BIO140 Exam 1

What is basic?

less H+ bonds than OH-; a base accepts an H+ bond

What are organic molecules?

molecules containing carbon very important to life; molecules of life

What are isomers?

molecules that form different chemical structures but with the same formula

What is acidic?

more H+ bonds in it than OH-; an acid donates an H+ bond

What does non-polar mean?

more even electron distribution; no parts in compounds that have positive or negative charge, so they assemble themselves to have less contact with water

A lower pH indicates _____ H+ ions. A higher pH indicates _____ H+ ions.

more, less

energy

needed to do work within biological systems

In general, C-H bonds are _____ and _____.

non polar, hydrophobic

DNA and RNA are different types of _____ _____ polymers.

nucleic acid

What is broken off of ATP during hydrolysis?

one phosphate group

Entropy measures _____ in the universe. Unless you put energy in to overcome it, entropy will _____ over time.

order, increase

phototrophs

organisms able to capture energy from sunlight

chemotrophs

organisms that acquire energy from chemical compounds

autotrophs

organisms that can convert carbon dioxide into glucose; plants

heterotrophs

organisms that obtain carbon from organic molecules that other organisms synthesized; animals

What is electronegativity?

the ability of an atom to attract bonding electrons to itself

How would the cell membrane change in response to colder temperatures?

the amount of unsaturated fatty acids would increase

What is an atom?

the fundamental and smallest unit of matter

What does the atomic number on the periodic table tell you?

Number of protons and electrons

In the cell what is the purpose of DNA?

Stores genetic material and makes RNA

What is the relationship between strength of covalent bond and the amount of chemical energy it contains?

Stronger covalent bonds have less chemical energy. Examples are CO2 and H2O. Weak bonds contain a lot of chemical energy. *Because carbohydrates, proteins, and lipids have a lot of C-C and C-H (weak bonds), they have a lot of energy stored inside of them.

catabolism

a set of chemical rxns that break down molecules into smaller units + produce ATP

The two larger nucleobases called _____ are _____ and _____

purines, adenine, guanine

What is the difference between the N14 isoform (atomic mass = 14) of nitrogen and the N15 isoform (atomic mass = 15) of nitrogen?

# of neutrons

What is the general formula for all simple sugars?

(CH2O)n

Carboxyl group

-COOH

A solution at pH = 2 has ________ H+ atoms then a solution at pH = 4.

100x more

How many more or less H+ is found at pH=8 then pH=10?

100x more

What are the maximum number of electrons in each shell of the Bohr model?

1n^2 = 2 2n^2 = 8 3n^2 = 18

components of an atom (How many particles?)

3 particles

If one chain was 5' GACTATTGCATC 3', what would the complimentary chain read?

3' CTGATAACGTAG 5'

5′-ATAGGCATTCGATCCGGATAGCAT-3′ What is the sequence of the opposite DNA strand?

3′-TATCCGTAAGCTAGGCCTATCGTA-5′

There are _____ nucleobases

5

How many protons, neutrons, and electrons are found in this neutral N atom? Atomic number is 7, Atomic Mass is 14.00674, Chemical Symbol is N

7 protons, 7 neutrons, 7 electrons

Ionic Attractions

A fully charged ion is attracted to another fully charged ion in water

Fatty acids are often attached to _____?

A glycerol (sugar molecule)

1. What is the difference between a monosaccharide and disaccharide?

A monosaccharide is one sugar, where as a disaccharide is two sugars linked together

A woman's doctor tells her to gargle with salt water. She stirs a tablespoon of salt into a cup of warm water and watches the salt dissolve. Why does the salt dissolve in water? A. The partial positive charges on hydrogen atoms in water molecules are attracted to chlorine ions, and the partial negative charges on oxygen atoms in water molecules are attracted to sodium ions. B. The partial positive charges on hydrogen atoms in water molecules are attracted to sodium ions. C. The partial negative charges on oxygen atoms in water molecules are attracted to chlorine ions. D. The partial negative charges on chlorine atoms are attracted to positive charges on hydrogen atoms in water molecules. E. The partial positive charges on hydrogen atoms in water molecules are attracted to sodium ions, and the partial negative charges on oxygen atoms in water molecules are attracted to chlorine ions.

A.

Compare the difference between Adenosine diphosphate and Adenosine triphosphate.

Adenosine diphosphate only has two phosphate groups, where as Adenosine triphosphate has three phosphate groups (di= 2 tri=3).

