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CELS 191 > Molecular Biology > Flashcards

Molecular Biology Flashcards

1
Q

What is the central dogma of molecular biology (macromolecules involved and their function)

A

theory stating- genetic information flows only in one direction, DNA to RNA to protein
DNA- the information
RNA- the messenger
Protein- the worker

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2
Q

Initiation of transcription

A

Transcription factors bind to the TATA box of the promoter region
RNA pol II binds which forms transcriptional initiation complex with transcription factors
Two DNA strands seperate and the RNA Pol starts MRNA synthesis

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3
Q

what is being synthesises during transcription

A

DNA dependent RNA synthesis in the 5’-3’ direction

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4
Q

what happens during elongation of transcription

A

RNA Pol-II uses the template strand that runs in the 3’-5’ direction as a template and inserts the complementary RNA nucleotides in the 5’-3’ direction.

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5
Q

what part of a gene is transcribed from DNA to RNA

A

5UTR , coding sequence and the 3’ UTR

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6
Q

what part of a gene is translated from RNA into protein?

A

Only the coding sequence

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7
Q

Function of the promoter region

A

DNA segment recognised by the RNA polymerase to initiaite transcription, particularly important ijn the TATA region

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8
Q

How are mutations in the non coding regions harmful?

A

They disrupt the normal gene expression

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9
Q

Function of the 5’ G cap

A

prevent mRA degradation, promote intron excision and act as a binding site for small ribosomal subunits

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10
Q

Function of the 3’ poly-A tail

A

prevents mRNA degradation and helps the export of mRNA from the nucleus into the cytoplasm

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11
Q

where does transcription take place

A

in the nucleus

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12
Q

where does translation take place

A

in the cytoplasm

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13
Q

how many amino acids are there?

A

20

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14
Q

what codon specifies for start

A

AUG

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15
Q

what codons specifiy to stop?

A

UAA , UAG and UGA

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16
Q

what are the features that make tRNA an adaptor molecule?

A

It has a region that can bind an amino acid and a region that can interact with mRNA

17
Q

how does a tRNA become charged?

A

An enzyme recognises a specific amino acid and the correct tRNA for this amino acid and joins them together therefore charging the tRNA

18
Q

order of tunnels from left to right, and which does the exit tunnel extend from?

A

E, P, A. exit tunnel extends from the P tunnel

19
Q

describe initiation of translation

A

small ribsomal subunit binds to the mRNA through specific initiation tRNA, these identify the 5’ G cap and attach to the mRNA
the small ribosomal subunit/ initiator tRNA complex moves along the mRNA to find the AUG ( start codon)
the large ribosomal subunit attaches

20
Q

describe elongation of translation

A

charged tRNA with an anticodon complementary to the site A codon lands in A site.
2 things occur at the same time, the amino acid from the first enzyme is transferred to the second enzyme. The ribosome moves along the mRNA codon so the amino acids are going through the exit tunnel ( p site)
the last part of elongation is to get the enzyme out of the E site.
A new charged tRNA with an anticodon complemenatry to the next site A codon enters ribosome at the A site and repeats itself

21
Q

describe the termination process of translation

A

eventually the ribosome meets one of the stop codons (UGA, UAG, UAA).
siteA accepts a release factory enzyme and frees the polypeptide chain of amino acids
Ribosome units break off and dissociate and can be used again.

22
Q

what is mendels first law

A

law of segregation- genes segregate at meiosis so that each gamete contains only one of the two possed by the parent

23
Q

what is mendels second law

A

law of independent assortment, alleles of different genes assort independently during gamete formation

24
Q

when does segragation of chromosomes occur?

A

during anaphase I and anaphase II of meiosis

25
Q

what is incomplete dominance

A

when no allele is phenotypically dominant over another, results in a blended phenotype. heterozygous= blended phenotype

26
Q

what is codominance

A

both phenotypes exist side by side within an organsim eg blood type AB

27
Q

what are polygenetic traits and how are they represented in the population

A

phenotype controlled by many different genes that have an additive effect- eg height and weight.
example is skin colour that is coded by 3 genes where each has an allele for colour or no colour
polygenetic traits have a normal distributoon in a population

28
Q

how does the environment effect phenotype

A

effects phenotype, eg hydrangers pink in alkaline, blue in acidic soil
the environment smooths differences among phenotypes.
eg 50% effect wouldn’t know the genotype and a combination of phenotype and environment create a normal distribution.

29
Q

why would we want to estimate the genotype frequencies in a population?

A

to predict how many individuals will inherit a genetic disease
to estimate the proportion of individuals who are carrires of a genetic disease

30
Q

what are the 7 ways that allele frequency can change

A

bottleneck effect
founder effect
random genetic drift
natural selection
mutation
migration
non random mating (assortative mating and inbreeding)

31
Q

what is a cline with an example

A

gradual geographic change in genetic or phenotypic composition
eg the cyanide production in clover- increasing from warm to cooler temperatures

32
Q

what is stablising selection

A

when medium/ normal individuals are favoured
doesnt change the mean but it reduces variation

33
Q

what is directional selection

A

extreme individuals are favoured (eg large or small)
this causes the mean to shift to to one extreme

34
Q

what is disruptive selection

A

this is when both large and small individuals are favoured
favouring the two extremes means that two peaks form

35
Q

how does frequency dependent selection work

A

natural selection remains in equal proportion as there is a fluctuation in which species are favoured.
rare trait does better, more individuals copy that trait

CELS 191 (7 decks)

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