Lesson 1-4 Biochemistry Flashcards
What is the trend of electronegativity in a column of the periodic table?
Electronegativity increases from bottom to top in a column
What is the trend of electronegativity across a period in the periodic table?
Electronegativity increases from left to right across a period
What does electronegativity measure?
Electronegativity is a measure of an atom’s ability to attract a shared electron pair when it is participating in a covalent bond
What type of bonds do elements that are far apart in the periodic table usually form?
Ionic bonds
What type of bonds do elements that are closer together in the periodic table usually form?
Covalent bonds
How is the polarity of a molecule determined?
By the element whose valence shell has a greater hold on the electron that is being shared
What characterizes a non-polar covalent bond?
Electronegativity difference is zero
What characterizes a polar covalent bond?
Electrons are shared unequally
True or False: Non-polar covalent bonds have electrons shared equally.
True
What is a polar molecule?
A molecule with an unequal distribution of charge as a result of its polar bonds and its shape
What is an example of a polar molecule?
Water (H2O)
What charge does the Oxygen end of a water molecule have?
Slightly negative charge
What charge do the Hydrogen atoms of a water molecule have?
Slightly positive charge
What are the forces of attraction between water molecules called?
Hydrogen bonds
What happens to salt when it dissociates in water?
Water molecules quickly form hydration shells around the Na+ and Cl- ions
What effect do surrounding water molecules have on the attraction between salt ions?
They reduce the attraction so much that ions separate from their normal crystal lattice structure
What is the density characteristic of water when frozen?
Water expands when frozen
What geometric shape do water molecules form when frozen?
Hexagonal shape
What property allows a lizard to run across the top of water?
Surface tension and cohesion
What is adhesion?
Attraction between the molecules of two different substances
What is cohesion?
Attraction between the molecules or atoms of the same substance
What are polar substances said to be?
Hydrophilic (‘water-loving’)
What are non-polar substances said to be?
Hydrophobic (‘water-fearing’)
Fill in the blank: Hydrophilic substances create a _______ contact angle with water.
smaller
Fill in the blank: Hydrophobic substances create a _______ contact angle with water.
larger
What is autoionization of water?
When two water molecules react, one transfers an H+ ion to the other, forming a hydronium ion (H3O+) and a hydroxide ion (OH-)
What does autoionization of water always produce?
An equal number of hydronium and hydroxide ions
Define calorie (cal).
A unit of heat required to raise the temperature of 1g of water by 1°C
Define kilocalorie (kcal).
Quantity of heat required to raise the temperature of 1 kg of water by 1°C
What is the specific heat capacity of water?
1 cal/(g * °C)
What is the heat of vaporization?
The quantity of heat a liquid must absorb for 1g of it to be converted from liquid to gaseous state
What does the phrase ‘like dissolves like’ refer to?
The principle that polar solvents dissolve polar solutes and non-polar solvents dissolve non-polar solutes
What does hydrophobic mean?
“water-fearing” - Any substance that does not have an affinity (or likeness) for water (water fearing)
What does hydrophilic mean?
“water loving” - Any substance that has an affinity (or likeness) for water
What property of water allows for the bubble shield to be created around the wash cloth in space
Cohesion (water molecules stick together and form a shield)
Adhesion (water molecules stick to his hands)
Describe in more detail how the lizard is able to run across the water
strong hydrogen bonds formed between water molecules (water molecules stick together - cohesion), which results in a high surface tension of the water enabling the lizard to quickly run across.
*Surface tension/cohesion
What is dehydration synthesis?
Larger molecules are joined by the removal of water
Water is a product in this reaction, commonly used to assemble macromolecules like complex carbohydrates and proteins.
What is the 1-2 glycosidic linkage?
A bond that forms between larger molecules as water is removed during dehydration synthesis
The 1-2 notation denotes which carbons are involved in the bond.
What is a hydrolysis reaction?
The reverse of dehydration synthesis, where water is used to split large molecules into smaller ones
Water acts as a reactant in this process.
What occurs during a neutralization reaction?
A reaction between acids and bases that produces salt and water
What are redox reactions?
Reactions involving the transfer of electrons
They include oxidation (loss of electrons) and reduction (gain of electrons).
What does LEO goes GER stand for?
LEO: losing electrons is oxidation; GER: gaining electrons is reduction
What is produced during complete oxidation?
Carbon dioxide (CO2)
What is produced during incomplete oxidation?
Carbon monoxide (CO)
What elements comprise roughly 99% of the mass of most cells?
