Unit 2 - Cellular Chemistry/Macromolecules Flashcards
Lipid Bilayer
-double layered sheet of lipids which is studded with proteins
lipids
-serve as permeability barrier
-carbohydrates are attached as well
-all lipids in membrane are amphipathic
-composition varies
-form spontaneously
closed, self-sealing, important feature for cell fusion
-energetically favourable state is sealed compartment
Lipid aggregates in water
-form surface film and small micelles
Phospholipids
- major component of cell membranes
- polar head group and 2 hydrophobic fatty acid tails
- two -OH groups in glycerol are linked to fatty acids, while 3rd -OH group is linked to phosphate group
- phosphate is further linked to an alcohol
- amphipathic
Unsaturated Fats
-one or more double bonds in hydrocarbon tail
-double bond creates kink in chain, allowing for 2 transfigurations:
1. cis - same side
2. trans - opposite side
liquid at room temp.
Saturated Fats
-no double bonds in hydrocarbon tail
-linear molecule
solid at room temp.
Steroids
-common multiple ring structure
Fats/Oils/Triglycerides
-glycerol with 3 fatty acids attached to it
long hydrocarbon chain (tail) - not very reactive
-carboxyl group (head) - behaves as an acid, chemically reactive
-stored as energy reserve through ester linkage to glycerol to form triacyglycerols
Functions of Carbs
- structural
- cell-to-cell recognition
- energy storage (short term)
Glycosidic Bonds
- bond formed between -OH group on one sugar and -OH group on another through a condensation reaction - water is expelled as the bond is formed
- bond created through condensation reaction can be broken though hydrolysis in which a water molecule is consumed
Cellulose
- polymer of beta-glucose
- joined by b-1,4 linkages
- hydrogen bonding between adjacent strands
- extremely stable, most abundant organic molecule on earth
Glycogen
- storage form of energy in plants
- consists of highly branched a-1,4 and a-1,6 bonds
Geometry of bond depends on… (carbs)
- whether OH group on C1 is in alpha or beta position
2. which C of the other sugar is involved in the linkage
Formation of Disaccharides
- monomers linked when C1 of one binds to C of another (usually C4)
- carbon of first molecule determines structure of bond
Anomers of Glucose
- alpha-glucose = below plane of molecule
- beta-glucose = above plane of molecule
Structural features of sugar monomers include…
- carbonyl group
- lots of -OH groups
- monosaccharides form rings in solution
- isomeric forms have identical chemical groups but are arranged differently: structural isomers (bonded to different carbons) or stereoisomers (bonded in different orientation
Glycolipids
-carbohydrates attached to lipids
Glycoproteins
-carbohydrates attached to proteins through covalent bonds
Polysaccharides
very long sugar chains
Monosaccharides
simple sugars
Secondary Structure of RNA
- hydrogen bonds form between complementary base pairs
- final molecule is single-stranded
- complex folds result in some RNA having catalytic activity
Higher Order DNA Structure
- allows for short packaging and strict regulation of gene expression
- each DNA molecule is packaged into mitotic chromosome
DNA Double Helix
- stabilized by hydrogen bonds & hydrophobic interactions
- entire molecule is water-soluble
Secondary Structure of DNA
- two strands of DNA align anti-parallel with bases facing inwards hydrogen bonds between bases
- A pairs with T and C pairs with G
Polymerization
- endergonic condensation reaction
- involves making of new phosphodiester bonds forming 2 nucleotides
- occurs because energy level of free nucleotides is first raised by addition of two phosphate groups
- NTP generates NMP present in monomer
Phosphodiester Linkage
- between 5’ and 3’ carbon atoms
- joins nucleotides together
Functions of Nucleotides
- monomeric units of RNA and DNA
- important signal molecules within cells
- important agents in energy transfer reactions of metabolism
- act as coenzymes/cofactors
nucleoside
does not have phosphate group
nucleotide
