Chapter 2
Steroids
Lipids with entirely different structure from those of fats; backbone of 4 fused carbon rings
High levels of radiation are dangerous
because they can kill cells, damage DNA and cause cancer
Hydrolysis reaction
breaks down macromolecules by adding the components of water
Fatty acid
carbon hydrogen chain that ends with the acidic group -COOH
Four categories of organic molecules
carbs, lipids, proteins, nucleic acids
Molecule
chemical unit formed by atoms
Phospholipids
constructed like fats but have a phosphate or phosphate/nitrogen group in place of 3rd FA
Polysaccharides
contain many glucose units; starch, glycogen and cellulose
Organic
contains C and H
Peptide bond
covalent bond between 2 amino acids
1. What are the three sub-atomic particles?
• Protons • Neutrons • Electrons
Functional groups
attached to the carbon rings in steroids
Disaccharide; sucrose
2 monosaccharides joined by a dehydration reaction; glucose and fructose
double bond; triple bond
2 pairs of electrons shared; 3 pairs of electrons shared
Metabolic function of nucleotides
ATP: 3 phosphate groups, adenine, and ribose
Lipids
Absence of polar groups; they do not dissolve in water; little oxygen, mostly C and H
pentose, hexose, glucose
5-carbon sugar, 6 carbon sugar, hexose our body uses for immediate source of energy
DNA bases
A G T C
RNA bases
A G U C
10. Why are some molecules polar while others are not?
A polar molecule is a molecule in which electric charge isn't distributed symmetrically, while non-polar molecules have equally distributed charge throughout the entire molecule.
16. What are Acids and Bases? What is a buffer? Why is blood a highly buffered solution?
Acids are substances that dissociate in water, release hydrogen (H+) ions. Bases are substances that either take up hydrogen (H+) ions or release hydroxide (OH-) ions. Buffers are substances that tend to prevent pH changes of a solution, thus stabilizing its relative acidity and basicity. Buffers help keep the pH within normal limits because they are chemicals or combinations of chemicals that take up excess hydrogen (H+) ions or hydroxide (OH-) ions. Blood is a highly buffered solution because it has to have a very specific pH, and buffers help prevent any specific changes in pH.
8. What is an ion? How are ions formed? Why are ions more stable than atoms?
An ion is a particle that carries either a positive or a negative charge. After an ionic reaction (transfer of electrons), one particle will be positive and the other particle will be negative. Ions are more stable than atoms because they have a stable outer shell with 8 electrons.
7. How are ionic bonds different from covalent bonds?
An ionic bond is when an atom gives up or takes an electron so that both atoms have a stable outer shell (8 electrons in the outer shell). A covalent compound, on the other hand, is when atoms share electrons so that both atoms have 8 electrons in their outer shells. Covalent bonds are stronger than ionic bonds.
Saturated fats cause what disease
Atherosclerosis- formation of lesions on inside of blood vessels
w are atomic number and atomic mass calculated?
Atomic Number (the number above the symbol) is the number of protons (and therefore the number of electrons) that an atom has when it is electrically neutral. Atomic Mass (the number below the symbol) is the average mass of all the atoms of a particular element.
9. Why are only covalent compounds called 'molecules' and not ionic compounds?
Because the definition of a molecule is a covalent compound.
6. How are elements arranged in the Periodic Table? Why is the table called Periodic?
Elements in each row of the periodic table are arranged according to the increasing atomic number. The elements show periodicity—to show periodicity means that each column behaves similarly during chemical reactions.
Function of lipids
Energy storage molecules; others (phospholipids) form a membrane so that the cell is separated from its environment
Triglyceride
Glycerol molecule with 3 FA tails; neutral fats because they are nonpolar
5. What are Isotopes? Are all isotopes radioactive?
Isotopes are atoms that have the same number of protons (atomic number) but different number of neutrons. Not all isotopes are radioactive. Some are stable, whilst others are unstable and break down. A radioisotope is radioactive.
Are phospholipids neutral like fats?
No, the phosphate group is ionized (polar head); the rest of the molecule is hydrophobic tail
Emulsification
Process in which fats mix with water; emulsifiers are polar; the position themselves about an oil droplet with the polar end facing outward which enables it to disperse in water
Protein function
SUPPORT- structural, ENZYMES- catalyze chemical reactions, TRANSPORT - hemoglobin in blood, channel and carrier proteins in plasma membrane, DEFENSE- antibodies that bind with foreign substances called antigens, HORMONES- regulatory proteins that serve as intercellular messengers, MOTION- contractile proteins in muscles (SHEMTD)
Tracer (low level radioisotope)
Small amount of radioisotope (behaves exactly like isotope) that is inserted into the body to detect molecular changes- gives off radiation
Fats
Solid at room temperature found in animals; long term energy storage, insulation, protective cushion
Trans fats
artificially created using vegetable oils; partial hydrogenation causes trans fats to be semi solid and reconfigures some double bonds
15. Why is it significant that water boils at 100 degrees C? And freezes at 0 degrees C?
Water has high heat vaporization. This helps moderate the earth's temperature so that life can continue to exist. Because water is a liquid at room temperature we are able to drink, cook with it, and bathe in it. It also allows for hydrogen bonds.
13. What are two unusual physical properties of the water molecule that are most important to life on Earth?
Water is a liquid at room temperature, so we are able to drink it, cook with it, and bathe in it. The temperature of liquid water rises and falls slowly, preventing sudden or drastic change. Water has a high heat of vaporization, keeping the body from overheating. Frozen water is less dense than liquid water, so ice floats in water. Water molecules are cohesive, yet still flow freely and therefore liquid fills vessels.
