Biochemistry

Question 1

What are carbs and lipids mainly composed of ? What role do they play?

Answer 1

mainly composed of carbon, hydrogen & oxygen

They are energy sources in the body.

carbs play a role in structural support & cell to cell communication
it’s raw material is used to build other
important molecules like amino acids,
lipids, and nucleic acids

Lipids are in all biological membranes. and they provide insulation for nerve cells and have water proof qualifiers
ex: hormones, vitamins and defence
mechanisms all include lipids
also lipids provide insulation for nerve
cells (sheath wrap) & waterproof
qualities (wax)

Question 2

monosaccharides combine to form

Answer 2

link together to form a complex carbohydrate. some are important for energy storage and others for structural support

starch and glycogen are important for energy storage
cellulose and chitin are important of structural complex carbohydrate

Question 3

polysaccharides are

Answer 3

a chain ⛓️ of monosaccharides joined together by glycosidic linkages

polysaccharides are macromolecule (very large molecule combined by covalent linkage of smaller molecules)

they are very POLAR but they only ATTRACT water and not dissolve. think of a paper towels

Question 4

What is a monomer? &examples

Answer 4

A monomer is a building block – if I had some large substance, the parts that make up that substance are called
monomers.

Carbs: monosaccharides. (glucose is a monosaccharide)

Protein : amino acids. proteins consist of many amino acids bonded together. There are different types of amino acids.

Lipids do not have a true polymer or true monomer. [Because they don’t have a true polymer, many sources will include them as a non-polymeric macromolecule]
Why do lipids lack a true monomer? Unlike the others, they do not have a repeating unit.

Nucleic acids: nucleotide

Question 5

Which macros are hydrophobic/hydrophilic and why. what in its structure?

Answer 5

Carbohydrates are hydrophilic as have many polar OH groups which makes them soluble in water. (think of glucose)

Lipids are hydrophobic as they consist of long hydrocarbons which are nonpolar. they all have all have a polar “head” and a large nonpolar “tail””. and contain fewer polar hydroxyl groups (-OH)

Proteins are hydrophilic as they consist of long chains of amino acids joined together by peptide (CONH) bonds.
Proteins have polar
C=O and N-H groups, so they are able to form hydrogen bonds with other molecules and with each other.

Question 6

why water has surface tension

Answer 6

Surface tension, due to the cohesive forces between water molecules. This tension arises from H bonding.

water molecules form H-bonds all around except for the side facing air. which creates an imbalance in bonding.
Producing force that places the water molecules under tension and makes them more resistant to separation compare to molecules below surface Surface Effects:

Surface tension is created by the net inward cohesive forces at the water surface.
It makes the surface act like a stretched elastic membrane.
Consequences:

Allows small objects to “float” on water.
Leads to the formation of droplets and enables insects like water striders to glide on the water surface.

Question 7

some imp chemical reactions

Answer 7

dehydration –> water removed to form bigger molecules

hydrolysis –> larger molecules react with water & break down into smaller units

Question 8

why functional groups r imp

Answer 8

they determine chemical properties & reactivity of organic molecules

they contribute to specific characteristics like polarity, acidity, and basicity. which influences the molecule’s overall behaviour & interactions

Question 9

example of the imp reactions

Answer 9

dehydration: a cell would use dehydration to build polysaccharides from monos.
ex: glucose links through hydration to
form glycogen or starch

–sort of like reverse–

hydrolysis: hydrolysis break down polys into simple sugars
ex: glucose or starch –> individual
glucose units

Question 10

Disaccharides

Answer 10

two monos joined tog by a dehydration synthesis reaction

sucrose (glu + fru) sugar cane
lactose (glu + gal) milk
maltose (glu+glu) starch

Question 11

alpha glucose

Answer 11

carbon 1 is down

both OH’s are down (1 & 4)

digestible by humans
(glu + glu) is maltose.
joined by an α-1,4-glycosidic linkage with an -o- in the middle

Question 12

beta glucose

Answer 12

Carbon 1 is up. so OH 1 is up

INDIGESTIBLE by humans. think of cellulose. made of alpha glucoses.

