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Bio 97 > Midterm 2 > Flashcards

Midterm 2 Flashcards

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1
Q

human somatic cells are

A

DIPLOID

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2
Q

how many chromosomes do human somatic cells have

A

46 chromosomes

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3
Q

describe further the 46 chrosomes

A

22 pairs of autosomes and 1 pair of sex cells

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4
Q

how many chromosomes do human gamets have

A

23 chromosmes each

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5
Q

what is the same as haploid set

A

monoploid set

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6
Q

homologous chromosomes have the same ___ But different _____ of those ___

A

homologous chromosomes have same genes but may have different alleles of those genes

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7
Q

on average how much do homologous chromoses differ

A

they differ from each other about 1 per 1000 bps, just as any two people

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8
Q

sister chromatids are the

A

two double strands that result from one round of semi-conservative DNA replication

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9
Q

sister chromatids are highly likely to be

A

100% identical to each other

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10
Q

what is a chromosome

A

is a DNA containing structure containing a centromere

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11
Q

what is a chromtid

A

a double stranded DNA molecule (plus protein )

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12
Q

what are sister chromatids

A

two copies of the same double stranded DNA molecule joined by a centromere

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13
Q

where are homologous chromosomes found

A

in diploid cells

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14
Q

what is mitosis

A

a diploid somatic cell replicates its DNA once and divided once to form 2 diploid genetically identical daughter cells

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15
Q

G1 phase of Mitosis

A

the cell contains two pairs of homologous chromosomes

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16
Q

S phase mitosis

A

DNA replication creates identical sister chromatids for each chromosome

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17
Q

metaphase fo mitosis

A

chromosomes align randomly along the metaphase plate with the aid of mitotic spindle

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18
Q

telophase in mitosis

A

two daughter cells are produces by mitosis –> sister chromatid seperation to form daughter chromosmes

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19
Q

mitotic cell cycle phases

A

G1, G0, S, G2, M phase

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20
Q

what is the G1 phase

A

active gene expression and cell activity, preparation for DNA synthesis

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21
Q

what is the S phase

A

DNA replication and chromosome duplication

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22
Q

G2 phase

A

preparation for cell division

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23
Q

M phase

A

cell division Mitosis and meiosis

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24
Q

G0 phase

A

terminal differential and arrest of cell division

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25
Q

G0 phase can lead to

A

cell remaining specialized but not dividing, eventual cell death (apoptosis)

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26
Q

mitosis creates

A

geneticaly identical daughter cells (although one of them might have a new muation

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27
Q

Mitosis definition

A

a diploid somatic cell replicates its DNA once and divides once to form 2 diploid genetically identical daughter cells

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28
Q

Meiosis definition

A

a diploid germline stem cell replicates its DNA one and divided twice to form 4 haploid cellls that are not genetically identical

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29
Q

what is in the cell at the beginning of meiosis

A

homologous pair: two copies of chromosome 1, one from mom and one from pap

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30
Q

human females arrest where in meiosis untill menstration

A

after crossing over but before disjunction

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31
Q

where does crossing over occur in Meiosis

A

prophase of meiosis 1

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32
Q

What are fine-scale mutations? Provide some examples

A

involve less than 1000 BPs; single base pair is changed

ex: substitutions, deletions, insertions, duplications

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33
Q

substitution mutations

A

replace/substitute a base pair

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34
Q

Single base-pair substituations are often called ______ _________

A

point mutations

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35
Q

insertions

A

add BP

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36
Q

deletion

A

delete BP

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37
Q

duplication

A

add BP (repeated)

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38
Q

What is a silent mutation? What are they also called?

A

changes a codon, but not the encoded amino acid

also called synonymous mutation

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39
Q

What is a missense mutation?

A

changes the encoded amino acidW

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40
Q

What is a nonsense mutation?

A

an amino-encoding codon becomes a stop codon

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41
Q

What is a frameshift mutation?

A

insertion or deletion of a base(s) changes the reading frame

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42
Q

What are examples of spontaneous mutations?

A

mistakes (e.g. replication errors, recombination errors) and endogenous DNA damage

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43
Q

What are REPLICATION errors?

A

polymerase misincorporation, strand slippage in repeated regions

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44
Q

What are recombination errors?

A

unequal crossing over, etc.