11. Why is water a polar molecule?
Water is a polar molecule because the negatively charged electrons are closer to the oxygen atom, so the oxygen atom becomes slightly negative while the hydrogen becomes slightly positive.
14. Why is water the universal solvent? Why don't lipids and fats dissolve in water?
Water is the universal solvent because polar molecules dissolve in water and it facilitates chemical reactions both inside and outside of our bodies. Lipids and fats don't dissolve in water because they don't have polar groups.
Quaternary
When many polypeptides are arranged together
12. How does water interact with substances that dissolve in water? (Both Ionic and covalent compounds).
When substances are put into water, the negative ends of the water molecules are attracted to the positively charged ions and the positive ends of the water molecules are attracted to the negatively charged ions, causing the substance to dissolve in water. When ionic compounds interact with water the ions separate and dissolve in water and are considered hydrophilic (water-loving), while covalent compounds don't interact with water, and are considered hydrophobic (water-fearing).
Sugars in DNA and RNA
deoxyribose, ribose
what does water's cohesiveness allow for
dissolved and suspended molecules to be evenly distributed throughout the system
Unsaturated fatty acids
double bonds in the carbon chain wherever the number of hydrogens is less than 2 per carbon
DNA strand
double-stranded with base pairing (double-helix shape); rungs are base pairs, uprights are phosphate sugars
To show periodicity
each column of elements behaves similarly during chemical reactions
What makes water polar?
electrons spend more time circling the oxygen (larger atom) vs. the smaller hydrogen atom (positive side)
buffers
feature of the body and the environment to maintain a stable pH (they takeup excess hydrogen (H) or hydroxide (OH) ions)
Tertiary structure
final 3D shape caused by various bonding between R groups: ionic, covalent and hydrogen
Cellulose
found in plant cell walls; glucose is linked differently (we are unable to digest this linkage)- passes through our digestive tract as fiber
Glucose and ATP
glucose has too much energy to be used; converted to ATP which is a usable supply of energy for cell
Carbohydrate molecules
have the atomic grouping H-C-OH in which ratio of H to O atoms is 2-1; function for quick and short-term energy in all organisms
ATP
high energy molecule b/c the 2 last phosphate groups are unstable
why does water temp rise and fall slowly
hydrogen bonds that link the water molecules cause water to absorb a great deal of heat before it boils; water is a great temperature buffer
RNA
intermediary that conveys DNA's instructions regarding amino acid sequences
As a solvent, how does water facilitate chemical reactions?
ions and molecules disperse in water, they move and collide allowing reactions to occur
Denaturation
irreversible change in shape of proteins due to exposure to extreme heat or pH
water has a high heat of vaporization
keeps the body from overheating; moderates Earth's temperature
Benefits of high levels of radiation
killing bacteria and viruses; can be introduced into body to destroy cancer cells only
ADP
last phosphate bond is hydrolyzed
Primary structure
linear sequence of aminos
Strand
linkage of nucleotides with a backbone of phosphate sugar
Oils
liquid derived from plants
Proteins
macromolecules with amino acid subunits; amino group (NH2), acidic carboxyl group (COOH), and R group (rest of molecule)
Simple carbs
made up of one ring and only has 5-7 carbon's; simple sugar called a monosaccharide
Nucleotide
molecular complex of three types of subunits- phosphate, pentose sugar, and a nitrogen containing base
Compound
molecule in which the atoms are different
macromolecule
molecule that contains many subunits
waxes and their function
molecules made up of 1 FA combined with another single organic molecule like alcohol; coat the body and prevent heat loss
the 4 elements of the body
nitrogen, carbon, hydrogen and oxygen
DNA
nucleic acid that contains many genes which specify the sequence of amino acids in proteins
hydrogen bond
occurs whenever a covalently bonded hydrogen is slightly positive and attracted to a negatively charged atom some distance away (weak bond)
DNA and RNA are ________ of nucleotides
polymers
Secondary structure
polypeptide takes on a certain orientation in space; polarity causes polypeptide to coil in a helix shape or fold in a pleated shape
Cholesterol
precursor of steroids
Why are oils liquid at room temperature
presence of the double bond creates a bend in the FA chain which prevents close packing of molecules
calorie of heat energy
raises the temperature of 1g of water 1 degree C
starch
readily stored forms of glucose in plants (long chains); starch is broken down by the human body into glucose- release of insulin from pancreas promotes storage of glucose as glycogen
RNA strand
single stranded
Atom
smallest unit of an element that still retains the chemical and physical properties of the element
When the outer shell is full the atom will be the most...
stable
Acids
substances that dissociate in water, releasing hydrogen ions
Bases
substances that either take up hydrogen ions or release OH
Dehydration reaction
synthesis reaction that forms macromolecules; -H and -OH group (water basically) are removed
What is the energy from ATP breakdown used for?
synthesizing macromolecules such as carbs and proteins
An element is
the basic building block of matter it cannot be broken down by chemical means
Saturated fatty acids
the chain has all the hydrogen atoms it can hold (no double bonds between carbons)
Why are bases in nucleotides called bases?
they raise the pH
Polypeptide
three or more amino acids linked together (polar); oxygen is slightly negative and hydrogen is slightly positive
Fiber
various nondigestible carbs derived from plants; insoluble fiber promotes water absorption into fecal material and also adds bulk; soluble fiber combines cholesterol in the small intestine and prevents it from being absorbed
R groups
vary between molecule; can be polar or nonpolar
Frozen water is less dense than liquid water
water expands when it freezes because in ice, water molecules form a lattice in which the hydrogen bonds are farther apart than in water
Cohesive
water molecules cling together because of their polarity and hydrogen bonding
