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Test 2 Flashcards

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Biology 101 flashcards
1
Q

incomplete dominance

A

a blend of the two phenotypes

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2
Q

codominance

A

both phenotypes are expressed, no new phenotype

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3
Q

lethal alleles

A
  • don’t evolve, no phenotype
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4
Q

lethal recessive alleles

A

no phenotype for the recessive (3:0)

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5
Q

lethal dominant alleles

A

Rare, since it usually results in death before reproduction (0:1)

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6
Q

epistasis

A

when the expression of a gene is modified (masked, inhibited or suppressed) by the expression of one or more other genes.

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7
Q

multiple alleles

A
  • small differences in the DNA sequence of a gene which result in differences in the structure of the protein
  • when a single gene is made up of 2+ alleles
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8
Q

polygenetic inheritance

A
  • several genes contribute to the overall phenotype of the trait (quantitative traits ; height, eye color, etc)
  • many genes control a single trait
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9
Q

what are sex-linked genes?

A

genes on the sex chromosomes (X,Y)

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10
Q

what is the difference between the inheritance of a X-linked gene in a male and a female?

A

Females need to have the gene on both X chromosomes and males only need to have it on their only X

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11
Q

where are the sex genes?

A

autosomes

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12
Q

autosomal dominant

A

allele is dominant and carried on autosome

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13
Q

autosomal recessive

A

allele is recessive and carried on autosome

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14
Q

X-linked dominant

A

allele is dominant and carried on X chromosome

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15
Q

X-linked recessive

A

allele is recessive and carried on X chromosome

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16
Q

what does it mean if there is a skip in generation?

A

recessive

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17
Q

if recessive and more men than women

A

probably X-linked, if not, probably autosomal

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18
Q

what is the particularity in X-linked recessive?

A

affected mother always has affected sons

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19
Q

what is the particularity in X-linked dominant?

A

affected father always has affected daughters

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20
Q

what is the Mendelian pattern of blood type?

A

multiple alleles

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21
Q

rhesus blood type

A

Rh+ is completely dominant over Rh-

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22
Q

IM and IN blood type

A

codominance

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23
Q

what is a testcross?

A

crossing the phenotypically dominant with a recessive homozygote to determine the genotype of individual one.

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24
Q

what is the typical ratio for incomplete dominance in F2?

A

1:2:1 (2 of the new phenotype)

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25
Q

what is the typical f2 for codominance?

A

both phenotypes expressed, no new phenotype. Half will have both

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26
Q

what is the typical f2 ratio for lethal recessive allele?

A

3:0 (one is dead before showing phenotype)

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27
Q

what is the typical f2 ratio for lethal dominant allele?

A

0:1 (3 are dead)

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28
Q

what is the typical f2 ratio in epistasis?

A

9:3:4

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29
Q

what are the complementary base pairs in dna?

A

A-T, C-G

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30
Q

what are the complementary base pairs in rna?

A

A-U, C-G

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31
Q

how to perform transcription on an open reading frame?

A

transcription: from dna to rna with complementary base pairs (from start to stop)
translation: from rna to amino acids using table

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32
Q

missense mutations

A
  • do not change reading frame
  • alter the identity of one aa
  • one base pair is different from normal
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33
Q

consequences of missense mutations on mRNA and protein

A
  • an altered codon in the mRNA
  • moderate to deleterious effects on protein (cannot function properly, since an aa is wrong)
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34
Q

nonsense mutation

A
  • generates an early stop codon (premature termination)
  • mutated base pair creates a stop codon
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35
Q

consequences of nonsense mutations

A
  • stop codon created early in mRNA
  • protein is truncated, not done, = severe effects on protein
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36
Q

silent mutations

A
  • generate no change
  • mutated base pair creates a changed codon but codes for same amino acid
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37
Q

consequences of silent mutations

A
  • mRNA is different of one base pair
  • protein is unchanged
38
Q

frameshift mutation

A
  • insertion/deletion of a base pair (DNA) causes reading frame to be off by one on mRNA
  • aa altered due to frameshift
39
Q

consequences of frameshift mutation

A
  • reading frame off by one in mRNA
  • rest of protein after mutation is changed
40
Q

what are the SNPs?

A

missense, nonsense, silent, and framshift

41
Q

what are the LCRs?

A

deletion, duplication, translocation, inversion

42
Q

what is deletion? example

A
  • deletion of a segment of DNA
  • may cause severe problems if the missing segment contains genes that are essential for the normal development or cellular function
  • ex: one deletion from human chromosome 5 leads to severe cognitive impairment and a malformed larynx = cri du chat
43
Q

what is translocation? example

A
  • a segment of DNA breaks from one chromosome and attaches to another nonhomologous chromosome
  • Burkitt lymphoma (cancer) caused from translocation that moves a segment of chromosome 8 to chromosome 14
43
Q

what is duplication? example

A
  • a segment of DNA is duplicated
  • can be harmful or beneficial, depending on the genes and alleles contained in duplicated genes
  • ex: mammals have additional hemoglobin genes (beneficial) that come from duplication followed by mutation on duplicates
44
Q

what is inversion? example

A
  • a. chromosome segment breaks and reattaches to the same chromosome, but in reverse order
  • important in evolution of plants and animals
  • 5 of the chromosome pairs in humans show translocation and inversion not present in gorillas (helped us evolve more)
45
Q

what does snp mean and how can it affect an organism?

A
  • they affect only one gene
  • single nucleotide polymorphism (not always one nucleotide, but only one gene)
46
Q

what does lcr mean and how can it affect an organism?

A
  • large chromosomal rearrangements
  • affects many nucleotides
  • creates a very large change in organism
47
Q

what are the 3 steps of transcription?

