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MCAT ALL > DNA and Biotechnology > Flashcards

DNA and Biotechnology Flashcards

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MCAT flashcards
1
Q

Nucleotide

A

3 parts

  1. Nitrogenous Base (A, T U, G or C)
  2. Pentose sugar
  3. Phosphate group
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2
Q

Nucleoside

A

2parts

  1. Nitrogenous Base (A, T U, G or C)
  2. Pentose sugar
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3
Q

What are the base pairing rules according to Watson Crick?

A

A with T (in DNA) with 2 H-Bonds

G with C with 3 H-Bonds

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4
Q

How does the aromaticity of purines and pyrimidines underscore their genetic function

A

Their aromaticity of nucleic acids makes these compounds very stable and unreactive. Stability is important for storing genetic information and avoiding spontaneous mutations.

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5
Q

DNA is read from

A

5 to 3

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6
Q

Purines

A

Pur As Gold
Adenine (A) and Guanine (G)
2 rings

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7
Q

Pyrimidines

A 
CUT the Pye
Cytosine (C)
Thymine (T)
Uracil (U)
1 ring
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8
Q

B-DNA

A

Most common in nature

Double helix is right handed and makes a turn every 3.4nm and contains 10 base pairs

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9
Q

Z-DNA

A

Double-helix is left-handed
makes a turn with 12 base pairs
unstable
In areas of greater CG or salt concentration

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10
Q

A nucleotide connects to another nucleotide by…

A

Dehydration (lost of water)

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11
Q

A nucleotide connects to another nucleotide by which bond?

A

Phosphodiester bond

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12
Q

What are the 5 histone proteins in eukaryotic cells? which one is not part of the histone core around which DNA wraps to form chromatin?

A

H1, H2A, H2B, H3, and H4

H1 is the only one not in the histone core

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13
Q

Heterochromatin

A

Dense, Dark and silent

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14
Q

Euchromatin

A

Not dense (uncondensed), light and active

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15
Q

Which property of telomeres and centromeres allow them to stay tightly raveled, even when the rest of DNA is uncondensed?

A

High GC content increases h-bonds, making the association between DNA strands very strong at telomeres and centromeres

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16
Q

DNA wrapped around histone makes up the

A

Nucleosomes which make up the chromatin in the nucleus

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17
Q

Telomeres

A

Repeating ends of a chromosome, with high GC to prevent the ends of DNA from unraveling.
During replication they are slightly shortened but the enzyme telomerase can add them back up

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18
Q

Centromeres

A

Located in the middle of chromosomes and hold sister chromatids together until they are separated during anaphase. Also high GC content

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19
Q

Helicase

A

Unwinds the DNA

Both

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20
Q

Single Stranded DN- Binding Proteins

A

Prevents reannealing of DNA double helix during replication

Both

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21
Q

Primase

A

Places -10 nucleotide RNA primer to begin DNA replication

Both

22
Q

DNA Polymerase III

A

Adds nucleotides to growing daughter strand

Prokaryotes

23
Q

DNA Polymerase alpha

A

Adds nucleotides to growing daughter strand

Eukaryotes

24
Q

DNA Polymerase I

A

Fills in gaps left behind after RNA primer excision

Prokaryotes

25
Q

RNase H

A

Excises RNA primer

Eukaryotes

26
Q

DNA ligase

A

Joins DNA strands (especially between Okazaki fragments)

Both

27
Q

DNA topoisomerases

A

Reduces torsional strain from positive supercoils by introducing nicks in DNA strand (introduce negative coils)
Both

28
Q

Telomeres

A

Are the end of eukaryotic chromosomes and contain repetitive sequence of noncoding DNA. These protect the chromosome from losing important genes from the incomplete replication of the 5’ end of the DNA strand
- eukaryotes

29
Q

Sliding clamp

A

helps strengthen the interaction between polymerases and the template strand

30
Q

DNA Polymerase Proofreading

A

Phase of cell cycle: S

Key enzyme: DNA Polymerase

31
Q

Mismatch repaire

A

Phase of cell cycle: G2

Key enzyme: MSH2, MLH1 (MuS and MutL in prokaryotes)

32
Q

Nucleotide excision repaire

A

Phase of cell cycle: G1, G2

Key enzyme: Excision endonuclease

33
Q

Base excision repaire

A

Phase of cell cycle: G1, G2

Key enzyme: Glycosylase, AP endonuclease

34
Q

What is the difference between oncogene and tumor suppressor gene?