DNA is made up of two ___________ chains.

Anti-parallel

The _____ of a chemical reaction are transformed into different molecules called _____. A. products; compounds B. reactants; products C. reactants; isomers D. products; reactants E. compounds; products

B. reactants; products

Why isn't life Silicon based?

Because silicon has only 9 orbitals in its 3rd shell, its four valence electrons have limited movement and cannot form a wide variety of bonds.

Compare and contrast the Bohr Model with the Quantum Model

Bohr Model: - organizes electrons into shells - defines exact location of nucleus Quantum Model: - organizes electrons into orbitals - gives probability of finding an electron in a given area Both: - each level still has the same amount of max electrons - protons and neutrons are in nucleus

Oak trees are categorized as: A. photoheterotrophs B. chemoheterotrophs. C. photoautotrophs. D. chemoautotrophs.

C

Carbonyl group

C=O

Organize the CHNOPS elements in order from most abundant to least abundant in a *dehydrated* cell:

COHNPS

What are the four major types of molecules in our cells that contain carbon (macromolecules)?

Carbohydrates, Fatty Acids, Nucleotides, Amino Acids

Argue for the central importance of the element carbon in life on Earth.

Carbon is the foundation of so much life. It can bond and create myriads of different molecules.

What does CHNOPS stand for and why is it important?

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus. They are important because they are the most common elements of life in a cell.

What are the four most common elements in organic molecules and which common macromolecules always contain all four of these elements?

Carbon, hydrogen, oxygen, and nitrogen are the four most common elements in organic molecules. Lipids, proteins, nucleic acids, and carbohydrates are common macromolecules that always contain these four elements.

A young girl is staring at the raindrops running down her window. She notices that the raindrops remain more or less intact, even as they cascade down the windowpane. This is a result of: A. covalent bonds between water molecules. B. ionic bonds between water molecules. C. oxygen bonds between water molecules. D. hydrogen bonds between water molecules. E. polar covalent bonds between water molecules.

D

Consider the two elements sodium (Na) and magnesium (Mg), which occupy the same row in the periodic table of elements. Sodium and magnesium atoms have: A. the same number of electrons in their outermost orbitals. B. the same atomic number. C. a different number of orbitals. D. different atomic masses. E. different atomic masses and the same number of electrons in their outermost orbitals.

D. different atomic masses

What sugar does DNA contain that RNA doesn't?

Deoxyribose

Carbon-carbon covalent bonds, such as the ones in carbohydrates and lipids, are _____ and have _____. A. weak; little potential energy B. strong; a lot of kinetic energy C. strong; little kinetic energy D. strong; a lot of potential energy E. weak; a lot of potential energy

E

Of the molecules, which has the greatest chemical potential energy? A. water B. sodium chloride C. carbon dioxide D. alanine E. glucose

E

What is Electronegativity and why does it help decide what type of bond is formed between two atoms?

Electronegativity is a measure of how strongly atoms attract bonding elctrons to themselves (Increases as you move from left to right across a period and decreases as you move down a group) If the EN difference is less than .4 = Non polar Covalent bond If the EN difference is between .4-1.7 = Polar covalent bond

T/F: RNA contains thymine, not DNA

False

What are Non-covalent interactions? Give one reason why they are important within the larger context of biology. (Hint: think about how they would act on certain molecules)

Forces being attracted to one another, NO sharing or transfer of electrons Non-covalent interactions are critical in maintaining 3D structure of large molecules such as proteins and nucleic acids (between molecules, not just atoms)

Because Carbon is so flexible, it can...

Form myriads of different types of molecules

Glucose is stored in _____ in human cells.

Glycogen

What is the bond between simple sugars called?

Glycosidic bond

Why do containers of water, milk and soda and other liquids sometimes burst when frozen?

H+ bonds create highly organized crystalline structures in ice that make the milk containers bulk up and burst.

_____ bonds are weak bonds that result from an electrostatic attraction between a partially charged _____ and an _____ atom.

Hydrogen, Hydrogen, electronegative

Phospholipid Bilayers form because:

Hydrophobic grouping increases the entropy and electrostatic interactions of water

Where do nucleotides store energy?

In a phosphodiester bond

What are the differences between covalent bonds and polar covalent?

In covalent bonds, there is an equal sharing of electrons, however, in a polar covalent bond, there is an unequal sharing of electrons, so one of the atoms to be more electronegative than the other.

Why is Carbon the backbone of life?