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45
Q

What are two examples of endogenous DNA damage?

A

spontaneous base damage, byproducts of metabolism

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46
Q

What are examples of spontaneous base damage?

A

deaminations, depurinations

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47
Q

What byproducts of metabolism damages DNA?

A

oxygen radicals

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48
Q

A good polymerase domain has a misincorporation rate of __________.

A

1/100,000

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49
Q

Any misincorporations are clipped off with _____% efficiency by the proofreading activity of the ___________.

A

99%, polymerase

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50
Q

What is DNA mismatch repair?

A

removes mismatches bases in DNA with 99.9% accuracy

chooses to repair the newly replicated strand; carried out by multi-protein complex

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51
Q

About ___ mismatch error per ______ ______ _______ is not detected.

A

1 per human cell division

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52
Q

deamination of cytosine

A

water attacks cytosine (removes C’s amine group) and replaces it with a double-bonded O (carbonyl group)

–> creates URACIL

NOTE: there is no CH3 at the 5 position on either C or U (therefore turns deamination coverts to U)

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53
Q

deamination of 5-Me-Cytosine

A

water attacks cytosine (removes C’s amine group) and replaces it with a double-bonded O (carbonyl group)

–> creates THYMINE

NOTE: 5-Me-Cytosine has a methyl at 5 position, T also has CH3 at 5 position (that’s the reason why the deamination turns into T rather than U)

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54
Q

What’s the difference between cytosine and 5-Me-Cytosine?

A

there’s a CH3 (methyl) at the 5th position on the carbon ring!!!

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55
Q

___________ _____________ are caused by exogenous (_________) sources of DNA damage.

A

induced mutations, outside

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56
Q

What are sources of exogenous DNA damange?

A
  1. CHEMICALS
    natural: in foods
    man-made/man-increased: nitrogen mustard, benzopyrene
  2. UV RADIATION
  3. IONIZING RADIATION
    natural: radon gas, cosmic rays
    man-made: x-rays, nuclear tests
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57
Q

(DNA Damage) UV radiation creates…? How?

A

pyrimidine dimers

by photon hitting bases

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58
Q

What is a pyrimidine dimer?

A

cross-links adjacent bases on SAME strand

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59
Q

What is the fate of DNA damage? (HINT: 3)

A
  1. may be repaired
  2. may kill the cell or cause the cell to kill itself
  3. may become “FIXED” (becomes a permanent mutation)
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60
Q

How do DNA strand cross-links (ON THE SAME STRAND) kill cells?

A

block replication and replication and transcription

pyrimidine dimer is unrecognizable to polymerase (DNA and RNA) so polymerase stalls or falls off

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61
Q

What does it mean for DNA damaged to be “fixed”?

A

DNA damage becomes a permanent mutation

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62
Q

How do DNA strand cross-links (BETWEEN STRANDS) kill cells?

A

block replication and replication and transcription

inter-strand crosslink physically blocks polymerase from unwinding DNA

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63
Q

What are the two EXAMPLE damaged base mispairs?

A

O6-ethyl-guanine pairs with thymine

deaminated cytosine pairs with adenine

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64
Q

What are examples of mutation fixation?

A
  1. replication of unrepaired misincorporation
  2. replication of an unrepaired cytosine deamination
    –> deminated cytosine = U
    –> deaminated 5-Me-cytosine = T
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65
Q

If the cell containing damanged bases (e.g. deaminated cytosine or 5-Me-cysotine) then replicates its DNA before the deamination is repaired, then the mutation becomes ______. This results in…?

A

FIXED

one daughter cell with the fixed mutation and the other daughter cell with no mutation

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66
Q

What are examples of repair mechanisms?

A
  1. polymerase proofreading
  2. DNA mismatch repair
  3. Uracil DNA glycosylase
  4. Thymine DNA glycosylase
  5. nucleotide excision repair
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67
Q

What is uracil DNA glycosylase?

A

enzyme that removes U from DNA

*resulting abasic site is filled in by polymerase

IF U IS NOT REMOVED, it will pair with A
**causing C/G –> T/A transition

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68
Q

What is thymine-DNA glycosylase?

A

enzyme that removes thymine from T/G mismatches

*resulting abasic site is filled in by polymerase

IF T IS NOT REMOVED, it will pari with A
**causing C/G –> T/A transition

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69
Q

What is nucleotide excision repair?

