Final Study Guide Deck Flashcards

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1
Q

What are 2 strands of DNA held together by

A

Hydrogen bonds

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2
Q

How many hydrogen bonds are between G and C

A

3

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3
Q

How many hydrogen bonds between A and T

A

2 ( that’s why there is a TATA box at the beginning of Transcription- break apart the A-T double bond bc its weaker than G-C triple bond)

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4
Q

Nucleoside vs Nucleotide

A

Nucleoside: Sugar and base
Nucleotide: Sugar, Base, Phosphate group

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5
Q

What are the purines and what are the pyrimidines

A

Purines: A/G (double ringed)
Pyrimidines: C and T, U (single ringed)

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6
Q

What are 3 structural features of DNA

A
  • Right handed double helix, antiparallel, complementary
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7
Q

Which enzyme seperates the 2 strands of DNA during replication

A

Helicase

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8
Q

Which enzyme makes the RNA primer

A

Primase

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9
Q

Difference between DNA polymerase 1 and DNA polymerase 3

A

1: Removes DNA primers
3: Adds DNA bases 5’–>3’

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10
Q

What are telomeres

A

At the end of the chromosomes, prevent gene loss ( In somatic cells, the telomeres shorten whith every dvision. In Stem/Cancer cells, telomerase ensures that telomeres do not shorten).

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11
Q

Where is the telomerase gene found

A

In stem cells and gametes

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12
Q

What is a clinical application with telomerase

A

Premature aging occurs when there is no telomerase.
Telomerase is expressed in 90% of cancers, stimulates cell division.

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13
Q

What is Mismatch repair, and which cancer is related to it?

A

Mismatch repair: One nucleotide is removed by an exonuclease and strand is repaired
Colorectal cancer (lynch syndrome) loss of function in DNA mismatch repair

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14
Q

What is nucleotide excision repair and its clinical application

A
  • Remove bulkey DNA lesions (caused by UV light, i.e. skin cancer)
  • Xeroderma Pigmentosum is a defect in nucleotide excision, skin cells can’t fix themselves, so early and frequent skin cancers
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15
Q

Base excision repair

A

One or a few bases damaged, corrected easily

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16
Q

Double strand break repair and clinical correlation

A
  • Most dangerous- A number of bases are damaged and there is non-homologous end joining, not accurate, and DNA lost in process.
  • BRCA 1 associated (Breast Cancer)
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17
Q

rRNA function

A

site of translation, structural and functional components of ribosome

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18
Q

tRNA function

A

transfers amino acid for protein synthesis

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19
Q

Common structure of tRNA

A

cloverleaf

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20
Q

mRNA function

A

template for protein synthesis, carries genetic information from DNA to ribosome

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21
Q

What do eukaryotes have in their mRNA that differs from prokaryotes?

A

Poly- A tai and Cap

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22
Q

Enhancer vs silencer at promotor

A

Enhancer: bound by enhancer-binding transcription factor
Increase the rate of txn

Silencer: Decrease the rate of txn

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23
Q

3 steps of transcription in Eukaryotes

A

Initiation, Elongation, Termination

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24
Q

Transcription difference between bacteria and Eukaryotes:

A

SImilar
Steps: initiation, elongation and termination
Differences:
Euk have 3 different polymerase and bacteria have one
Euk DNA is complexed with proteins

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25
Q

Where does splicing occur

A

in the nucleus ( Introns taken out, exons left in and EXPRESS)

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26
Q

Beta Thalassemia is a condition where there is an error in which protein?

A

Splisosome, there is inproper splicing of the genes.

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27
Q

4 steps of protein synthesis

A

tRNA charging
Initiation
Elongation
Termination

28
Q

Difference between Silent, missense, and nonsense mutations

A

Silent
Changed base results in the same amino acid

Missense
Changed base codes for a different amino acid

Nonsense
Changed base becomes a stop codon

29
Q

Describe tRNA charging

A

Amino acid is transfered to RNA

30
Q

Where does mRNA bind during initiation in prokaryotes?

A

mRNA binds to small subunit at Shine Dalgarno sequence

31
Q

3 ribosome sites in elongation

A

A - aminoacyl
P- peptidyl
E - exit

32
Q

Negative control vs positive control in operons

A

Negative control:
Regulatory protein is a repressor

Positive control
Regulatory protein is an activator

33
Q

Inducible vs repressible control of an operon

A

Inducible
Transcriptional is usually off
Repressible
Transcription is usually on

34
Q

What is a negative inducible

A

Negative control
Regulator protein is a repressor
Inducible
Txn is normally off
Something must happen to turn it in

35
Q

What type of control is the LAC operon

A

Negative control- regulator protein is a repressor (Transcription is normally off, but if glucose is absent AND lactose is present, it is on)

36
Q

Which 3 proteins does the Lac operon induce transcription of when it is on

A

A, Y, Z

37
Q

Do eukaryotes have operons?

