BU BI203 Beffert Exam 1
DNA is a double helix with ______ base pairs per complete turn of the helix
10
How many amino acids are commonly incorporated into proteins?
20
Transmembrane proteins typically have an alpha helical region of how long?
20-25 hydrophobic amino acids
The restriction enzyme Notl recognizes a specific DNA sequence of eight base pairs and cleaves at that site. Statistically, in any genome there should be one Notl recognition site for every ___ base pairs
4^8
How many different RNA triplets specify amino acids?
61
Heat denatured DNA will renature when cooled to about
65 degrees celsius
DNA was first identified as the genetic material in experiments done by
Avery, MacLeod and McCarty
What is the function of restriction endonucleases?
Cleavage of DNA specific sequences
A disulfide bond is formed between _______
Cysteine
What is a cDNA molecule?
DNA synthesized from an RNA template using the enzyme reverse transcriptase
What is the order of the 3 steps of PCR?
Denaturation, annealing, extension
What is true about ABC transporters?
Each member of the family has shared domain structure features Each member of the family has an ATP binding cassette They are the largest family of membrane transporters in humans
In polysaccharides, sugars are linked together by means of what kind of bond?
Glycosidic
Lipid with unsaturated fatty acids
Increase fluidity of membranes
The movement of ____ , a single atom, is the major component determining membrane potential
K+
Transport of glucose into the intestinal epithelium is driven by ion gradients established by the
Na+/K+ pump
Can you predict a 3D shape of a protein from its amino acid sequence?
No
Which of the following classes of amino acids is buried within the folded structure of the protein?
Nonpolar
Which characters are necessary in a plasmid vector to facilitate successful cloning?
Restriction site, Gene conferring resistance to antibiotic, origin of replication
The alpha helix is an example of which level of protein structure?
Secondary
A protein's alpha helices and beta sheets fold together to create an overall shape at the _____ level of protein structure.
Tertiary
Could a peripheral membrane protein interact with hydrophilic portions of phospholipids?
Yes
Is cholesterol a membrane lipid similar to testosterone and estrogen?
Yes
A feature common to most transmembrane proteins in a(n)
alpha helical region of about 20-25 hydrophobic amino acids
Enzymes affect the transition state of a chemical reaction by
binding to substrates, altering the conformation of the substrates to approach that of the transition state, providing a surface on which reactions converting substrate to product occur more rapidly
Larger polar molecules must enter cells by binding to
carrier proteins that facilitate the passage of specific molecules across membrane
Which of the following lipids are distinctly enriched in lipid rafts?
cholesterol and sphingolipids
What is involved in receptor mediated endocytosis?
clathrin, an internalization signal and a receptor
In the fluid mosaic model of biological membrane structure, transmembrane proteins are
embedded nearly randomly in the lipid bilayer
Phospholipids consist of a 3-carbon core to which two fatty acids and a phosphate group are linked. The most common 3-carbon core is
glycerol
Two examples of membrane lipid that are present in small amounts are
glycolipids and phosphatidylinositol
Taq polymerase is used in PCR because it
is stable at high temps
Introducing a double bond into a fatty acid puts a(n) _______ into the conformation of the molecule.
kink
Membrane proteins are able to move
laterally within the plane of a membrane.
in addition to serving as the building blocks for nucleic acids, what other important functions do nucleotides have?
nucleotides serve as carriers of metabolic energy and signaling molecules
What transport mechanism can bring whole cells into a cell?
phagocytosis
Proteins must have more than one _______ to have a quaternary structure.
polypeptide chain
LDL uptake by cells is one of the functions of
receptor-mediated endocytosis
The enzyme that synthesizes DNA using RNA templates is
reverse transcriptase
The first enzymatic step in making a cDNA uses which of the following?
reverse trasncriptase
Although Na+ is smaller than K+, its passage through the K+ channel is blocked by the _______ filter.
selectivity filter
A codon is a
sequence of three nucleotides on an mRNA that binds to specific tRNAs.
Monosaccharides are to ____, as ____ are to RNA
starch, nucleotides
Which molecule serves as an adaptor between amino acids and mRNA during translation?
tRNA
In Meselson and Stahl's experiment, they demonstrated
that DNA is semiconservative
About 50% of the mass of most biological membranes consists of lipids and about 50% consists of proteins. Therefore, a. the membranes contain fewer molecules of lipid than of protein. b. the membranes contain equal numbers of lipid and protein molecules. c. the membranes contain more molecules of lipid than of protein. d. only a few membrane proteins are exposed at the cell surface.
the membranes contain more molecules of lipid than of protein
In PCR what is the purpose of the step in which the temperature is between 70 and 75 degrees celsius?
to allow primers to anneal
When thymidine and adenosine interact within the DNA molecule, they form
two hydrogen bonds
The most abundant molecule in cells is
water