A

carried out by mutl-protein complex

removes bulky adducts from DNA (e.g. pyrimidine dimers caused by UV, benzopyrene-DNA adducts) ; also excised nearby nucleotides

**resulting single-strand gap is filled in by polymerase

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70
Q

What are the steps to nucleotide excision repair?

A
  1. damage recognition
  2. dual incisions
  3. excision
  4. gap-filling (by polymerase)
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71
Q

Xeroderma Pigmentosum

A

autosomal recessive, very rare

DEFECT OF NUCLEOTIDE EXCISION REPAIR

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72
Q

Lynch Syndrome

A

autosomal dominant, multigenic

DEFECT IN MISMATCH PAIR

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73
Q

About ____ new mutation becomes _____ every time a human cell divides

A

1, fixed

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74
Q

~___ mutation per genome per human cell division

A

1

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75
Q

Although the mutation rate per cell division is low, these mutation will ________ over the course of many _____ _________.

A

accumulate, cell divisions

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76
Q

What is the mutation rate per human generation?

A

~70 new mutations in each kid:
–> 60 point mutations
–> 10 other types of mutation (e.g. insertions, deletions, transposable element insertions)

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77
Q

Most mutations don’t have the potential to effect _______. Why?

A

phenotype

coding sequences, promoter sequences, etc. are MUCH less abundant than introns, spacers, heterochromatin, etc.

**most random mutations will probably be in the unexpressed regions

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78
Q

What mutations DO have the potential to affect phenotype?

A
  1. missense/nonsense mutations in protein-coding sequences
  2. mutations that alter splice sites
  3. mutations that alter binding sites for transcription factors in the promoter
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79
Q

Roughly __ _____ _____ mutation in each new kid. This new allele is probably _______.

A

1 new gene (not present in either parent)
**gene mutation: meaning changing gene function and phenotype

recessive

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80
Q

autosomal traits are caused by genes on

A

autosomes (chromosomes 1-22)

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81
Q

sex linked traiats are caused by genes on the

A

sex chromosomes (X orY)

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82
Q

Females have what two sex chromosomes

A

XX

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83
Q

Males have what sex chromosomes

A

XY chromosomes

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84
Q

what is special about the Y Chromosome

A

key genes that initiate the male developmental program

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85
Q

if someone doesnt have an Y chromosome they are

A

a female

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86
Q

Are the X and Y chromosome similar?

A

non-identical but share a small number of genes

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87
Q

when do the X and Y chromosomes pair and segregate (sperm)

A

meiosis 1

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88
Q

how many base pairs are on the X chromosome

A

there are 160 million base bairs

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89
Q

how many base pairs are on the Y chromosome

A

70 million bairs pairs

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90
Q

Y specific genes are involved in

A

male sexual differentiation

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91
Q

Most x sepecific genes encode

A

functions essential to both males and females

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92
Q

what is the male to female ration

A

1:1

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93
Q

where does a male get his X chromosome from and who do they transmit it too

A

A male gets his X chromosomes from his mother and transmits it only to one of his daughters

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94
Q

men are more frequantly affected by diseases caused…

A

by recessive alleles of X linked genes

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95
Q

Normal X chromosome contains

A

wild type allele of the X linked gene of interesta

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96
Q

affected X chromosome

A

contains recessive allele of the X linked gene of interest

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97
Q

X linked gene =

A

a genes that is on the X chromosome

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98
Q

X linked disease =

A

a genetic disease that results from inheriting disease-causing alleles of an X-linked gene

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99
Q

female carrier mates with normal male

A

*half her daughters will be carriers
*half her sons will be affected

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100
Q

affected male mated with normal female

A
  • all his daughter will be carries
  • none of his sons will be affected
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101
Q

Hemophilia A symptoms

A

excessive bleeding (including internally) and easy bruising

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102
Q

Hemophilia A is what type of disease

A

X-linked recessive pattern of inheritance

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103
Q

Hemophilia A is caused by what mutation

A

cause by mutation in the gene encoding Factor V111 which is required for blood clotting

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104
Q

treatment history of Hemophilia A (idk if we need to know this )

