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Transcript of Biology
Unsaturated: have C,C double bonds
Polyunsaturated: have a lot of C,C double bonds Steroids Ring Shaped-Structure 6/5 members Functional Groups -OH Hydroxyl(polar)
-PO3 3- Phosphate(polar) E.g. Cholestrol, Testosterone, Progresterone. Triglyceride 3 fatty acids + 1 glycerol H2O is released H is lost from glycerol and OH is lost
from the carboxyl group of the fatty acid and the
remaining C O from the fatty acid and the O from the
glycerol molecule will form -C double bond O and a single bond O Phospholipid Hydrophilic head(phosphate group)
Hydrophobic tail(hydrocarbon chain)
Amiphipathic molecule. Amino Acids Alpha Carbon in the center bonded to
Amino group(H2N / H3N+), Carboxyl group(COOH/COO-)
H and R side chain Peptide bonds. Single bond OH from
first amino acid is broken and the H from the H2N
in the second amino acid is broken. The C = O then
bonds with the NH. R-side chain: negative: acidic
no charge: uncharged(hydrophilic)
Special case:thyol groups will be able to form
disulfide bridges(H2 is lost) for cystine only. Protein levels of structure:
Primary : Amino Acid sequence
Secondary : alpha-helix(DNA) beta-pleated
Quaternary : >1 polypeptide chain Protein denaturation pH- Addition of H+
Unfold and lose shape - Lose function Opposite of Hydrolysis : Condensation Carbohydrates Ring/ Linear form Monosaccharides: Glucose, Fructose, Galactose - Simple Sugars. X broken down
Oligosaccharides(2-10 Monosaccharides): Sucrose, Lactose
Special case 4 - 6 Monosaccharides(Oligosaccharide) usually form bonds with other molecules(e.g. glycoproteins)
Polysaccharides: Polymers of Monosaccharides, Starch, Cellulose Protein functions Structural Protein: Support
Storage Protein: Storage of amino acids
Transport Protein: Transports substances
Hormonal Protein: Coordination of an organisms activity
Receptor Protein: Helps the cell respond to chemical stimuli
Contractile Protein: Movement
Defensive Protein: Protection
Enzymes: catalyzes reaction General Formula:(CH2O)n Monosaccharides n in the general formula can be between 3 and 8
have 2 or more hydroxyl(OH) groups.
Either contain a aldehyde group(C double bond O single bond H)
These are called aldoses.The C can form 1 more bond.
or they can contain kentone group(Cdouble bond O) and are called Ketoses. The C can form 2 more bonds.
The aldose is normally found at the head or tail.
The Ketose is normally found in the middle. Formation of Ring Shape from Linear The aldose group at the head will interact with the
C4 Hydroxyl group and will "bend" to form a ring shape. Isomers Differ by spatial arrangement of atoms. Differ only
in the H, OH around 1 carbon. These small changes make minor changes in the chemical
properties of sugars. These changes are recognized by enzymes and other proteins so isomers have a large biological effect. The change in the arrangement of the H
and OH around the C1 will cause the
formation of alpha glucose(H on top)
and beta glucose(OH on top). Disaccharides One monosaccharide loses the H
from the hydroxyl group of the C1
and the other loses the hydroxyl group in C1.
there is a reducing end and the right of the molecule
which is HOH. The carbon is called the anomeric carbon. Polysaccharides Differ in the nature of monosaccharide
and the arrangement of the monosaccharide.
Can also form branch polymers(nucleic acids and
proteins cannot) Nucleotides Nitrogeneous base: usually modified from either the
pyrimidine ring or the purine ring.
Common pyrimidine: Cytosine Uracil and Thymine
Purine: Adenine and Guanine.
Adenine, Thymine, Cytosine and Guanine are found in DNA.