C, H, O, N
These are the most abundant elements in organic matter.
What are some trace elements important in organic matter?
S, P, Na, K, Cl, Mg
What differentiates organic compounds from inorganic compounds?
Organic compounds must contain carbon atoms, while inorganic compounds usually do not
Organic compounds are often found and produced by living organisms and typically have carbon-hydrogen bonds and are organized into chains or rings. Inorganic compounds have none of these things.
What is the central atom in organic compounds?
Carbon
Why is carbon considered versatile in biological systems?
It can bond covalently with other atoms, forming various geometrical structures
What are functional groups?
Specific groups of atoms within complex biomolecules involved in chemical reactions
They influence the chemical behavior of a macromolecule.
List the six functional groups.
- Hydroxyl (OH)
- Carbonyl (-C=O)
- Carboxyl (O=C-OH)
- Amino (C-NH2)
- Sulfhydryl (C-SH)
- Phosphate (C-PO4)
What is true about the functional groups in terms of solubility?
They are hydrophilic and polar, which can make macromolecules soluble in water
Can many compounds have more than one functional group?
Yes
What is the role of each functional group in cell metabolism?
Each functional group has a specific role in influencing the organic molecules they are found in
What are the four groups of lipids?
- Fats
- Phospholipids
- Steroids
- Waxes
What is the primary function of fats?
Long-term energy storage and insulation
How much energy does 1 gram of fat store compared to carbohydrates?
1 g of fat = 9 cal; 1 g of carb = 4 cal
What elements are lipids primarily composed of?
Carbon, hydrogen, and oxygen
What characteristic makes lipids non-polar biological molecules?
Lipids are hydrophobic and do not dissolve in water
Name three food sources of lipids.
- Fish/krill oils
- Nuts
- Avocado
What two molecules are fats (triglycerides) made from?
- Glycerol
- Fatty acids
What is a glycerol molecule?
A 3-carbon chain with 3 hydroxyl groups
What type of bond forms between glycerol and fatty acids in triglycerides?
Ester linkages
What reaction creates a triglyceride?
Dehydration synthesis reaction
What distinguishes saturated fatty acids from unsaturated fatty acids?
Saturated fatty acids have single bonds and maximum hydrogen atoms; unsaturated have one or more double bonds
What happens to the structure of unsaturated fatty acids due to double bonds?
They have kinks and bends in the molecule
Why are saturated fats typically solid at room temperature?
They can be easily stacked due to no bends or kinks
What are the two types of unsaturated fatty acids?
- Monounsaturated (one double bond)
- Polyunsaturated (more than one double bond)
What are phospholipids composed of?
- 2 fatty acids
- Glycerol
- Phosphate group
- Choline
What are the hydrophobic and hydrophilic components of phospholipids?
- Hydrophobic tails (2 fatty acids)
- Hydrophilic head (glycerol, phosphate group, polar unit)
What is the term for molecules that contain both hydrophobic and hydrophilic regions?
Amphipathic molecules
What is the structure of phospholipids in water?
They self-assemble into a bilayer with hydrophobic tails inward and hydrophilic heads outward
What is a micelle?
A spherical structure formed by surfactant molecules in water with hydrophobic tails facing inward
What are steroids characterized by?
A carbon skeleton consisting of 4 fused rings
What is the role of cholesterol in the body?
It is an important component of animal cell membranes and a precursor to lipid-based hormones
What health issue is associated with high cholesterol levels?
Cardiovascular disease
What are waxes primarily composed of?
Long fatty acid chains linked to alcohols or carbon rings
What is atherosclerosis?
A cardiovascular disease characterized by plaque deposits in blood vessels
What is thrombosis?
A dislodged mass that causes a blockage in blood vessels
True or False: Trans fats are associated with increased rates of coronary artery diseases.
True
Fill in the blank: Saturated fatty acids have _______ double bonds.
no
Fill in the blank: Unsaturated fatty acids with hydrogen atoms on the same side are called _______.
cis
Fill in the blank: Unsaturated fatty acids with hydrogen atoms on opposite sides are called _______.
trans
Function of fats
Long term energy storage and insulation
Function of phospholipids
Forms cell membranes
Function of steroids
Hormone signalling
Function of waxes
Water resistance and protection
What elements do proteins contain?
Carbon, hydrogen, oxygen, and nitrogen
What are the monomers that make up proteins?
Amino acids
What distinguishes proteins from other biological molecules?