A

no, not usually. Mostly bacteria.

38
Q

What are heavily methylated regions associated with

A

repression of transcription

39
Q

Describe restriction endonuclease and its pattern

A

often in a palindrome, binds and cleaves DNA at restriction sites

40
Q

What do you find with FISH staining

A

See parts of chromosomes to find abnormalities, use flourescent staining

41
Q

PCR steps

A

Denaturing
Heat up DNA to 95 degrees Celsius
Separate dsDNA into single strands

Annealing
Cool the solution to 50 degrees Celsius
Primers anneal to complementary sequences of ssDNA

Extension
Warmed to 72 degrees Celsius
DNA polymerase is active and synthesis strands on 3’OH primer

42
Q

What does Northern Blot examine

A

mRNA (measures expression)

43
Q

What does ELISA examine

A

antibodies in the blood

44
Q

Which pattern of inheritance only appears in males

A

Y-linked

45
Q

Which pattern of inheritance has emales passing onto their offspring, but not males?

A

Mitochondirial

46
Q

Describe the significance of the P53 gene

A

Tumor suppressor gene, triggers cell-cycle arrest. Most common genetic change in cancer

47
Q

What is the proto-oncogene and what is the common mutation for cancer?

A

This gene is responsible for making the cell divide.

If defective, the cell will divide continuously, causing cancer.

48
Q

What are oncogenes

A

mutated version of proto-oncogene, causes cells to grow out of control. Gain of function mutation.
RET/MET are examples.

49
Q

Describe the 4 types of aneuploidy

A

Nullisomy
Loss of both membranes of chromosome pair
2n-2

Monosomy
Loss of a single chromosome
2n-1

Trisomy
Gains of a single chromosome
2n+1

Tetrasomy
Gains of two homologous chromosomes
2n+2

50
Q

What chromosome is linked to Down Syndrome

A

Trisomy on chromosome 21

51
Q

Which disorder commonly accompanies a robertsonian translocation

A

Down’s syndrome- extra part of chromosome 21 is attached to another chromosome

52
Q

Describe Edward’s Syndrome dysfunction

A

Extra chromosome 18 ( not viable pregnancy, die soon after birth. Often born with intestines external to body).

53
Q

Describe Patau syndrome

A

Extra chromosome 13, average survival of 10 days (not viable).

54
Q

What is the chromosomal abnormality in Klienfelter syndrome

A

Male with an extra X chromosome (usually sterile, hypogonadism, tall)

55
Q

What is the chromosomal abnormality in Poly X syndrome

A

3 or more X chromosomes in women
Usually benign condition, increases in severity (decreased intelligance with more X’s).
Increased risk of spontaneous abortions

56
Q

What is the chromosomal abnormality in XYY males

A

Extra Y chromosome, possible learning disabilities.

57
Q

What is the chromosomal abnormality in Turner’s syndrome

A

XO chromosomes (webbed neck common, broad chest, short stature, hypogondaism).

58
Q

How many Barr bodies in XXYY

A

1

59
Q

How many Barr bodies in XXXXX

A

4

60
Q

Angelman vs Prader-Willi syndrome

A

Angelman: Maternal inheritance is lost on ch 15, inappropriate laughter, developmental delay, neurological symptoms.

Prader-Willi: Paternal Inhritance is lost on ch 15, mental handicap, anorexia early in life, obesity later in life.

61
Q

Diseases with genetic anticipation

A

Huntington’s disease, Fragile X syndrome, Friedrich ataxia

62
Q

What is the inheritance pattern of cystic fibrosis

A

Autosomal recessive

63
Q

What is the pathology in Sickle Cell disease

A

Point mutation, leads to sickled RBC shape, hypoxia.

64
Q

What is the pathology in Tay-Sach’s disease

A

Mutation on HEXA gene on Chromosome 15

Premature neuron death, progressive degeneration of neurons.

Death between 3-4 years in infantile onset, death between 5-15 in juvanile onset.

65
Q

What type of mutation is found in the BRCA 1 gene

A

DNA damage repair gene (Double strand breaks) not functioning.
Activation of P53.

66
Q
A