Biology Exam 1

What are the key components of life?

Must be composed of cells, need energy to survive, have the ability to reproduce, contain genetic information, and participate in evolution

What is a theory versus hypothesis?

An explanation for a very general class of observations that are widely supported by evidence versus a testable statement to explain a focused question

What are heritable traits?

Traits that help a species survive natural selection by evolving

What is the chromosome theory of intelligence?

Says cells have information encoded in gene units (DNA)

What affects structure?

Function

What makes carbon useful?

They can easily share 4 covalent bonds with molecules, are able to make many structures giving molecule shape, and are in all organic molecules but water

What makes the mass number?

The sum of protons and neutrons (everything in the nucleus)

What are orbitals?

Areas electrons are found on valence shells

What is the relationship between protons and electrons?

Protons want to pull electrons but the further electrons are from nucleus the harder that is to do, so there is less electronegativity

What dictates reactivity?

Valence electrons

Atom’s reactivity

O > N > S = C = H = P

What is an atom’s “valence” refer to

The number of unpaired electrons it has

What is a covalent versus ionic bond?

Covalent means that electrons are shared between atoms but ionic means they are fully transferred

What does it mean to be electronegative?

An atom’s willingness to take, give, or share electrons

Is water polar or non polar?

Polar

What type of charge do polar versus nonpolar molecules have?

Polar has uneven charge, non polar has no charge

What makes a hydrogen bond?

An attraction between a hydrogen atom with a partial positive charge and another atom that’s partially negative

What makes a substance hydrophilic vs. hydrophobic?

Substance that dissolves evenly in water versus does not dissolve easily

What is surface tension?

Cohesion, for example water has a high surface tension because of its “membrane” making it harder to push apart than it is to push apart air

What would unequal sharing of electrons look like?

The electrons will gravitate toward negatively charged atoms creating a bent shape and bond will have that partial charge

Example of celery or lime/lemon juice

Electron pairs have an extremely negative charge so it binds and interacts with DNA in skin cells

What is Miller’s Discharge Experiment?

Simulated early earth conditions by putting a bunch of things in a closed system, and then added water vapor to carry molecules. Needed to add electrodes for energy that would break bonds and allow them to rebuild.

What were other old ideas for chemical evolution?

Prebiotic soup model (molecules were synthesized my gas, condensed with rain, and went into oceans) or surface metabolism model (gas contacted with minerals lining walls of vents making complex organic molecules)

What is potential energy and what has the most of it?

This means stored energy, non-polar has the most because they want to break, while polar bonds are stronger and shorter therefore less willing to break

What is believed to be how Earth started?

Through the spontaneous reproduction of carbon-based macromolecules

Why is water so important?

it is a perfect solvent, meaning things react to it, and it is in 75% of cells

What is cohesion versus adhesion?

Attraction between like molecules versus unlike molecules

When is water the most dense?

As ice in 0C because ice molecules form rigid bonds making it float but in liquid have energy to break/reform

What is specific heat?

The energy required to raise the temperature of 1 gram by 1 degree celsius

Why does water have high specific heat?

Because higher polarity equals more hydrogen bonds which equals more energy needed

What is heat of vaporization?

Energy required to convert 1 gram of liquid into gas, which is why sweating cools you off as the sweat on your skin absorbs a lot of heat in order to evaporate

When does a chemical reaction occur?

When a substance is either combined with another or broken down into a substance, water moves reactions forward through being an acid or base

How is water broken down in solution?

When water molecule dissociates into a hydroxide ion and hydronium ion

What are acids?

Molecules that donate or give up protons to raise hydronium ion concentration, have pH of 7>

What are bases?

Molecules that acquire or take protons and lower hydronium ion concentration, have pH 7<

What is heat?

The transfer of energy

What bond is particularly electronegative?

OH (mostly oxygen)

Polar bond examples

Carbon to oxygen, hydrogen to oxygen, hydrogen to nitrogen, nitrogen to carbon

Nonpolar bond examples

Carbon to hydrogen and carbon to carbon

Monomers for Carbs, Proteins, and Nucleic Acids

Sugars, amino acids, nucleotides

What is thought to be the first thing to form on Earth?

Proteins because they contain information, replicate, and evolve

How is carbon good for large molecules?

It can participate in double bonds, generating straight lines that then form structure for carbon rings with a very strong, stable structure

What is the difference between the amino acid group and the carboxyl group?

Amino acids act as a base because it accepts a proton, and carboxyl acts as acid because it donates a proton

What is the key difference between DNA and RNA structure?

DNA has H and RNA has OH, the additional OH allows RNA molecules to fold over and mind onto themselves for self-replication

What are things made up of proteins?

Muscle tissue, hair, collagen, protein channels in cell membranes, receptors, enzymes, antibodies, hormones

Atomic structure of carbs, lipids, proteins, and nucleic acids

CHO, CHO, CHON, CHONP

Proteins do what for the cells?

Act as a catalysis (reactions through enzymes), give structure, move them around, convey signals between them, allow molecules in or out of cells, and defend pathogens (through antibodies)

Example of importance of amino acids

Hemoglobin residue sequence usually has glutamate but in sickle cell disease that “6” spot is replaced with valine, resulting in structure change and less oxygen the protein can carry

What is the structure of amino acid?

A central carbon will covalently bond to H, NH2 (amino acid), COOH (carboxyl), and an “R” group side chain

What are R groups?

Make each of the 20 amino acid groups unique

What is hydrolysis versus dehydration reaction?

Adding water breaks up polymer versus taking away water

What is a peptide bond?

C-N covalent bond that gives molecule a backbone

Protein structure

Primary — arrangement of individual amino acid in a chain

Secondary — Interaction between functional groups in peptide-bonded backbone, uses only hydrogen bonds, a-helix or B-pleated sheet

Tertiary — Poplypetide folds, residues are brought together through hydrogen bonding, hydrophobic interactions, covalent and iconic bonding, and van Der Waals interactions

Quaternary — Combination of multiple polypeptides

What is a van der waal interaction?

Weak interactions with positive and negative charges

What are dimers, homodimers, and heterodimers?

Proteins with 2 polypeptide units, when structure has 2 identical subunits, and when structure has non-identical units

What does an acid do?

Donate protons or accepts a pair of valence electrons

What does a base do?

A substance that accepts protons or donates pair of valence electrons

What is a condensation reaction?

Needed for polymerization to occur and form a peptide bond

What is oligopeptide versus polypeptide

Chain of fewer than 50 amino acids versus chain of more than 50 amino acids

Key aspects of a peptide backbone?

Directionality, R-Group Orientation (starts with N-terminus and ends with C-terminus), Flexibility

How do polar versus non-polar side chains act?

Polar forms hydrogen bonds and are hydrophilic, non-polar is hydrophobic with no hydrogen bonds

What can go wrong with protein folding?

These “prions” can be infectious if they are misfolded or uncontrolled, PrP is responsible for mad cow disease and Alzheimers