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Biomolecules > Biomolecules I > Flashcards

Biomolecules I Flashcards

1
Q

5’ cap is useful for

A
  • removes exonuclease
  • promotes ribosomal binding
  • regulates nuclear export of mRNA
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2
Q

poly-A tail is useful for

A
  • promotes translation
  • regulates nuclear export
  • termination of transcription
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3
Q

RNA editing: CDAR

A

-deamination of cytosine to uridine by cytosine deaminase

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4
Q

RNA editing: ADAR

A

-deamination of adenosine to inosine by hydrolytic deamination

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5
Q

microRNA (miRNA)

A

-gene silencing: miRNA binds to mRNA regions which are further prevented from translation or sent for degradation

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6
Q

Ribosomal RNA (rRNA)

A

-used for translation to make more ribosomes

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7
Q

Transfer RNAs (tRNAs)

A

-links codons in mRNA strands for corresponding AA for polypeptides

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8
Q

small nucleolar RNA (snoRNA)

A

-guide in covalent modifications of rRNA, tRNA, and snRNA through methylation and pseudouridylation (addition of an isomer of nucleotide uridine)

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9
Q

small nuclear RNA (snRNA)

A
  • primary function is in processing of pre-mRNA in the nucleus
  • formation of sRNP
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10
Q

How does spliceosome work?

A
  • snRNA + snRNP

- removal of introns and ligating two exons together via trans-esterification reactions

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11
Q

How are proto-oncogenes converted into oncogenes?

A
  • Deletion/point mutation: leads to a certain protein being overly expressed or is produced in normal amounts but is hyperactive.
  • Gene amplification/increase in mRNA stability: prolongs the lifespan of mRNA which leads to more protein being over expressed
  • Chromosomal rearrangement: translocation to a regulatory sequence which causes normal protein to be overly expressed
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12
Q

Cell cycle repressor proteins

A

represses genes that are essential for continuation of the cell cycle

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13
Q

two-hit hypothesis

A

In order for the mutation to manifest, both alleles must be defective (i.e. recessive alleles must be mutated to lead to cancerous phenotype)

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14
Q

Tumor suppressor gene: retinoblastoma protein (pRb)

A
  • prevents the damaged DNA from replicating by preventing the progression of the cell cycle from G1 phase to S (synthesis) phase.
  • attracts histone deacetylase (HDAC) which leads to repression of transcription
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15
Q

p53 protein

A
  • Activates DNA repair protein when DNA has sustained damage
  • stops cell cycle in G1 - S phase
  • p53 binds to and activates several genes such as p21: which further binds to cyclin CDK complex that initiates the cell to move from G1 to S phase
  • apoptosis
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16
Q

Two-hit hypothesis: dominant negative

A

-mutated p53 protein prevents the protein product of normal allele from functioning

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17
Q

where do mutations come from?

A

-spontaneous or inherited

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18
Q

Non-sense mutation

A

-genetic mutation that leads to a stop codon

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19
Q

Conservative mutation

A

-New AA is the same type as the original (from Glu to Asp: both are acidic)

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20
Q

Non-conservative mutation

A

-New AA is different type as the original (From Ser (polar) to Phe (non-polar))

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21
Q

point mutations

A

changes in the base pair substitutions (ACC ATC – ACT ATC)

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22
Q

Transition

A

substitution of purines by purines (A –> G; C –> T)

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23
Q

purines and pyrimidines

A

A – G (purines)

C – T (pyrimidines)

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24
Q

tranversion

A

substitution of purines to pyrimidine (A/G – C/t)

25
Q

mispairing/mismatching

A

due to non Watson/Crick base pairings (usually A pairs with T; but mispairing: A pairs with G/C instead)

26
Q

What are frameshift mutations caused by?