It is the only atom that can form four highly flexible bonds so it can make a higher diversity of molecules.

Amino group

N - H - H

Cold air has less entropy than hot air. The second law of thermodynamics states that entropy always increases. Do air conditioners violate this law?

No, the cold air itself still has the same amount of entropy, because its physical properties do not change, although it reaches more space throughout a room because the machine is puffing it around.

What type of bond would be formed between 2 equally electronegative atoms?

Non polar covalent (EN would be less than 0.4)

Hydroxyl group

OH-

Stanley Miller's 1953 experiments absolutely proves that

Organic molecules can be synthesized under particular conditions that may have been present on Early Earth.

What 2 CHNOPS elements are the most electronegative?

Oxygen and Nitrogen

Which element has 5 electrons in its valance shell?

Phosphorus

Considering that the electronegativity of this N atom is 3.04 and the electronegativity of the H atom is 2.20, what type of bond will occur between these two atoms?

Polar Covalent Bond

Amino acids are building blocks for _____.

Proteins

RNA is used by the cells to make____________.

Proteins DNA->rRNA->Proteins

What is the difference between a saturated and unsaturated fatty acid?

Saturated fatty acids have no double bonded carbons, whereas unsaturated fatty acids have at least one double bond between carbons.

In the early 1900s Ernest Rutherford produced a beam of very small positive particles and directed it at a thin piece of gold foil just a few atoms thick. Most of the particles passed through the foil without changing their path; very rarely, a particle was deflected. What conclusions can you draw from this experiment about the structure of an atom?

The atom is tiny and massive, and made up of empty space, which allowed most particles to pass through the gold foil. Particles could have been deflected because some of the particles would get close to the positively charged nucleus. Two positive particles repel.

What are the three unusual properties of water and why do these properties make water conducive to life?

The hydrogen bonds in water provide it with cohesion, so they are able to stick to one another, which causes high surface tension, which is important for plants so water can move through them. Water is also resistant to extreme temperature changes, which is why the ocean is able to control its temperature to allow life to exist in it. Because liquid water is denser than ice because its molecules are more tightly packed together, ice floats on the surface of water, which allows fish and other organisms to survive in frozen lakes in the winter time, because it is not frozen all the way through.

What is a POLAR covalent bond?

Unequal sharing of electrons that generates a partial charge

What is the purpose of chitin?

Used for structural support, makes up the hard protective coating on insects

Which property of the hydrogen bonding of water molecules is FALSE?

Water molecules can be pulled apart by electronegative atoms and can then come together to create ionic bonds.

What is a non polar covalent bond?

a covalent bond between atoms that have the same or very close to the same electronegativity

chemical energy

a form of potential energy held in chemical bonds between pairs of atoms in a molecule

You have an aqueous solution with a pH of exactly 7.0. What would you add to make the solution more acidic?

a molecule with a carboxyl group

What is a proton?

a positively charged particle located in the nucleus

What is an orbital?

a shape/region in space that designates the location/path where electrons are present, although their exact paths are never known; a cloud of points that is denser where the electron is more likely to be

What is a product?

a transformed molecule that is the result of a chemical reaction

What is a chemical bond?

a type of attraction that holds atoms together

What is ATP?

a universal currency; it provides energy in a form that is usable for all cells; it does not have energy itself but contains energy in its chemical bonds; participates in a broad range of transactions

first law of thermodynamics

also known as the law of conservation of energy that states that the universe has a constant amount of energy; energy can be transferred or transformed, but not destroyed

What is an isotope?

an atom that has a different number of neutrons but is of the same element of another atom

What is an ion?

an electrically charged atom

What is an electron?

an electrically negative charged particle that rotates in clouds surrounding the nucleus of an atom

kinetic energy

associated with any kind of movement

An_____is the smallest unit of matter. It is made up of _____ charged _____ and neutral _____ , which are both located in the _____ . Negatively charged _____ rotate in a _____ outside of the nucleus.

atom, positively charged protons, neutrons, nucleus, electrons, cloud

Van Der Waal's Attractions

attraction of nucleus of one atom to the electrons of another, occurs when atoms are very close together, weakest form of bonding, happens between all atoms as long as they are the right distance apart

What is hydrophilic?

attractive with water

Carbon can also link to other_____ atoms through covalent bonds to form long chains. Similarly, carbon can associate itself with molecules that have the _____ chemical formula, but different structures, also known as _____.