A

Up until mid 1960’s: No treatment (often
fatal by age 20)
* Mid 60’s: Factor VIII purified from donor
plasma (and injected into hemophiliacs)
* 1978-1985: Half of hemophiliacs treated
with donor plasma get HIV
* 1984: Factor VIII gene cloned by
Genentech
* 1994: Recombinant factor VIII available

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105
Q

what are some examples of Some X-linked recessive human diseases/traits

A
  • hemophilia A
  • hemophilia B
  • Duchenne musculat dystrophy
    -Retinitis pigmentosum
  • Lesch Nyhan Syndrome
  • Red-green color blindness
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106
Q

4 important featured of X-linked recessive Inheritance

A

1) typically many more males than females have the trait due to hemizygosity

2) a recessive male mated to a homozygous dominant female produces all offspring with the dominant phenotype and all female offspring are carriers

3) Mating of recessive males with carrier females give half dominant and half recessive offspring of both sexes

4) mating of homosygous recessive females with dominant males oriduce all dominant (carrier) female offspring and all recessive male offspring

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107
Q

4 Features of X-linked Dominant Inheritance

A

1) the dominant phenotype is equally frequent in males and females. That is about equal numbers of males and females show the trait

2) Homozygous and heterozygous females are affected, as well as hemizygous males

3) Heterozygous females mated to wild type males transmit the dominant allele to hald their progeny of each sex

4) Dominant hemizygous males mated to homozygous recessive females transmit the dominant trait to all their daughters, but none of their sons

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108
Q

In Dominant inheritance the dominant trait is typically found in

A

every generation

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109
Q

In dominant inheritance the affected kid is never born to

A

unaffected parents

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110
Q

In DOminant inheritance two affected parents can have a

A

unaffected kid

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111
Q

In X-linked dominant inheritance the gene in question is found where

A

on the X-chromosome

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112
Q

in an X-linked dominant inheritance what genotype do affected males and females have

A

affected males: XDY
affected females: XD XD or XD Xd

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113
Q

affected males in X- linked dominant inheritance will pass on the disease to

A

all of their daughters and none of their sons

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114
Q

Recessive INheritance is typically not see in

A

every generation

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115
Q

In recesisve inheritance affected kids can be born to

A

unaffected parents

116
Q

X-linked recessive inheritance affected males and females have what genotype

A

affected males are Xd Y
affected females: Xd Xd

117
Q

who is most affected in X-linked recessive linkage

A

males are affected much more often than females

118
Q

what is penetrance

A

the probability that a genotype will manifest as a phenotype

119
Q

100% penetrance means

A

that is you have the genotype you will show the phenotype

120
Q

Less than 100% penetrance =

A

if you have the genotype you might not show the phenotype

121
Q

Polydactyly is an example of

A

a dominant traits that has partially penetrant pedigree

122
Q

what can make it hard or even impossible to distinguish a dominant inheritance from recessive inheritance

A

when there is partial penetrance

123
Q

what is a new mutation

A

a genetic alteration that is present for the first time in a new child

124
Q

what is are synonyms of new mutations

A

novo mutation or germline mutation

125
Q

what can be ruled out if unaffected parents have an affected kid

A

dominance both autosomal and x-linked

126
Q

what can be ruled out if two affected parents have an unaffected kid

A

recessivness both autosomal and x-linked

127
Q

If an unaffected woman has an affected son or an affected man has an unaffected daughter what can be rulled out

A

X-linked dominance

128
Q

if an affected women has unaffected son or unaffected man has affecteed daughter what can be ruled out

A

x-linked recessive can be ruled out

129
Q

if unaffected parents have an affected daughter
it must be

A

autosomal recessive inheritance

130
Q

if affected parents have unaffected daughter

A

it must be autosomal dominant

131
Q

if the problem tells you the disease is rare then

A

you can assume that multiple carriers do not marry into the family, you can assume that the founder is a heterozygote

132
Q

mitochondria have their own…

A

DNA genome which contains 37 genes

133
Q

a zygotes mitochondria comes from the

A

mom’s egg, not from the dad’s sperm

134
Q

Mitochondrial Inheritance is usually…

A

partially penetrant

135
Q

Huntington’s disease symptoms

A
  • slowly progressive brain disease that causes changes in movement, thinking, and behavior
  • neuronal degeneration
    -dealth
136
Q

