COMBINED Biomolecules Test Bio12AP

MCQ (28 marks), mole recognition and 8 descriptions (4 marks), written (14 marks, point form). Main topics: properties of water, dehydration synthesis/hydrolysis sketch (amino acids/carbs), levels of protein structure, phospholipids and bilayer (polarity)

Lipids

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen. (Are mostly non-polar)

• function in energy storage, cell membranes, insulation

• how a lipid functions in a cell depends on the lipid’s saturation level

3 major groups of lipids

• Fats (Triglycerides):

  • Made of glycerol and three fatty acids.

  • Primarily used for long-term energy storage.

• Steroids:

  • Lipids with a structure of four fused carbon rings.

  • Includes hormones like cholesterol and sex hormones.

• Phospholipids:

  • Composed of a glycerol, two fatty acids, and a phosphate group.

  • Key components of cell membranes, forming a bilayer due to their hydrophilic head and hydrophobic tail.

Components + characteristics of lipids

carbon, hydrogen, and oxygen

• completely hydrophobic or amphipathic (presence of long hydrocarbon chains/rings, which are nonpolar)

• ratio of hydrogen to oxygen in lipids is much higher than carbohydrates

Glycerol

A three-carbon alcohol to which fatty acids are covalently bonded to make fats and oils.

Triglyceride

a lipid made of three fatty acid molecules and one glycerol molecule

deoxyribose vs ribose

Ribose has a hydroxyl group (-OH) on the 2' carbon, while deoxyribose lacks this hydroxyl group, having a hydrogen (-H) instead. This structural difference makes ribose more reactive and less stable than deoxyribose.

saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton.

- NO DOUBLE BONDS BETWEEN CARBONS

Unsaturated fatty acids

Fatty acids that contain one or more double bonds between the carbon atoms in the hydrocarbon tail. These double bonds reduce the number of hydrogen atoms attached to the carbon skeleton, resulting in a bent structure. Unsaturated fatty acids are typically liquid at room temperature and are commonly found in plant oils and fish oils.

Phospholipids

• type of lipid molecule that is a fundamental component of cell membranes. It consists of two main parts:

  1. Hydrophilic (water-attracting) head: This part contains a phosphate group, which is polar and interacts well with water.

  2. Hydrophobic (water-repelling) tails: These are made up of two long fatty acid chains, which are non-polar and do not interact well with water.

• Function: Forms bilayers in cell membranes, with polar heads facing outward and non-polar tails facing inward, maintaining cell integrity.

Cholesterol

- sterol molecule

- not soluble in water

- contains C,H,O arranged in rings

- precursor (building block) to sex hormones (estrogen and testosterone)

-component of lipid membrane

Saponification

The chemical reaction between a fat (or oil) and a strong base (such as sodium hydroxide or potassium hydroxide) that produces glycerol and the salt of a fatty acid, commonly known as soap. This process involves the hydrolysis of the fat or oil, resulting in the formation of soap molecules that can emulsify fats and oils in water.

Why will soap mix with water where a fat or other oily substances won't?

Soap has both a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. The hydrophilic head interacts with water, while the hydrophobic tail binds to oils and fats. This allows soap to form micelles, where the hydrophobic tails surround and trap the oil, making it possible for the oil to mix with water and be washed away.

Key points:

• Soap is amphipathic (has both hydrophilic and hydrophobic parts)

• The hydrophobic tail binds to oil, while the hydrophilic head binds to water

• Soap allows fats/oils to be suspended in water for removal

Emulsification

physical process of breaking up large fat globules into smaller globules, thereby increasing the surface area that enzymes can use to digest the fat

• Soaps act as emulsifiers because they have both water-repelling and water-attracting parts. This lets them interact with water and oils, breaking up and suspending oil droplets in water, making emulsification possible

Saturated fats are typical of......

Animal fats

Unsaturated fats are typical of...

Plant fats

Four important uses of lipids in body

-insulation and protection
-long term energy storage
-structure of cell membrane
- basis of hormones (ex. Sex hormones)

How are phospholipids different from neutral (uncharged) fats

- instead of a 3rd fatty acid there is a phosphate group

• two fatty acid tails are non polar

• phosphate “head” is polar (neg charge attracts to a water molecule)

- not electrically neutral (non polar)
- soluble in water (have polar "head")

Proteins contain

carbon, hydrogen, oxygen, nitrogen, sulfur

• Carbon Helps Organisms Nurture Structures

Amino acid

organic compounds that serve as the building blocks of proteins.

• Each amino acid contains a central carbon atom, an amino group (–NH₂), a carboxyl group (–COOH), a hydrogen atom, and a variable side chain or R group that determines the specific characteristics of the amino acid. T

• There are 20 standard amino acids, each with unique properties, which combine in various sequences to form proteins essential for biological functions, including structure, function, and regulation of the body’s tissues and organs.

parts of an amino acid

Hydrogen atom, a carboxyl group (−COOH), an amino group (−NH2), and a R-group.