A

initiation, elongation, termination

48
Q

what happens in initiation of transcription?

A

-transcription factors bind to promoter and recruit RNA polymerase
- transcription can begin

49
Q

what are transcription factors?

A

proteins that bind to DNA and regulate gene expression by promoting/supressing transcription

50
Q

what is a promoter?

A
  • TATA box
  • attaches with RNA polymerase
  • contains necessary proteins to initiate transcription
51
Q

what is elongation in transcription?

A
  • RNA polymerase 2 moves along DNA to unwind it and add new RNA nucleotides in 5’ to 3’
  • behind, DNA reforms double helix
  • hybrid DNA-RNA dimer exists briefly
52
Q

in which way does RNA polymerase read DNA?

A

5’ to 3’

53
Q

what is termination in transcription?

A
  • RNA polymerase is released
  • we now have a pre-mRNA that still needs to be processed (releasing introns)
54
Q

what is RNA polymerase 1?

A

transcribes DNA to rRNA (ribosomal)

55
Q

what is RNA polymerase 2?

A

transcribes protein coding genes (mRNA - messenger)

56
Q

what is RNA polymerase 3?

A

transcribes DNA to tRNA (transfer - bring aa to ribosomes)

57
Q

what is rRNA?

A
  • ribosomal RNA
  • in ribosomes and responsible for reading the order of aa and linking them together
  • protein synthesis
58
Q

what is mRNA?

A
  • messenger RNA
  • carry protein information out of nucleus to ribosomes
  • contains protein info
59
Q

what is tRNA

A
  • transfer RNA
  • bind to mRNA by complementary bp
  • at one end of tRNA: anticodon that pairs with codon (mRNA)
  • other end: binds to aa to bring it
60
Q

what is initiation in translation?

A
  • start codon indicates beginning (reading frame)
  • establish reading frame in mature mRNA (splicing done)
61
Q

what is splicing?

A
  • when pre-mRNA is processed
  • exons stay, introns are spliced (released)
62
Q

what is elongation in translation?

A
  • uses aa instead of nucleotides
  • A-site: tRNA with an attached aa bind to mRNA with anticodon/codon
  • P-site: peptidyl transferase enzyme forms bond between aa (from P and A site) - N bonds with C, aa cleaved from tRNA, where polypeptide is forming
  • E-site: empty tRNA exists
  • A-site now free to receive next tRNA
63
Q

which is the template strand?

A

3’ to 5’ (TAC)

64
Q

which is the coding strand?

A

5’ to 3’ (ATG)

65
Q

what is the start codon in coding strand?

A

ATG

65
Q

what is the start codon on the template strand?

A

TAC

66
Q

in which way is mRNA transcribed?

A

from 5’ to 3’

66
Q

in which way is translation written?

A

amino sequence in N to C direction

66
Q

what must be done with an intron in an open reading frame?

A

RNA processing: deleting whole intron

67
Q

what are polysomes and what do they do?

A
  • a cluster of ribosomes traveling along the same mRNA strand
  • simultaneous translation by multiple ribosomes increases the efficiency (more proteins produced in less time)
68
Q

what are chaperones?

A
  • proteins that assist/help the folding of large proteins
  • make sure proteins are properly folded how they should be
69
Q

what is the lac operon?

A
  • an example of prokaryotic regulation
  • inducible
70
Q

what is an operon?

A

sequence of genes + a promoter and an operator involved in the same metabolic pathway

71
Q

how does the repressor act when there is no lactose in the lac operon?

A
  • the repressor is active and bonded with the operator, which prevents transcription
  • no RNA polymerase can bind = no transcription
  • when there is no lactose, there is no need to activate the genes that metabolize it (3).
72
Q

how does the repressor act when there is lactose in the lac operon?

A
  • even when there is no lactose, there is a basal level of the 3 gene products in the cell - they convert lactose to allolactose when it becomes present (with help of beta galactosidase)
  • the allolactose binds to the repressor, which inactivates it, so it doesn’t bind to the operator.
  • transcription can occur
73
Q

is the lac operon anabolic or catabolic?

A

catabolic: it produces enzymes that degrade lactose (produces energy)

74
Q

is the trp operon anabolic or catabolic?

A

anabolic: it produces products used to manufacture tryptophan (consumes energy)

75
Q

what is the trp operon?

A
  • 5 trp genes necessary for tryptophan anabolism
  • repressible
76
Q

what happens when there is no tryptophan in the trp operon?

A
  • need to make it
  • trp repressor inactie = does not attach to operator = transcription occurs
  • RNA polymerase is not stopped
77
Q

what happens when there is tryptophan in the trp operon?

A
  • no need to make it
  • tryptophan binds to repressor, activating it, it binds to the operator and stops transcription
78
Q

why are the trp and the lac operons negative gene regulators?

A

they are regulated by a repressor that turns off a gene expression when it binds to DNA

79
Q

which lac operon gene codes for beta galactosidase and what is the function of beta galactosidase?

A

lac Z, it cleaves lactose

80
Q

which lac operon gene is needed to allow lactose to enter E coli?

A

lac Y, it makes the cell permeable to lactose

81
Q

what does lac I gene code for?

A

the repressor (protein)

82
Q

what is the job of the promoter?

A

to bind with the RNA polymerase

83
Q

what is the start codon in the coding strand?

A

ATG

84
Q

what is the start codon in the template strand?

A

TAC

85
Q

what are the stop codons in the coding strand?

A

TAA, TAG, TGA

86
Q

what are the stop codons in the template strand

A

ATT, ATC, ACT

87
Q

what are the stop codons in mRNA?

A

UAA, UAG, UGA

bio 1 (5 decks)

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