Everything to know about Unit 1 of AP BIO

What is a hydrogen bond?

A weak bond between a partially positive hydrogen and an element more electronegative.

What elements are more electronegative than H

oxygen, fluorine, and nitrogen

Where does cellular chemistry and metabolism occur?

in water water-based goo of a cell called cytosol

What is a concave meniscus? Why does it happen

U-shaped, and it occurs when the substance is more attracted to the container than itself (through adhesion)

What is a convex meniscus?

The upward curve of a liquid's surface (like mercury in glass), where the liquid's molecules stick more to each other (cohesion) than to the container (adhesion)

What is capillary action?

The ability of a liquid to flow against gravity up a narrow tube with the work of cohesion and adhesion together.

What causes surface tension?

Surface tension is caused by unbalanced intermolecular forces acting on molecules at the surface of a liquid, pulling them inward and causing the surface to behave like a stretched elastic film. (cohesion of water) vs the surrounding air

What is a solvent?

The solvent is the substance that dissolves the solute. ( often cases, the solvent is water)

What makes water a good solvent?

Its polarity and ability to form hydrogen bonds. " universal solvent"

What molecules wouldn't dissolve in water?

anything hydrophobic such as hydrocarbon

What is a solution?

a homogeneous mixture of solvent _ solute

What can water form because of its polarity?

electrostatic interactions (charge-based attractions)

What is a hydration cell?

the sphere of water molecules around each dissolved ion

ex. Na would be surrounded by oxygen, whilst Cl by hydrogen

What does hydrogen bonding explain the effectiveness of?

explains the effectiveness of

- evaporative cooling (why sweating cools you off)

- the low density of ice (why ice floats)

What is constantly happening in hydrogen bonds?

They keep reforming and breaking due to kinetic energy

When water is heated, what happens to its hydrogen bonds?

hydrogen bonds break because the bonds are absorbing the energy, causing so much motion that it breaks

How does ice become less dense?

When water molecules in water become frozen, the kinetic energy slows down, and hydrogen bonds become more fixed. When this happens, the water molecules are farther apart, making it expand, and when they are farther apart, ice is less dense than water

Why is it harmful for living things to freeze?

When a cell freezes, its watery contents expand and its membrane (just like the soda bottle) is broken into pieces.

What is a substance with high specific heat?

water

Specific heat capacity is defined as

The amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius.

The amount of heat needed to raise the temperature of 1 g of water by 1 °C has its own name. What is it?

calorie

Because of the high specific heat capacity of water, what can it do?

minimize changes in temperature, for example. The ocean, which cools more slowly, releases the heat it stored during the day and helps keep nearby land warmer at night.

evaporative cooling/heat of vaporization

As water molecules evaporate, the surface they evaporate from gets cooler

Why is it that when water molecules evaporate, the surface they evaporate from gets cooler?

When water evaporates, the highest-energy molecules escape from the surface, reducing the average kinetic energy of the remaining molecules (hence temp lowering down) and causing the surface to cool.

What defines ph?

ph = -log[H^+]

At what pH is a substance called basic or acidic?

Basic pH is anything above 7

acidic pH is anything below 7

What is a buffer system?

-takes a strong base or acid and converts it to weak base or acid

-reaction occurs within seconds

-prevent big changes in pH

-Carbonic acid (H₂CO₃) neutralizes added bases

Bicarbonate (HCO₃⁻) neutralizes added acids

Is the concentration of H high or low in a basic solution?

it is low

What is the process of autoionization of water?

The process is H2O reversible to H+ ion + OH-.

What happens to the H+ ion during the autoionization of water?

The H+ ion will transfer to a neighboring water molecule, forming hydronium (H3O+).

the stronger the acid, the more readily it-_____

disassociates

What are the important properties of monomers?

- chemical subunits to create polymers

- have specific chemial paropeties that allow them to interact ith one another

What is a polymer?

It is a macromolecule made of many monomers. teh are specific to the mnomer sthye consist of

What is the monomer of a carbohydrate?

monosaccharide (glucose)

What is the monomer of a protein?

an amino acid

What is the monomer of a Nucleic Acid?

nucleotide (sugar, phosphate, nitrogen base)

What is the monomer of lipids?

They dont have true monomers

Dehydration Synthesis

Join monomers by removing OH from one & H from the other → remove H2O

Chemical bonds always made this way

Hydrolysis

- Release monomers by adding OH to one and H to the other → add H2O

Method of digesting food

Nucleic acids:

Biological information is encoded in sequences of nucleotide monomers

What are the polymer of Nucleotides?

DNA & RNA are polymers of nucleotides; nucleotides named by nitrogenous base

STRUCTURAL COMPONENTS OF NUCLEOTIDES

What are the two types of nitrogenous bases?

Purines: Adenine and Guanine with a double-ring structure

Pyrimidines: Thymine, Cytosine, Uracil with a single ring

what do both DNA and RNA contain the same of?

phosphate group

What is the 5-carbon sugar for DNA ( is it polar or non polar)?

deoxyribose and it is nonpolar

What do DNA nucleotides form?

double-stranded DNA

when phosphate group joins to sugar of another nucleotide what bond is used?

covalent

What are the two strands base-paired by?

paired by hydrogen bonds

If a nucleotide was being added to the DNA strand on which side are they added on?

