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AU13 - Biochem EX 3 > Leys > Flashcards

Leys Flashcards

1
Q

Cells acquire nucleotides through two processes

A

De novo synthesis

Salvage pathways

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2
Q

De novo synthesis of _____ results in the synthesis of ____ that can be converted into ______ & ______

A

Purines
Inosine
Adenosine
Guanosine

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3
Q

Atoms in a newly synthesized purine are derived from several sources including

A

Aspartate
Glutamine
Glycine
Methyl groups supplied by folic acid and CO2

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4
Q

____ and ___ regulate de novo synthesis of purines at ___ point(s) in the pathway

A

ADP
GDP
multiple

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5
Q

____ and ____ can be recycled through the salvage pathway with ______

A

Hypoxanthine
Guanine
Hypoxanthine guanine phosphoribosyl transferase (HGPRT)

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6
Q

_____ catalyzes a hydroxylase type reaction leading to the formation of ____ that can be excreted

A

Xanthine oxidase

uric acid

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7
Q

Excess or low levels of secretion of uric acid is the cause of ____

A

gout

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8
Q

Crystallization of _____ in the joints leads to a localized inflammatory response

A

Sodium urate

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9
Q

_____, a ____ analog, is used to treat gout. It inhibits _____ preventing the formation of uric acid.

A

Allopurinol
Purine
Xanthine oxidase

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10
Q

A ____ deficiency causes _____ syndrome that results in severe retardation, crippling gouty arthritis and self mutilation

A

HGPRT

Lesch-Nyhan

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11
Q

Lesch-Nyhan occurs only in ____ because the HGPRT gene is located on the ________

A

Males

X chromosome

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12
Q

The breakdown of purines can replenish _____ intermediates through the production of ______

A

TCA cycle

Fumarate

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13
Q

The atoms in a pyrimidine ring are derived from

A

Aspartate and Carbamoyl phosphate

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14
Q

The first 3 enzymes in pyrimidine synthesis are located on this protein

A

CAD protein

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15
Q

The pyrimidines _ and _ can be interconverted

A

U and C

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16
Q

____ is converted to ___ by _____, an enzyme requiring the transfer of a methyl group from tetrahydrofolate

A

dUMP
TMP
Thymidylate synthase

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17
Q

Inhibitors of ____ production are used as therapeutic agents for treating cancer and bacterial infections

A

tetrahydrofolate

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18
Q

___ substituted pyrimidine analogs that inhibit ____ are used as anticancer agents

A

Fluro

Thymidylate synthase

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19
Q

_____ converts ribonucleotides to deoxyribonucleotides

A

Ribonucleotide reductase

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20
Q

Base-pairing in DNA is ___ and ____. In RNA it’s ____ and ____

A

AT and GC

AU and GC

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21
Q

Why would homologous regions of DNA be compared among different species

A

To determine phylogenetic relationships

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22
Q

What is the difference in DNA between closely related organisms

A

They contain similar DNA compliments but are often arranged differently on the chromosomes

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23
Q

The 3 divisions/domains of the living world

A

Bacteria
Archaea
Eukaryotes

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24
Q

4 main processes for generating change in a genome

A
  1. Intragenic mutation (single base change/point mutations/changing AA composition)
  2. Gene duplication
  3. DNA segment shuffling (mixing of segments of 1 gene with those of another)
  4. Horizontal transfer (from one cell/organism to another)
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25
Q

What is different about bacterial genes

A

They are usually clustered into groups (operons) that are transcribed as a single unit

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26
Q

Non-coding region of DNA

A

intron

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27
Q

What is the difference in genes between closely related species

A

Exons are very similar (conserved)

Introns vary in size and content

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28
Q

Do bacteria have introns? Why?

A

No, bacterial chromosomes are densely packed with genes, leaving very little DNA that is non-coding

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29
Q

What is different about the DNA in higher eukaryotes

A

Most of it does not code for proteins

It is made up of repeated sequences, many of which are mobile elements that can move around in the genome

30
Q

What is the shape of bacterial and eukaryotic chromosomes?

