Learn: Biochemistry: Macromolecules, Water, pH, and Amino Acids | Quizlet
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122 Terms
What are the four major macromolecules?
Proteins, carbohydrates, nucleic acids, and lipids.
What are proteins polymers of?
Amino acids.
What are nucleic acids polymers of?
Nucleotides.
What is the primary function of nucleic acids?
Store genetic information and direct protein synthesis.
What is the most important carbohydrate?
Glucose.
What type of carbohydrate is glucose?
A hexose monosaccharide.
Which glucose isomer is utilized by plants and animals?
D-glucose.
What are the three classes of carbohydrates?
Monosaccharides, disaccharides, and polysaccharides.
What are lipids generally characterized by?
Most are insoluble in water.
From what molecule are lipids formed in vivo?
Acetyl-CoA.
What are the three classes of lipids?
Simple lipids, complex lipids, and derived lipids.
What is an example of a simple lipid?
Triglycerides.
What are examples of complex lipids?
Phospholipids and glycolipids.
What are examples of derived lipids?
Fatty acids and steroids.
What are the major functions of lipids?
Fuel, energy storage, membrane components, cell signaling, fat-soluble vitamins, and steroid hormones.
What is a structural protein example?
Collagen.
What is an example of an enzyme protein?
Proteases.
What protein functions in transport?
Hemoglobin.
What proteins function in defense?
Antibodies.
What proteins are responsible for contraction?
Actin and myosin.
What are examples of lipoproteins?
HDL, LDL, and VLDL.
What are glycoproteins?
Proteins with carbohydrate groups attached; many are cell membrane proteins.
Why is protein phosphorylation important?
It is a key regulator of protein activity.
Approximately what percentage of total body weight is water?
50-70%.
Approximately what percentage of all molecules in the body are water molecules?
About 99%.
What does it mean that water is dipolar?
Water has regions of partial positive and negative charge.
What is pH?
The negative logarithm of hydrogen ion concentration.
What is the pH of pure water?
7.0.
What does a low pH indicate?
An acidic solution.
What does a high pH indicate?
A basic solution.
What is an acid?
A proton donor.
What is a base?
A proton acceptor.
What is the approximate H+ concentration in blood?
Approximately 0.00004 M.
What is pKa?
The pH at which equal concentrations of an acid and its conjugate base are present.
What does pKa measure?
Acid strength.
Does a stronger acid have a higher or lower pKa?
A lower pKa.
Why do strong acids have lower pKa values?
They dissociate more readily in water.
What is a buffer?
A substance that minimizes changes in pH when an acid or base is added.
What type of acid-base pair commonly acts as a buffer?
A weak acid and its conjugate base.
What are the three major biological buffer systems?
Phosphate, bicarbonate, and proteins.
Where is CO2 constantly produced?
During the TCA cycle.
How is CO2 transported?
In the blood/plasma.
How is CO2 removed from the body?
By the lungs.
What two functional groups are present in amino acids?
An amino group and a carboxyl group.
What is the R group of an amino acid?
The variable side chain that determines the amino acid's properties.
What is the simplest amino acid?
Glycine.
What is the R group of glycine?
A hydrogen atom.
What is a zwitterion?
A molecule containing both a positive and negative charge.
What form do amino acids primarily have at approximately pH 7.4?
Zwitterions.
How many pKa values does every amino acid have at minimum?
At least two.
What do the two basic pKa values of an amino acid correspond to?
The COOH proton and the NH3+ proton.
Why do some amino acids have a third pKa?
Their R groups are ionizable.
Can amino acids act as buffers?
Yes.
What is chirality?
A property of molecular asymmetry.
Why are most amino acids chiral?
Their alpha carbon is attached to four different groups.
Which amino acids are used as building blocks of animal proteins?
L-amino acids.
Where are D-amino acids found?
Bacterial cell walls and some antibiotics.
What amino acid is not chiral?
Glycine.
Why is glycine not chiral?
Its R group is hydrogen, giving the alpha carbon two identical groups.
What are canonical amino acids?
The 20 genetically encoded amino acids incorporated into proteins.
How many canonical amino acids are there?
20.
What are non-protein amino acids?
Amino acids that are not incorporated into proteins.
Which non-protein amino acids are intermediates in the urea cycle?
Ornithine and citrulline.
What amino acid is an important neurotransmitter-related molecule in the brain?
GABA.
What amino acid is especially important in cats?
Taurine.
What is an essential amino acid?
An amino acid that must be obtained from the diet.
What is a non-essential amino acid?
An amino acid that can be synthesized by the body.
Why must essential amino acids be obtained from the diet?
The body lacks the necessary biosynthetic pathways or cannot produce enough of them.
What can taurine deficiency cause in cats?
Retinal degeneration and blindness, dilated cardiomyopathy, reproductive failure, poor growth, and skeletal deformities.
What cardiac disease is associated with taurine deficiency in cats?
Dilated cardiomyopathy.
What eye problem is associated with taurine deficiency in cats?
Retinal degeneration and blindness.
What is a glucogenic amino acid?
An amino acid whose catabolism yields pyruvate or intermediates of the TCA cycle.
What is a ketogenic amino acid?
An amino acid whose catabolism yields acetoacetate or acetyl-CoA.
Can an amino acid be both glucogenic and ketogenic?
Yes.
What are nonpolar amino acids?
Amino acids with hydrophobic R groups.
Why are nonpolar amino acids important for proteins?
They are important in protein folding and 3-D structure.
What are hydrophilic amino acids?
Amino acids with polar R groups that interact favorably with water.
What are the categories of polar amino acids?
Polar uncharged, positively charged, and negatively charged.
Where are hydrophilic amino acids commonly found on proteins?
On the external surface of proteins.
What are aromatic amino acids?
Amino acids containing aromatic groups in their R groups.
What does primary protein structure describe?
The amino acid sequence.
What does secondary protein structure describe?
Local structures such as alpha helices and beta sheets.
What does tertiary protein structure describe?
The overall three-dimensional structure of a single protein.
What does quaternary protein structure describe?
The arrangement of multiple protein subunits.
What are the four levels of protein structure?
Primary, secondary, tertiary, and quaternary.
What is primary protein structure based on?
Amino acid sequence.
What is secondary protein structure based on?
Alpha helices and beta sheets.
What is tertiary protein structure?
Three-dimensional folding of a protein.
What is quaternary protein structure?
Association of multiple protein subunits.
What are three major noncovalent interactions in proteins?
Hydrogen bonding, ionic bonding, and hydrophobic interactions.
Why are hydrophobic interactions important?
They help drive protein folding and contribute to 3-D structure.
What determines protein structure?
The amino acid sequence and interactions among amino acid side chains.
What is the N-terminus of a protein?
The end containing the free amino group.
What is the C-terminus of a protein?
The end containing the free carboxyl group.
How are amino acids numbered in a protein?
Starting at the N-terminus.
What are hydroxyproline and hydroxylysine important for?
Proper collagen structure and function.
What vitamin is required for hydroxylation of proline in collagen?
Vitamin C (ascorbic acid).
What happens to collagen with vitamin C deficiency?
Collagen formation/function decreases and signs of scurvy develop.
What are desmosine and isodesmosine?
Cross-linking products formed from lysine residues.
What protein contains abundant desmosine and isodesmosine?
Elastin.