Question 13

starch vs cellulose

Answer 13

Starch
Composition: Composed of glucose monomers.
Linkage: Glucose units joined by alpha (α)-1,4-glycosidic linkages.
Branching: Can have branches through alpha (α)-1,6-glycosidic linkage carb
Storage: Primary energy storage in plants.
Digestibility: Easily digested by enzymes in the digestive system. Used as a readily available energy source.

Cellulose:
Composition: Also composed of glucose monomers.
Linkage: Glucose units joined by beta (β)-1,4-glycosidic linkages.
Branching: Typically linear without branching.
Structural: Provides structural support to plant cell walls.
Digestibility: Generally not digestible by most animals due to the beta (β)-1,4-linkages and lack of necessary enzymes. Provides rigidity and strength to plant cell walls.

Question 14

alpha vs beta (arrows)

Answer 14

alpha: down down
beta: down ^

Question 15

structural differences amylose vs amylopectin vs glycogen

Answer 15

amylose; every 24-30 glu
Type: Linear polysaccharide.
Linkage: Consists of alpha (α)-1,4-
glycosidic linkages.
Branching: Unbranched chain, with
occasional slight coiling.
Function: Mainly used for energy storage
in plants.

Amylopectin: every
Type: Branched polysaccharide.
Linkage: Contains both alpha (α)-1,4-
glycosidic and alpha (α)-1,6-glycosidic
linkages.
Branching: Highly branched structure,
forming a tree-like appearance.
Function: Also serves as an energy
storage molecule in plants.

Glycogen: every 8-12 glu
Type: Highly branched polysaccharide.
Linkage: Comprises alpha (α)-1,4-
glycosidic and frequent alpha (α)-1,6-
glycosidic linkages.
Branching: Highly branched with shorter
linear chains.
Function: Principal form of glucose
storage in animals, especially in liver and
muscle cell

Question 16

how animals who only eat grass get energy

Answer 16

they do not have ability to digest beta glucose so how?

they have bacteria in their guts. they basically regurgitate their food and rechew it. the bacteria in their gut contain a specific enzyme. from a symbiotic relationship with bacteria living there

this enzyme is what helps breaking the IM forces like H bonding and beta 1-4 linkage.

google staircase beta 1-4 linkage

Question 17

In cellulose

Answer 17

Cell Wall H-Bonding:
H bonding occurs in cell walls, providing structural integrity.

Cellulose in Wood:
I. Imagine a wood; there are many cell walls, mainly made up of cellulose. (rlly strong)

Water and Hydrolysis:
Water, along with enzymes in hydrolysis, breaks the bonds between cellulose molecules.

H-Bonding Tightness:
Due to H bonding, water struggles to penetrate wood as cellulose chains are tightly held together.

Beta Glucose Arrangement:
The unique beta-glucose arrangement (flipping every other unit) allows closer chain proximity for effective H bonding, creating a linear appearance.

Coiling Structure:
The cellulose chains can rotate around a bond, resulting in a coiling shape.

Question 18

whats a lipid

Answer 18

a non polar biological molecule. composed of CHO

they do not dissolve in water which allows them to form cell membranes.
theyre also hormones.

5 main categories:
fatty acids, fats, phospholipids, steroids and waxes

Question 19

whats a fatty acid

Answer 19

a building block
carboxylic acid and a straight chain of carbons

as chain length increases, it becomes LESS water soluble
single bonds = saturated
double bonds = unsaturated

Question 20

what are fats

Answer 20

it is a lipid made of two types of molecules
fatty acid + glyceride (triple OH)
joined together through dehydration synthesis. triglyceride is a common fat

go look at diagram girlie

Question 21

saturated vs unsaturated lipid

Answer 21

saturated:
butter & lard. solid at room temp. higher BP.
less fluid as length increases
chains long and straight and packed closely
there’s LD forces in between.
triglycerides are an excellent source of energy. formed through dehydration synthesis
The absence of double bonds allows them to pack closely together, solidifying at room temperature.

unsaturated:
oils. fish oils
more fluid. liquid at room temp. lower BP
has double bonds or kinks formed
can be transformed to saturated by halogens but it then creates a trans isomer
The presence of double bonds introduces kinks, preventing close packing and keeping them liquid at room temperature.

