3.1 Biological Molecules Flashcards
What is an isomer?
Same chemical formulae, different arrangement
Monomers making Maltese?
2 glucose
Monomers making Sucrose?
Glucose + Fructose
Monomers making Lactose?
Glucose + Galactose
Bonds between sugars
Glycosidic
Isomers of glucose
Alpha glucose
Beta glucose- flip on carbon 1, alternating directions when in chain
Starch
Alpha glucose (stored on plants)
- mostly unbrancged and tight helix shape
- insoluble, compact, easily hydrolized, large molecule
Glycogen
Alpha glucose (stored in animals)
- short and branched, tight helix shape
- insoluble, compact, lots of ends for hydrolysis, large molecule
Cellulose
Beta glucose (cel walls)
- straight and unvranched, parrelel chains connected by hydrogen bonds
- Cross links so collectively strong, microfibrels and fiberals for more stregnth
- stops cell from wilting
Test for reducing sugar
2cm³ of food sample +Benedicts solution+ heat
Colour change blue to red (shows concentration by colour)
Testing for non reducing sugars
2cm³ of food sample + 2cm³ of HCl (hydrolize into monomers)
+ NaHCO3 (neutralize)
Then perform reducing sugars test
Test for Starch
Drops of iodine on 2cm³ of food sample
Colour change brown to blue/black
Colorimeter in test for sugars
tests solutions absorbance of light
- more intence the colour more absorbant it is
- need to caliberate device with water and known concentrations glucose (Quantative Data)
7 Functions of protiens with examples
- contractile (actin+myosin, cilia+flagellum)
- storage (ovalbumin (egg white) and in seeds)
- receptor and hormonal (nerve membrane and insulin)
- transport (haemoglobin)
- enzymatic (digestive enzymes)
- structural (silk fibers for webs, collagen and elastin, keratin for hair/feathers/horns)
Amino acid structure and properties of R groups
NH2-CHR-COOH (amine and carboxly group)
-20 natural occurring amino acids
R groups can be:
hydrophilic (charged) or hydrophobic
-acidic, basic or amphoteric (acid and base so used as buffers)
Simple protien
Made if only amino acids
Conjuncted protiens
Contain amino acids and a non-Amino acid part called “prosthetic group”
Primary structure of protiens
The sequence of amino acids joined by peptide bonds
-change to primary structure due to mutations in DNA
Secondary structure of protien
The way the polypeptide chain is folded into ALPHA HELIX or BETA PLEATED SHEETS
-joined by weak Hydrogen bonds
-chain can have some regions coiled and others folded
Tertiary structure of protiens
Protien folds further to give molecule a globular shape
- forms specific 3D shapes
- important for enzymes and antibodies
Types of bonds in tertiary structure of protien
Ionic- NH2 • • •COOH, broken by pH change
Hydrogen- strong in number, broke by temp or pH change
Disulphide- strongest bond in structure (S‐S)
Hydrophobic interactions- hydrophobic R group cluster together in presence of water (not a bond)
Structure of DNA
- nucleotide (phosphate group, deoxyribose pentosugar, nitrogeonous base)
- joined by PHOSPHODIESTER BONDS
- double helix
Bases and Base interactions
Adenine Guanine (purine) Thymine Cytosine (pyrimidines) A--T C---G Hydrogen Bonds
Structure of DNA to its functions
double stranded- template for semi conservative replication
weak h-bonds- can be broken for easy replication
many h bonds- overall strong
complementary base pair- accurate replication
sugar phosphate backbone- protects from corruption
large molecule- store lots of info
double helix- compact
importance of DNA
genetic code (for all protiens) mitosis variation
difference between DNA and RNA
RNA- ribose sugar, smaller, single helix, Uracil instead of Thymine
Process of DNA replication
- DNA helicase breaks H bonds, DNA unravel
- strands act as templates
- free floating activated nucleotides attract to specific complementary base
- DNA polymerase joins nucleotides (phosphodiester)
- Semi conservative, ensures genetic continuity
uses of ATP
- movement
- metabolism
- maintaining temperature
- active transport
- PHOSPHORYLATION to change protein shape
- cell division
- production/secretion of other products (e.g. from lysosomes)
Structure of ATP
-adenine
-ribose pentose sugar
-3 phosphate group (last bond unstable and easily broken)
KNOWN AS A NUCLEIC ACID
How does ATP release energy?
How does it return to ATP?
How much energy released?
- last phosphate covalent bond broken by ATP hydrolase
- reversible, joined back by ATP synthase
- immediate release of energy, in manageable amount (33kJ)
What is triglyceride made of?