A 
Bacterial = Circular
Eukaryotic = Linear
31
Q

DNA polymerase is a ___ dependent ___ synthesizing enzyme

A

DNA

DNA

32
Q

RNA polymerase is a ___ dependent ___ synthesizing enzyme

A

DNA

RNA

33
Q

Reverse transcriptase is a ___ dependent ___ synthesizing enzyme

A

RNA

DNA

34
Q

Primase is a ___ dependent ___ polymerase

A

DNA

RNA

35
Q

Role of primase

A

Synthesizes a small RNA primer that can be used by the DNA polymerase to elongate the chain

36
Q

_____ minimizes the number of mistakes by using a _ to _ ______ activity that is part of the same protein

A

DNA polymerase

3’ to 5’ exonuclease

37
Q

DNA polymerase as well as all other nucleic acid polymerases synthesize DNA in the _ to _ direction only

A

5’ to 3’

38
Q

During _____, each new nucleotide is added to the _ carbon on the last nucleotide of the new DNA chain

A

replication

3’

39
Q

Differences between the carbons in 5-C sugars

A

1’ - connects the base component of each nucleotide
2’ - differs between RNA and DNA
3’ and 5’ - Adjacent nucleotides attach here in a DNA chain

40
Q

DNA polymerase is an ____ enzyme; it cannot _____ synthesis. A ___ is required for elongation of a new strand using DNA polymerase

A

Elongating
Initiate
Primer

41
Q

Bacterial chromosomes contain ____ origin(s) of replication

A

One

42
Q

What is the direction of DNA synthesis?

A

It proceeds in both directions away from the origin until the two replication forks meet at a specific sequence on the other side of the chromosome

43
Q

What is different about the origin of replication in eukaryotes?

A

They contain many origins of replication that may change during the development of the organism

44
Q

Telomeres

A

Special structures placed at each end of linear eukaryotic chromosomes

45
Q

Telomeres are constructed with the enzyme ____ that uses a ___ template to synthesize a short repeated DNA sequence at the ends of chromosomes

A

Telomerase

RNA

46
Q

Because polymerase synthesizes DNA in the 5’ to 3’ direction, the two polymersae molecules must move _____ each other

A

Opposite

47
Q

Helicase function

A

Unwinds 2 DNA strands before polymerization of the new strands

48
Q

_____ keep the two complementary strands from reforming a double helix

A

Single-stranded binding proteins

49
Q

The polymerase on the leading strand moves ___ the replication fork and the one on the lagging strand moves ____ it

A

Toward

Away from

50
Q

The lagging strand is synthesized in short strands called

A

Okazaki fragments

51
Q

____ initiates synthesis of each Okazaki fragment by making a short ___ primer

A

Primase

RNA

52
Q

What signals that the DNA is unreplicated and ready to be used as a template for the next round of synthesis?

A

Methylation of the DNA

53
Q

Breaks in DNA (especially ___ breaks) facilitate initiation of _______

A

Double-stranded

Recombination

54
Q

A defect in _____ can cause abnormal amounts of recombination

A

DNA ligase

55
Q

This is the reciprocal exchange of genetic information

A

Recombination

56
Q

Recombination can be the result of

A
  1. Reciprocal exchange during cell division
  2. DNA damage (ex. X-ray damage)
  3. Introduction of foreign DNA
  4. Programmed recombination during development or maturation of a cell type (ex. antibody producting genes during B-cell maturation)
57
Q

This is the non-reciprocal exchange of genetic information

A

Gene conversion

58
Q

Can circular DNA be inserted into a chromosome?

A

Yes, via recombination between a region on a circular molecule and a homologous region on the chromosome

59
Q

What do x-rays do to DNA?

A

Cause breaks and induce recombination

60
Q

What species have transposable elements?

A

Everything from bacteria to human

61
Q

What do transposable elements do?

A

Move from one location in DNA to another location in cell. Can cause changes in DNA at site of insertion

62
Q

Two major types of transposable elements

A
  1. Contains inverted repeated sequences at the ends and causes a short region of genome to be duplicated at site of insertion
  2. Structurally similar to a retrovirus and trasposes through an RNA intermediate
63
Q

Recombination that resulted from imprecise pairing of tandemly repeated sequences is ___

A

Unequal crossing-over

64
Q

Results of unequal crossing-over

A

Loss or gain of gene copies

65
Q

Two types of mutations

A
  1. DNA rearrangements

2. Base substitutions

66
Q

Is a cell able to repair its DNA?

A

Yes, there are many mechanisms for it

67
Q

A permanent mutation results from

A

Damage to a nucleotide (ex. deamination) that cannot be repaired

68
Q

Causes of mutations

A

Errors during replication

Injury to the DNA from chemicals or radiation

69
Q

About 3% of the human genome is this

A

Made up of segmental duplications or large regions of DNA that are present in more than one copy

70
Q

What process creates duplicated DNA in a genome

A

Gene amplification

71
Q

Results of gene amplification

A

Resistance to drugs
Transformation into cancerous cells
Other changes in cell phenotype

72
Q

Should I worry about defects in my DNA repair enzymes?

A

HOLY FUCKSTICKS BATMAN, YES! THEY CAN BE THE CAUSE SEVERAL HUMAN DISEASES.

AU13 - Biochem EX 3 (3 decks)

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