Unit 3 - Biomolecules

A1.1, D2.3, A1.2

Water

• Medium for life

• Most biochemical processes happens in water

• Water is a solvent in which these reactions can happen

• Main component for many fluids such as the cytoplasm, blood, etc.

Cohesion

• The ability of like molecules to stick together

• Water is very cohesive (forms hydrogen bonds)

Surface tension of water

• Water molecules stick close together due to cohesive force

• The tension must be broken in order for something to enter the water

• The surface of the water is a habitat for animals

Xylem transportation

• Water in plants move through the xylem

• Because of cohesive force, there is tension which pulls the water up the xylem from the roots

• Transpiration - water evaporates from the leaves

Water adhesion

• The ability for dissimilar molecules to stick together

• Water will form intermolecular associations with polar and charged molecules

• Water can form menicuses and capillary action

DeoxyriboNucleic Acid (DNA)

• De-oxygenated

• Codes forinformation

• Makes RNA during transcription

RiboNucleic Acid (RNA)

• Codes for proteins during translation

• Multiple versions (3) - tRNA, mRNA, rRNA

Virus

• Are not cells - lack the properties required to be considered a “living” cell

• Have RNA or DNA as genetic material

Nucleotide (RNA & DNA)

Components:

• 5 carbon pentose sugar - ribose or deoxyribose

• Phosphate group

• Nitrogenous base

• Nitrogenous base connects to 1’carbon of the sugar

• Phosphate base attached to 5’ carbon of the sugar

• When connecting two nucleotides, a covalent bonds forms from a condensation reaction - 5’carbon on one molecule to the 3’ carbon of another (sugar phosphate backbone)

Purines (larger)

Adenine, Guanine

Pyrimidines (smaller)

Cytosine , Thymine(+Uracil)

Nulceosome structure

• Negatively charged DNA strand binds to the positively charged histone proteins

• DNA strand is wrapped around 8 histones, one secures the form

• 4 different types of histones in each nucleosome

• Nucleosomes are connected together by linker DNA

Supercoiling

• Wrapping around of histones protects DNA

• Histones also assist in the supercoiling of DNA (mitosis & meisosis)

• DNA cannot be read when it is supercoiled

Hershey-Chase experiment

• Bacteriophages grew in 2 different conditions - radioactive phosphorus & sulfur

• DNA doesn’t contain sulfur

• Bacteriophages infected bacteria - those injected with sulfur did not have any left - those injected with phosphorus were found to still contain phosphor

• Genetic information was deemed to have been made of DNA

Chargaff’s rule

DNA contains the same number of adenine as thymine (or any other base pairing)

Capillary action

• Ability of water to flow in narrow spaces, even against gravity

• Due to cohesion and adhesion

In soil

• Adhesion - water adheres to soil particles

• Cohesion - water molecules stick together, bringing each other up through tiny pores of the soil

In xylem

• Water in xylem can adhere to the sides - adhesion

• Water molecules pull each other up - cohesion

Solvent properties of water

• Hydrophilic particles dissolve in water - (polar, positive or negative - amino acids, some proteins, or substances that adhere to water)

• Hydrophobic molecules do not dissolve in water - (lipids - oils, fats)

Physical properties of water

• Buoyancy

• Viscosity

• Thermal conductivity

• Heat capacity

Origin of water theory

Most water on Earth exists in two forms:

• Water

• Heavy water (H+ with a neutron) - deuterium

• Ratio of water & deuterium is similar to that on asteroids

  • Theory that water came from asteroids bringing minerals, releasing water - as early Earth only had magma on the surface

Goldilocks zone

• The certain distance between the sun and a planet in a solar system in order to have water - with correct temperature and gravity to retain water

• Earth also has an atmosphere and magnetic field to protect against harmful radiation

Water potential - Ψ

• Measures the potential energy per unit volume in water

• Main factor for the movement of water in living organisms

• Measurements are compared to pure water as a reference point (at room temperature & atmospheric pressure)

• Kilopascals (kPa) or megapascal (mPa)

• Solute potential + pressure potential = water potential

• High Ψ → low Ψ

Water movement in plants

• Ψ decreases from root to tip - from soil (high Ψ) → to roots (low Ψ)

• Water also moves from low solute concentration → to high solute concentration (in cells) - osmosis

• Transpiration, water loss - makes pressure potential drop

• Pressure potential dropping → more water moves up

Water potential in plant tissue

Hypertonic solution - less solute conc. inside cell

• Higher Ψ in the roots - higher solute potential outside of the cell

• Ψ goes from high to low - water moves out of the roots

• Plant will wilt as pressure potential drops - flaccid cell?

Hypotonic solution - higher solute conc. inside the cell

• Roots have a lower Ψ - solute potential is higher inside of the cell ??

• Water moves into the root

• Pressure potential will increase until its high enough to stop inward movement

Polar covalent bond

• Oxygen and two hydrogens unequally share electrons

• Oxygen becomes slightly negative, hydrogen becomes slightly positive

Carbon

• Atom that can form up to 4 covalent bonds with other atoms

Carbohydrates

• Organic compounds, consisting of one(monosaccharide) or more(di- polysaccharide) simple sugars

Glucose - Monosaccharide

• Form of sugar - hexose

• Fuels respiration

• Base unit for many polymers

Fructose - Monosaccharide

• Pentose sugar

• Found in fruits, honey

• Sweetest natural occurring carbohydrate

Polysaccharides

• Cellulose - plants

• Amylose - plants

• Amylopectin - plants - branched

• Glycogen - animals - branched

Lipids

• Water insoluable organic molecules

Glycoproteins

• Polypeptide with an attached carbohydrate

• Part of the plasma membrane - cell to cell recognition

Nucleotide

Consists of:

• Phosphate group

• Nitrogenous gas

• Pentose sugar (ribose or deoxyribose)

Amino acid

Consists of:

• Central carbon

• Amine group

• Carboxyl group

• Variable group (R-group) - what gives amino acids different properties (polar, charge)

Hydrolosis

• When organic molecules break apart

• Water is needed to break the bond

  • Is done because smaller molecules are easier to absorb

• Enzymes control the process

Condensation reaction

• When organic molecules join together

• Water is formed as a byproduct

  • Used to build up & store large molecules

Ribose - Pentose

• Sugar in RNA

• Has 5 carbons

Deoxyribose - Hexose

• Sugar in DNA

• Has 6 carbons