Proteins contain nitrogen
What percentage of the mass of most cells is made up of proteins?
50%
Give two examples of proteins.
- Meat
- Enzymes (biological catalysts)
What is the primary function of enzymatic proteins?
Selective acceleration of chemical reactions
What is a function of defensive proteins?
Protection against disease
What do storage proteins do?
Store amino acids
What is the role of transport proteins?
Transport of substances
What function do hormonal proteins serve?
Coordination of an organism’s activities
What is the role of receptor proteins?
Response of cells to chemical stimuli
What do contractile and motor proteins facilitate?
Movement
What is the primary structure of a protein?
The unique linear sequence of amino acids in a polypeptide chain
What is the secondary structure of a protein characterized by?
Coils and/or folds in the polypeptide chain
What is an example of a coil structure in secondary protein structure?
α-helix
What is an example of a folded structure in secondary protein structure?
β-pleated sheet
What determines the tertiary structure of a protein?
Interactions between various R-groups
What type of bonds stabilize a protein’s tertiary structure?
Disulfide bridges (S-S)
What is a polypeptide?
A polymer of more than 50 amino acids in length
What is the quaternary structure of a protein?
When two or more polypeptide chains interact to form a protein
What is sickle-cell disease a result of?
A single amino acid change in primary structure
What is denaturation of proteins?
The loss of a protein’s normal shape
What can cause a protein to denature?
Changing the pH or temperature
What is the significance of protein folding?
Determines the protein’s function
What is the protein folding problem?
Proteins can be folded in new/different ways that yield a new/altered/beneficial function
What diseases can result from protein misfolding?
- Alzheimer’s disease
- Parkinson’s
- ALS
What role do tau proteins play in neurons?
Support the stability of microtubules
What happens when tau proteins misfold?
They lose their function and microtubules can fray, becoming unstable
What is the consequence of the accumulation of misfolded tau proteins?
Limits the number and quality of synapses made in the brain
Fill in the blank: Essential amino acids must be obtained from _______.
our diets
Fill in the blank: The N-terminus of a peptide chain has an _______ group.
amino
Fill in the blank: The C-terminus of a peptide chain has a _______ group.
carboxyl
What are the common overall function of proteins?
Some recurring functions include: Structural support, Storage, Transport, Cellular communications, Movement and Defense against foreign substances
What is a peptide?
A chain of amino acids linked by peptide bonds
Alanine
Ala - A
Arginine -
Arg - R
Aspartic Acid -
Asp - D
Asparagine -
Ash - N
Cysteine -
Cys - C
Glutamic acid -
Glu - E
Glutamine -
Gln - Q
Glycine -
Gly - G
Histidine -
His - H
Isoleucine -
Ile - I
Leucine -
Leu - L
Lysine -
Lys - K
Methionine -
Met - M
Phenylalanine -
Phe - F
Proline -
Pro - P
Serine -
Ser - S
Threonine -
Thr - T
Tryptophan -
Trp - W
Tyrosine -
Tyr - Y
Valine -
Val - V
What are amino acids composed of?
Amino acids are composed of five components: central 𝛂-carbon, amino group (-NH2), carboxyl group (-COOH), hydrogen atom, R-group (1 of 20 different side chains)
Function of structural proteins:
support. Ex. Keratin (in hair), collagen provide fibrous framework in connective tissues.
What is the function of a protein dependent on?
The function of a protein is dependent on the combination of types of amino acids.
How do peptides form proteins?
General
Peptides → Polypeptides → Proteins
Peptides fold up or combine with other peptides to form proteins
By what type of reaction are peptides formed?
Peptides are formed by dehydration synthesis
How are peptide bonds formed?
Peptide bonds are formed by the dehydration synthesis between the amino group of one amino acid and the carboxyl group of another
What are the bonds formed by dehydration synthesis between amino groups and carboxyl group of amino acids?
Peptide bonds
What chemical properties result from the functional group in fatty acids?
Acidic
What type of bonds contribute to secondary structure?
Secondary structure is due to hydrogen bonds between different amino acids in the polypeptide chain
What relationship between proteins does sickle cell disease represent?
Sickle cell disease represents the protein structure and function relationship
Sickle-cell disease: the amino acid glutamic acid is switched to valine in the protein hemoglobin
A single amino acid change in structure can alter or destroy the biological function of the protein.
Which is the good steroid - HDL or LDL?
HDL
Which is the bad steroid - HDL or LDL?
LDL
Which steroid contributes to cardiovascular disease?
LDL
