Bio Exam I
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All, without exception, nucleic acids contain which five elements?
Why do the rings in nucleic acids differ from others?
they contain nitrogen
What is the function of 1-6 linkages?
What linkage does amylose have? amylopectin? glycogen?
- 1-4 alpha linkages
- 1-6 alpha linkages
- 1-6 and 1-4
What is the catch with structural polysaccharides?
they cannot be hydrolyzed by the organisms that make them
What are the two shapes of proteins?
- fibrous (relatively straight and long)
- - usually just primary, secondary, and quaternary
- globular (spherical)
- - has all four levels
What are the three classification systems of proteins?
- based on:
- - levels of structure
- - composition
- - function
What are the protiens based on levels of structure?
fibrous proteins: exhibit primary and secondary structure; somes quaternary; insolubale; stable; form tough structures
globular proteins: exhibit primary, secondary, tertiary, and sometimes quaternary; arranged so that the R-groups are on the inside and the ones on the outside are hydrophilic
What are proteins based on composition?
- simple proteins: composed of only amino acids in a polypeptide chain
- Conjugated proteins: composed of one or more polypeptide chains plus a non-amino acid component called a co-factor; the cofactor has to be there for the protein to function
What are proteins based on function?
- contractole (muscle)
- receptor proteins
What are the disaccharides?
- maltose= glucose + glucose
- lactose= galactose + glucose
- sucrose= fructose + glucose
What does sucrose do?
- transform form of sugar in the plant
- -storage of carbs in larger sizes
what is lactose?
What are oligosaccharides?
- a short chain of 3 - 100s of monosaccharide molecules joined together via glycosidic bonds
- - usually linked to some other molecule (lipid, protein)
- - most common location: poking out surface of plasma membrane
What are the two basic functions of oligosaccharides?
What is linkage?
a designation of which carbon atoms in adjacent monosaccharide subunits are bonded together; can also indicate whether in alpha or beta form
What are the two forms of starch?
What are examples of lipids?
What are the components of phospholipids?
- one glycerol
- two fatty acids
- one phosphate (may/ may not include an organic group attached to the phosphate)
What are the three classifacations of amino acids on basid of chemical characteristics of the R group?
- polar but uncharged
- electrically charged (acidic or basic)
What do proteins differ in?
- - total number of amino acids (size); each type of protein contains a specific number of amino acids
- - relative quantities of each specific type of amino acid
- - specific sequence (order) of amino acids
- - specific 3D shape
What are the subunits of DNA?
What is the 5' end?
end where the phosphate group is not attached to another nucleotide
What is a 3' end?
end where sugar of nucleotide is not linked to another nucleotide
How many hydrogen bonds form with adenine?
How many hydrogen bonds form between guanine and cytosine?
Who proposed the structure of DNA?
- alpha double helix
- Watson and Crick (+ Rosalind Franklin)
DNA molecules differ in?
- number of base pairs
- relative quantities of each specific base pair
- specific sequence (order) of base pairs
What is the function of DNA?
stores genetic info in the sequence of genes
What are the alternative forms of DNA?
- single stranded v. double stranded
- linear vs. circular
- 3D structures
What is the difference between organic and inorganic?
- organic contains carbon
- inorganic may contain carbon iin a very energy poor state
All chemical reactions in the cell occur where the reactants __.
dissolve in water
Why is water a very good solvent?
- its a polar molecule
- Oxygen has a partial negative charge, while hydrogen has a partial positive charge, enabling attraction to other compounds.
What are two other important functions of water?
- it acts as a lubricant to decrease friction
Hydrolysis can only occur if __.
the molecule is combined through dehydration reactions.
What are the benefits of linking monosaccharides togehter?
decreases amount of material in cell, lowering the concentration of dissolved material in the cell
What do lipids consist of?
Which are dominant?
- and sometimes P and N
Lipids are insoluble in __, but soluble in __.
In fats and oils, what does glycerol not contain? How many carbons are usually present in hydrocarbon chains?
True or False: If a molecule has even a slight charge, it will dissolve in water.
What is the function of the phosphate group in a phospholipid?
- interact well water water due to charge (polar/ hydrophilic)
- tails are hydrophobic and are away from the water
What are steroids?
four-fused rings of carbon; the sharing of carbons enables fusion
Animal hormones are one of two types:
What makes steroids different?
the attachments to the ring
What is the solubility characteristic of steroids?
- rings don't dissolve in water (hydrophobic)
- the only hydrophilic substance is the -OH group
- cholesterol: major function of animal membranes ONLY
- liver makes it
- starting point for making other steroids
- animal hormones
What are the elements in proteins?
Peptide bonds link two __. Are they straight or branched?
Which amino acid usually starts the chain?
How do the ends of the chains in polypeptides differ?
Explain the linkages in each stage of protein structure?
- Primary: carboxyl and amino acid (peptide bond)
- Secondary: hydrogen bonding between carboxyl and amino acid
- Tertiary: bonds between the side chains of same polypeptide, giving it an folded, 3D shape
- Quaternary: bonds between two or more polypeptide chains
Do all proteins have:
In DNA, which components are responsible for bining the nucleotide together?
phosphates and sugar--> phosphodiester linkage
What are the purines?
adenine and guanine
What are the pyrimidines?
cytosine and thymine
- single stranded DNA?
- double stranded DNA?
- viruses usually contain
- most common form
- linear DNA.
- circular DNA.
- Linear common in most organisms
- Bacteria, mitochondria, and chloroplasts contain circular DNA.
What are the 3D Structures of DNA?
- B-DNA: most common; right-handed helix/ set number of base pairs per turn
- A- DNA: right- handed helix; higher set of base pairs per turn exists
- Z- DNA: same base pair number per turn as B-DNA; very temporary; left-handed helix
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