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MCAT Biology > Class 3 > Flashcards

Class 3 Flashcards

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1
Q

What is a nucleotide composed of?

A

Sugar (ribose or deoxyribose)
Base
Phosphate

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2
Q

What is the difference between ribose and deoxyribose?

A

Deoxyribose is missing 2OH

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3
Q

On a nucleotide where does the base attache?

A

At the 1 carbon

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4
Q

On a nucleotide where does the phosphate attach?

A

At OH group 5’ carbon

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5
Q

What is a nucleoside?

A

Sugar and base only, no phosphate

-can specify the number of phosphates (ATP,UDP)

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6
Q

What does the 3’OH attack of a nucleotide?

A 
#1 phosphate and leaving group is pyrophosphate
-forms phosphodiester bond between 2 nucleotides
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7
Q

What way does polymerization happen in a nucleotide?

A

5’ to 3’ synthesis and base sequence.

-the strands are anti parallel and complimentary and held together by H bonds

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8
Q

What is a pyrimidine?

A

CUT (cyclohexane)

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9
Q

What is a purine?

A

GA (cyclohexane with cyclopentane)

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10
Q

What is another word for separation?

A

Denaturing and melting

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11
Q

What is another word for complimentary binding?

A

Hybridization and annealing

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12
Q

What is a genome?

A

All DNA in an organism

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13
Q

What kind of DNA foes prokaryotes have?

A

Have circular DNA in cytosol

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14
Q

What can degrade prokaryote DNA?

A

Endonuclease

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15
Q

How can prokaryotic DNA avoid degradation?

A

Methylate the DNA so the endonuclease doesn’t fit

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16
Q

What does DNA gyrase?

A

Causes super coiling of DNA

-makes endonuclease not able to come in

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17
Q

What does eukaryote DNA look like?

A

Several linear chromosomes in a nucleus and wrap around histone proteins

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18
Q

How does DNA wrap around histone?

A

At pH7 the AAs that are basic will be + the phosphate on DNA is -

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19
Q

What is euchromatin?

A

DNA unwound, active to be transcribed (has more transcription)
-light staining

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20
Q

What is a heterochromatin?

A

Tightly wound, inactive and dark staining (has more histones)

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21
Q

What is a centromere?

A

Where 2 replicated stands of DNA (sisterchromatids) are held together
-also where mitotic spindle attaches (repeated sequence area)

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22
Q

What are telomeres?

A

Ends of linear chromosomes are short sequences repeats TTAGGG and stabilize the ends of the chromosomes

  • degraded over time
  • dont code for anything
  • can base pair with itself to avoid degradation
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23
Q

What is the central dogma?

A

DNA>RNA>Proteins

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24
Q

What are the exceptions to the central dogma?

A

Reverse transcriptase and non coding RNA where they r transcribes into proteins (RNA Final product)