Question 22

Phospholipid

Answer 22

first imagine an image or google it girlie

makes up lipid bilayer of cell membrane. it has a polar and a non polar side

polar has a phosphate and glycerol.

nonpolar is just hydrocarbon chain

Question 23

carboxyl hydroxyl and ester…

Answer 23

carboxylic acid + alcohol = ester + water.
3 hydroxyl functional groups combine with fatty acids to from ester

Question 24

Oil is converted into fat by…

Answer 24

changing unsaturated bonds to saturated bonds.

Process: Oil is converted to fat through esterification and hydrogenation processes.
Saturated Fats:

Structure: Saturated fats result from single bonds, promoting close packing.
Source: Can be produced through hydrogenation, making them solid at room temperature.
Unsaturated Fats:

Structure: Contain double bonds, introducing kinks and preventing close packing.
Source: Hydrogenation reduces double bonds, making them more saturated, yet still liquid at room temperature.
London Dispersion Forces (LDFS):

Influence: Both saturated and unsaturated fats experience LDFS, but saturation affects the strength.

Question 25

Why are the London Forces weaker in polyunsaturated fats than saturated fats? How does
this effect the melting points of these molecules?

Answer 25

LDFs are weaker in polyunsaturated fats due to the presence of double bonds in unsaturated fats

saturated fats, hydrocarbons have single bonds –> more extended and linear structure –> more surface area.

double bonds creates kinks in the structure which reduces SA for contact between molecules, weakening the LDFs.

—-> Stronger IMs like in saturated fats require more energy to break. since polyunsaturated has weaker LDS —> lower melting points. the structure makes it easier for the molecules to transition from a solid to a liquid

Question 26

Compare the number of C - H bonds in fat molecules with carbohydrate molecules. How
does this effect their energy storage capability?

Answer 26

Comparison of C-H Bonds:

Fat Molecules:

C-H Bonds: Fats have a higher number 
of C-H bonds, resulting from their 
 predominantly hydrocarbon structure.

Carbohydrate Molecules:

  C-H Bonds: Carbohydrates generally 
  have fewer C-H bonds compared to fats 
    due to their inclusion of oxygen in the 
  form of hydroxyl groups.

Effect on Energy Storage Capability:

 Fat Molecules:   Impact: Higher number of C-H bonds in    fats provides a more energy-dense    storage form.   Reason: C-H bonds store a considerable    amount of energy, and the abundance in    fats enhances their capacity for long-term    energy storage.

 Carbohydrate Molecules:   Impact: Carbohydrates have a lower    energy density due to fewer C-H bonds.   Reason: While carbohydrates serve as a    quick energy source, the presence of    oxygen atoms reduces their overall     energy storage efficiency compared to 
fats.

Question 27

Cholesterol

Answer 27

a group of lipids

it increases risk of atherosclerosis.
it is a vital component for cell membranes
hydrophobic but have dual solubility due to -OH differences in side groups which distinguish from one another

Question 28

MC:
Sugars are soluble in water because they:
A. contain polar regions.
B. are slightly acidic.
C. ionize completely.
D. are not as dense as water.

Answer 28

A. contain polar regions.

Explanation: Sugars are typically polar molecules due to the presence of hydroxyl (OH) groups. Water, being a polar solvent, interacts well with these polar regions, facilitating the dissolution of sugars.

Question 29

MC:
Ribose, glucose, and fructose are all similar because they are all
A. polysaccharides.
B. fatty acids.
C. monosaccharides.
D. disaccharides.

Answer 29

C. monosaccharides

Explanation: Ribose, glucose, and fructose are all monosaccharides, which are simple sugars consisting of a single sugar unit.

Question 30

MC:
Which association is NOT correct?
A. nucleic acid - genes
B. carbohydrate - enzymes
C. fats - long-term storage of energy
D. proteins - cell membrane

Answer 30

D. proteins - cell membrane.

Explanation: Proteins are not typically associated with cell membranes. Lipids, especially phospholipids and proteins, are the primary components of cell membranes.

