Atoms and molecules are nonliving materials from whihc all of nature is built
Cells are organized into increasingly complex levels:
-tissues
-organs
-organ systems
-organisms
Organisms, in turn, form:
-populations
-communities
-ecosystmes
-biosphere
homeostasis
homo, same, and stasis, standing
A physiological state in which the physical and chemical conditions of the internal environment are being maintained within tolerable ranges
dynamic balance
Ex: About 12 to 24 hours after the last meal, a person's blood sugar level normally varies from 60 to 90 milligrams per 100 millileters of blood, though it may rise to 130 mg/100 ml after meals high in carbohydrates. That the blood sugar level is maintained within a fairly narrow range despite uneven intake of sugar is due to the body's ability to carry out homeostasis.
What are the basic charactertics of life?
Taking in energy and materials
Sensing and responding to changes in the environment
Consisting of one or more cells
Reproducing and growing
What do these terms mean?
I. producers (plants)
II. consumers (animals)
III. decomposers (bacteria)
Producers: plants, trap energy of the sun by photosynthesis
Consumers: animals, feed on the stored energy in plants, using cellular respiration
Decomposers: bacteria and fungi, break down the biological molecules of other organisms in order to recycle raw meterials
What is the ultimate source of energy for the biosphere?
The sun
Define the word "theory" as correctly used in science.
A related set of hypotheses that form a broad-ranging explanation of many phenomena.
Theories are accepted or rejected on the basis of tests and are subject to revision (as new evidence comes to light) - Universally accepted = law
Explain the features of the scientific method:
REaliability of Data:
Sample size:large enough to represent the whole
Trials:
Hypotheses: Possible explanation of a natural event or observation, educated gueses using all known information
Controls:allows a standard of comparison for the experimental group.
Control groups: the standard to compare test group against.
Independent variables:
Dependent variables:
Aspect of an object or event that may differ with time or between sujects
Which of the following does not belong in the domain Eukarya?
D. Bacteria
A eukaryotic cell is a cell that has a "true nucleus" and other membrane-bound organelles.
Prokaryotic Cell
A single-celled organism that has not nucleus or any of the other membrane-bound organelles characteristic of eukaryotic cells
Example: Bacteria
Is an opinion associated with valid critical thinking?
Yes or No
No
Critical thinking is an objective evaluation of information - not opinions or hearsay
Fats that appear to be dangerous to the human body are:
E. trans fats
Protons
are part of the atomic nucleus and have a positive charge. Their quanitity is called the atomic number (unique for each element)
Electrons
Have a negative charge. Their quanitity is equal to that of the protons. They move around the nucleus
balance (=)
Neutrons
also part of the nucleus; they are neutral. Protons plus neutrons = atomic mass number
Varies
What two subatomic particles are almost always equal in number?
protons and electrons
Half-Life
The time it takes for half of a quantity of radioisotope to decay into a more stable isotope
Isotope
Varying forms of atoms andare the basis for organization of materials and the flow energy in living things. how they interact & bind to molecules
Tracers
A sugar or other molecule in which radioisotopes have been substitued for some atoms
Radiation therapy
Uses the radiation from isotopes to destroy or impair the activity of cells that do not work properly, such as cancer cells
Destroy cancer cells - iodine
What is a chemical bond (reaction)?
A union between the electron structures of atom (most stable when outer orbital is filled)
In chemical reactions, an atom can share electrons, with another atom, accept extra electrons, or donate electrons
Electrons are attracted to protons, but are repelled by other electrons
Orbitals can be thought of as occupying shells around the nucleus, representing different energy levels
Three types of chemical bonds
Molecule: contain more than one atom of the same element; N2
Compounds: consist of two or more elemetns in strict proportions (can have more than 1 atom)
Mixture: an intermingling of molecules in varyng proprtions
Ionic Bond - Chemical Bond
Joins atoms that have opposite charges 1(+) 1(-)
Gives atom to another one
When an atom loses or gains one or more electrons, it becomes positively or negatively charged (an ion)
Linked by mutual attraction of opposite charges, for example NaCl (sodium chloride)
give away = more (+)
take = more (-)
Covalent Bond - Chemical Bond
The bond formed when atoms SHARE electrons.
Strongest bond
nonpolar - share electrons equally
polar - share electrons unequally (slight difference in charge between the two atoms)
Hydrogen Bond
Weak bond
joins a hydrogen (H+) atom in one polar molecule with an electronegative atom in another polar molecule.
