Cell Bio - Biomolecules Lectures 1

what is organic molecule?

An organic molecule is a compound primarily consisting of Carbon and Hydrogen bonds, and also other main atoms like oxygen and nitrogen.

Living organismes consist or carbon-based compounds bc 4 covalent bonds → large, complex, diverse molecules eg. proteins, dna, carbs

Carbon chains = skeletons of most org molecules

functional molecular groups

the 4 macromolecules

• carbohydrates

• proteins

• nucleic acids

• lipids (not polymers)

all living things are made of these macromolecules, that are covalently bonded and play essential roles in biological processes.

• molecular stucture and function are inseparable

top 5 elements found in human body

CHO CHO CHON CHOP

molecules vs compounds

Molecules are groups of two or more atoms bonded together, while compounds are molecules that contain at least two different elements.

All compounds are molecules, but not all molecules are compounds.

eg. CH4 is a compound, H2 is a molecule (pure element)

Covalent Bonds

strong bonds between atoms, they share one or more pairs of electrons, usually between non-metals to form molecules.

They can be polar or non-polar

Ionic Bonds and what are ions?

complete transfer of electron(s) → ions: an atom or molecules w 1 or more units of electrical charge

the types of chemical bonds and their function

Between atoms: covalent and ionic (strong bonds)

Between molecules: hydrogen (weak bonds)

Strong bonds want to complet outer shell (octet rule), either by sharing or transferring

Polartiy and Electronegativity

Covalent bonds are strong so require lots of energy to break them, and they store a lot of energy (metabolism)

Covalent bonds are polar or non-polar depending on difference of Electronegativity of atoms (how greedy, how much attracts)

i- non-polar: electrons shared equally eg.CH4, lipids

ii- polar: atom > electronegativity pulls electrons closer→ poles

Molecule as a whole is neutral

O>N>C=H

Table of elements, electronegativity, ionization, atomic radius

Lipids

• four rings, consist of C - H covalent bonds→ non polar

• b/c of this→ Hydrophobic

weak bonds

• molecules to interact

• -adhering molecules briefly when collide

• stability within large molecules (proteins, dna)

hydrogen bonds

• often -OH, -NH, -SH, very important in livings bc many water molecules

• inter/intramolecular

• individually they are weak, but strong in numbers (DNA)

molecular shape and function

• molecules recognize, interact and respond based on shape

• similar shapes → similar bio effects

shape based on electronegativity

hydrocarbons

• only C and H, many org molecules eg. fats

• release a lot of energy (covalent bonds )

hydrophobic (bc non-polar)

functional groups

atom groups w function, attached to carbon skeletons, most form ionic and hydrogen bonds w other molecules

• can cause hydrophilic properties (soluble)

• non-polar → hydrophobic properties

macromolecules vs polymers

• polymer = macromolecules, consisting of similar, repeating building blocks = monomers

synthesis & breakdown of polymers

dehydration reaction : joining 2 monomers into polymer by removing water molecule

hydrolysis: water molecule is used to breakdown

these processes are facilliated and sped up in our cells by Enzymes!

carbohydrates

• sugars and polymers of sugar

• monomers: monosaccharides

• macromolecules are polysacchrides→ polymers composed of many sugar

monosacchrides

• multiples of CH2O

• major fuel source, very easy to break (easier than protein and fats )

explain what happens when even one amino acid is substituted for another in a polypeptide

• alters primary structure of protein

• the new functional group will change Hydrogen bonding → 2 structures a helices and B sheets

• if secondary changes→ 3rd (change in bonds=> hydrophobic interactions, ionic bonds and disulphide bonds) → quaternary structure too

• Protein shape change = function altered

if a salamander relies on hydrogen bonds to cling to surfaces what surface would cause problems?

A surface made with carbon and hydrogen atoms covalently bonded: Hydrogen bonds needs to encounter Polar Molecules, H atoms bonded to highly electronegative atom like O or N.

What is needed to mimic effects of a hormone ?

a compound with same 3d shape as part of the hormone.