1 glycerol molecule( 3 hydroxyl groups)
and 3 fatty acid molecules (each has 1 carboxyl group)
Connected by ester bond
Saturated lipid
No carbon-carbon double bonds
Straight and closely packed (dense)
-so solid at room temp
E.g. fats/butter
Unsaturated lipids
Has carbon-carbon double bond
Causes chain to bend, less dense
- liquid at room temp
E.g. oil
Properties of triglycerides
-good energy store
(high proportion of H so provides 2× more energy than respiration and provides water so reduces mass needed to be carried by animals)
-non polar (doesn’t affect water potential, provides waterproof layer)
-thermal and electrical insulation
-protect internal organs (as cushioning)
- less dense than water (aids in buoyancy)
Phospholipid structure
1 phosphate group (PO⁴R) negative ion
1 glycerol (3 hydroxyl groups)
2 fatty acid chains (each has 1 carboxyl group)
Head is charged so polar so hydrophilic
Tails are unchanged so hydrophobic
Shapes formed by phospholipids
- monolayer ontop of water
- MICELLES- monolayer ball
- BILAYER- fluid membrane but stable shape
- barrier and electrical insulation
- ions dissolved in water so cant go through membrane (surrounds nerve cells)
Test for lipids
EMULSION TEST
If sample solid it must be crushed
2cm³ of sample and add 5cm³ of ethanol
Shake tube and add 5cm³ of water, reshake
WHITE EMULSION
Light Microscope
pros and cons
uses light and lenses
low mag and resolution
for bacteria/tissue
simple and cheap
Electron Microscope
pros and cons
uses electron and electromagnets
high mag and resolution
for organelles/organisms
complex and expensive
Setting sample for Electron microscope
Killed, Dehydrated, stained with heavy metals (which can cause artifact/debris to damage sample), fixed in a vacuum
TEM (pros and cons)
- to see organelles inside (stains absorb electron)
- has slightly better resolution that SEM
- used for cells, cant use it for organisms
SEM (pros and cons)
- to see surface of specimen (stain reflects electron)
- 3D
- can be used to see specimens
steps in Differential Centrifugation
- chop and place in ICE COLD ISOTONIC BUFFER
- homogenize
- spin in centrifuge, remove supernatant
- repeat at faster speeds
-first pellet: nucleus, 2nd pellet: chloroplast/mitochondria
creating temporary mount
-cut thin enough for light to pass through
-flatten then stain with Iodine SOLUTION
(unless looking at something pigmented)
-use mounting needle to lower cover slip at an angle
Why is cells placed in ice cold, isotonic, buffer solution? (for centrifugion)
cold-reduce hydrolytic enzyme activity
isotonic- so doesn’t affect water content of cells
buffer- constant pH so structural proteins not changed
difference in 2 strands of DNA
-antiparallel strands
-phosphate end (5 prime/leading), sugar (3 prime/lagging)
DNA POLYMERASE WORKS FROM 5 TO 3 PRIME
Experiment for Semi Conservative Replication
bacteria grown in heavy nitrogen, next replications done in light nitrogen for 3 generations
-spun in DENCITY GRADIENT CENTRIFUGION
what is density gradient centrifugation?
DNA centrifuging in a solution of caesium chloride, DNA separates at its densities
compare bands to normal light nitrogen bands
Results of Experiment of Semi Conservative Proof
- all heavy so at bottom
- half heavy have hybrid
- half hybrid half light
4 quarter hybrid, rest light
structure of ATP
adenine, ribose pentosugar, 3 phosphate groups
properties of water
cohesion water tension high heat capacity high latent heat of vaporization used in metabolism universal solvent amphoteric low density as solid
Properties of water- cohesion
attraction between molecules
h20 sticks together so can FLOW (needed in phloem)
Properties of water- metabolism
used in HYDROLOSIS and produced in CONDENSATION
- many reactions happen in aqueous conditions
- needed in photosynthesis
Properties of water- as a solvent
H2O has dipole so can dissociate ions in ionic compounds
-gasses waste products, inorganic molecules DISSOLVE in water to be TRANSPORTED
Properties of water- Latent heat of vaporization
needs lot of energy to turn water to vapor (COOLANT)
-use as a way for organism to get rid of excess heat SWEATING
Properties of water- surface tension
-hydrogen bonds strong at surface molecules, allows insets to walk on water
Properties of water- amphoteric
is an acid (H+) and base (OH-)
BUFFER for chemical reactions, keeps constant pH
Properties of water- high heat capacity
needs lot of energy for an increase in temperature, allows organisms to MAINTAIN TEMPRATURE, NO SUDDEN CHANGE in temp
Properties of water- low density as solid
h-bonds keep molecules further in solid than liquid
- ice FLOATS on water
- acts as insulator to water and organisms below
