Chapter 1 Flashcards
Name the mass and charge of each subatomic particle
proton: +1 , 1 amu
neutron: 0 , 1 amu
electron: -1 , 0
An atom in the elemental state (as an element) always has a neutral charge because
the number of protons (+) equals the number of electrons (-)
Why is electron configuration important?
it determines how a particular atom will react with atoms of other elements
Explain ground state
electrons in the lowest available energy level
Explain excited state
when an atom absorbs energy, its electrons move to a higher energy level
Provide an example of atoms in an excited state.
During photosynthesis, chlorophyll molecules absorb light energy, which boosts electrons to higher energy levels.
- The excited electrons provide the energy to make sugar as they return to their ground state and release the energy they previously absorbed
Isotopes
atoms of 1 element that vary only in the number of neutrons in the nucleus
Chemically, all isotopes of the same element are identical because
they have the same number of electrons
Radioisotopes are
isotopes that are radioactive, for example, carbon-14
Explain half-life
the nuclei of radioisotopes emit particles and decay at a known rate
How can we use half-life?
measuring the age of fossils or to estimate the age of Earth
Define tracer.
a radioactive substance that can be used to track a substance as it moves through an organism or through a metabolic pathway
-radioactive carbon can be used as a tracer
When a bond is formed, _____
When a bond is broken, ______
energy is released
energy must be supplied or absorbed
Ionic bonds
form when electrons are transferred
Give examples of ions that are necessary for our health
Cl-, Na+, and Ca2+ are important for normal cell, tissue, and organ function
Covalent bonds
form when atoms share electrons
What type of bond results in a molecule?
a covalent bond
The two types of covalent bonds are _______
What are these classifications based on
nonpolar and polar
whether electrons are shared equally or unequally
What are the characteristics of nonpolar covalent bonds?
electrons are shared equally
formed between any 2 atoms that are alike
for ex. H2, O2, etc.
What are the characteristics of polar covalent bonds?
electrons are shared unequally
formed between any 2 atoms that are unlike
for ex. CO and H2O
Intermolecular attraction are
attractions between molecules
Dipole - Dipole forces
Polar-Polar attraction
attractive forces between the positive end of 1 polar molecule and the negative end of another polar molecule
Dipole-dipole bonding can result in
either a polar (unbalanced) molecule or nonpolar (balanced)
Which bond has stronger attractions between them? Polar or Nonpolar molecules
polar molecules
for ex. water is a highly polar molecule
Hydrogen Bonding
a special type of dipole-dipole attraction between molecules to a hydrogen atom
What does a hydrogen bond result from?
results from the attractive force between a hydrogen covalently bonded to a very electronegative atom such as a FON molecule
(or another very electronegative atom)
Functions of hydrogen bonding
- keeps the 2 strands of DNA bonded together, forming a double helix
- causes water molecules to stick together and is responsible for many special characteristics about water
van der Waals bonding
Nonpolar molecules
caused by temporary attractions between fluctuating polarization of nearby molecules
- the weakest attractions
- ex. CO2, linear and balanced
_______ substances dissolve in water
_______ substances will not dissolve in water
polar , nonpolar
Remember: _____ dissolves ____
like dissolves like
Why does an open can of soda go flat?
since CO2 is a nonpolar molecule and water is polar, CO2 does not dissolve in water
so, when you open a can of soda, the gas escapees and it goes flat
Lipids are _____ and _____ meaning they do not _______ in water. This is why ___ and _____ salad dressing separate.
nonpolar, hydrophboic, dissolve
oil, vinegar
What substances can dissolve through the plasma membrane? Which cannot? How do these substances travel?
- Nonpolar substances can dissolve
2. Large polar molecules cannot unless they are in special hydrophilic (protein) channels
Water is ______. It also has strong ______ attractions and exhibits strong _____ bonding.
asymmetrical, intermolecular polar, hydrogen
The 6 characteristics of water are:
- high specific heat
- high heat of vaporization
- high adhesion properties
- universal solvent
- strong cohesion tension
- ice floats because it is less dense than water
Large bodies of water, like the ocean ________.
This provides ___________.
Coastal areas exhibit relatively ________.
- absorb a lot of heat and resist changes in temperature
- a stable environment for the organisms that live in them
- little temperature change because oceans moderate their climates
A relatively ________ is needed to evaporate water.
Ex. Evaporation of sweat,_______.
- great amount of heat
2. significantly cools the body surface
What is adhesion and how does it affect plant survival?
