Biology 20 Biochemistry
Where do chemical reactions occur in the body?
Within water of the cells and tissues
When is a solution neutral?
When hydrogen ions equal hydroxide ions
When is a solution Acidic?
When there are more hyrdrogen ions than hydroxide ions
When is a solution basic?
When the number of hydroxide ions is greater than the number of hydrogen ions
What different levels of acidity are in the human body?
pH 2.5-3.0 -> Stomach acid
pH 8 -> intestines
What happens when the pH of the body is changed and why?
Cellular functions need a specific pH to work, and when this is changed they cannot carry out their necessary tasks
What are OH- and H+ receptors in the body?
They act as "buffers" within the body to regulate pH changes by absorbing excess acid or base
What is the difference between netralization and buffers?
Neutralization is changing an acid or base to neutral
Buffers maintain a specific acid or base level and don't change it
What are the four essential macromolecules?
1)carbohydrates
2)Lipids
3)Proteins
4)nucleic acids
What is the element that makes up the framework of all macromolecules and why?
Carbon, because it has four places to bond with other molecules/atoms
What are organic molecules?
Molecules within the body containing carbon
What are inorganic molecules?
Molecules in the body not containing carbon
What is Anabolism?
the formation of larger molecules from smaller ones
Needs energy to work
What is Catabolism?
The breaking down of larger molecules into smaller ones
Releases energy
What is the medium for metabolism?
Water because of its solvent properties
What is the body's most important source of energy?
Carbohydrates
What are carbohydrates made of?
Oxygen, hydrogen, and carbon
How do humans get carbs?
Cannot make them ourselves, rely on plants
What are the two forms carbs can take?
single sugar units or polymers of many sugar units
What is a monosaccharide?
A single sugar unit containing oxygen, hydrogen, and carbon in a 1:2:1 ratio
What is the difference between an isomer and a polymer
isomer - one single unit of sugar
polymer - multiple conjoined sugar units
What is a Disaccharide?
Double or two conjoined sugar units
how are polymers (disaccharides and polysaccharides) formed
Through a condensation reaction which takes water out of the molecules to allow them to join
What are examples of Disaccharides?
maltose, sucrose, lactose
What are polysaccharides?
polmers made from condensation of 3 or more sugar units
starch is an example
What is starch?
present in plant cells
long chains of carbs
comes in two forms - amylose and amylopectin
starch is stored in seeds and used as energy until plant can photosynthesize
What is glycogen?
Storage molecule in animals
stored in liver and muscle cells
used for cellular respiration
what is the difference between starch and glycogen?
glycogen contains more chains of glucose
What is hydrolysis?
breakdown of Polysaccharides to Monosaccharides - takes in one water molecule
What is cellulose?
storage molecule for plants
made up of chains of glucose attached by hydrogen bonds
these bonds make the plant's cell wall stiff and tirgid
this is a structural molecule
cannot be broken down by mammals
Why are starch and glycogen good energy molecules
Can easily undergo condensation or hydrolysis to store or use as energy
Why are polysaccharides always storage molecules?
Because of their larger size they are relatively insoluble
starch and glycogen are examples of this
they hold many bonds that 'store' energy until it is needed
How do you calculate the number of hydrogen bonds in a polysaccharide?
Number of monomers = n
Number of bonds = (n-1)
Cellulose (2)
Source: Plant
Subunit: B-glucose
Bonds: 1-4
hydrogens are opposite and staggered in chain
shape is linear and parallel
Starch (2)
Amylose
Source: plant
Subunit: a-glucose
bonds: 1-4
No branches
hydrogens are on same side as one another, no gaps
shape is helical
Amylopectin
Source: Plant
Subunit: a-glucose
bonds: 1-4 and 1-6
Branching (about every 20 subunits)
Shape is branching but not super compact
Glycogen (2)
Source: Animal
Subunit: a-glucose
Bonds: 1-4 and 1-6
Branching (about every 10 subunits)
Shape is branched and very compact
Function of Alpha glucose?