- consists of a nitrogenous base
- a pentose sugar
- a phosphate group (makes nucleotide negatively charged)
To build RNA we require…
- Phosphate group
- ribose sugar
- Base (A, U, C, G)
To build DNA we require…
- Phosphate group
- Deoxyribose sugar
- Base (A, T, C, G)
RNA
- ribonucleic acid
- directs ordering of amino acids into peptide chain
DNA
- deoxyribonucleic acid
- sequence of subunits in DNA polymer directs RNA synthesis
Functions of proteins`
- Enzymes –> catalyzing reactions
- Transport
- Support
- Signalling
- Movement
- Defense
Misfolding
-many human diseases caused by this
-protein can fold properly at first, but then it may unfold —under certain conditions
when the protein misfolds, it disrupts the cell’s activity, leading to its premature death
Renaturation
-when a protein is able to fold back up
Denaturation
-when a protein is unfolded back to its primary structure
4th structure of proteins
- when two or more polypeptides interact to form final functional protein - isn’t always occurring
- linked by covalent or non-covalent bonds
2nd structure of proteins
-alpha helix and beta pleated sheets beta pleated sheets -can be parallel or anti-parallel -weak hydrogen bonds in backbone -primary structure dictates whether it gets twisted in shape
1st structure proteins
-linear amino acid sequence, N-terminus (+) and C-terminus (-)
Sickle Cell Anemia
- red blood cells abnormally shaped
- when sickled, cannot fit through capillaries
Polypeptide Chain
- side chains extend from peptide-bonded backbone
- chain is flexible, backbone is directional and asymmetrical
- starts at N-terminus
Peptide Bonds
- covalent bonds between amino acids
- created through condensation reaction
- joins carboxyl carbon to amino nitrogen
- allows bond rotation and peptide flexibility
Hydrophilic R Groups
- uncharged, but partial charges can form H bonds
- charged, groups containing acids or bases
- highly soluble in water
Hydrophobic R Groups
- no charged or electronegative atoms to form H bonds
- insoluble in water
- R groups bury themselves within polypeptide to ‘hide’ from water
- mostly C & H
- not very reactive
Hybrid Amino Acid
- ionized form
- increases solubility
- facilitates interactions with other amino acids/solutes
- increases reactivity
Amino Acids
- small subunits of proteins
- carboxylic acid & amino acid & r group
- connected in linear polymers of specific sequences
- 20 genetically encoded amino acid monomers
- central carbon of amino acid is referred to as ‘alpha’ carbon
- L-amino acids & D-amino acids, only L-amino acids are found in proteins
Hydrolysis Reaction
- chemical reaction in which water is added back across the bond
- separating larger molecule into smaller molecules
Condensation Reaction
-chemical reaction in which two or mole molecules combine and form water as a byproduct
Base
-substance that accepts protons resulting in a decrease of [H+]
Acid
-substance that gives up/donates protons resulting in increase of [H+]
the longer the bond…
the weaker the bond
water
- most abundant molecule in biological organisms
- known as universal solvent
- 2 types of interactions with compounds:
1. hydrophobic = water fearing
2. hydrophillic = water loving
H Bonds
- electrical attraction between electronegative atom and partial positive of hydrogen
- 3rd strongest in biological systems
Ionic Bonds
- ionic bonding
- ionization
- second strongest in biological systems
Covalent Bonds
- strongest bonds of biological systems
- two or more atoms share electrons…
1. equally - non-polar covalent bond
2. unequally - polar covalent bond, one atom has stronger pull on electrons than the other
4 atoms matter in organisms are made of (99%)
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
Regulatory Molecules
regulation of enzyme activity allows cell to control which enzymes are active at any time depending on the needs of the cell
3rd structure proteins
-global structure (3-D) twisted, coiled and folded into unique shapes -ionic interactions -hydrogen bonds -disulphide bonds -covalent bonds