- the clinging of 1 substance to another
2. forces of adhesion contribute to capillary action, which helps water flow up from the roots of a plant to the leaves
Since water is a highly polar molecule, it ________
dissolves all polar and ionic substances
Define cohesion tension and explain 2 biological phenomena it causes
- molecules of water tend to stick to each other
- water moves a tall tree from the roots to the leaves without the use of energy by transpirational-pull cohesion tension
- surface tension allows insects to walk on water without breaking the surface
In a deep body of water, floating ice __________.
insulates the liquid water below it, allowing life to exist beneath the frozen surface during cold seasons.
Explain spring overturn.
- In spring, ice melts, becomes denser water, and sinks to the bottom of the lake
- this causes water to circulate throughout the lake
- oxygen from the surface returns to the depths, while nutrients released by the activities of bottom-dwelling bacteria are carried to the upper layers of the lake
- this cycling of nutrients in a lake is spring overturn and is necessary to the health of a lake
Define pH
a measure of acidity and alkalinity of a solution
-the negative logarithm of the hydrogen ion concentration in mol/liter
How do we know if a substance is acidic, alkaline, or neutral?
acidic- pH less than 7
basic/alkaline- pH greater than 7
neutral- neutral
As the concentration of H+ increases, ____________
the pH decreases
A solution of pH 1 is ______ more acidic than a solution with a pH 2.
and ______ more acidic that pH 3
and _____ more acidic than pH 4
10 times
100 times
1000 times
pH vs. molarity ph 1 --> concentration of H+ ph 2 --> ph 3---> ph 4 --->
1 x 10^-1 , 0.1 molar
1 x 10^-2 , 0.01 molar
1 x 10^-3 , 0.001 molar
1 x 10^-4 , 0.0001 molar
pH of stomach acid
2
pH of orange juice
3.5
pH of carbonated drinks
3.0
pH of acid rain
<5.6
pH of milk
6.5
pH of human blood
7.4
pH of seawater
8.5
The internal pH of most living cells is _____.
Even a slight change _______.
close to 7
can be harmful
How do biological systems regulate their pH?
What is the most important ______ in human blood?
buffers
buffer, bicarbonate ion (HCO3-)
Define buffers and explain how they work.
- substances that resist change in pH
2. works by absorbing excess hydrogen ions or donating hydrogen ions when there are too few
What is acid rain a result of? How is it harmful?
results from certain pollutants in the air (SO2, SO4, and CO2)
-has caused damage to many lakes and stone architecture
Define organic compounds and list their classes.
compounds that contain carbon there are 4 classes: carbohydrates lipids proteins nucleic acids
Carbohydrates consist of ______.
What are their characteristics?
3 elements, carbon, hydrogen, oxygen.
- supply quick energy
- 1 g of any carb releases 4 cal of heat when burned
- dietary sources include rice, pasta, bread, and cookies
3 classes of carbohydrates
monosaccharides, disaccharides, polysaccharides
Monosaccharides:
Chemical formula
Examples
How these examples relate to each other?
C6H12O6
glucose, galactose, and fructose
They are isomers of each other
Isomers
compounds with the same molecular formula but different structure
they have different physical and chemical properties
Disaccharides
Chemical formula
Composed of ________.
C12H22O11
consist of 2 monosaccharides joined by a process known as dehydration synthesis
Dehydration synthesis (aka synthesis)
process in which molecules are bonded together to form a larger molecule with the removal of water
Dehydration synthesis of monosaccharides
C6H12O6 + C6H12O6 =
C12H22O11 + H2O
solve.
Glucose + Glucose =
Glucose + Galactose =
Glucose + Fructose =
maltose + water
lactose + water
sucrose + water
Hydrolysis
the chemical breakdown of a compound due to reaction with water.
this opposite of dehydration synthesis
-occurs during digestion
ex. sucrose + water = glucose + fructose
Polysaccharides
Definition
How they are formed.
The 4 important examples.
polymers of carbohydrates
form as many monosacccharides are joined together by dehydration synthesis
cellulose, strach, chitin, and glycogen
Polysaccharides found in plants are:
found in animals:
- cellulose
- starch
- chitin
- glycogen
Cellulose
makes up plant cell walls
Starch
the way plants store carbohydrates
Chitin
makes up the exoskeleton n arthropods and cell walls in mushrooms
Glycogen
‘animal starch’ ; in humans, this is stored in the liver and skeletal muscle
Lipids
What they are.
What they consist of.
organic compounds that include fats, oils, and waxes
most consist of one glycerol and 3 fatty acids
Fatty acid
Definition
Types
a hydrocarbon chain with a carboxyl group at 1 end
saturated or unsaturated
Saturated fats Consist of Where they come from Characteristics An example
-contain only single bonds between carbon atoms
1.come from animals
2.solid at room temperature
3.when ingested in large quantities are linked to heart disease
butter
Unsaturated fats
Consists of ?
