Unit:1 Biochemistry

Question 1

What is the cell membrane made up of and what are some things that is embedded inside?

Answer 1

1) The cell membrane is made up of a phospholipids bilayer

2) Things that are embedded in the cell membrane
- Choloestrol: Maintains fluidity at various temps
- Proteins: Embedded throughout the membrane layers to allow the cell to interact with external enviorment.

Question 2

Which enviorment do cells in?

Answer 2

Only lives aqueous enviorment

Question 3

What does the cell membrane allow to come in without requiring specialized structures made up of proteins to help?

Answer 3

Barrier only allows gases like oxygen and carbon dioxide to cross and some other small nonpolar molecules.

Question 4

Which parts of the phospholipids is Polar and non-polar?

Answer 4

The polar part is the: Polar head groups ( hydrophilic surface)

The non-polar part is the: Nonpolar tail ( Hydrophobic interior)

Question 5

Define Hydrophobic and Hydrophilic

Answer 5

Hydrophobic - Lacks affinity for water

Hydrophilic - Has a strong affinity for water

Question 6

What is Diffusion?

Answer 6

Diffusion is the passive transport of materials through the membrane due to molecular motion. ( Doesn’t require ATP)

Particles spread from high concentration to low concentration. So materials will flow across the memebrane with this concentration gradient.

Question 7

What is facilitated diffusion?

Answer 7

protein channels are used to allow ionic, polar and larger molecules to cross the membrane but they still follow the the concentration gradient.

Question 8

What are Periphereal proteins and what is their purpose?

Answer 8

Perphreal porteins are used for communication on the outside and structural support on the inside.

On the outside:
- Sugars attached to the external proteins (glycoproteins) act as cell identifictaion tags and provide a cite for cell to cell attachement. This is vital for immune response and proper developement of tissues.

• Receptor proteins have specific shapes to detect signal molecules(hormones) and pass on info

Internally:

Internally, proteins provide attachment sites for the cytoskeleton to assist in movement, structural support & internal transport.

Question 9

What are integral proteins and what is their purpose?

Answer 9

These proteins are specialised so that they only perform one job at a time.Even a small error during the manufacture or placement of a membrane protein can cause serious harm to the cell.

Question 10

What are enzymes?

Answer 10

A functional protein that tends to be globular in shape.
(A blob with a job.)
Generally perform only one reaction on one specific molecule.
Names end in “-ase” (ie. lipase, amylase, etc)

Question 11

What is osmosis?

Answer 11

Water diffuses constantly but only through proteins (aquaporins) or water sensitive membrane regions

water does follow the gradient but will always flow to the side of the membrane with a higher solute concentration.

Question 12

Define Hypertonic, Isotonic and Hypotonic

Answer 12

Hypertonic - A solution that has higher concentration of solutes outside the cell compared to inside

Isotonic - The solute concentration is equal inside and outside the cell

Hypotonic - There is a higher concentraion of solutes inside the cell compared to outside of the cell

Question 13

Osmosis in Plants

Answer 13

Plants absorb water into a large vacuole.

Rigid cell wall prevents cell from bursting.

Pressure of water pushes on cell wall giving strength to plant tissue.
Called turgor pressure.
Swollen cell is call turgid.

Plasmolysis
Lack of water causes cell to shrink away from cell wall.

Plamolysis - Hypertonic
Flaccid - Isotonic
Turgid -Hypotonic

Question 14

Active Transport

Answer 14

Against the concentration gradient thus requires the use of energy as ATP.
Molecules too big or hydrophilic to pass through membrane.

Question 15

What is Bulk transport?

Answer 15

This bulk transport uses the cell membrane itself to create transport vesicles that can engulf or empty large amounts of materials at once.

Secretory cells use this to pre-package a large amount of material and then release it all at once into the bloodstream. It can also be used to consume other cells whole, like in your immune system.

Question 16

Exocytosis

Answer 16

Intracellular vesicle fuses with membrane.
Waste removal.
Molecule secretion.

Question 17

Endocytosis

Answer 17

Membrane pinches off.
Phagocytosis
Solids & whole cells.

Pinocytosis
Liquids

Receptor Mediated Endocytosis
Molecules bind to surface receptors that trigger engulfment by membrane.

Question 18

Why do proteins spontaneously fold?

Answer 18

Proteins spontaneously fold due to the interaction of the R groups with each other and the enviorment.

The interaction will change with temperature, pH, ion molarity and presence of other chemicals.

Question 19

What causes a protein to denature?

Answer 19

A change in temp, pH, ion molarity and presence of other chemicals.

denatured proteins have no function

Question 20

Linear proteins are used for?

Answer 20

are used for structural support like in muscle tissue

Question 21

Globular proteins are used for?

Answer 21

globular proteins are functional molecules, like enzymes

Question 22

what is dehyradtion synthesis?

Answer 22

Dehyradtion sysnthesis links the amino group of one

amino acids to the carboxyl group of another.

Question 23

What determines the function of a protein?

Answer 23

The order of amino acids is key in determining the function of the protein

Question 24

What are 4 steps of creating folding protein?

Answer 24

1) Primary structure
- sequence of amino acids
2) Secondary structure
- Interaction of polar R groups to form helices and sheets
3) Tertiary structure
- Complex folding due to all R group interactions
4) Quaternary structure
- Association of two or more Tertiary structure

Question 25

What is the monomer of carbs?

