BIO 160 Exam 1

Define biology.

Biology is the scientific study of life and is the branch of science that studies living organisms and the way organisms interact with their environments.

What are the characteristics of life?

Be made of materials organized in a hierarchical pattern. Use energy and raw materials to survive. Sense and respond to changing environments and maintain internal stability, or homeostasis. Grow, develop and reproduce with the help of DNA. Evolve.

The cell is.....

the smallest unit that displays all of these characteristics. Also, the fundamental unit of life.

Matter is....

any substance that has mass and takes up space.

hierarchy of life consists of.....

atom, molecule, Macromolecules, cell, organelles, microorganisms. Tissues, Organs, organ system, Organisms, population, community. ecosystem. Biosphere

What level of organization is found within all of the other levels

population

Emergent Properties

Characteristics of a system that do not appear in any one of its component parts alone, but that appear when all parts are combined.

Life is organized into....

hierarchical levels of increasing complexity

Life is an emergent property, and one that appears at...

the cellular level of organization.

What is the first level of hierarchical organization that possesses the emergent property of "life?"

cell

Organelle

A compartment inside the cells of eukaryotes that contain specific groups of macromolecules and carry out specific cellular functions.

Structure determines...

function.

Living organisms maintain.....

homeostasis.

Energy flows through living systems; matter....

is recycled

Life's components are....

interconnected and interdependent

Organisms grow, develop, and....

reproduce.

evolutionary processes explain both the unity and....

adaptive diversity of life

The structure of something is determined by two factors....

its three-dimensional shape, and the materials from which it is made.

Enzyme

A protein that speeds up the rate of chemical reactions that support life.

Cells typically keep their internal pH (acidity) within a narrow range. This is important because....

changes in pH can cause molecules like enzymes to change their shapes.

Homeostasis

The tendency of organisms and cells to maintain stable internal conditions. The term comes from the Greek words homeo (same, alike) and stasis (standing).

Ultimately, if homeostasis is not restored, an organism will....

die.

Humans maintain a blood pH between 7.35 and 7.45. In order to maintain homeostasis, how will your body respond if your blood pH drops to 7.0?

If you blood pH is 7.0, your body will raise your pH.

Matter is made of...

atoms.

Any matter an organism needs but cannot make for itself is considered a _____ for that organism

Nutrient

The atoms retain their ____ through the processes of life, even though they can be combined with other atoms in different ways.

Identity

Atom

The basic unit of matter that cannot be further broken down without losing its unique properties. One atom consists of a dense nucleus surrounded by a cloud of electrons.

Energy

The capacity to do work or to make a change in the location, temperature, or structure of matter.

Energy flows through living systems, changing...

forms as it goes

Matter cycles within...

living systems.

All organisms grow and develop. Growth is just an increase in size. In development...

structure and function change in an orderly way as an organism passes through its life cycle

An individual's pattern of development is partly determined by genetic instructions. DNA....

the molecule of inheritance, encodes proteins and other molecules that build cells and make them work.

Reproduction occurs when an individual organism passes on its genetic information to...

a newly independent organism, or offspring.

Evolution

A scientific theory explaining how and why genetic changes occur in populations or higher-level groups over generations of time.

Scientific Method

observation, question, hypothesis, scientific experiment, and conclusion

Independent Variable

A cause or factor; a variable that is thought to cause another variable to change. In an experiment, an independent variable is deliberately changed in one group at the beginning of the study.

Dependent Variable

An effect; a variable that is thought to change as a result or consequence of some other variable. In an experiment, a dependent variable is used to describe the result, or outcome.

Other variables must be kept as similar as possible between the study groups and are called...

control variables

The changes in the atomic composition of a substance that occur as a result of the attraction or repulsion of two or more atoms is called a chemical reaction.

A chemical reactions produce one or more products resulting from a chemical change that transforms a set of molecules.

All atoms have a nucleus, made up of...

protons (+) and neutrons(+-), and are surrounded by electrons(-).