Huntington’s disease is which type of inheritance and penetrance

A

Rare autosomal dominante- complete penetrance

137
Q

Huntington;s disease has what type of onset

A

Late onset -> 35-50 years of age

138
Q

Huntington;s disease is an example of what type of mutation

A

gain of function mutation

139
Q

wild-type protein function is

A

normal

140
Q

null or amorphic protein function

A

dead–> zero

141
Q

hypomorphic protein function

A

weak, less, leaky diminished, reduced but not zero

142
Q

what are the loss of function types of mutations

A

null or amorphic, and hypomorphic

143
Q

what is hypermorphic mutation protein function

A

increased, more than there should be

144
Q

neomorphic mutation protein function

A

New, novel, something completely different from what the wild type protein does

145
Q

what are the gain of function mutations types

A

hypermorphic and neomorphic

146
Q

loss of function alleles are usually …

A

recessive but not always

147
Q

when the genotype –> normal pheontype of a LOF, we say that the locus id

A

haplo-sufficient (half is enough)

148
Q

when the genotype of LOF has disease phenotype we say that the locus is

A

haplo- insufficient (half if not enough)

149
Q

what type of allele is haplo-insufficeient

A

when a LOF allele is dominant

150
Q

Gain of function alleles are usually

A

dominant

151
Q

huntingtons disease is what type of protein mutation type

A

Gain of function –> neomorphic

152
Q

incomplete dominance

A

heterozygotes have a phenotype intermediate to the two alleles

153
Q

co-dominance:

A

the phenotype of both alleles is fully expresses in heterozygotes

154
Q

multiple alleles

A

more than two alleles affect a phenotype

155
Q

penetrance and expressivity

A

a mutation does not affect every individual or may cause phenotypes that differ in severity

156
Q

pleiotropy:

A

one gene affects greater than one phenotypic character

157
Q

environmental impacts:

A

genetically identical individuals show differnet phenotypes as a result of environmental factors

158
Q

epistasis

A

a gene at one locus alters the phenotypic expression of a gene at a second locus

159
Q

example of incomplete dominance in humans

A

hypercholesterolemia–> where HH has the best ability to make LDL recptors, Hh has mild ability to make LDL recpetors and hh has inability to make LDL receptors

160
Q

allelic series

A

there is an order of dominance when multiple alleles are present

161
Q

lethal alleles

A

sometimes the homozygous recessive genotype is embronic lethal

162
Q

expressivity

A

the same mutant allele produces different phenotypes in different individuals

163
Q

____ of all cancers are diagnosed at age 55 and older.

A

3/4

164
Q

If you get cancer, a 5-year survival rate is ___%.

A

66%

165
Q

Cancer is a ______ of ________ __________.

A

loss of growth regulation

166
Q

Cells grow WHEN they shouldn’t, forming a _______.

A

tumor

167
Q

Cells grow WHERE they shouldn’t –> _________, _________

A

invasion, metastasis

168
Q

Cancer is a _________ __________ of __________ cells.

A

genetic disease of somatic cells

169
Q

Mutations in specific genes can cause a normal cell to become _________.

A

cancerous

170
Q

Somatic mutations occur _________ and are normally _________.

A

frequently, inconsequential

171
Q

What are some of the genes that lead to cancer when mutated?

A

oncogenes and tumor suppressor genes

172
Q

What is the comparison for oncogenes? What is the comparison when there is a mutation in this gene?

A

gas pedal for cell proliferation

mutation –> gas pedal stuck down

173
Q

What is the comparison for tumor suppressor genes? What is the comparison when there is a mutation in this gene?

A

brakes for cell division

mutation –> brakes don’t work

174
Q

Mutations in ________ _________ _______ are required for a normal cell to become cancerous.

A

several distinct genes

175
Q

The progressive _________ of ___________ explains why cancer occurs mainly in older adults.

A

accumulation, mutations

176
Q

What types of mutations cause cancer?

A

spontaneous and induced mutations

177
Q

Cancer is often the result of ___________ _____________.

A

spontaneous mutations

178
Q

What are two INDUCED mutations that can lead to cancer?

A

UV radiation: caused from excessive sunbathing –> skin cancer (pyrimidine dimers)

benzopyrene: caused from cig smoking –> lung cancer (benzopyrene covalently bonds to G)

179
Q

Cancer cells are typically ________ with many chromosome abberations.