A

-deletions and insertions

27
Q

large scale mutations

A

-caused at chromosomal level and affects multiple genes instead of few base pairs

28
Q

large scale mutations: Translocation

A

-Gene from one chromosomal level is swapped for a gene on a different non-homologous chromosome

29
Q

Large scale mutations: chromosomal inversion

A

-Genes that are swapped on the same chromosome

30
Q

endogenous vs. exogenous mutagen

A

-endogenous mutations arise from inside the body (ROS) whereas exogenous mutations arise from the environment

31
Q

types of exogenous mutations

A
  • Intercalators: Ethidium bromide [EtBr]

- Base analogues: they pretend to be a certain base but act differently [5-bromouracil]

32
Q

good mutation: streptococcus pneumonia

A

-this bacteria causes pneumonia, when given antibiotics (i.e. penicillin) it will kill this bacteria. human host bacteria becomes penicillin resistant in the long run

33
Q

Bad mutation: CFTR gene

A

-CFTR gene produces a thick mucus which makes it harder to breathe

34
Q

co-dominant phenotype

A

-two alleles are dominant together; both alleles show up in the phenotype (both blue/red)

35
Q

Incomplete dominance

A

-a mixture of the alleles in the genotype is seen in the phenotype (e.g. red + blue flower= purple)

36
Q

gel electrophoresis

A

-Separation of different size fragments of DNA by their size via using an electrical charge

37
Q

polymerase chain reaction (PCR)

A

-process used to copy DNA which requires to denature the double strands by applying heat and make copies of the given DNA (ex: Taq Polymerase)

38
Q

repeating steps of PCR yields an _____ increase in a particular DNA sequence

A

there’s an exponential increase in a particular DNA sequence.

39
Q

Restriction enzymes

A

-allowed to clip the specific fragments of the gene in DNA cloning

40
Q

microarrays

A

-assaying a mixture: detecting the expression of thousand of genes at the same

41
Q

DNA cloning: transformation

A

-taking a cDNA and placing it in a plasmid with antibiotic resistant genes

42
Q

Steps in expressing cloned genes

A

a. mRNA to cDNA via reverse transcriptase
b. transforming the cDNA in a plasmid with Ab resistant genes
c. Plasmid (with resistance) placed in the bacteria
d. bacteria allowed to replicate

43
Q

Southern blot

A

a procedure for identifying specific sequences of DNA, in which fragments separated on a gel are transferred directly to a second medium where hybridization takes place

44
Q

Steps involved in southern blots

A

a. Take DNA and cleave certain fragments
b. Gel electrophoresis
c. place the gel onto a filter
d. expose to radio labeled DNA (complement to gene of interest)
e. expose to x-ray

45
Q

DNA sequencing

A

a. PCR to amplify the genes
b. Add nucleotides with dideoxynucleotides (ddNTP) which prevents elongation
c. Gel electrophoresis to separate DNA fragments by size

46
Q

Friedrich Miescher

A

Isolated protein and nucleic acid from pus

47
Q

Wilhem Roux

A

-material in the nucleus is genetic material, worked with dividing cells (organelles were not divided in organized fashion but nucleus material was)

48
Q

Hershey-Chase experiment

A

showed that nucleic acid, rather than protein is the genetic material (worked with bacteriophages)

  • Phosphorus 32: DNA
  • Sulfur 35: protein (AA)
49
Q

Watson and crick

A

identified the structure of DNA

(nucleic acids); it is a ds helix with sugar/phosphate backbone with nitrogenous bases inside

50
Q

Colour blindness and hemophilia are _____ trait

A

X-linked recessive trait

51
Q

synaptonemal complex

A

a protein complex forms between the pairs of chromosomes, where crossing over (or genetic recombination) occurs

52
Q

Evolution

A

change in heritable traits of a population over generations

53
Q

pre-zygotic barriers

A
  • mechanical isolation
  • habitat/temporal isolation
  • behavioural isolation
  • gametic isolation
54
Q

post-zygotic barriers

A
  • Zygote mortality
  • Hybrid inviability
  • Hybrid sterility
55
Q

4 mechanisms of Evolution

A
  • genetic drift
  • gene flow
  • natural selection
  • mutation
56
Q

gene flow

A

alterations in the composition of a gene pool due to migration of individuals between different populations

57
Q

positive Gibbs free energy is _____ reaction whereas negative Gibbs free energy is ____ reaction

A

positive Gibbs free energy is exergonic reaction whereas negative Gibbs free energy is endergonic reaction

58
Q

exergonic energy is ___ whereas endergonic energy is ____

A

exergonic energy is released whereas endergonic energy is absorbed

Biomolecules (1 decks)

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