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25
What is the starting codon?
AUG = methionine
26
What is the stop codon?
UAA UGA UAG -doesnt code for anything
27
How many chromosomes does the human genome have?
46 chromosomes
28
What are point mutations?
Single base pair change
29
What are the 3 point mutations?
Missense: codon for 1 AA because a new codon for AA Nonsense: codon for AA becomes a Stop codon Silent: Codon for AA becomes new codon for some AA
30
Which silent change is worse?
Change in 3rd position is normally silent 2nd Position change almost always a different AA
31
What is a frameshift mutation?
Insertion and deletion changes the reading frame | -dont get this when they occur in multiples of 3
32
What are sources of mutations?
``` Polymerase errors Endogenous Damage RGS Physical Damage Exogenous Damage Radiation Chemicals Transposons ```
33
What do Polymerase errors cause?
Point mutation Small repeats Insertion and deletion
34
What do Endogenous Damage errors cause?
Oxidative DNA | Crosslinked basses
35
What do RGS/Physical Damage errors cause?
Double or single stranded breaks, lead to polymerase errors
36
What do Exogenous Damage errors cause?
UV- pyrimidine dimers (CUT) Chemicals can lead to physical damage Polymerase errors Xray- double stranded breaks
37
What do transposons (jumping genes) errors cause?
Insertion/deletion Inversions Duplications
38
What do transposons do?
Cut and paste enzyme and surrounded by inverted sequence repeat on each side
39
What are the 3 different kinds of transposons?
IS element Complete transposons with genes Composite transposons -if put in the middle of a coding region it can no longer be expressed
40
What are the 2 different kinds of chromosome rearrangements?
Same direction: Can base pair with themselves and delete a gene be degraded our reinsert somewhere else Opposite direction: can. base pair with themselves and leads to inversion of gene -can result in amplification and therefor get more protein
41
What are polymerase errors?
Repaired by mismatched repair path (after replication) | -take out incorrect base and replaces with correct one
42
How do polymerase know which strand to repair?
daughter strand its not methylated so that's how they know which copy is right
43
What is endogenous and exogenous damage repaired by?
Base excision repair and can happen anytime | -it identifies damaged base, takes tout and replaces it with same base just not damaged
44
What does homology dimated repair?
Repairss DS breaks and uses sister chromatid as template | -happens at the end of G2 or wherever you have sister chromatids
45
What is non homologous end joining ?
Np template just cleanse it up and sticks it back together (DS) -this is mutagenic
46
What is a translocation?
Due to faulty DNAP repair (nonhomologous end joining) or abnormal recombination
47
How do you fix pyrimidine dimers?
Directly reverse by exposing to white light
48
what can transposons be repaired by?
Nothing
49
What are characteristics of DNA Replication?
Semiconservative Replication Happens 5' to 3' OH Needs a primer made from RNA Requires a template DNA
50
What dopes helices do?
Separates the DNA strands
51
What does topoisomerase do?
Relaxes supercoiling on either end of the replication bubble
52
What does DNA polymerase do?
Replicate DNA and removes primers with DNA
53
What does ligase do?
Links Okazaki fragments
54
How many replications are in prokaryotes and eukaryotes?
Prokaryotes only have 1 replication Eukaryotes have more than one
55
What does DNA pol 3 do?
High processivity and fast 5' to 3' polymerase and 3' to 5' exonuclease Break phosphodiester bond at the end of DNA Has proofreading abilities Starts 400 base pairs down of ORI
56
What does DNA pol 1 do?
Low processivity and slow 5' to 3' and 3' to 5' to exonuclease 5' to 3' to removes the primer and adds nucleotides to primer DNA exception pair
57
What does DNA 2 do?
5' to 3' and 3' to 5' exonuclease Back up for DNA pol 3 Does DNA repair
58
What does DNA pol 4 and 5 do?
Error prone 5' to 3' | DNA repair but fast
59
How many origins and bubbles doo eukaryotes have?
Multiple origins and multiple bubbles
60
In eukaryotes how are primers added?
RNA primers added to the 3'end of parent strand | -lagging has SS DNA where it is degraded leading to smaller telomeres
61
What are telomerase?
Elongated telomeres on parent strand Carries own RNA template Has reverse transcriptase activity (RNA>DNA)
62
What are immortal cells?
Are resistant to decrease in telomeres and expresses telomerase always (sperm and cancer cells)
63
What are the characteristics of DNA?
``` DS Helix Thymine Deoxyribose One type ```
64
What are the characteristics of RNA?
``` SS 3D Shapes Uracil Ribose Multiple types ```
65
What is hnRNA?
Heterogenous nuclear RNA Initial unprocessed transcript will become mRNA -this is only in eukaryotes
66
what are miRNA and siRNA?
Complimentary to mRNA and bind mRNA ro make DS mRNA so it cant be translated and regulates translation
67
In transcription what kind of mRNA is being formed?
it is complimentary/antisense strand to template and identical lens strand to coding
68
What are the 2 kind of DNA binding proteins?
Repressor: bind DNA but make it harder for DNA polymerase to bind activators Activators: bind to enhancers and help recruit RNA polymerase and help increase transcription
69
What do prokaryotes have that eukaryotes do not?
operators
70
What is characteristic of prokaryote transcription/translation/replication?
Transcription and translation happen at the same time No mRNA processing, it can be immediately translated Polycistronic 1 RNA polymerase
71
What is characteristic of eukaryotes transcription/translation/replication?
Transcription and translation dont happen at the same time MRNA is processed from hnRNA>mRNA then 5' G cap to get out of nucleus, 3' poly a tail is stop sit, splicing introns and exons Monosistronic (1 gene 1 protein) Multiple RNA polymerases
72
How are AAs attached?
at the 3' end of tRNA
73
What is the anticodon complimentary too?
mRNA | -UAC on tRNA to AUG on mRNA
74
What can the 3rd codon normally be?
Wobbly, so its more likely to change | -happens when there is a GU or I at the end of the anticodon
75
What is and aminoacyl tRNA?
tRNA binds to it AA | -an=minoacyl synthase attache AA to tRNA, have 1 for every tRNA and this costs 2 ATP
76
What is thee difference between ribosomes in prokaryotes and eukaryotes?
Prok: 50S large SU, 30S small SU Eukaryote: 60S large SU, 40S small SU
77
what is the flow to make proteins?
A to P to E
78
What are the different sites in the ribosome?
A: new AA added P: Growing protein help E: Empty tRNA exit
79
Do tRNA's recognize stop codons?
NO tRNA recognizes stop codon and the release factor binds A site and breaks dont between final tRNA and final AA, releasing completed protein
80
What is the equation for determining how much ATP a protein needs to be formed?
#AA x 4= #ATP needed
81
What are chaperones?
Used by tertiary proteins to help[ them fold
82
What are coolant modifications of proteins?
Disulphide bridge Glycosylation Phosphrylated

MCAT Biology (9 decks)

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