Biochem Ch 6-7 Flashcards Preview

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Flashcards in Biochem Ch 6-7 Deck (19):
1

Why are HIV patients at risk for cancers

- with retroviruses, DNA gets randomly incorporated into the genome
- it could be in an oncogene and turn it on; or turn off a Tumor suppressor gene
- However, when gene therapy uses retroviruses, they replace part the retroviral gene with the therapeutic gene, making the retrovirus incapable of self-replication
- retroviruses only invade cells that are dividing

2

Northern Blot

- analyzes RNA
- electrophoresis required
- probe used: 21p-DNA
- used to measure sizes and amounts of specific mRNA molecules to answer questions about gene expression
- typically used to see if genes are being expressed
- ex) pattern of gene expression may give info about disease prognosis and help tailor treatment
S --D: Southern Blot = DNA
N--R: Northern Blot = RNA
O O
W P: Western Blot = Protein

3

- Retroviruses can invade cells that are ___
- Adenoviruses can invade cells that are ____

- Retroviruses can invade cells that are dividing
- Adenoviruses can invade cells that are not dividing
- however, adenovirus DNA is NOT integrated into the host cell's chromosome and is eventually lost
- this necessitates repeated treatment with the delivery vector if an adenovirus vector is used

4

Chimeric mice

- contain 2 different sets of stem cells:
- one from the blastocyst donor and one from the original stem cell line
- result is the mouse will have patches of cells (including germ cells) derived from each of the 2 lineages
- composed of 2 distinct cell lines derived from 2 different strains of mice
- can be produced by mixing cells from 2 strains of mice early in embryogenesis, well before the immune system develops
- self-tolerance will allow both types of cells to survive and potentially contribute to the somatic and gremlin tissues of the chimeras
- Chimeras can breed to produce mice that are heterozygous for the transgene and mice that are homozygous for the transgene
- these transgenic mice can transmit the transgene to offspring

5

Southern Blot

- analyzes DNA
- electrophoresis is required
- probe used: 32p-DNA
- used to determine which restriction fragments of DNA are associated with a particular gene
S --D: Southern Blot = DNA
N--R: Northern Blot = RNA
O O
W P: Western Blot = Protein

6

k

k

7

Dot

- analyzes DNA, RNA or protein
- NO electrophoresis required
- use ASO probes (bind specifically to a single allele of a gene: allele-specific oligonucleotide = ASO)
- used to detect specific DNA, RNA, protein or antibody

8

ampicillin inhibits

peptidoglycan synthesis

9

the DNA sequence recognized by restriction endonuclease EcoRI

- 5' GAATTC 3'
- pallindrome = an inverted repeat in DNA
GAATTC
CTTAAG

10

Western Blot

- AKA immunoblots
- analyzes Protein
- electrophoresis required
- probe used: 125-I or enzyme-linked antibody
- used to measure AMOUNT of antigen (proteins) or antibody
- ex) detect the presence of antibodies to the HIV virus in HIV testing
S --D: Southern Blot = DNA
N--R: Northern Blot = RNA
O O
W P: Western Blot = Protein

11

uses of PCR

- direct mutation testing
- diagnosing bacterial and viral infections
- HIV testing in situations where antibody tests are uninformative (importantly, infants whose mothers are HIV positive)
- comparing DNA samples in forensic cases (ie paternity testing)
* for PCR to work you need to know the sequence bordering the target region at each of its 3' ends

12

- STR
- VNTR
- RFLPs
- Genetic fingerprinting

- STR = short tandem repeats
- VNTR = variable number of tandem repeats
- RFLPs = restriction fragment length polymorphisms
- PCR amplification of repetitive sequences such as VNTR
and STR (short tandem repeat) sequences can be used for genetic fingerprinting
- bc expansion of these repetitive sequences in spacer DNA is highly polymorphic in the population and individual specific

13

cDNA is made from

- mRNA
- only has coding region, no introns

14

measuring viral loads in AIDS patients

- measures the concentration of active circulating virus in the blood of an AIDs patient
- can monitor the status of the infection and the infection's response to antiviral drugs
1. a blood sample is treated with reverse transcriptase to produce cDNA from any RNA in the sample
2. the cDNA is PCR-amplified using primers specific for the end-sequences of the HIV cDNA
- the amplified product is quantitated and related to the original amount of HIV RNA present

15

statins

competitively inhibit HMG-CoA reductase

16

methotrexate

- competitively inhibit DHFR
- depriving deoxythimidine, interferring w DNA synthesis during S phase

17

When looking at a line weaver-burk plot if the lines CROSS you're looking at a graph of?

competitive inhibition

18

When looking at a line weaver-burk plot, the point where the line crosses the Y-axis represents the

1/Vmax

19

how do you treat methanol poisoning?

- give ethanol
- both are substrates for ADH, but ethanol has a much lower Km.
- this prevents methanol from being converted to formaldehyde (= toxic and not metabolized further)