Question 31

MC:
4. Glycogen is
A. a monosaccharide used for quick energy.
B. a protein found in cell membranes.
C. a polysaccharide used as stored energy.
D. a fat found in margarine.

Answer 31

C. a polysaccharide used as stored energy

Explanation: Glycogen is a polysaccharide consisting of glucose units and serves as a storage form of energy in animals, particularly in the liver and muscles.

Question 32

MC:
A fatty acid which contains a large number of double bonds is
A. saturated.
B. unsaturated.
C. a neutral fat.
D. a triglyceride.

Answer 32

B. unsaturated.

Explanation: Fatty acids with double bonds are unsaturated. The presence of double bonds introduces kinks in the fatty acid chain, preventing them from packing tightly and resulting in a liquid state at room temperature.

Question 33

MC:
A nucleotide is composed of:
A. a phosphate base, a sugar and a nitrate group.
B. two or more polypeptides in quaternary association.
C. a nitrogenous base, an amino acid and a sulphate group.
D. a nitrogenous base, a sugar and a phosphate group.

Answer 33

D. a nitrogenous base, a sugar, and a phosphate group.

Explanation: Nucleotides, the building blocks of nucleic acids, consist of a nitrogenous base, a sugar (ribose or deoxyribose), and a phosphate group.

Question 34

MC:
The bond which holds together complementary base pairs in a D.N.A. molecule is called
A. ionic.
B. covalent.
C. hydrogen.
D. disulphide.

Answer 34

C. hydrogen.
Explanation: Hydrogen bonds hold together complementary base pairs (adenine-thymine, guanine-cytosine) in a DNA molecule.

Question 35

MC:
There are several bonds involved in the formation of complete/functional proteins. After the
amino acids are liked together during translation, hydrogen bonds cause the polypeptide to twist into a
helix or coil. What level of protein structure is represented by the helical coil?
A. primary
B. secondary
C. tertiary
D. quaternary

Answer 35

B. secondary.

Explanation: The helical coil formed by hydrogen bonds between amino acids represents the secondary structure of a protein.

Question 36

A straight chain (linear sequence) of amino acids in a polypeptide is called a
A. tertiary structure.
B. primary structure.
C. globular structure.
D. secondary structure.

Answer 36

B. primary structure.

Explanation: The primary structure of a protein is the linear sequence of amino acids.

Question 37

MC:
A functional group is composed of nitrogen and two hydrogens. It has the group name:
A. amino (amine)
B. hydroxide.
C. acid.
D. carboxyl.

Answer 37

A. amino (amine).

Explanation: The amino (amine) functional group consists of a nitrogen atom and two hydrogen atoms.

Question 38

Which one of the following substances is a protein?
A. Glucose
B. Collagen
C. Glycogen
D. Cholesterol

Answer 38

B. Collagen.

Explanation: Collagen is a fibrous structural protein found in connective tissues.

Question 39

MC:
In water, hydrogen bonding occurs between hydrogen and
A. an oxygen atom in the same molecule.
B. an oxygen atom in a different molecule.
C. a hydrogen atom in the same molecule.
D. a hydrogen atom in a different molecule.

Answer 39

B. an oxygen atom in a different molecule.

Explanation: Hydrogen bonding in water occurs between the hydrogen of one water molecule and the oxygen of another.

Question 40

Which of the following is not a property of water?
A. is an organic molecule
B. is a polar molecule
C. contains hydrogen bonds
D. is more dense as a liquid than a solid

Answer 40

A. is an organic molecule.

Explanation: Water is an inorganic molecule, not an organic one.

Question 41

MC:
Chemical analysis of a substance shows that it contains amino groups and carboxyl groups.
Which one of the following would this substance most likely be?
A. A fat.
B. An enzyme.
C. A cofactor.
D. A carbohydrate.

Answer 41

B. An enzyme.

Explanation: Amino groups and carboxyl groups are characteristic of amino acids, the building blocks of proteins, including enzymes.