A

Oncogenes code for cell cycle-promoting proteins, when matures, proto-oncogene becomes an oncogene, promoting rapid cell cycling. (Pressing gas pedel)
Tumor suppressor genes code for repair or cell cycle inhibiting proteins; when mutated, the cell cycle is allowed to proceed unchecked. (cutting breaks)

35
Q

What is the key structural difference in the types off lesions corrected by nucleotide excision repair vs those corrected by base excision repair?

A

Nucleotide excision repair corrects lesions that are large enough to distort the double helix
Base excision repair corrects lesions that are small enough not to distort the double helix

36
Q

Oncogenes

A

Mutated genes that cause cancer

37
Q

Proto-oncogenes

A

Before genes are mutated

38
Q

Antioncogenes

A

Tumor suppressor genes that encode proteins that inhibit cell cycle or participate in DNA repair
eg: p53 or Rb

39
Q

Genomic library

A

Include all of the DNA in an organism’s genome, including both coding and noncoding regions. They cannot be used to make recombinant proteins or for gene therapy. Useful for studying DNA in introns, centromeres or telomeres

40
Q

cDNA

A

Expression libraries
-Contain smaller fragments of DNA, only include the exons of genes expressed by the sample tissue. They can be used to make recombinant proteins or for gene therapy

41
Q

What techniques are made available by Recombinant DNA technology?

A

Allows for gene editting, cloning, or PCR. Can provide a source of specific protein (like human insulin)

Recombinant DNA is the act of adding a segment of DNA to a plasmid or chromosome

42
Q

What is DNA cloning? What is needed to perform DNA cloning?

A

technique that produces large amounts of a desired DNA sequence. Usually the DNA is heterogenous with other DNA sequences and in small quantity.

Cloning requires that one ligates the DNA of interest into the vector (i.e. plasmid) to generate a RECOMBINANT VECTOr using restriction enzymes. These are transferred to a host bacteria or virus.

It is important to include antibiotic resistance gene in the recombinant vector, such that all strains without your vector of interest are then eradicated easily. The resulting bacterial colony can then be grown in large quantity.

The colonies can either be made to express the gene of interest to generate RECOMBINANT PROTEIN or lysed to generate large quantities of the CLONED DNA

43
Q

What function do restriction enzymes perform in bacteria?

How are they used in recombinant DNA production?

A

They slice (sticky or blunt) at sites with dyad symmetry in a bacterial viral DNA defense mechanism. - palindromic sequence needed

If used in recombinant DNA, cutting sticky ends with restriction enzyme can allow reannealing between vector DNA and segment of interest

44
Q

What are the components of recombinant DNA plasmids?

A 
Recombinant Plasmid contains:
DNA of interest
Antibiotic Resistance Gene!
Restriction enzyme cut site(s)
and an Origin of Replication site.
45
Q

What is hybridization? What techniques rely on this property?

A

Hybridization is the joining of complementary base pair sequences (DNA-RNA, or DNA-DNA)

Used in polymerase chain reaction and Southern Blot tests.

46
Q

What is needed to perform the Polymerase Chain Reaction?

A

Can produce millions of copies of DNA sequence without amplification the DNA bacteria

  • Requires Primers, nucleotides, temperature control, and (temperature resistant) DNA Polymerase
    1. DNA denatured (high temp so separated)
    2. Primer annealing
    3. Primer extension via polymerase
    4. doubled number of DNA (repeat)
47
Q

Gel electrophoresis

A

Separate macromolecules like DNA and Protein by size and charge

  • DNA negatively charged so moves to anode (+)
  • agarose gel for big dna and SDS-PAGE for small
  • longer DNA slower migration
48
Q

Southern Blotting

A
  1. Take DNA and cleve using restriction enzymes
  2. Gell Electrophoresis to separate fragments
  3. transfer to filter
  4. Expose to radio-labled DNA- single strand DNA that is complementary to gene sequence of interest- bind to gene sequence
49
Q

How is the genome of transgenic mice altered? What is the name of the introduced gene?

A

Transgenic mice are altered at their GERM LINE. A TRANSGENE is inserted to produce the transgenic organism. The transgene coexists in the animals with their own copies of the gene, which have not been deleted. Therefore this technique is most useful when studying dominant effects of the inserted transgene

50
Q

How do knockout mice differ from transgenic mice.

A

Knockout mice are similar, but a gene has been intentionally deleted rather than gene insertion as in transgenic.

MCAT ALL (56 decks)

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