lecture 5 Flashcards
what is the function of carbohydrates?
serves as fuel and building material
What are the simplest carbohydrates?
monosaccharides, or simple sugars
What are polysaccharides?
polymers composed of many sugar building blocks
What is the most common monosaccharide and what is it’s formula?
glucose C6H12O6
How are monosaccharides classified?
The location of the carbonyl group
The number of carbons in the carbon skeleton
a carbonyl or hydroxyl on each carbon
asymmetric carbons (chiral centers) large number of isoforms
How is a disaccharide formed?
when a dehydration reaction joins two monosaccharides in covalent bond called a glycosidic linkage
What is the function of polysaccahrides?
storage and structural ; depending on its sugar monomers and the positions of its glycosidic linkages
Are lipids hydrophilic or hydrophobic?
Hydrophobic
_____ are the one class of large biological molecules that does not include true polymers
lipids
What is the unifying feature of lipids?
they mix poorly, if at all, with water
What are the most biologically important lipids?
fats, phospholipids, and steroids
Why do lipids not mix with water?
They mostly consist of hydrocarbon regions
What are fats constructed of?
two types of smaller molecules: glycerol and fatty acids
What is glycerol?
a three-carbon alcohol with a hydroxyl group attached to each carbon
What does a fatty acid consist of?
a carboxyl group attached to a long carbon skeleton
What is another word for three fat molecules?
Triglyceride
What are saturated fatty acids?
maximum number of hydrogen atoms possible and no double bonds
What are unsaturated fatty acids?
have one or more double bonds
What are steroids?
lipids characterized by a carbon skeleton consisting of four fused rings
What is cholesterol?
a type of steroid, is a component in animal cell membranes and a precursor from which other steroids are synthesized
What can high cholesterol do?
cause cardiovascular disease
What accounts for more than 50% of the dry mass of most cells?
protein
What are some functions of proteins?
speed up chemical reactions (enzymes), defense storage, transport, cellular communication, movement, and structural support
What are proteins constructed out of ?
the same set of 20 amino acids
What are polypeptides?
unbranched polymers built from these amino acids
Why do amino acids differ in their properties?
due to differing side chains, called R groups
How are amino acids linked?
covalent bonds called peptide bonds
True or False: polypeptides vary in length
True
What is the structure of polypeptides?
a linear sequence of amino acids with a carboxyl end and an amino end
What are proteins constructed of?
one or more polypeptides that are twisted, folded, and coiled into a unique shape
What is primary structure and how is it determined?
its like the order of letters in a word and its determined by inherited genetic information, it determines the higher level of protein structures
How do the coils form on secondary structures?
from hydrogen bonds between repeating constituents of the polypeptide backbone (the atoms that are the same in each amino acid)
What are typical secondary structures and what are they called?
they are a coil called an alpha helix and a folded structure called a beta pleated sheet
What is a tertiary structure and how does it form?
the overall shape of a polypeptide, it results from interactions between R groups (interactions such as hydrogen bonds, hydrophobic interactions, and Van der Waals interactions)
What are disulfide bridges?
strong covalent bonds that may reinforce a proteins structure
How does a Quaternary structure form?
when 2 or more polypeptide chains form one macromolecule
Given 2 examples of a quaternary structure.
collagen and hemoglobin
What is collagen?
a fibrous protein consisting of three polypeptides coiled like a rope
What is hemoglobin?
a globular protein consisting of four polypeptides; two alpha and 2 beta
How is the amino acid sequence of a polypeptide programmed?
By a gene
What do genes consist of?
DNA (polymer of monomers called nucleotides)
What are the two types of nucleic acids?
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
What is the role of DNA and RNA?
DNA directs synthesis of messenger RNA (mRNA) and, mRNA directs protein synthesis (gene expression)
How are nucleotides linked together?
phosphodiester linkage
What does a phosphodiester linkage consist of?
phosphate group that links the sugars of two nucleotides
Nitrogenous bases are _____.
appendages
True or False; The sequence of bases along a DNA or mRNA polymer is unique for each gene
True
What is the basic structure of DNA molecules?
two polynucleotides spiraling around an imaginary axis, forming a double helix
How does the backbone of DNA run?
antiparallel> opposite directions
What are the complimentary base pairs?
adenine (A) with thymine (T)
guanine (G) cytosine (C)
How does RNA differ from DNA?
RNA is often single-stranded although complementary pairing can also occur between two RNA molecules or between pairs of the same molecule
In RNA thymine is replaced by uracil (U) so A and U pair
RNA uses ribose (an extra hydroxyl compared to DNA)
What is sickle cell anemia?
in low oxygen conditions, red blood cells deform to a “sickle shape” which clogs capillaries
It was one of the first genetic diseases to be treated with gene editing therapy
Who was William W Cardozo?
a medical doctor and a pioneer in the field of sickle-cell research. He discovered that it was almost exclusively in those of African decent