Count the number of protons in the atom's nucleus, and that will tell you what kind of element that atom is..

The number of protons in an atom is denoted by the atomic number displayed for each element in the periodic table

major elements

carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S). These elements represent more than 95% of the mass of a cell.

Protons and neutrons reside in the nucleus (center) of the atom and have a mass of...

one atomic mass unit (amu) each

Electrons are found outside of the nucleus, in zones that are called "shells."

Electrons have almost no mass.

The atomic mass is the sum of....

the number of protons and the number of neutrons.

By summing the atomic mass of all the atoms in a molecule, one can estimate the...

molecular mass of the molecule.

Isotopes

Two atoms with the same atomic number , but different atomic mass Carbon-12 (the number after the hyphen, 12 in this example, indicates the atomic mass), which has 6 protons and 6 neutrons and Carbon-13, which has 6 protons and 7 neutrons are two isotopes of carbon.

The electron is the reactive part of the atom. The number and location of electrons determines the interactions between atoms. As you recall, negatively charged electrons are....

pulled toward the positively charged nucleus. But electrons are kept in orbit by kinetic energy. Electrons that are close to the nucleus are less energetic than those electrons farther from the nucleus.

The first shell can hold two electrons; the second and third...

shells can hold up to eight electrons.

The electrons that occupy the outermost shell are called valence electrons and are the electrons that are involved in chemical bonding...

The chemical properties of an element depend mostly on the number of valence electrons.

A key characteristic of atoms is that they are most stable when...

they have full outer electron shells

Neon. Neon (Ne) has an inner shell with two electrons and a full second shell with eight electrons.

In fact, all of the elements in that column of the periodic table have full outer shells, are stable, and do not react with other elements

Carry a negative charge, because they have more electrons than protons...

Anions...They readily take on one or more extra electrons. charge of -1.

On the periodic table, elements to the right (with the exception of the last column) are likely to take on...

extra electrons.

Conversely, elements on the left side of the periodic table tend to give up one or more electrons and become....

cations with a positive net charge

Radioactive isotopes emit energy in the form of radiation when they decay into different isotopes.

Radioactive isotopes can be used to visualize certain tissues for medical diagnosis.

Covalent bond...

strongest bond, occurs between atoms in the same molecule, Electron pairs are shared, creating a strong bond between atoms

Ionic bond...

moderate strength, occurs between atoms in the same molecule (i.e., between the ions), Electrons transfer from one atom to another, resulting in a moderately strong electrostatic attraction between oppositely charged ions

Hydrogen bond...

weak, Occurs between atoms in different molecules or parts of molecules, Weak electrostatic attraction between areas of molecules with opposite partial charges

Chemical bonds are attractions between...

atoms that hold atoms and molecules together.

The most stable situation for an atom is to have its..

outer shell completely filled with electrons

Ionic bonds are the interactions between...

ions of opposite charges. Elements in the outer columns of the periodic table often react in this manner.

A single pair of shared electrons makes a single covalent bond. Atoms can share...

two pairs of electrons (in a double bond), or even three pairs of electrons (in a triple bond).

Sharing of electrons is called...

a covalent bond

Oxygen has an atomic number of eight. How many electrons are in its outermost shell?

6

How many covalent bonds can oxygen form to fill its outer shell?

2

How many hydrogen atoms will probably form covalent bonds with oxygen?

2

When two atoms are joined by a covalent bond, the new structure that forms is called...

a molecule

Contrast to the structure formed when two atoms are joined by an ionic bond, which is called an...

ionic compound

The molecular mass or weight of a molecule is the sum of...

the individual atomic weights.

The first carbon actually formed two bonds with the oxygen atom; this is called...

a double bond.

Electronegativity

The ability of an atom to draw shared electrons closer to itself. Strongly electronegative atoms bonded to weakly electronegative hydrogen atoms, in a molecule, result in hydrogen bonding.