Answer 25

Saccharides
- This monomer are the main energu fuel for cells and are polymerised for storage, transport and use as building materials

Question 26

What happens during the dehydration synthesis of carbs?

Answer 26

Dehyradtion sysnthesis links the monomers together at the hydroxyl groups forming glycosidic linkages.

Question 27

What are the 2 isomers of Glucose?

Answer 27

alpha glucose - the OH group on C1 is below the plane

beta glucose - the OH group on C1 is above the plane

Question 28

What are lipids?

Answer 28

Lipids are mostly nonpolar molecules that tend to exist more as monomers or simple polymers.

Question 29

What are the functions of lipids?

Answer 29

They vary widely in function but can be used as long term energy storage, lubrication and protection, hormones and are the major component of cell membranes.

Question 30

How is dehyradtion synthesis used in lipids?

Answer 30

Dehyradtion synthesis is sued to join fatty acid monomers to a glycerol backbone for long term energy storage.

This creates a triglyceride molecule with carboxyl linkages created between hydroxyl and carboxyl groups.

Question 31

What are sterols?

Answer 31

Sterols are generally signalling molecules or hormones. Many are built by modifying cholestrol by altering the side groups on the four carbon ring structure

Only exists as monomers

Question 32

what are waxes?

Answer 32

Waxes tend to be extremely long fatty acids that are mainly used for waterproofing.

Question 33

What is the polymer and monomer of nucleic acids?

Answer 33

Polymer: Nucleic acids

Monomer: Nucleotide

Question 34

what is each monomer of nucleotide made up of?

Answer 34

Each monomer nucleotide is composed of a 5 carbon sugar, a phosphate group and a nitrogenous base.

Question 35

how is nucelic acids created using dehydration synthesis?

Answer 35

Dehydration synthesis is used to form the bond between nucleotides which is called a phosphodiester linkage.

Question 36

What nitrogenous bases pair up and what type of bond holds them together?

Answer 36

Cytosine can form three hydrogen bonds with guanine, creating a strong association between nucleotides.
Adenine can form two hydrogen bonds with thymine (DNA) or uracil (RNA) which will hold the bases together, but not as strongly.
Notice also that in order to pair up one chain is inverted to the other.

Question 37

what is a biochemical catalyst?

Answer 37

Enzymes are biochemical catalysts

Speeds up reactions by lowering activation energy.
Not consumed by reaction.
Reusable approximately 1000 times.

Question 38

Why are enzymes necessary?

Answer 38

Reactant molecules must collide with enough force (ENERGY!) and with the correct geometric orientation for bond breaking to occur

This happens in a random and uncontrolled manner in non-catalyzed environments (=slow!)

therefore we need enzymes to speed up these chemical reactions

Question 39

Activation energy

Answer 39

Activation energy is the energy that must be overcome for a chemical reaction to occur

Question 40

How do enzymes reduce the amount of time for a reaction to take place?

Answer 40

The purpose of an enzyme in a cell is to allow the cell to carry out chemical reactions as quickly as possible without using too much energy.

Enzymes do this by lowering the activation energy

Question 41

Define Endothermic reaction and Exothermic reaction

Answer 41

Endothermic reacrtion: Absorbs more energy than it releases.

Exothermic reaction: Releases more energy than absorbed.

Question 42

what is part of the enzyme structure?

Answer 42

Substrate

• Reagent molecule(s)
• Enzymes are substrate specific

Active Site
- Binding site for substrate

Question 43

Explain the process of the substrate getting attached to the enzyme

Answer 43

1. The substrate binds (attaches) to a specific site on the enzyme called the active site.
2. The substrate(s) fits closely into active sites because enzymes can adjust their shapes slightly to accommodate the substrate
   This adjustment is referred to as ‘induced fit’ and forms the Enzyme-Substrate Complex
3. Then it become Enzyme-product complex
4. Then the product leaves the active site

Question 44

what is the Allosteric Site?

Answer 44

Binding site for activator & inhibitor.
Alters shape of active site.
Activator – turns on enzyme.
Inhibitor – turns off enzyme

Question 45

what is Competitive inhibition?

Answer 45

Competitive inhibition is where the inhibitor can bind to the active site, blocking the substrate. Increasing the substrate concentration will reduce the effect of the inhibitor.

Question 46

what is Noncompetitive inhibition?

Answer 46

Noncompetitive inhibition is where the active site is blocked or it’s shape is altered so that the substrate will not fit. Substrate concentration has no effect on the effectiveness of the inhibitor.

Question 47

Factors that affect enzyme activity

Answer 47

Concentration: The rate of enzyme activity depends on the concentration of substrate present.

Temperature and pH: Every enzyme has an optimal temperature and pH that the enzyme works best at

due to the particle theory and denaturation

Question 48

what do some enzymes need to function properly?

Answer 48

Some enzymes also require non protein cofactors, such as inorganic substances (Zn2+ and Mn2+ ) or organic coenzymes, (many vitamins) before they can work properly

Question 49

what is a (De)hydrogenase enzyme

Answer 49

(Removes) Adds hydrogen along with its electrons & energy.

Notice that this requires a coupled reaction.

Question 50

what is a (De)hydrase enzyme

Answer 50

(Removes) Adds a water molecule.

Ex. hydrogenase

Question 51

what is a (De)carboxylase enzyme

Answer 51

(Removes) Adds carbon dioxide molecules.

Question 52

what is a Phosphorylase enzyme

Answer 52

Adds or removes phosphate groups.

Ex. kinase