Where they come from
Characteristics
- have at least 1 double bond between carbon atoms in the hydrocarbon chain, thus they have fewer hydrogen atoms
- extracted from plants
1. liquid at room temperature
2. good dietary fats
Lipid Functions
- energy storage: 1 g of any lipid will release 9 cal of heat per gram when burned in a calorimeter
- structural: phospholipids are a major component of the cell membrane
- endocrine: some lipids are hormones
What are proteins?
proteins are polymers or polypeptides consisting of repeating units called amino acids joined by peptide bonds
What do amino acids consist of?
a carboxyl group, an amine group, and a variable (R) . all attached to a central carbon atom
-the R group, or variable, differs with each amino acid
What are proteins responsible for?
proteins are complex macromolecules and are responsible for growth and repair
Protein characteristics
- dietary sources include fish, poultry, meat, and certain plants called legumes like beans and peanuts
- 1 g of protein burned in a calorimeter releases 4 cal of heat
- proteins consist of the elements SOCPHN
How many amino acids are there? What can they build?
20 different amino acids
can build thousands of different proteins
Name an example of proteins
enzymes
Two amino acids can form a ____.
Define ______.
dipeptide
A dipeptide is a molecule consisting of 2 amino acids connected by 1 peptide bond
Define each: peptide peptide bond polypeptide peptidases polymer
- a string of amino acids which are the ‘building blocks’ of proteins (doesn’t have as many amino acids as a protein does)
- a covalent bond joining the a-amino group of 1 amino acid to the carboxyl group of another with the loss of a water molecule
- a chain of amino acids linked together by covalent (peptide) bonds
- enzymes that break down proteins into amino acids
- molecules that are chains of repeating units; proteins and DNA are examples
The shape of a protein is the result of
the result of four levels of structure
Primary structure
results from the sequence of amino acids that make up the protein chain (linear)
Secondary structure
results from the hydrogen bonding within the molecule. the helical nature of many proteins is the result of hydrogen bonding
(think of a spiral of ‘slinky’)
Tertiary structure
3d shape or conformation of a protein and most directly determines the way it functions and its specificity.
( ‘knotted’ structure)
tertiary structure is directly responsible for the shape of a protein and how it functions
Enzymes _________ in high temperatures or adverse pH. When a protein/enzyme denatures, it cannot function because ________.
denature (lose their natural shape)
its tertiary structure has been altered beyond repair
Quaternary structure
refers to proteins that consist of more than 1 polypeptide chain
-hemoglobin exhibits quaternary structure because it consists of 4 chains
(several ‘knot’ structure bonded together)
Define enzymes and their functions
- large proteins
2. speed up reactions by lowering the energy of activation (Ea), the amount of energy needed to begin a reaction
Define substrate.
Explain how enzymes related to substrates.
- the chemical that an enzyme works on
- enzymes are specific, only substrate A will bind to it’s enzyme
Explain the induced-fit model
describes how enzymes work
As the substrate enters the active site, it induces the enzyme to alter its shape slightly so the substrate fits better
Why was the lock and key model abandoned?
because it implied that the enzyme never changes
What happens to an enzymes during a reaction?
enzymes are not degraded during a reaction and are reused
How are enzymes named?
they are named after their substrate and the name ends in the suffix ‘ase’
ex. sucrase is the name of the enzyme that hydrolyzes sucrose
Enzymes function with the assistance from
cofactors (minerals) or coenzymes (vitamins)
What is the efficiency of the enzyme affected by?
affected by temperature and pH
average body temp is 37 degrees C near optimal for human enzymes
-if the body temp rises above 40 degrees C, the enzymes will stop functioning
As enzymes denature, they
lose thier unique shape and ability to function
Gastric enzymes become active at ________
Intestinal amylase work best in _______
low pH, when mixed with stomach acid
an alkaline environment
Prions
infectious proteins that cause several brain diseases (i.e. mad cow)
- its a misfolded version o a protein normally fond in the brains of mammals.
If a prion gets into a normal brain, it ______
causes all the normal proteins to misfold in the same way
What are nucleic acids and what to they do?
- deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
2. carry hereditary information
What are nucleic acids?
What does a single nucleotide consist of?
- polymers (chains of repeating units) of nucleotides
2. consists of a phosphate, a 5-carbon sugar (deoxyribose or ribose), and a nitrogenous base
In DNA, the nitrogen bases are:
In RNA, the nitrogen bases are:
adenine, cytosine, guanine, thymine
adenine, cytosine, guanine, and uracil (instead of thymine)
Adenine and guanine are:
Cytosine, thymine, and uracil are:
purines
pyrimidines