The most important strongly electronegative elements in biological systems are...

oxygen and nitrogen.

Bonds in which electrons are unequally shared between the atoms are called...

polar covalent bonds.

Many of the important molecules of life, like DNA, proteins, and even ordinary water, share a key characteristic:

they all form hydrogen bonds.

Hydrogen bonds are not like the covalent bonds.. They do not join atoms into molecules. Instead, they are the attraction...

of an electronegative atom to a hydrogen that is covalently bonded to another electronegative atom.

Involves the attraction of the hydrogen with a partial positive charge to the electronegative atom with a partial negative charge.

Only hydrogen covalently bonded to an electronegative atom can participate in hydrogen bonding.

water behaves the way it does because..

of the hydrogen bonds that attract water molecules to each other.

four properties of water that make it such a unique and important molecule...

Water is an excellent solvent and can dissolve a wide range of substances. Water is cohesive. Water's temperature tends to remain stable. Solid water (ice) is less dense than liquid water.

Solutions are..

homogeneous mixtures.

solvent: the component of the solution...

in the greatest quantity.

solutes: the component(s) present in...

lower quantities

Water is the ____ and the salt is the ____.

solvent, solute

Hydrophilic

Substances that dissolve in or are attracted to water. Hydrophilic (from Greek meaning "water-loving") refers to molecules that are water soluble. Ionic and polar substances are hydrophilic. That is, hydrophilic molecules contain polar functional groups that can form hydrogen bonds or ionic bonds with water.

Hydrophobic

Hydrophobic, or water-fearing, molecules do not interact with water and are characterized by a complete lack of electronegative atoms. In aqueous solutions the hydrophobic molecules are driven together to the exclusion of water.

Polar molecules also are...

hydrophilic.

Ionic substances like table salt (NaCl) are...

hydrophilic.

Nonpolar molecules are hydrophobic. Examples, include...

hydrocarbons and fatty acids with their abundant nonpolar C-H bonds

The interaction between a polar bond on water and polar bonds on hydrophilic molecules is given a special name....

the hydrogen bond, because it involves a hydrogen that forms a bridge between the two molecules.

Hydrogen bonds are fairly stable...

so quite a bit of energy is released when they are formed.

Since hydrophilic molecules contain polar bonds...

they are often referred to as polar molecules.

Hydrophobic molecules lack the electronegative atoms that are required to generate a polar bond. Thus, hydrophobic molecules are also referred to as...

nonpolar.

The fact that nonpolar molecules cannot form hydrogen bonds in one reason why they have low solubility in water...

however, there is another far more important force that drives nonpolar molecules from water, called the hydrophobic effect.

Hydrophobic Effect---When a non-polar molecule dissolves in water it becomes completely surrounded by water molecules. The water molecules cannot form hydrogen bond with the non-polar molecule, however they do form...

hydrogen bonds with the other water molecules that surround the non-polar molecule, forming a layer of hydrogen bonded water molecules that cover, or form a cage, around the dissolved non-polar molecule

The energy cost of ordering water molecules around nonpolar compounds is so high that they are forced out of the water, leading to a separation of phases; oil and water don't mix because of the...

hydrophobic effect

Molecules that contain a very polar part and a very nonpolar part are called

amphipathic.

The carboxylate group (COOH) on the left interacts strongly with water, while the remaining part of the molecule is...

very hydrophobic and is forced away from water.

Fatty acids form structures. These spherical structures have the hydrophilic part exposed to water on the surface of the sphere and bury the hydrophobic part in the center of the sphere.

micelles.

You might be wondering why triglycerides are not amphipathic, given that they are similar to fatty acids, with a polar group of atoms and a nonpolar group.

The reason is that the polar region of triglycerides interacts weakly with water because there is no free -OH group.

Adhesion

The attraction of water molecules to molecules other than water. Capillary action (in which water will spontaneously climb up the walls of a tube without pumping) is a result of the adhesion of water molecules with the surface of a tube containing the water.