- used to build starch and glycogen
- energy molecule
Function of beta glucose?
- Used to build cellulose
- energy molecule
Function of D-Ribose?
- component of genetic material RNA (ribonucleic acid)
Function of Deoxyribose?
- component of DNA (deoxyribonucleic acid)
Function of Maltose?
- intermediate in the digestion of starch
- used as sweetener and found naturally in peaches and pears
Function of Sucrose?
- source of energy
- used as the most common sweetener
Function of Lactose?
- energy providing nutrient
- "milk sugar" produced by lactating mammals
Function of starch (amylose)?
- storage
- more difficult for humans to digest compared to amylopectin
- low glycemic index - slow rise is blood sugar
Function of starch (amylopectin)?
- storage
- easier for humans to digest compared to amylose
- high glycemic index (fast rise in blood sugar)
Function of glycogen?
- storage in muscles and livers of mammals
Function of Cellulose?
- Structure inplant cell wall
What are the characteristics of a Lipid?
- non-polar
- insoluble inpolar solvents
- hold more energy per unit than both carbs and proteins (9Kcal/g)
- Composed of two structural units (glycerol and fatty acid)
What is a phospholipid?
- hydrophobic tail (fatty acids) and hydrophilic head (phosphate and glycerol)
Why do phospholipids make up the most of a cell membrane?
They keep the inside of the membrane dry due to their bilayer configuration keeping the heads submerged in water and the tails dry and compacted next to one another
What are the polar differences between the head and tail of the phospholipids?
head - polar
tail - non-polar
What are the three types of lipids?
- tryglycerides
- phospholipids
- steroids and waxes
What are the two types of fatty acids?
Saturated and unsaturated
Characteristics of saturated fatty acids
- solid at room temp
- single bond between carbons (no double or triple bond and no bend in molecule)
- denser and more harmful formations than unsaturated fats
Characteristics of Unsaturated fatty acids
- liquid at room temperature
- more doble bonds -> lower melting point
- the double bonds of the carbons allow molecule to bend and form less dense formations
What are the two types of unsaturated fats?
Cis -> hydrogens attached to double bond are on same side -> more bends in molecule
Trans -> hydrogens are on opposite sides -> creates unatural linear shape that is the most unhealthy for you
How are trans fatty acids made?
industrial process of hydrogenation -> adding hydrogens for longer shelf life
What state are cis vs. trans fatty acids in?
cis -> liquid
trans -> solid
What are the characteristics of triglycerides?
- most common and largest class of lipids
- stored in animals as solids
- stored in plants as liquids
- formed when condensation reaction occures between three fatty acids and one glycerol molecule
What are the functions of triglycerides?
- long-term energy storage
- thermal insulators to body temperature in our habitat
Functions of lipids (5)
1) phospholipids make up cell membrane and some lipids act as hormones
2) lipids have twice the energy content of carbs and proteins
3) heat insulation in animals
4) storage molecule - doesn't require water
5) for protection of exposed internal organs
What are some characteristics of proteins?
- structural components of all cells
- composed of hydrogen, carbon, oxygen, AND nitrogen (sometimes sulphur)
- made up of amino acids
- has a central carbon atom
What are the components of an amino acid?
- carboxyl group
- amino group
- hydrogen atom
- R group - specific to 20 different amino acids
What determines if an amino acid is polar or non-polar?
- depends on the side chains of the amino acids
- non-polar -> non-polar side chains (R groups)
- polar amino -> polar side chain (R group)
Number values of amino acids
20 total
12 of them created naturally
8 of them through diet (essential amino acids)
Characteristics of Nonpolar side chains
- hydrophobic
- no overall charge or unequal distribution of electrons on R group
- only change is the R group, which gives different chemical properties
- there is no oxygen in nonpolar side chains
Characteristics of Polar side chains
- hydrophilic
- partial or unequal distribution of electrons in R group
- contains oxygen and sulfur
Characteristics of Electrically charged side chains
- hydrophilic
- polar
full gain or loss of electrons resulting in complete charge
- contains NH+ if positive
- contains O- if negatively charged
Steps to identifying properties of an amino acid?
