rates increase?
When:
the reactants are more concentrated
the temperature rises
a catalyst is present
Define metabolism
All chemical reactions of the body
Define catabolism
Energy-releasing decomposition reactions that break covalent bonds and produce smaller molecules
Define anabolism
Energy-storing synthesis reactions that require energy input and the production of protein or fat
Catabolism and anabolism are inseparably linked. Why?
Anabolism is driven by energy released by catabolism
Define organic chemistry
The study of compounds containing carbon
What are the four categories of carbon compounds/ organic molecules?
Carbohydrates, lipids, proteins, and nucleic acids
Define macromolecules
Very large organic molecules with high molecular weights
Define polymers and give an example
Macromolecules made of a repetitive series of identical or similar subunits (monomers).
Ex: starch is a polymer of about 3,000 glucose monomers.
Monomers are linked together by ____________ and polymers are broken apart by _____
Monomers are linked together by dehydration synthesis and polymers are broken apart by hydrolysis
Define dehydration synthesis
Monomers covalently bind together to form a polymer with the removal of a water molecule
Define hydrolysis
Splitting a polymer by the addition of water
What is the primary function of carbohydrates?
Energy
What is the general formula of carbohydrates? Give an example.
(CH2O)n, n = # of carbon atoms
Ex: glucose, n = 6, so formula is C6H12O6
What are the three sizes of carbohydrate molecules
Monosaccharides, disaccharides, and polysaccharides
What are the three types of monosaccharides? How are they produced?
Glucose, galactose, and fructose. They’re produced by digestion of complex carbohydrates
What is glucose known as in medicine?
Blood sugar
Define isomer
Same molecular formula – different arrangment
What are the three types of disaccharides?
Sucrose, lactose, and maltose
What is sucrose?
A disaccharide known as table sugar
Glucose + fructose
What is lactose?
A disaccharide known as sugar in milk
Glucose + galactose
What is maltose?
A disaccharide known as grain products
Glucose + glucose
Give an example of a polysaccharide
Glycogen
What is glycogen and where is it found in the body?
A glucose polymer that is stored in the liver and skeletal muscles
Define starch
Energy storage in plants in the form of carbohydrates that is digestible by humans
Define cellulose
A structural molecule in plants that’s a carbohydrate that is important for human dietary fiber (but indigestible to us)
Are carbohydrates hydrophilic or hydrophobic?
Simple carbohydrates are small polar molecules (containing several -OH groups) which makes them hydrophilic
Why are lipids only made up of one group?
Because either part of or the entire molecule is hydrophobic.
What makes lipids different from carbs and proteins?
Usually contains more nonpolar covalent bonds than carbs or proteins
True or false: lipids are a very diverse group
True
What is the difference between saturated and unsaturated fatty acids?
Saturated fatty acids have a lot of hydrogen
Unsaturated fatty acids contain some double bonds
Essential fatty acids must be obtained from food
What are triglycerides (neutral fats)?
Three fatty acids linked to glycerol
What is the primary function of triglycerides (neutral fats)? What other thing does it help with?
Their primary function is energy storage (2x more energy than carbs or proteins). They also help with insulation and padding (shock absorption (adipose tissue))
Since triglycerides are hydrophobic, how are they transported in the human body?
Proteins have to carry them (not sure about this one)
What are phospholipids?
They are similar to neutral fats except one fatty acid is replaced by a phosphate group
Phospholipids are made up of a ___ and ____
head and tail
What is the “parent” steroid from which the other steroids are synthesized?
Cholesterol
Give some examples of steroids
Cholesterol, cortisol, progesterone, estrogens, testosterone, and bile acids
What are steroids important for?
They’re important for nervous system function and structural integrity of all cell membranes
15% of our cholesterol comes from our diet, where does the other 85% of cholesterol come from?
85% is internally synthesized (mostly in liver)
Define a protein
A polymer of amino acids
Define amino acids and what three things are attached to it.
They are a central carbon with three attachments:
an amino group (NH2), carboxyl group (—COOH), and a radical group (R group)
What determines the properties of an amino acid?
The R group
How many amino acids are there?
20
Amino acids only differ from each other in what way?
The R groups differ
What is a peptide?
Any molecule composed of two or more amino acids joined by peptide bonds
How are peptides named?
According to the number of amino acids they have: Dipeptides have 2 Tripeptides have 3 Polypeptides many Proteins have more than 50
Peptides are a component of ____
Proteins
How do peptide bonds form?
Dehydration synthesis creates a peptide bond that joins the amino acid of one group to the carboxyl group of the next.
What does the confirmation of a protein mean?
The unique, three-dimensional shape of protein crucial to function
What is crucial to the function of a protein?
Its confirmation
True or false: Proteins can reversibly change conformation and thus function
True
Define denaturation and what causes it. Give an example.
Extreme conformational change that destroys the function of a protein caused by extreme heat or pH.
Example: when you cook an egg
What are three specific examples of body functions that require proteins?
Muscle contraction, enzyme catalysis, and membrane channel opening
What are the four levels of protein structure?
