Chapter 2 The molecules of Cells Flashcards
What is essential to the normal functioning of cells and part of a cells outer membrane, and serves as a precursor to hormones such as testosterone and estrogen (sex hormones)?
Cholesterol
Cholesterol on its way from the tissues to the liver for recycling is called?
HDL- high density lipoproteins
“Good” cholesterol
HDL- high density lipoproteins- reduces the likelihood of the formation of plaque in the arteries
Cholesterol on its way to the tissues is called?
LDL- low density lipoproteins
“Bad” cholesterol
LDL- low density lipoproteins-contributes to the development of plaque which can result in heart disease
Anything that takes up space and has mass refers to?
Matter
Four distinct states of matter?
Solid
Liquid
gas
plasma
All matter, non living and living is composed of?
elements
Elements
substances that cannot be broken down into substances with different properties; composed of only one type of atom
Each element has its own unique properties such as
density, solubility, melting point and chemical reactivity
__ naturally occurring elements serve as the building blocks of all __.
92; matter
Which six elements are essential to cells and are basic to life and make up about 95% of the body weight of organisms?
Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur
What other elements are important to all organisms?
Sodium Potassium Calcium Iron Magnesium
Earth crust primarily contains the elements?
Silicon
Aluminum
Oxygen
Elements consist of tint particles called
atoms
John Dalton in 1800s said that elements consist of tiny particles called __ which was the __ theory?
atoms; atomic theory
An __ and its atom share the same name.
element
Elements are identified by an __ that is composed of one or two letters.
atomic symbol
Ex: H means hydrogen atom
Three subatomic particles that make up atoms are called?
Protons: + charged
Neutrons: x uncharged
Electrons: - negatively charged
Protons and Neutrons are located within the ___ of an atom and electrons move __ the nucleus.
nucleus; around
electron shell or orbital
the average location, or energy level, of an electron in an atom. often drawn as a circle around the nucleus.
atomic number
number of protons in the nucleus.
EX:
29- atomic number
CU
coppermass number
number of protons plus the number of neutrons within the nucleus.
Atomic mass unit
AMU protons and neutrons are assigned one atomic mass unit each. electrons are so small that their amu is considered zero.
Isotopes
“equal”; same atomic number but a different mass number due to a variation in the number of neutrons. Ex: carbon12, carbon13 carbon 14
atomic mass
refer to the average mass for all teh isotopes of the atom.
atomic number element symbol atomic mass (carbon)
6
carbon
c
12.0112
On the periodic table the vertical columns are
groups
on the periodic table the horizontal rows are
periods
group VIII of atoms are called the
noble gases
EX: helium and krypton
Radioactive isotope
unstable; has a nucleus with excess neutrons that is often unstable and emits energy as it decays
Carbon 14 changes over time into nitrogen 14. As carbon 14 decays it releases rays and subatomic particles. This is an example of a __ isotope.
radioactive.
Instrument that is commonly used to detect radiation?
The Geiger
Radioactive isotope in small samples are used as _ to detect molecular changes.
tracer or chemical tag
__is a way to determine the comparative activity of tissues.
PET- positron emission tomography
__is used to illustrate the structure of an atom.
Bohr model;
Named after Niels Bohr, its useful in examining the number of __ in an atom.
electrons
The first shell contains
up to __ electrons. The shell after is most stable with __ electrons. In all atoms, the _ shells are filled with electrons before the next higher level contains any electrons.
2;8; lower
The __ shell helps determine the atoms chemical properties and how many other elements it can interact with.
Valence; outermost
Bohr diagrams the energy level of the electrons called __are drawn as __ about the __.
electron orbital; circle; nucleus
The __ of the periodic table tells you how many _ an atom has. The __ tells you how many electrons an atom has in its __ shell.
Periods or horizontal rows ; electron shells or electron orbitals;
groups; outer
EX sulfur is in the third period and contains 3 shells and in group VI meaning 6 electrons
Valence shell
the outer electron shell of an atom which determine the chemical reactivity of the atom.
octet rule
an atom is more stable when its outer shell is complete with 8 electrons. except hydrogen which only requires 2 to be complete
The number of electrons in an atoms valence shell determins whether an atom __
gives up, accepts or shares electrons to get to 8 in the outer shell
When two or more atoms bond together they form a?
molecule
Molecule
union of two or more atoms of the same element. smallest part of a compound that retains the properties of the compound.
EX: O2
When two or more different elements bond its called
compound Ex: H2O
Compound
Substance having two or more different elements in a fixed ratio.
Ions form when electrons are transferred from one atom to another. True or False.
True
Ions
charged particle that carries a negative or positive charge.
Ionic bond
chemical bond in which ions are attracted to one another by opposite charges
covalent bond
chemical bond in which atoms share one pair of electrons. Results when two atoms share electrons that each atom has an octet of electrons in the outer shell.
In a hydrogen atom the outer shell is complete when it contains two electrons. Hydrogen can share with another atom and thereby have a completed outer shell. Their two shells overlap and the electrons are shared between them. Each atom has a completed outer shell due to the sharing electrons. This is known as?
A covalent bond
H-H is the ___explaining that atoms are sharing electrons
structural formula
H2 in the __ is explaining that atoms are sharing electrons
molecular formula
__ occurs when two atoms share two pairs of electrons and even triple covalent bonds like as in __ gas.
double covalent bond; nitrogen
Molecules consisting of only two atoms are always
linear
Molecules such as methane with five atoms have a __ shape.
tetrahedral: each bond is pointing to the corners of a tetrahedron
The __ model of a molecules shape comes closest to the actual shape of the molecule.
space-filling
“structure equals function” means
the shape of a molecule is important to the structural and functional roles it plays in an organism.
Antibodies combine ith disease causing agents like a key fits a lock to protect us. This is an example of?
“structure equals function”
When the sharing of electrons between two atoms is fairly equal the covalent bond is said to be a
nonpolar covalent bond
Non polar covalent bond
Equal; bond in which the sharing of electrons between atoms is fairly equal.
H2O, the sharing of electrons between oxygen and each hydrogen is not completely equal because one atom is able to attract electrons to a greater degree than the other atom. The atom that has a greater attraction for a shared pair of electrons has a greater ___.
Electronegativity.
Electronegativity
the ability of an atom to attract electrons toward itself in a chemical bond
polar covalent bond
bond in which the sharing of electrons between atoms in unequal