1. is it an amino acid? Do you see an amine group, a carboxyl group, and an alpha carbon?
2. Find the R group, do you see an oxygen atom?
a. NO.. amino acid is non-polar
b. YES.. do you see a charge?
i. NO.. amino acid is polar
ii. YES..amino acid is an ion
What is a peptide bond?
Amino group of one AA links with the Carboxyl group of another, they undergo a condensation reaction and a water molecule is removed, linking them together
What is it called when multiple peptide bonds are linked together?
Polymerization
What is a polypeptide?
3 or more amino acids
What is a protein made up of?
one or more polypeptides
The functions of a protein?
1. transport
2. contraction of muscles
3. enzymes
4. hormones
5. antibodies
6. structural proteins
7. storage
8. plasma proteins
9. receptors
what is entropy?
measure of the unusable energy within a system
what are energy systems?
involve energy input, energy conversions, and energy output
where do energy conversions occur?
Within cells.
what are metabolic reactions?
are reactions that occur within the cells of plants and animals
what is activation energy?
energy required to initiate a chemical reaction
what are reactions that release energy called?
Exergonic
What are reactions that need a constant stream of energy?
Endergonic
what are metabolic pathways?
a series of steps from a starter molecule or precursor toward a final end product
How do enzymes contribute to metabolic reactions?
1) speed up reactions in the form of biological catalysts
2) control metabolism within all organisms
3) lower the amount of activation energy necessary for a metabolic reaction, therefore less energy is needed for the goal to be reached
What are catalysts?
chemicals which regulate the rate of chemical reactions without themselves being altered
What are the energy requirements for all reactions?
1) reactants need to have bonds broken
2) molecules need to re-orient
3) new bonds need to be formed
What will enzymes do in a catabolic reaction?
Will break apart a substrate into two or more pieces
What will enzymes do during a anabolic reactions?
They will join two or more substrates together into one product
How do substrates and enzymes join?
Substrates can only fit into very specific enzymes, but because they are both in abundance within the body random collisons ensure that they will join together
What is an enzyme-substrate complex?
When the two components are bonded together
What determines the shape of an enzyme and the type of substrate it can take on?
The folding of its amino acids within the protein
What are the components of an enzyme?
Pocket/Active site
Enzyme body
Allosteric inhibitor site
What are the two different theories surrounding substrate-enzyme complexes?
Lock and Key model
Induced fit model
Describe the induced fit model
When the active site of the enzyme shifts in shape slightly to accomodate the substrates entering it and changing them during the reaction. The substrates will be changed after this, but the enzyme will return to its original shape and can be used again.
What are the factors that affect enzymes?
- temperature
- pH
- enzyme concentration
- substrate concentration
What will happen to an enzyme if its not in the proper conditions
It will denature, meaning that its folds will loosen and the active site will no longer fit the correct substrate
Describe temperature in relation to enzymes
- reaction rate increases as temperature increases
- this is because temperature increases the number of collisons
- temperature cannot be too high or low or it will denature (too low and no movement, too high and too much movement as well as denaturation)
What is the optimal human body temperature?
about 37 degrees celcius
Describe pH in relation to enzymes
- different parts of the body function at different pH's, and therefore the enzymes within those parts will have different optimums
- a pH too low or high will denature an enzyme
Describe how concentration of substrate molecules can affect enzymes?
- the greater the number of substrate molecules the greater the number of collisons and substrate-enzyme complexes formed
- this will increase until the number of enzymes becomes a limiting factor
(this is the same for enzyme concentration)
What is allosteric regulation of enzymes?
changing of an enzymes capabilities or activity due to an outsider molecule called an effector
this binds to a part of the enzyme other than the active site
this is reversible