Adenine, Uracil, Cytosine, Guanine are found in RNA Pentoses in DNA: Deoxyribose(C2 does not have hydroxyl group)
Pentose in RNA: Ribose(C2 has hydroxyl group) Nucleosides: Phosphate group linked to sugar in glycosidic linkage. No phosphate is is linked to the OH group in the sugar. (Adenosine Triphosphate). We add a -idine if the ring is a pyrimidine and a -osine if it is a purine.(Sort of like Monosaccharides)
Nucleotides: Polymers of Nucleosides. Phosphuric acid is linked to the OH group in the Sugar forming a phosphodiester linkage. Glycosidic linkage The HOCH2 will lose
its Hydroxyl group and will
form a bond with one of the
O- in the phosphuric acid. Phosphodiester linkage The hydroxyl group in the sugar is lost and
the O- in the Phosphuric acid will form a bond with
the Carbon. Enzymes How do enzymes catalyse reactions? By reducing the activation energy required for the reaction to occur Can accelerate reactions up to 10^16 times Very specific One type of enzyme
has only one type
of substrate. The sub
strate does not need to
be directly complimentary
to the active site(induced
fit) Regulation of enzyme activity Zymogens: Inactive precursors.
Only activated when one or more of
the peptide bonds are broken. pH Temperature Inhibitors Competitive Directly fights with the substrate
If enzymes are flooded with substrates,
the competitive inhibitor will have little
or no effect Non-competitve Takes up the non-active site or allosteric site which
causes a conformal change in the active site and therefore
substrate cannot bind to enzyme- no ES complex formed- no product formed Feedback Inhibition The product becomes the inhibitor. The more products formed more
inhibitors are formed the rate of reaction drops. e.g. Threonine to Isoleucine E.g. Detergents(Lipase breaks down Lipids)
Pectinase(breaks down pectine found in cell wall of plants. turns
fruit juice from cloudy to clear) Cells Eukariyotic: Complex and has nucleus Prokariyotic: no nucleus. Simple Organelles Nucleus Nucleolus Stores genes(DNA)
Control center of the cell synthesizes RNA and forms ribosomal subunits Structure:
Circular with pores at the side and
connected to the Rough Endoplasmic Reticulum Ribosomes Free Membrane bound Synthesizes all proteins except for
secretory proteins Synthesizes secretory proteins Structure 2 subunits. 1 large and 1 small. Matches mRNA sequence with the tRNA sequence bound to the amino acids to form a polypeptide chain(primary structure) Endoplasmic Reticulum Rough Smooth Contains ribosomes which
produce secretory proteins. Since
many secretory proteins are glycoproteins
it also contains enzymes that link the oligosaccharide chains to the proteins.
Studded with ribosomes. Synthesizes phopholipids, steroids and oils.
Has enzymes that produce glucose from glycogen.
Also has enzymes that detoxify drugs and poisons.
E.g. the enzymes add hydroxyl groups to the chemicals which allow the chemical to easily flow through the body. Vesicles bud off the sER and joins into the Golgi Apparatus. Golgi Apparatus Looks like a stack of roti prata Modifies and synthesizes and packages proteins. Vesicles bud off the golgi apparatus and go to their intended
location. Lysosomes Digestive system of the cell. Has acidic pH- optimum for the enzymes
working in the lysosomes Enzymes hydrolyze DNA,RNA,polysaccharides,protein
and lipids. Peroxisome Carries out oxidation reaction leading to the production of hydrogen peroxide(H2O2). Breaks down amino acids fatty acids are broken
down by oxidisation. Oxidisation produces energy for the cell. The proteins found are synthesized by free ribosomes. Some peroxisomes synthesize lipids. Mitochondria 2 membranes Inner membrane is highly folded. Has their own DNA and ribosomes- can synthesize
their own proteins. Extract energy from simple sugars and other fuel molecules(glucose) and conserve the energy released into a high-energy compound: adenosine triphosphate. Chloroplasts 2 membranes, contain their own DNA, ribosomes. no folding in inner membrane have thylakoids convert the energy found in sunlight to energy needed for the cell. Cytoplasm portion not occupied by the nucleus. has interconnected filaments and tubules called the cytoskeleton. assembled from their protein building blocks. like lego(railway track). Microfilaments and microtubules are responsible for contraction of muscle cells beating of flagella and cilia and movement of chromosomes and locomotion of the cell. Cytoskeleton is responsible for the positioning and moving of organelles. Centrosome initiation site for assembly of microtubules to form mitotic spindle during cell division. mitotic spindle is important in the separation and distribution of chromosomes to daughter cells. Membrane structure and function Phospholipid bilayer Hydrophilic region keeps out hydrophobic
molecules and hydrophobic region keeps
out hydrophilic molecules(H2O). Only amphipathic molecules and small covalent
compounds can enter.(O2) Fluid Mosaic model Cholestrol aligns thenselves with hydroxyl group which immobilizes the hydrocarbon chain close to the polar head group.
