unit 1 - biochemistry

characteristics of life

there are 8, living things must have all 8 to be considered alive

DR. G CHEER

made up of cells

must be made of cells

• unicellular or multicellular

reproduce

must reproduce

• asexual - requires only one parent (exact copy)

• sexual - requires two parents (more diverse)

based on a genetic code

• must have dna

• found in every cell; inherited from parents and controls traits

grow and develop

must grow during at least one part of their life

need for materials and energy

must need a constant supply

• metabolism

metabolism

the combination of chemical reactions through which an organism builds up and breaks down materials as it carries out life processes

respond to the environment

organisms must detect and respond to stimuli from their environment

• can be internal or external

must maintain an internal balance

homeostasis - the process of keeping the internal environment stable/balanced/ constant

evolution

must change over time

• over hundred, thousands, and millions of generations organisms have the potential to change

matter

anything that takes up space and has mass

*mass and weight are not the same

atoms

basic unit of matter

• composed of protons (+), electrons (-), and neutrons (0)

parts of an atom

• protons and neutrons are located in the nucleus

• electrons move around the nucleus

  • the number of electrons is equal to the number of protons

elements

a pure substance that contains only one type of atom

• 96% of living things are composed of C.H.O.N.

isotopes

atoms of the same element that have a different number of neutrons

ex.) carbon-12, carbon-13, carbon-14

compounds

a substance formed by the bonding of 2 or more elements in definite proportions

bohr models

1st electron shell - 2 electrons

2nd electron shell - 8 electrons

3rd electron shell - 8 electrons

chemical bonds 

the forces that hold together atoms that make up a compound

ionic bonds

transfer of electrons takes place resulting in ions

• ion - a charged atom

• ions of opposite charges attract strongly, forming an ionic bond

• ionic bonds are weak when aqueous

covalent bonds

sharing of electrons 

• single covalent bond shares 1 electron

• double covalent shares 2 electrons

• covalent bonds result in molecules (the smallest unit of a compound)

water

the single most abundant compound in most living things

water is a polar covalent compound

• polar - the electrons are shared unevenly between oxygen and hydrogen

• oxygen pulls on the electron greater than hydrogen, so the electron is closer to oxygen

• water has a partial positive pole and a partial negative pole like a magnet

hydrogen bonding 

partial positive and negative charges allow H₂O molecules to attract to each other through hydrogen bonds 

• hydrogen bonds are weak

• responsible for water’s special properties

cohesion

attraction of molecules between the same substance

ex.) bugs can walk on water due to high surface tension

adhesion 

attraction between molecules of a different substance 

other properties of water

• can absorb heat before its own temperature rises

  • water acts like a buffer to the globe

• ice is less dense than liquid water

  • when ice freezes its atoms expand

• water is very effective at dissolving other substances (universal solvent)

solution

a mixture in which 1 or more substances are evenly distributed in another

solute

the substance that gets dissolved

solvent

the substance that does the dissolving

acid

great number of H⁺ ions

base 

greater number of OH^- ions

buffer

chemical substances that neutralize small amounts of either an acid or base

carbonic acid system - maintains blood pH (7.4)

H₂CO₃ ^→_← HCO₃ ^- + H⁺

• if the blood starts to become too basic, then carbonic acid will donate H⁺

• if the blood starts to become too acidic, then bicarbonate ion will accept H⁺ ions

carbon is special 

• 4 valence electrons so it can form 4 covalent bonds

• can form long complex molecules

macromolecules

the 4 molecules of life are called macromolecules (large)

monomer

building blocks

polymer

large compound made up of smaller monomers

functional groups

the non - hydrocarbon part of the molecules 

• clusters of atoms that control the function of the molecules

hydroxyl

-OH

carboxyl

-COOH

amino

NH₂

carbonyl

-CO

sulfhydryl

-SH

phosphate 

-PO₄^-

carbs contain

CHO

carb function

source of energy

carb functional group

-OH (hydroxyl) and -CO (carbonyl)

carb monomer

monosaccharide

• simple sugar

• contain CHO in a 1:2:1 ration

ex.) C₆H₁₂O₆

most common carb monomers

glucose - fuel for cells

fructose - sweetest

galactose - milk sugar

*hexose - contain 6 carbons

isomer

compounds of the same element with the same chemical formula but different structural formulas

carb polymer

disaccharide - 2 monosaccharides combine in a dehydration synthesis reaction

• maltose = glucose + glucose

• sucrose = glucose + fructose

• lactose = glucose + galactose

polysaccharide - 3 or more monosaccharides combine in a dehydration synthesis

• starch = sugar storage in plants

• glycogen = sugar storage in animals (muscles)

• cellulose (fiber) = structural component of plant cells (cell wall)

dehydration synthesis reaction

reaction that links smaller molecules together to make a larger molecule by removing water

hydrolysis reaction

reaction that breaks apart larger molecules by adding water (essential for digestion)

proteins contain 

CHON

protein functions

1. act as enzymes to speed up reactions

2. help transport molecules in and out of cells

3. act as cell surface receptors

4. help cell structure

… and more

protein functional group

-NH₂ (amino) and -COOH (carboxyl)

protein monomer

amino acids

R group

a place holder for different type of amino acids

• there are 20 different amino acids

protein polymer

folded polypeptide chain

• amino acids join by a dehydration synthesis rxn to for dipeptides and polypeptides

protein folding - primary structure

forma a chain of amino acids

protein folding - secondary structure

twist or fold the chain (alpha helix or beta pleat)

protein folding - tertiary structure

fold the chain onto itself (globular subunit)

protein folding - quaternary structure

bring 2 - 4 subunits together

why correct folding is critical

if conditions are not right (pH, temp, salinity) this process will not take place or can be reversed (denaturation) and proteins can’t function 

• causes of many illnesse

enzymes (helper molecules)

• made of proteins

• they help speed up reaction and are unchanged by the reactions

lipids contain

CHO

lipids function

depends on the type

lipid functional group

-COOH (carboxyl)

lipid monomer

most lipids contain glycerol and fatty acids

fatty acids

long hydrocarbon chain with carboxyl group attached

saturated fatty acids

carbons are full of hydrogens (no double bonds)

• straight chain

• typically solid at room temp

ex.) butter

unsaturated fatty acids

carbons are not full of hydrogens (double bonds)

• chain bends

• typically liquid at room temperature

ex.) olive oil

lipid polymer - triglycerides

3 fatty acids + 1 glycerol

function: storage of energy

lipid polymer - phospholipid

2 fatty acids + 1 phosphate group + 1 glycerol

function component of cell membranes

lipid polymer - steroids

4 fused rings with carboxyl group attached

function: component of cell membranes (cholesterol), starting material for sex hormones

lipid polymer - wax

fused rings with carboxyl group attached

function: prevents water loss or dehydration

ex.) why plants are shiny

nucleic acids contain

CHONP

nucleic acids function

1. store and transmit infor to carry out cell processes and make protein

2. transmit genetic info from one generation to the next

nucleic acids functional group

-PO^₄- (phosphate)

nucleic acid monomer

nucleotide 

1. sugar

2. phosphate group

3. nitrogen base 

nucleic acid polymer

1. dna

2. rna