A

ANEUPLOID

180
Q

Many cancers are genetically ________, particularly at the __________ ______.

A

unstable

chromosomal level

181
Q

Some chromosome rearrangements are ________ ________ to occur in specific types of cancer. Provide an example.

A

repeatedly found

ex: Philadelphia chromosome
–> translocation occurs in chronic myelogenous leukemia; causes over-expression of the ABL gene

182
Q

What is carcinogenesis/tumorigenesis?

A

creation of cell capable of forming a tumor from a normal cell

183
Q

What is tumor progression?

A

the progressive “evolution” of a tumor from a more benign to a more malignant state

184
Q

What are the stages of tumor progression?

A

Stage 1: BENIGN (NOT CANCER)
–> 1 gene mutated
–> tumor cells grow only locally and cannot spread by invasion or metastasis

Stage 2, 3, 4: MALIGNANT (CANCER)
2: 2 genes mutated
3: 3 genes mutated
4: 4 genes mutated
–> invades neighboring tissues, enter blood vessels, and metastasize to different sites

185
Q

benign tumor cells

A

NOT CANCER

grows only locally and cannot spread by invasion or metastasis

186
Q

malignant tumor cells

A

CANCER

invades neighboring tissues, enter blood vessels, and metastasize to different sites

187
Q

We are all ______ _________. Why?

A

genetically defective

*70 new mutations per child
*1 new gene mutation per child
*PLUS mutations that were inherited from parents

188
Q

Who coined the term eugenics?

A

Francis Galton

189
Q

What is eugneics?

A

idea that society should promote the marriage of the “fittest” people by providing $ incentives

190
Q

What did the US eugenics movement focus on?

A

preventing “unfit” people from having children by forced sterilization

191
Q

Buck v Bell

A

allowed forced sterilizations to continue

192
Q

Over 60,000 _________ ___________ were performed on mostly _______ (and often _________-__________) people confined to _________ ___________.

A

forced sterilizations
African-American
mental hospitals

193
Q

Despite being discredited after WWII, _________ __________ of marginalized groups continued to persist up until the _______’s in the US.

A

forced sterilizations
1970s

194
Q

Define euploid.

A

cell that contains a WHOLE NUMBER multiple of the haploid set of chromosomes

195
Q

Genes alone are not responsible for all ___-

A

variation seen between organisms

196
Q

Human somatic calls (2n) and human gametes (1n) are both ______.

A

euploid

197
Q

PKU (phenylketonuria)

A

autosomal recessive –> very rare caused by the absence of an enzyme involved in phenylaline breakdown

198
Q

Aneuploid calls contain _______ or ___________ ______________.

A

missing or additional chromosomes

199
Q

What are common types of aneuploidy?

A

monosomy: only 1 copy of a given chromosome in an otherwise diploid cll

trisomy: 3 copies

200
Q

The most frequent cause of aneuploidy is __________ ____________.

A

chromosomal nondisjuction

201
Q

What is polyploidy?

A

euploid but > 2n

202
Q

Triploid plants are often ______.

A

infertile

203
Q

epistasis requires

A

two or more different gene loci that control the same trait

204
Q

when does epistasis occur

A

when there is phenotypic interaction between these two different genes

205
Q

for epistatic genes, a dihybrid cross produces a

A

modified 9:3:3:1 ration of phenotypes

206
Q

complementation analysis

A

a screen to find many mutants with phenotypes related to that process

207
Q

what questions can be answered by complementation testing

A

do these organisms have mutations in the same or in different genes?
How many genes are responsible for the phenotypes observed?

208
Q

two pure breeding strains with similar mutant phenotypes are mated –> if complementation occurs then

A

wild type offspring are obtaines –> the mutations affect two different genes

209
Q

Two pure-breeding strains with similar mutant phenotypes are
mated if mutations fail to complement

A

the offspring have the
mutant phenotype à the mutations affect the same gene

210
Q

In humans, ______ is lethal before or shortly after birth.

A

polyploidy

211
Q

Each gamete contains how many total chromosomes?

A

23

212
Q

Describe the process of meiosis.