Hormone (compound)= key needs to fit into the lock = receptor for it to respond w same bio trigger reaction

Which group of biomolecules is not synthesized exclusively through dehydration?

Odd one out: Lipids (not polymer) Steroids are derivatives of cholesterol

Triacylglycerides are formed by dehydration (glycerol+fatty acids, but the fatty acids have multi-steps of reactions )

What helps absorb water into large intestines?

cellulose (fiber) isn’t branched so undigested→ bulk so intestines absorb water to soften stool and push it out

How do they make liquid oils into (semi)solid?

through Hydrogenation process → replace double bonds in fatty acids with hydrogen atoms

the info in the DNA is contained in…

the sequences of nucleotides along the length of the 2 strands of the DNA molecule

explain dehydration process

joining 2 small monomers → polymer + H2O

Carbohydrates (blocks, functions, bonds, examples)

monossacharides, polysaccharides, fuel source/ structure + shape, glycosidic link

Lipids (blocks, functions, bonds, examples)

glycerol+ fatty acid chains (not polymer not polymerize),

• Energy storage, form cells, insulation, regulation cell functions

• ester linkage

Proteins (blocks, functions, bonds, examples)

amino acids → polypeptide, protein, peptide w peptide bond

many diverse: catalyse, communication, storage, defensive, transport, hormonal, receptors, structural, contractile/motor

Nucleic Acids (blocks, functions, bonds, examples)

functions of proteins

transport: facilitate movement of substances (hemoglobin), protein channels

biological catalyst (amylase)

Hormonal : communication+coordination of activities (insulin)

defensive: protect by identifying and neutralizing (antibody)

mouvement within cells and tissue(myosin)

support and shape (collagen)

storage of AA (ovalbumin in eggs AA source for developing embryo)

receptors: of chem stimuli (built in nerve cells)

contractile/motor: actin and myosin → contraction of muscles, in the cilia and flagella

functions of proteins + examples

Glucose properties, functions, types

Hexose structure, form rings in aq solution, not hydrophobic, soluble

in cell. Resp → ATP

a glucose and B glucose: isomers = OH group at C1

stereoisomer is galactose at C-4

Explain 2 types of Diabetes mellitus

1: deficiency of insulin

2: body no response to insulin

explain what happens when blood sugar spikes

Pancreas (control center) secrets insulin (hormone)→ binds to receptors of fat, muscle and liver cells → promotes transport of glucose into cells

• uptake in muscles,

• adipose cells (store E as fat)

• prevents breakdown of glycogen (liver)

explain what happens when blood sugar drops

pancreas secretes glucagon

• stimulates glycogen → glucose (liver)

• breakdown of protein→ amino acid (muscle)

• breakdown of fats → release of fatty acids (adipose)

explain the formation of complex sugars

monosaccharides form → disaccharides + H2O with glycosidic linkage

polysaccharides

Fats (Triacylglycerol / triglycerides)

with dehydration, Esther linkage

what causes different fats?

different fatty acid chains:

• length : number of C

• location and number of C=C double bonds

Types of fats

trans fats elevate cholesterol→ plaque deposits abnormal blood flow (clog)

Hydrogenation: change the double bonds with H atoms to make liquid to (semi)solid.

phospholipids

• amphipathic, main component of cell membrane

• phosphate head + 2 fatty acids (different combinations )

what is cholesterol

waxy substance produced by liver for building animal cell membranes. Produce hormones and vitamin D.

High levels → plaque buildup → cardiovascular disease

steroids

4 fused rings

derivatives of cholesterol→ they are stripped into steroids to make enzymes for steroid hormones

structure determines function

protein structure

amino acid, carboxyl acid, variable side chain, Central alpha C

depending on R, shape of protein changes→ structure determines function

Levels of protein structure

denaturation of a protein

heat and pH change protein’s structure & function

sometimes can renature

nucleotide struture

functions of nucleic acids

sequence determines sequence of amino acids for protein synthesis

DNA and RNA (information storage)

→ DNA: replication blueprint for cell growth

→ Instruction for mRNA

protein synthesis

DNA transcribed →mRNA → ribosome reads to make AA chain→ protein goes to rough ER