carbon, same, isomers

What are the four major components on an amino acid molecule?

central carbon, amino group, carboxyl group, and the R group (side chain - varies in amino acid)

What is a nucleus (of an atom)?

central core of an atom that contains protons, neutrons, and is positively charged

Three pyrimidines, smaller molecules, are _____, _____, and _____

cytosine, thymine, uracil

entropy

degree of disorder; lack of order or predictability

What is atomic mass?

designated by the number of protons and neutrons in an atom

What is a neutron?

electrically neutral charged particles located with protons in the nucleus; with protons they make up the mass of an atom (also called atomic mass)

The negatively charged components of atoms are referred to as:

electrons

What are Valence electrons?

electrons located the outermost from the nucleus as well as on the outermost of an atom's orbitals

What is a shell?

energy level; shells can have multiple orbitals within them like a bass section can be one line on the stage, but have multiple basses within it, some with bows and some without, as orbitals can be with or without the maximum number of electrons they can contain; electrons in the outermost shells have more energy than innermost electrons

What is a double bond?

formed when two adjacent atoms share two pairs of electrons; two sharing two; double line between element symbols; four orbitals with one electron each become two orbitals with two electrons each

What is a covalent bond?

formed when two atoms share a pair of electrons in a molecular orbital; two sharing one (pair, which is two electrons); single line between element symbols

What is a polar covalent bond?

formed when two atoms unequally share electrons

What are elements?

foundational substances combined in a variety of ways that are found in parts of nature

It is false that any covalently bonded H atom can participate in a _____ bond if it comes in close proximity with an oxygen atom of a water molecule.

hydrogen

The phospholipid bilayer has a _____ head and _____ tail.

hydrophilic, hydrophobic

What are the two forms of energy? Provide an example of each.

kinetic - associated with movement, potential - stored energy. Ex) ball at top of steps has potential energy, the ball has kinetic energy as it is in motion rolling down the stairs

What is the logic behind how the periodic table of elements is organized?

organized so that fundamental substances can be arranged based on their chemical composition/properties; elements are indicated by a chemical symbol and arranged based on their increasing atomic number; vertical columns or groups have the same number of electrons in the outermost shell

What features of carbon allow it to form diverse structures? One feature is that carbon's electrons move around the _____ orbital so that each of the four shapes within that orbital has _____ electron. This makes carbon able to form _____ bonds, with each rotating freely, defining its structural diversity.

outermost, one, covalent

Hydrogen Bonds

partially charged hydrogen atom is attracted to a partially charged electronegative atom

What are the ways that organisms obtain energy and carbon from the environment? What are the names used to describe these organisms?

phototrophs - from the sun, heterotrophs - from other organisms, chemotrophs - from chemical compounds, autotrophs - convert carbon dioxide into glucose

What is a Hydrophobic Effect?

polar molecules (water) with unequal distribution of electrons with parts of positive and negative charge exclude nonpolar molecules

A hydrophilic molecule is _____ and _____ dissolve in water

polar, can

Which subatomic particles contribute to the atomic mass for any given element?

protons and neutrons

What is "polar"?

refers to the unequal sharing of electrons; a molecule that has regions of negative and positive charges

What is hydrophobic?

repellent with water

anabolism

set of chemical rxns that require input of energy from ATP and build molecules

metabolism

set of chemical rxns that sustain life

What is a molecule?

single units that comprise of two or more atoms attached together

Water is considered the universal _____.

solvent

What is a solvent?

something that is able to dissolve many substances

What does cohesion mean?

sticks to water

potential energy

stored energy

Hydrophobic Effects

tendency for a non polar substance to aggregate with other non polar substances after being pushed away from water molecules in a solution

If an organism is a photoheterotroph then....

the organism uses food as a carbon source

What are reactants?

the starting molecules in a chemical reaction

second law of thermodynamics

the transformation of energy is associated with an increase in disorder in the universe

What is a molecular orbital?

two atomic orbitals that both have one electron each combine into a single orbital with a full complement of two electrons

What is a chemical bond?

two individual atoms interacting together while they are attached in a molecule

What is an ionic bond?

two ions are not covalently bound, but their opposite charges attract

A membrane that's more fluid is going to have more _____ fatty acids, where as a membrane that's less fluid is going to have more _____ fatty acids.

unsaturated, saturated

What does aqueous mean?

watery

What is a Hydrogen Bond?

when the slightly positively charged hydrogen atom bonds with another electronegative atom of different molecule