Primary, secondary, tertiary, and quaternary
What are the seven main functions of proteins?
Structure, communication, membrane support, catalysis, recognition & protection, movement, and cell adhesion
Give an example where proteins help with structure
In keratin and collagen.
(Keratin—tough structural protein of hair, nails, skin surface
Collagen—contained in deeper layers of skin, bones, cartilage, and teeth)
Give an example where proteins help with communication
Between some hormones and receptors
Give two examples where proteins help with membrane transport.
Channel proteins in cell membranes govern what passes. Carrier proteins transport solutes to other side of membrane.
Give an example where proteins are needed for catalysis
Most enzymes are globular proteins
Give an example where proteins help with recognition and protection
Antibodies are proteins
Give an example where proteins help with movement
Motor proteins are molecules with the ability to change shape repeatedly
Define motor proteins
Molecules with the ability to change shape repeatedly
Give examples where proteins help with cell adhesion
Proteins bind cells together (example: sperm to egg)
and keep tissues from falling apart
What are enzymes and what do they do for our bodies?
They’re proteins that function as biological catalysts by lowering activation energy. They permit reactions to occur rapidly at body temperature
What permits reactions to occur rapidly at body temp?
Enzymes
Define substrate
A substance an enzyme acts upon
How are enzymes named?
Named for substrate with -ase as the suffix
Amylase enzyme digests starch (amylose)
What are the three steps of an enzymatic reaction?
1) Enzyme and substrate
2) Enzyme-substrate complex
3) Enzyme and reaction products
True or false: enzymes are reusable and not consumed by their reactions
True
Are enzymes fast or slow?
They work at an astonishing speed: One enzyme molecule can consume millions of substrate molecules per minute
What can change enzyme shape and function? What does changing an enzymes function do?
Temperature, pH and other factors can change enzyme shape and function, which can alter ability of enzyme to bind to substrate
Are proteins hydrophilic or hydrophobic?
Hydrophilic
Nucleic acids: Monomers are called _____
nucleotides
Nucleic acids: What are the four components of nucleotides?
1- Nitrogenous base
2- Adenine, Guanine, Cytosine, Thymine or Uracil
3- Sugar (ribose or deoxyribose)
4- One or more phosphate groups
Nucleotides become polymers called nucleic acids; what are three examples of nucleic acids?
ATP, RNA, and DNA
Nucleic acids: Describe DNA
Contains millions of nucleotides
Constitutes genes
Instructions for synthesizing proteins
Nucleic acids: Describe RNA’s function
A nucleic acid that follows DNA instructions to assemble proteins
Nucleic acids: Describe ATPs function
ATP is body’s most important energy-transfer molecule
Holds energy in covalent bonds
Most energy transfers to and from ATP involve adding or removing the third phosphate
Which of the following are examples of compounds? a) O2 and CO2 b) O2 and H2O c) CO2 and H2O d) all of the above Bonus points: Why?
c) CO2 and H2O
Explanation: a compound contains two or more elements, and although O2 is a molecule, it is not a compound because it only has one element
True or false: a proton or electron of Carbon will act the same as a proton or electron of Oxygen.
True
Why do our bodies need iron?
Iron is needed for our blood; oxygen doesn’t go through blood on its own, so iron is needed to grab it and carry it around. This is why we have things like iron infused cereals.
Why do our bodies need iodine?
Iodine is used by the thyroid in thyroid hormones which are used for metabolism; you don’t need a lot, but if you don’t have it, you can’t make those hormones. This leads to low energy, cold feeling, etc. This is why we use iodized salt.
Give an example of why minerals are important to our bodies using potassium
High or low potassium (K) = cardiac arrest
What can radioactive isotopes do that stable isotopes can’t?
They disintegrate and give off energy, and this energy can break chemical bonds
Give an example of using radioactive isotopes to negatively effect the human body
A former spy of soviet union was poisoned by someone putting a radioactive story in his tea (head this story before) and died due to radiation poisoning over a period of weeks.
Give an example of how radioactive isotopes are used in human medicine
We have ways to detect energy (like energy given off by radioactivity) and pick it up on a scan, so we can use these radioactive isotopes to see different parts of the brain (like plaques on the brains of Alzheimer’s pts)
True or false: atoms are not electrically neutral when they’re not ions
False; they are electrically neutral
True or false: you always fill the inner electron shells first
True
Give an example of something that’s a molecule but not a compound, and explain why
O2 is a molecule but not a compound, because compounds have two or more different elements.
Give an example of the importance of structural formula
Shape/location/structure can determine function (ex: glucose, fructose, and galactose all have the same formula, but different properties)
Give an example of inert elements with a full outer shell
Noble gasses
How are single covalent bonds usually represented?
Represented by a solid line
A weak charge attraction is also called a ____ ____
Hydrogen bond
Define intermolecular and intramolecular
Intermolecular: between individual molecules
Intramolecular: within an individual molecule
The intramolecular bonds in water are ____ _____ bonds, the intermolecular bonds between water molecules are _____ bonds
The intramolecular bonds in water are polar covalent bonds, the intermolecular bonds between water molecules are hydrogen bonds
