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26 Cards in this Set

  • Front
  • Back
How do you define genetics?
Field of biology that studies the transfer of traits from one generation to another.
In genetics, what is the flow of information in the cell, from DNA to RNA and eventually to proteins called?

How do viruses contradict this?
Central dogma

Contradict it by going from RNA to DNA to protein, etc.
What is the the information containing region of the chromosome? How many of these regions are in E. coli?

What is it transcribed into?
Gene; E.coli contains 3,000 to 4,000 different genes.

Into an RNA message
What is the the total complement of genes found in a cell?

What is the genetic composition of an organism?

What is called when an organism expresses observable characteristics?
Genome

Genotype

Phenotype
How is phenotype observed in microbes?
By looking at factors such as utilization of carbs or virulence
T or F: A microbe can be virulent even though it has a simplistic metabolic pathway

If true, name an example
TRUE FOOL

Ex: mycoplasma genitalium is deadly to infants but has small kbp
The genetic information contained in the DNA is first copied into mRNA a process called...

The mRNA relays information to synthesize protein molecules. This synthesis is called...
transcription

translation
Prokaryotic mRNA is often BLANK (more than one cistron or gene).

This type of mRNA encodes for?
polycistronic

Encodes for several proteins
What are the four bases of the genetic code? How many codons? How many code for AAs?
A,G,U,C; 64 codons; 61 codons
What are the three nonsense or termination codons?

What is their purpose?
UAA, UAG, and UGA

They signal the termination of protein synthesis
Many amino acids are represented by more than one codon, thus...

The third position of the codon is...
the code is degenerate.

the most degenerate.
Describe the degenerate codons for alanine

Which AAs are specified by one codon?
They all start with GC (GCU, GCC, GCA and GCG); only the 3rd position matters

Tryptophan and methionine
Describe the two experiments that proved DNA was the genetic material.

What does this lead to? OTOH, very few strains...
In 1928, Giffith found that nonvirulent R strains of S. pnuemoniae could be made virulent when mixed with heat killed S virulent strains.

In 1944, Avery, MacLeod, and McCarty found that this occured because DNA was taken up by R strains from S strains.

This led to transformed recipients but very few strains of bacteria in nature are transformable
What did Watson and Crick find?

DNA details:
The helix has a diameter of BLANK, and makes a complete turn every BLANK. There are BLANK per turn of the helix.

BLANK bonding link the bases between the strands. The nucleotides are joined to each other in a chain by covalent BLANK bond between the BLANK carbon of one to a BLANK carbon of the adjoining deoxyribose.
In 1953, DNA molecule consists of 2 polynucleotide chains arranged in a slender double helix.

20 A; 34 A; 10 bp

Hydrogen; phosphodiester; # 3 (3’); # 5 (5’)
Species of bacteria vary as to their proportion of G+C to A+T. This ratio is as expressed as...

It ranges from BLANK to BLANK in bacteria.

DNA with a high percentage of BLANK bonding tends to be more stable to unwinding or denaturation
the mole % of G+C in the DNA (thermal mel curve)

22% to 74%

G+C
As DNA denatures there is a sharp increase...

The temperature that corresponds to the midpoint of their increase in absorption is their BLANK.

Differences in mole % between bacteria mean they are...
in their UV abs, @ 260 nm.

Tm

probably different species.
DNA structure details:
1. A binds to....and G binds to...

2. 2 polynucleotide chains in DNA helix are complementary and are...

3. So one strand is BLANK to BLANK, the other BLANK to BLANK.

4. What is the overall net charge?
A=T and G=C

antiparallel

5’-PO4 to 3’-OH, the other strand is 3’-OH to 5’-PO4

negative
The chromosome in E. coli is BLANK bps and has a MW of BLANK.

Thus the DNA molecule is BLANK times longer than the E.coli cell length.
4.7 x 10^6 bps; MW of 2.5 x 10^9

550
Who came up with the semiconservative replication of DNA in 1958?

Describe their experiment.
Meselson and Stahl

Grew isotope labeled nitrogen; after several generations, found that strands served as template for daughter strands as hybrid labeled DNA was seen.
DNA replication is both BLANK and BLANK. DNA was seen as a circular molecule with 2 replication forks, called BLANK replication.

Who discovered this replication pattern and how?
Sequential and bidirectional; theta (Ө)

Cairns used autoradiographs by exposing 3H-thymidine treated lysed cells to photographic film, revealing the shape and replication pattern of the replicating DNA molecule.
In DNA replication, BLANK proteins recognize/bind to specific DNA sequence of BLANK bases at the...

This protein complex then binds to a DNA helicase which...

DNA topoisomerases assist in...

What are the two types of topoisomerases?
Initiator; 300, origin of replication (ori C)

unwinds short sections of the helix in advance of the replication fork

the DNA unwinding and rejoining of the DNA molecule

type 1: works on 1 strand; type 2: works on both strands
Describe the sequences/steps of enzymes involved in DNA replication
Dna A (9-mer/9bp from origin)

Dna C

Dna B

Dna polyemerase III loads the sliding clamp

Dna polymerase binds to clamp and leading strand synthesis at the beginning of each template
In the process of DNA replication, Okazaki fragments in 1964 demonstrated that one of the DNA daughter strands was ...

These strands are called...
synthesized discontinuously in short segments of 1,000 to 2,000 nucleotides in a 5’ to 3’ direction

The lagging strand
E. coli, has 3 different polymerases, I,II, and III. They all add mononucleotides to...

DNA polymerase III, will polymerize...

DNA polymerase I, the Kornberg enzyme, is involved in...
3’-OH end of a preexisting growing polynucleotide.

up to 30,000 nucleotides per minute

DNA repair of UV damage, the excision-repair mechanism of DNA.
DNA polymerases, as studied in E. coli, are similar in size but...

DNA poly III is unique in that it is...

DNA poly I primarily works on BLANK damage while DNA poly III is primarily for...
but they polymerize different numbers of nucleotides.

the biggest and polymerizes the most nucleotides

UV damage; synthesis
What is another mechanism of DNA replication? What things use this mechanism?

Describe this mechanism
The rolling circle mechanism; seen in bacterial viruses/bacteriophages and during DNA replication in conjugation.

One of the strands is nicked at a specific site and the subsequent free 3’-OH end is extended by a DNA polymerase.