Nucleotides are added to the 3' end of the strand

Whats the directionality of DNA?

Antiparallel ⇒ double helix

One strand is arranged 5' → 3' end & other is 3' → 5'

What does the antiparallel directionality give DNA?

gives DNA stability and allows for replication--if wasn't then nucleotides wouldn't be complementary

For the Binding of DNA nitrogenous bases which base pair is stronger and why?

Cytosine and Guanine; this is because they have 3 hydrogen bonds while thymine and adenine have 2

When does phosphodiester bonding take place?

takes place during DNA replication when nucleotides are joined together, linking the 3′ -OH of one sugar to the 5′ phosphate of the next nucleotide.

Whata are some features of RNA

Single strand

Ribose 5-carbon sugar

Hydroxyl functional group

Uracil not Thymine

What are the functions of proteins?

Structural: ex: keratin in hair, collagen in tissues

Storage: ex: casein in milk

Transport: ex: membrane of cells and oxygen carrying hemoglobin in red blood cells

Defensive: Ex: antibodies that protect against foreign substances

Enzymes: regulate the rate of chemical reactions

What bond is used for protein?

peptide bond which holds amino acids together

What is a polypeptide chain?

Multiple combinations of amino acids bonded together

What is the structure of an amino acid?

contain amine group to the left and carboxyl group to the right

Below centeral carbon is R side chain

What does the R group detemrine?

determine chemical properties & differences of amino acids

R groups determine if they are polar or nonpolar

What do Polar R groups contain?

N, S or O

What do nonpolar R groups contain?

C or H

What is a dimer?

protein with two tertiary structures

What is the primary structure of a protein?

Order of amino acids connected by covalent bonds which determines the overall shape and function of a protein

Secondary Structure?

Local folding of the amino acid chain (polypeptide) into elements such as alpha-helices and beta sheets through hydrogen bonding

What is the tertiary structure of a protein?

The overall 3D shape of the protein as a result of different interactions between amino acids.

What type of proteins usually have a tertiary structure?

Globular proteins.

What does the tertiary structure of a protein do to free energy?

It minimizes free energy.

How does the tertiary structure affect the stability of a protein?

It increases stability.

What are the components of a tertiary structure?

Hydrogen bonds and ionic bonds between R groups of amino acids

Disulfide bonds: sulfur atom in amino acid cysteine bonds to sulfur atoms in another cysteine

Helps maintain folds of amino acid chain

Hydrophobic interactions/effect: occurs when hydrophobic R groups move toward the center of protein (away from water in which protein is usually in)

Quaternary Structure?

Arises from non-covalent interactions between MULTIPLE polypeptide units (ex. hemoglobin)

Basically, two or more polypeptides (2nd) into single protein; not all proteins have it

Carbohydrates function?

main source of energy (for ATP) and provide structural support

Carbs (+fats, lipids) are high energy bcuz have many hydrogen atoms with e-

Pentoses:

(5-carbon sugars) include ribose and deoxyribose & make up nucleic acids

Hexoses:

(6-carbon sugars) are in the food that we eat and include glucose, fructose, and galactose (monosaccharides)

What are simple carbohydrates?

Monosaccharides and Disaccharides

Dehydration synthesis of two monosaccharides makes a disaccharide (e.g is lactose)

For structural isomers if the placement of carbosm are different then it results in?

different functions

e.g aplha nd beta glucose

Why do monosacharies provide immediate energy?

bcuz don't need hydrolysis

Why are simple carbs polar?

Simple carbs are polar bcuz of -OH functional group which makes them hydrophilic

Whata re ome pollysachharides thata re insoluble?

cellulose+ startch

Always has ring structure hexagon =

gluose

Always has ring structure pentagon =

fructose

Glucose + Glucose

Maltose

1-2 glycosidic linkage

Glucose + Fructose =

Sucrose

Glucose + Galactose =

Lactose

What is a Complex carbohydrate

Polysaccharides = energy storage

what is a Polysaccharides made of?

Polymer made of repeating monosaccharide monomers; usually consisting of glucose

Cellulose :

make up plant wall, non digestible (fiber) in humans, long chains of b glucose

Chitin:

fungi cell wall

Glycogen:

energy storage in liver and and stomach cells (animals)

Starch:

long term storage carb for plants, quick energy for humans

Lipids function?

cell membrane (phospho,) insulation, protection, fat is long term and high energy

What are the 3 lipids?

triglyceride, Steroids, Phospholipids

Triglyceride is knwon for?

fats and oils

What is the structure of a Triglyceride?

3 fatty acids (sat/ unsat) each join to glycerol by esther linkage

What is the basic structure of a fatty acid?

A hydrocarbon with a carboxyl group.

Are fatty acids polar or nonpolar?

Nonpolar.

How do fatty acids vary in structure?

By the number of carbon atoms and the placement of single or double bonds.

Saturated fatty acids:

single bonds between carbons and two H (is saturated with H)

No double bonds/kinks in chain = molecule can compact together = solid/rigid → build up in bloodstream

Unsaturated Fatty Acids:

Two or more double covalent bonds

what do Unsaturated Fatty Acids do?

Stops carbon from packing together and hydrogen from saturating them which makes fat more flexible/liquid is also very kinky

Monounsaturated Fatty acid:

one double bond and each has only one H