Question 42

MC:
Which of the following is not a lipid molecule?
A. Amylopectin
B. Stearic acid
C. Cholesterol
D. Wax

Answer 42

A. Amylopectin.

Explanation: Amylopectin is a branched polysaccharide, not a lipid.

Question 43

MC:
Polymers common in organisms are
A. starch
B. glycogen
C. cellulose
D. all of the above

Answer 43

D. all of the above.

Explanation: Starch, glycogen, and cellulose are all polymers commonly found in organisms.

Question 44

MC:
Steroids
A. are not naturally found within living systems
B. have a chemical structure similar to cholesterol
C. include the sex hormones and aldosterone
D. two of the above

Answer 44

D. two of the above.

Explanation: Steroids include sex hormones and aldosterone, and their chemical structure is similar to cholesterol.

Question 45

A dipole occurs when
A. two atoms with an electronegativity difference bond.
B. electrons are transferred from one atom to another.
C. two atoms of the same electronegativity bond.
D. electrons are shared equally between two atoms.

Answer 45

A. two atoms with an electronegativity difference bond.

Explanation: A dipole arises when there is an uneven distribution of electrons, creating a positive and a negative end in a molecule.

Question 46

MC:
When chemical bonds are formed, energy is
A. absorbed and the process is exothermic.
B. released and the process is exothermic.
C. absorbed and the process is endothermic.
D. released and the process is endothermic.
E. either released or absorbed, depending on the bond.

Answer 46

B. released and the process is exothermic.

Explanation: Energy is released when chemical bonds are formed, resulting in an exothermic process.

Question 47

MC:
When compounds form, the resulting structure is
A. more stable and has a state of lower energy.
B. less stable and has a state of lower energy.
C. more stable and has a state of higher energy.
D. less stable and has a state of higher energy.

Answer 47

A. more stable and has a state of lower energy.

Explanation: The formation of compounds generally leads to a more stable state with lower energy.

Question 48

The reason why all chemical bonds are formed is to
A. fill inner orbitals with electrons.
B. split lone pairs into bonding electrons.
C. cause electrons to reach a more stable configuration.
D. cause electrons to be transferred

Answer 48

C. cause electrons to reach a more stable configuration.

Explanation: Chemical bonds are formed to achieve a more stable electron configuration.

Question 49

MC:
When compounds form, the resulting structure is
A. more stable and has a state of lower energy.
B. less stable and has a state of lower energy.
C. more stable and has a state of higher energy.
D. less stable and has a state of higher energy.

Answer 49

A. more stable and has a state of lower energy.

Explanation: The formation of compounds generally leads to a more stable state with lower energy.

Question 50

MC:
Which is true about the enzyme-substrate complex in a reaction ?
A. It acts as a catalyst
B. It is a stable compound
C. It always forms products.
D. It possesses more energy than the reactants or the products.

Answer 50

A. It acts as a catalyst.

Explanation: The enzyme-substrate complex acts as a catalyst, facilitating the reaction without being consumed in the process.

Question 51

MC:
The minimum amount of energy required to bring about a reaction is called
A. enthalpy.
B. entropy.
C. activation energy.
D. reaction mechanism energy.

Answer 51

C. activation energy.

Explanation: Activation energy is the minimum energy required to initiate a chemical reaction.

Question 52

MC:
In a chemical reaction, the use of a catalyst results in a decrease in the
A. activation energy
B. potential energy of the reactants
C. heat of reaction
D. amount of products

Answer 52

A. activation energy.

Explanation: Catalysts lower the activation energy required for a reaction, making it proceed more efficiently.

Question 53

MC:
A chemical reaction that joins two molecules with the loss of a molecule of water is called:
A. A hydrolysis reaction
B. An acid-base reaction
C. An oxidation-reduction reaction.
D. A condensation reaction

Answer 53

A chemical reaction that joins two molecules with the loss of a molecule of water is called:

D. A condensation reaction.
Explanation: Condensation reactions involve the joining of molecules with the elimination of a water molecule.

Question 54

MC:
Which of the following is an example of a disaccharide?
A. Ribose
B. Lactose
C. Glucose
D. Fructose

Answer 54

B. Lactose.

Explanation: Lactose is a disaccharide composed of glucose and galactose.