Makes the bilayer less deformable and thus reducing the permeability of the bilayer. Cholestrol also prevents the membrane from crystallizing at low temperatures. Membrane proteins are involved in cellular transport(integral), intercellular joining(integral), enzymatic activity(peripheral and integral), cell-cell recognition(via oligosaccharide chain)(integral and peripheral protein), signal transduction(integral) and attachment the cytoskeleton(integral and peripheral) Difference between alpha and beta glucose helical structures with branches
Long chains that branch out at intervals
Hydroxyl groups found on the same side
Fewer hydrogen bonds alpha beta Linear chain
alternating hydroxyl groups
more hydrogen bonds starch cellulose effects effects branches allow starch to be broken down easily
therefore able to store energy
Helical structures and branches allow for greater packing yet remaining available to enzymes a lot of hydrogen bonds makes a stronger bonding and a rigid structure of cellulose.
Allows cell wall to be strong. Transport Across Membranes Diffusion Active Passive Requires energy . Needs no energy. Against concentration gradient. Together with the concentration gradient Energy is provided through 3 ways ATP Light Energy The diffusion of another substance ATP Driven Path. Light Driven Path Coupled Carrier Flow of molecule up the concentration
gradient provides the energy for a molecule
to move down the concentration gradient. Biomolecules Tests Emulsion Test Steps 1. Add 2.0cm3 of ethanol into the test tube.
2. Cover the mouth of the test tube and shake vigorously.
3. Observe Contents.
4. Add 2.0cm3 of distilled water into the test tube.
5. Observe Contents. Positive Test White Emulsion formed.
Lipids will dissolve in ethanol. Addition
of water will cause the lipids to form a emulsion. Test for Lipids Benedict's Test Steps 1. Fill a beaker with tap water to half-full. Heat over Bunsen Burner to prepare a boiling water bath.
2. Add 2.0cm3 of solution into a clean test tube.
3. Add an equal volume of Benedict's reagent.
4. Shake the test tube and put it into the boiling water.FOR NOT MORE THAN 5 MINUTES
4. Observe contents. Positive test Orange Red precipitate formed.
Reducing Sugars reduce Copper II ions(blue) to copper I ions(brick-red)
If overheated, a brown colour forms. Test for Reducing Sugars. Starch Test Biuret Test Steps 1. Add 2.0 cm3 of NaOH into the solution.
2. Shake the test tube.
3. Add 1% copper sulfate solution.
4. Shake well and observe contents A purple colour develops.
In the presence of dilute copper sulfate in alkaline solution, the nitrogen atoms in the peptide chain form a purple complex with copper II ions. Types of Solutions Hypotonic Isotonic Hypertonic water potential outside is more than inside
resulting in water moving inside the cell and causing
an animal cell to burst. If it is a plant cell then the cell wall
stops the cell from bursting and the plant cell becomes
Water potential outside
is the same as water potential inside
the cell resulting in water moving out and in.
There is no net movement of water. Therefore,
an animal cell will be normal and a plant cell will
be flaccid. Water potential outside is lesser than
inside the cell. There is a net movement of water
outside. An animal cell will become shriveled. A plant
cell, will become plasmolyzed because the cell wall keeps
the plant cell rigid and air sacs form in the cell to account for the water lost.