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Genetics
Genetics test 3
36
Medical
Professional
09/19/2011

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Term
What is the basic dogma of biology?
Definition
DNA is used to produce RNA which is used to synthesize proteins
Term
What is genetics?
Definition
The analysis of inehritance patterns to identify and characterize genes.
Term
What are the nucleic acis and what are they?
Definition
Nucleotides plymerized by phosphodiester bonds
-RNA
-DNA
Term
What is the name of a structure that is a single molecule of DNA often millions of base pairs long.
Definition
A chromosome.
Term
What is a single functinal unit of DNA that controls a specific trait?
Definition
A gene
Term
Define ribose. What is its purpose?
Definition
A ribose is a five carbon sugar.
It makes up the central moity of nucleotides.
Term
Which ribose carbons are most important for polymerization?
Definition
The carbons at 3' and 5'
Term
What are bases in terms of nucleic acid structure? What is their purpose?
Definition
Bases are the side groups of nucleotides.
Term
At what carbon do baes attach to riboses?
Definition
At the 1' carbon or ribose.
Term
Which nucleotide types are composed of a base and one ring?
Definition
Pyrimidine
Term
What nucleotides have a single ring?
Definition
-Thymine
-Cytosine
-Uracil
Term
Which nucleotides
Definition
Term
A nucleotide with a base and two rings is considered what? Specifically, which nucleotides does this include?
Definition
Purines
Adenine
Guanine
Term
What is a nucleoside?
Definition
A nucleotide precursor that has a base attached to the 1' carbon of ribose but lacking a phosphorylated 5'
Term
What is the difference between thymidine and uracil?
Definition
Thymidine has a methyl group while uracil does not
Thymidine is used by DNA
Uracil is used by RNA
Term
Which is larger DNA or RNA?
Definition
DNA is significantly larger-millions of base pairs-versus RNA which is about 50-40,000 nucleotides
Term
What are some differences between DNA and RNA?
Definition
DNA-double stranded
RNA single stranded
DNA-much larger than RNA
DNA-composed of deoxynucleoties which lack 2' hydroxyl groups
RNA is made of unmodified nucleotides which have the 2' hydroxyls
Term
T/F. Factors that bind DNA often bind to the minor groove b/c it forms a stronger bond.
Definition
False. Factors bind the major groove b/c it allows better acess to the DNA.
Term
What is the standard DNA confirmation?
Definition
B DNA. Double right handed turn with about 10 BP per turn. Bases are held together at the core and the sugar phosphate backbones wrap around the periphery.
Term
Describe the differences between A and B DNA.
Definition
A DNA is more compact than B DNA
A DNA has a hole through the center
A DNA is formed from DNA/RNA or RNA/RNA strands
A DNA is more stable than B DNA
Term
Describe Z DNA. What is it sometimes associated with.
Definition
Z DNA is composed of left handed turns
Z DNA forms when there are alternating purine and pyrimidine nucleotides.
Z DNA is sometimes involed in gene repression
Term
How is a triple helical DNA formed?
Definition
Forms between one polypurina nd two polypyrimidine strands
Term
How many hydrogen bonds are between CG and AT?
Definition
CG have three
AT have two
Term
What is a function of supercoiling? Why does supercoiling occur?
Definition
Stores energy.
Occurs b/c DNA is partially unwound
Term
Define chromatin.
Definition
DNA plus proteins
Term
What are the differences between heterochromatin and euchromatin?
Definition
Heterochromatin is tightly would DNA that is not transcribed.
Eukromatin is actively transcribed and is less tightly bound.
Term
What amino acids do histones contain a large number of? Why?
Definition
Lysine and arginine b/c they are basic (positively charges) amino acids which allows them to bind to the negatively charged DNA.
Term
T/F. Prokaryotes have histones.
Definition
False
Term
Define nucleosome.
Definition
DNA and the associated histones. Does NOT include the linker region
Term
How many times does DNA wrap around a histone octamer? In what direction?
Definition
DNA wraps around 1.75 times in a left handed superhelix.
Term
Define solenoid.
Definition
A hollow tube formed when nucleosomes coil around each other.
Term
What form does DNA take on as the cell enters prophase?
Definition
All chromosomes condense into solenoids during prophase.
Term
What is the most abundant class of DNA proteins? Second most abundant?
Definition
Most common histones
Second most scaffold proteins
Term
What are the possible roles of scaffold proteins?
Definition
-Tie the solenoids togethers to form the condensced chromatin
-Maintian supercoiling
Term
T/F. Dark bands are more active
Definition
Term
What are the diffences between a promoter region and an enhancer region of DNA?
Definition
Promoter region
- position cannot be moved
- located just upstream of the gene (poly I and II)
-located within the gene (poly III)
Enhancers
-can be moved relative to the gene it controls
- its 5-3 prime orientation can be flipped in a transgenic expression assay
-often located many much further away from the gene it controls than promoters.
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