Peptide bonds

covalent bond that links two amino acids together, forming a dipeptide. It is created through a dehydration synthesis (or condensation) reaction, where the carboxyl group (–COOH) of one amino acid reacts with the amino group (–NH₂) of another, releasing a molecule of water (H₂O).

peptide bond formation

amide bond formed by amino group joining with carboxyl group and removing an H2O molecule

- results in C - N bond

Primary protein structure

sequence of a chain of amino acids joined by peptide bonds

• resulting polypeptide has directionality, with amino (NH2) terminus and a carboxyl (COOH terminus)

• order of amino acids in chain determines primary structure of protein

secondary protein structure

• Folding or coiling of a polypeptide chain.

• Cause: Hydrogen bonding between backbone atoms of amino acids.

• Forms: Alpha helices (coils) or beta-pleated sheets (folds).

• Stabilized by: Hydrogen bonds.

tertiary structure of protein

he three-dimensional shape formed by the folding of the secondary structure (alpha helices and beta sheets), driven by interactions between the R groups (side chains) of amino acids. These interactions include hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions. This structure is critical to the protein’s function.

Key Point: Tertiary structure = 3D shape, stabilized by various interactions (ionic, hydrophobic, etc.).

quaternary structure of a protein

multiple polypeptide chains (called subunits) come together and interact in a protein. The subunits are held together by non-covalent bonds like hydrogen bonds, ionic bonds, and hydrophobic interactions. An example is hemoglobin, made of four subunits.

Key points:

• Made of multiple polypeptide chains.

• Held by non-covalent bonds (e.g., hydrogen, ionic, hydrophobic).

Dipeptide

• a molecule formed when two amino acids are joined by one peptide bond

• product of a rxn between 2 amino acids, single peptide bond links them together

• peptide bond = BOND ITSELF, dipeptide = molecule formed when 2 amino acids are linked

What causes protein denaturation?

- extreme high temperatures
- non-optimum ph
-addition of heavy metals (Pb, Hg)

nucleic acids

biological macromolecules that store and transmit genetic information in living organisms. They are polymers made up of nucleotides, each consisting of a nitrogenous base, a five-carbon sugar (either ribose or deoxyribose), and a phosphate group. The two main types of nucleic acids are DNA and RNA

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus (CHONP)

types of nucleic acids

DNA, RNA

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar (deoxyribose or ribose), a nitrogenous base (adenine, thymine, cytosine, guanine or uracil), and a phosphate group

• when nucleotides link together in a chain, they form nucleic acids → essential for storing/transmitting genetic information

directionality of nucleotides

• phosphate group is always attached to the 5’ carbon in sugar

• 3’ carbon always has a hydroxyl group to which new nucleotides may be added

general nucleic acid strand has...

a sugar-phosphate backbone and nitrogenous bases projecting to the side

Pyrmidines

Pyrimidines: "CUT the PYe"

• Cytosine

• Uracil

• Thymine

bases with a single ring structure

• thymine, uracil, cytosine

purines

Bases with a double-ring structure.
Adenine and Guanine

RNA

A single-stranded nucleic acid that contains the sugar ribose. RNA is typically shorter than DNA and plays crucial roles in protein synthesis and gene expression. It consists of nucleotide units made up of a nitrogenous base (adenine, uracil, cytosine, or guanine) and a phosphate group.

3 kinds of RNA

mRNA, tRNA, rRNA

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

ribosome

site of protein synthesis

nitrogenous bases of RNA

Adenine, Uracil (instead of thymine), Cytosine, Guanine

DNA vs RNA

DNA:

• five carbon sugar: deoxyribose

• nitrogenous bases: adenine, thymine, cytosine, guanine

• strands: double stranded helix

• function: holds genetic info

• location: usually in nucleus

RNA

• five carbon sugar: ribose

• nitrogenous bases: adenine, uracil, cytosine, guanine

• strands: usually single stranded but can form 3D structure when folded

• function: translates + regulates expression of genetic info

• location: in both nucleus and cytoplasm

ATP

(adenosine triphosphate) main energy source that cells use for most of their work
- "energy currency"
- used for large number of energy demanding reactions

ADP

• Adenosine Diphosphate (ADP): The compound formed when ATP loses a phosphate group, releasing energy.

• "Low-energy" form of ATP.

• Energy release: Provides free energy, which is used in energetically unfavorable reactions.

nucleotides are…

• Composed of a nitrogenous base, sugar, and phosphate group

• Building blocks of DNA and RNA

dehydration synthesis

A chemical reaction in which two molecules are bonded together with the removal of a water molecule.

What are the structural differences between glycogen, cellulose and starch?

