Unit One Grade 12 Biology Study Notes Essay

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Unit One Grade 12 Biology Study Notes

Lipids (Fats, phospholipids, sterols)

used to insulate the body as well as protect organs

-better for you
-one or more double bonds between carbons
-less hydrogens
-oils (sunflower, flax)
-lower melting point

-worse for you
-single bonds between carbons
-more hydrogens
-animal fats
-higher melting points

-2 fatty acids, 1 glycerol, – phosphate group, + choline group -hydrophobic tails
-hydrophilic heads

Phospholipid Bilayer
Groupings of phospholipids move together and create a protective membrane with the hydrophilic heads one the outside and very inside of the cell and the hydrophobic tails facing one another.

-4 hydrocarbon chains fused together
-many functional groups attached
-a big part of the cell membrane
– cells turn cholesterol into vitamin D and bile salts

Carbohydrates (mono, di, poly saccharides)

Monosaccharides- hold energy and store it for cellular respiration Simple sugars – provide short term energy and storage
-most common one is Glucose (C6H12O)
-glactose and fructose are chemical isomers meaning they have the same chemical formula but different structures.

2 monosaccharides combined
glucose + glucose = maltose

Many monosaccharides combined together to create STARCH, CELLULOSE and GLYCOGEN

Starch (amylose-simpler diagram)- long term energy and storage Glycogen (more branched diagram) – unused glucose is turned into glycogen and stored for later use

Cellulose- plant cells are made of this which is why they are rigid. Used in digestion in humans, cleans out colon and intestines.

Proteins – building blocks of life

Amino acids – organic compound containing an amino and a carboxyl group Have R-groups or side chains that are responsible for how it bonds with other amino acids. The bonds between amino acids are peptide bonds. NON POLAR LIKES NON POLAR


Primary structure
A bunch of amino acids bind together through a certain sequence coded in the DNA -the number and order of acids is specific to each different protein

Secondary Structure
Peptide chains begin to bond with each other through the r groups. Bonds done in the secondary structure are usually done between amino acids close together. This causes the polypeptide chain to become ALPHA HELIX or a BETA PLEATED SHEET

-main bonds are hydrogen bonds between the carboxyl and oxygen atoms

Tertiary Structure
More bonds occur between amino acids but this time they are father apart from each other causing it to bend and fold even more

4 bonds
DISULPHIDE BOND- a bond between cysteine amino acids
ELECTROSTATIC BOND- an ionic bond between negative a positive side chains HYDROGEN BONDS- a bond between polar r-groups
HYDROPHOBIC INTERACTIONS- a bond between non-polar r-groups

Quatrinary Structure
Highest level of organization
The bonding of two or more tertiary proteins, making a lot of proteins into functional proteins.

Dehydration synthesis- removal of h2o and putting two molecules together Hydrolasis- adding of water and breaking apart two molecules Redox- give an electron away = oxidized, getting an electron = reduced

The constant state cells try to be
Certain things pass in and out of the cell at specific times and rates so
that the internal environment stays stable. Concentration gradient- difference between and are of high and an area of low concentration Brownian motion- the continuous movement and collision between molecules in a liquid

Passive transport – needs no energy
Simple diffusion- the movement of molecules from an area of high to low concentration. Small uncharged molecules like oxygen are passed through the membrane of a cell easily so that the cell can have oxygen.

Osmosis- movement of water across a semi permeable membrane from and area of higher concentration to an area of lower concentration


Facilitated diffusion- movement of molecules that are too big to be passed through the phospholipid bilayer or are not lipid soluble. Protiens throughout the membrane assist with the movement

Carrier protiens – move only specific molecules. Bind to that molecule and go through a series of movements and shape changing to move the molecule into the cell and then goes through those steps again to return to its original shape. Channel protiens- proteins with a hole in the middle that allows bigger molecules to pass in and out of the cell.

Active transport- requires extra energy
Cells need higher concentrations of certain nutrients to survive so sometimes molecules are moved against the concentration gradient using applied energy. moving them against the concentration gradient is active transport

Sodium potassium pump

Bulk transportation
Not many materials are too big to pass through the cell membrane. For those that cant, the cell membrane can wrap around the molecule to absorb it.

-when the cell wraps around the molecule to absorb it
-pinocytosis- cell “drinking”, small drop of extracellular fluid with small molecules within it (most common) -phagocytosis- cell “eating”, large drop of extracellular fluid with organic or bacterial molecules Exocytosis

-when the vesicle moves to the outside. The vesicle fixes the cell membrane and the contents are moved out of the cell

Cell membrane
Acts as a barrier for the cell, protecting the internal environment from the external environment. Cell membranes around the cell as well as around the organelles. -regulates what goes in and out of the cells and organelles

4 components= phospholipid bilayer, proteins, cholesterol and carbohydrates

phospholipid bilayer
2 fatty acids, 1 glycerol, – phosphate group, + choline group provides the physical barrier
separates the extracellular fluids from the intracellular fluids

-integral= bound in the hydrophobic interior of the cell
-peripheral=bound in the hydrophilic exterior of the cell

-figments of the cytoskeleton= microtubules creating a framework for the membrane

act as patching system and gives the cell fluidity

can connect to proteins (glycoproteins) or lipids (glycolipids) and act as
communicators between cells

Biological catalysts
Speed up reactions 1000000x
Reduce required reaction energy
Very sensitive to their environment
When exposed to extreme conditions they can “denature” and become completely dysfunctional Aren’t created nor destroyed during a reaction

pH and temperature affect the activity of an enzyme because they will only work at there maximum when in the perfect conditions. Anything other than that wont be optimal and eventually cause the enzyme to denature.

Enzymes are proteins with a depression called the active site. R groups stick out of the active side and attract substrates with similar R groups. The catalyzing occurs in the active site.

How is the active site shape determined by the 4 levels of protein structure? -polypeptide chain- sequence of amino acids and how the r groups react with eachother which causes a shape -then they fold and bend into secondary and tertiary structure causing for the final shape -the substrate is polar so the r groups facing out into the active site have to have some sort of polarity to attract it.

SIMPLE ENZYMES- enzymes made only of protein and the function results from the 3D arrangement of the amino acids

CONJUGATED ENZYMES- enzymes with both protein and non protein parts a) apoenzyme- protein part of the enzyme
b) cofactor-non protein part, close to active site.
-coenzyme= vitamins that are altered during a reaction. These have to be replaced by unaltered molecules before a new substrate can attach -activators=minerals (metal ions)

not only do environmental factors (pH and temperature) effect enzymes but substances can inhibit the actions of an enzyme.

Competitive inhibiters- so similar to the substrate that they enter the active site and block the substrate from bonding with the enzyme. This can be reversed by adding more concentration of the substrate.

Non-competitive inhibiters- attach to a different part of the enzyme and cause the shape to change so the substrates cant bond correctly

Allosteric sites- some enzymes have allosteric sites a ways away from the active site. When substrates attach to it they can inhibit or simulate enzyme activity. Binding an activator to an allosteric site stabilizes the proteins conformation and leaves all active sites open. Binding an allosteric inhibitor stabilizes inactive forms of the enzyme.

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