Weak on (-)(+) end of molecules
Life depends on water:
Water is polar molecule because of a slightly negative charge at the oxygen end and a slightly positive charge a the hydrogen end
Water molecules can form hydrogen with each other
tends to stabilize temperature because it has a high heat capacity (absorb considerable heat before its temperature changes)
Keeps stability - evaporative and freezing processes
Biological solvent -
Hydorphilic
Polar
water loving
Example: sugar, salt
Hydrophobic
Nonpolar
water dreading
repelled by water
Example: oils
Heat Capacity
the ability to absorb considerable heat before its temperature changes
Water can absorb and hold heat and tend to stablize temperature because it has a high heat capacity
A free radical will "steal" what particle from a stable molecule?
an electron
This happens when oxidatins in our cells realease highly unstable molecules called free radicals
Antioxidant
Substance that can give up an electron to a free radical before the rouge does damage to DNA or some other vital cell component
Example: hormone melatonin
pH Scale
Indicates the concentration of hydrogen ions
the greater the H+ the lower the value on the pH scale (more acidic)
the scale extends from 0 (acidic) to 7 (neautral) to 14 (basic)
Organic
If a molecule contains carbon and at least one atom of hydrogen it is considered organic
Enzymes
Proteins that speed up metabolic reactions
Acids
Give up hydrogen ions in a solution
Bases
Release ions that can combine to hydrogen
Example: Baking Soda
Buffers
Protect against shifts in pH
Combine with, r release hydrogen to prevent drastic changes
Bicarbonate is one of the body's major buffers
Functional Groups
atoms or groups of atoms covalently bonded to carbon backbone - convey distinct properties, such as solubility, to the complete molecule
set group of atom when attached give it a property
Condensation reaction is also referred to as _______
dehydration synthesis
means to take out water
two molecule fragments joined to form a new compound (H+ & OH-)
Hydrolysis reactions
the reverse of condensation reaction
one molecule is split by the addition of H+ and OH- (from water) to yeild the individual components
means to add water
Polymer
a large molecule built of three to millions of subunits
Which elements are most common in living things?
carbohydrates
lipids
proteins
nucleic acids
contain carbon
living organisms mostly oxygen, hydrogen, and carbon
Carbohydrate
Simple sugar or larger molecule composed of sugar units
The most ABUNDANT biological molecules
serve as energy sources - structural roles
Monosaccharides (simple sugar)
Oligosacharides (short-chain carbohydrates)
Polysaccharides (complex carbohydrates)
Examples of Carbohydrates and their functions
Glucose - energy source
Sucrose ( a disaccharide) - Most common form of sugar; the form transported through plants
Starch, glycogen - Energy source
Cellulose - structural roles
Lipids
compsed mostly of nonpolar hydrocarbon and are hydrophobic
do not dissolve in water but do dissolve in nonpolar substances, cuch as alcohols and other lipids
Glycerides - glycerol backbone with one, two, or three fatty acid tails (e.g. tryglycerides)
Phospholipids - Glycerol backbone, phosphate group, another polar group, and often two fatty acids
Waxes - alcohol with long-chain fatty acid tails
Sterols - four carbon rings; the number, position, and type of functional groups differ among sterols
Examples of Lipids
Fats (butter) & Oil (corn oil) - energy source
Lecithin - key componenet of cell membranes
Waxes in cutin - conservation of water in plants
Cholesterol - component of animal cell membranes; precursor of many steroids and vitamin D
Proteins
Most diverse of the large biological molecules
function as enzymes in cell movements; as storage and transport agents, as hormones, as antidisease agents, and as structural material througout the body
One or more polypeptide chains, each with as many as several thousand covalently linked amino acids
Mostly fibrous proteins - long strands or sheets of polypeptide chains; often strong water insoluble
Mostly globular proteins - one or more polypeptide chains folded int oglobular shapes; many roles in cell activities
Examples of Protiens
Keratine - structural component of hair, nails
Collagen - structural component of bone
Mysoin, actin - Functional components of muscles
Enzymes - Great increase in rates of reactions
Hemoglobin - Oxygen transport
Insulin - Conrol of glucose metabolism
Antibodies - Immune defense
What are the structures of protein
Primary Structure - defined as the chain (polypeptide) of amino acids; determines the shape and function of proteins by positiong different amino acids so that hydrogen bonds can form between them and by putting R groups in positions that force them to interact
Secondary structure - helical coil or sheetilke arrayresult from hydrogen bonding of side groups on the amino acid chains (coil = alpha helix or fold - beta pleated)
Tertiary structure - caused by interactions among R groups, resulting in complex three dimensional shape (R groups interact with each other)
Quaternary structure - two complete different chains work together to form globular or fibrous proteins (to do a job)
Protein Shape
Gycoproteins - sugar attached; lipoproteins have lipids
Cetain proteins combine with triglycerides, cholesterol, and phospholipids to form lipoproteins for transport in the body
Form when oligosaccharides are added to proteins
funcion in cells recongizing each other
Denaturation is when a prtein's shape is disrupted through high temperatures or chemicals (often irreversible; like a scrambled egg or hair perm)
Nucleotides and Nucleic Acids
Nucleotides are energy carriers, have five-carbon sugar (ribose or deoxyribose), nitrogen-containing base, and a phosphate group
ATP molecules - transfer energy
coenzymes - accpet and transer hydrogen atoms and electrons during cellular reactions
Nucleic acids include:
DNA - double-stranded; genetic messages are encoded in its base sequences
RNA - single stranded; it functions in the assembly of proteins