Glycogen: highly branched

Cellulose: rigid, straight

Starch: slightly branched

Simple sugars (monosaccharides)

building blocks of carbohydrates; glucose, fructose, galactose

• all isomers of eachother

Polysaccharides

Carbohydrates that are made up of more than two monosaccharides

hydration shell

water molecules that surround an ion during dissociation (disolving ionic compounds) → stabilizes ions in solution and prevents them from recombining

dissociation

the process by which an ionic compound breaks apart into its individual ions when dissolved in a solvent like water

Starch

A storage polysaccharide in plants made up of long chains of glucose molecules. It consists of two types of molecules: amylose (unbranched) and amylopectin (branched). Amylopectin is the more predominant form, making starch somewhat branched.

Glycogen

storage form of glucose in animals
- branched

Cellulose

Carbohydrate component of plant cell walls. - rigid, straight

Lactose = ______ + ______

glucose + galactose

maltose = __ + __

glucose + glucose

sucrose = __ + __

glucose + fructose

Four types of macromolecules

carbohydrates, lipids, proteins, nucleic acids

Four reasons why water is vital for life

- high heat of absorption (allows large bodies of water to maintain constant temperature)

- freezes from top -> down (protects organisms living in ponds/lakes)

- acts as a solvent, dissolves other polar molecule (it transports nutrients + waste in organisms, facilitaes chemical reactions, maintains structure/function of cells)

- adhesive + cohesive qualities

water's adhesive properties

- Water molecules are polar, with partial positive and negative charges. This polarity allows them to form hydrogen bonds with other polar or charged surfaces, leading to adhesion.

- helps in capillary action, where water moves through narrow spaces against gravity. This is vital for plants, as it allows water to travel from the roots up through the xylem to the leaves, facilitating nutrient and water distribution.

water's cohesive properties

- Water’s attraction to itself, causing molecules to stick together. They're polar and form hydrogen bonds with each other. This results in high surface tension and the tendency of water to form droplets.

- cohesion helps maintain the structure of cellular fluids and supports the formation of cellular membranes.

surface tension

The force that causes the surface of a liquid to act like a stretched elastic sheet, minimizing its surface area.

Why It Happens: Molecules at the surface of a liquid experience stronger cohesive forces inward because they are not surrounded by other molecules on all sides, creating a “skin” that resists external forces.

what's the relationship between water's high specific heat and its resistance to temperature changes?

it can absorb and release large amounts of heat with only small changes in temperature. This property makes water resistant to rapid temperature changes, helping to stabilize temperatures in both the environment and within organisms.

evaporative cooling

The process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state.
-

what allows ice to float on water?

its solid form is less dense than its liquid form due to the arrangement of water molecules in a crystalline structure, which creates more space between them.

solvent

A liquid substance capable of dissolving other substances

solution

A homogeneous mixture of two or more substances

solute

A substance that is dissolved in a solution.

how does water dissolve ionic compounds

The hydrogen in the water pulls off the negative ion, and the oxygen in the water pulls off the positive ion. This causes the ions to split up, and for the compound to become dissolved.

hydrophobic

Having an aversion to water; tending to coalesce and form droplets in water.

hydrophilic

Having an affinity for water.

buffer

compound that prevents sharp, sudden changes in pH
- maintains pH and homeostasis in living beings

carbohydrates contain

carbon, hydrogen, oxygen

Ratio of carbohydrates

1 carbon: 2 hydrogen: 1 oxygen

hydrolysis

Breaking down complex molecules by the chemical addition of water

polysaccharides

Carbohydrates that are made up of more than two monosaccharides

examples of polysaccharides

starch, glycogen, cellulose

when acids dissociate, ___ are released

H+ ions

when bases dissociate, ___ are released

OH- ions

disaccharides

double sugars

• formation of these sugars through dehydration synthesis (removal of water to join 2 molecules)

• sucrose, lactose, maltose

using surcose and its constituent simple sugars, show a hydrolysis reaction

sucrose + water → glucose + fructose

using maltose and its constituent simple sugars, show a dehydration synthesis reaction

glucose + glucose → water + maltose

Steroids

• Lipids with a structure of four fused carbon rings. Examples include cholesterol (maintains cell membrane fluidity) and steroid hormones like testosterone and estrogen, which regulate growth and metabolism.

R group

• a side chain attached to a molecule, particularly in amino acids.

• unique for each amino acid

• Determines amino acid’s identity and whether the amino acid will be non polar, polar, acidic, basic

Function of proteins

• enzyme catalysis

• maintaining cell structures

• cell signaling

• cell recognition

example of a pentose sugar

ribose

Hexose sugars derived from the hydrolysis of sucrose:

The two hexose sugars are glucose and fructose

Biomolecule stored in the adipose tissue of mammals

Triglycerides (fats) are stored in the adipose tissue

Number of carbon rings in the distinctive steroid compounds

Steroid compounds have four carbon rings

Chemical used as the building block for all steroid compounds in the human body

Cholesterol is the building block for steroid compounds.

identify this molecule

saturated fatty acid

identify this molecule

cholesterol

identify this molecule

lipid

identify this molecule

amino acid

identify this molecule

ribose

identify this molecule

nitrogenous base

identify this molecule

simpe sugar (fructose) monosaccharide