A
  1. meiosis I: starts with 2 sets of chromosomes (one from each parent)
  2. disjunction I: divides into 2 (each cell has 2 sets of chromosomes)
  3. meiosis II/disjunction II: both cells divide again (each cell has one set of chromosomes)
213
Q

What happens in a meiosis I non-disjunction? What are the gamete results?

A

set of chromosomes do not separate in meiosis I (e.g. X + Y do not separate)

RESULTS: (sex) XY, XY, 0, 0

214
Q

What happens in a meiosis II non-disjunction? What are the gamete results?

A

ONE set of chromosomes do not separate in meiosis II (e.g. set of X chromosomes don’t separate)

RESULTS: (sex) XX, 0, Y, Y

215
Q

If there was a non-disjunction in meiosis II with the Y set of chromosomes during sperm production and these perm fertilize a euploid egg, what would the resulting zygotes be?

A

X gametes: normal
–> euploid female (46, XX)

0: aneuploid female (45, X)

YY: aneuploid male (47, XYY)

216
Q

What is a nondisjunction?

A

chromosomes or chromatids that fail to “disjoin” during meiosis

217
Q

Nondisjunction in meiosis I produces gametes with a ______ of _________ _________.

A

pair of homologous chromosomes (e.g. XY)

218
Q

Nondisjunction in meiosis II produces gametes with a ______ of __________ _________.

A

pair of sister chromatids (e.g. XX or YY)

219
Q

Fertilization with a gamete that experienced a non-disjunction produces a zygote with a _________ or a __________.

A

monsomy or trisomy

220
Q

The risk of nondisjunction ________ dramatically with maternal age.

A

increases

221
Q

trisomy-X

A

47, XXX (female)
0.1% (1 per 1000 female births)

222
Q

double-Y

A

47, XYY (male)
0.1% (1 per 1000 male births)

223
Q

Klinefelter Syndrome

A

47, XXY (male, sterile)
1 per 1000 male births

224
Q

Turner Syndrome

A

45, X (female, sterile)
1 per 2000 female births

225
Q

An extra or missing X or Y chromosome as a relatively _____ effect in comparison to an extra or missing ______.

A

mild, autosome

226
Q

About _____ of human pregnancies are lost spontaneously after implantation. What’s the lead known cause of this?

A

1/3

chromosome abnormalities are the leading known cause

227
Q

A minimum of ____-____% of conceptions have a chromosomal abnormality.

About approximately what percent of these conceptions spontaneously abort because the fetus died?

A

10-15%

at least 95%

228
Q

Trisomy 21

A

most common autosomal aneuploidy

–> leads to down syndrome
–> approx. 75% of trisomy 21 conceptions are spontaneously aborted

229
Q

Trisomy 13

A

patau syndrome

230
Q

Trisomy 18

A

edward syndrome

231
Q

All other trisomies and monosomies are ___________ _______.

A

embryonic lethals

232
Q

What is translocation?

A

interchange of genetic info between non-homologous chromosomes

233
Q

Translocation is a result from a mistake by the ___________ __________.

A

recombination machinery

234
Q

What is inversion?

A

genetic rearrangement in which the order of genes is reversed in a chromosome segment

235
Q

Both translocation and inversion are __________ _________. They do not result in a _____ or ______ of much chromosomal material.

A

balanced rearrangements

loss or gain

236
Q

What are chromosome deletions?

A

missing chromosome segment

237
Q

Large deletions are often _______ (even in ______________).

A

LETHAL

even in heterozygotes

238
Q

What are gene duplications?

A

chromosomes segment present in MULTIPLE copies

239
Q

Gene duplications provides material for _______.

A

evolution

240
Q

Tandem duplications are…? They are often a result from?

A

ADJACENT repeated segments

unequal crossing-over

241
Q

Deletion and duplications are ____________ _________. They result in a ________ (__________) or __________ (___________) of a chunk of chromosome.

A

UNBALANCED rearrangements

loss (deletion) or gain (duplication)

242
Q

Deletions are often ______ _______ than duplications.

A

MORE SEVERE

243
Q

What is recombination?

A

the process responsible for crossing-over in meiosis

also used in some forms of DNA repair

244
Q

Recombination mistakes can lead to _________ ________.

A

chromosome rearragement

245
Q

When there is a recombination mistake between similar sequences on NON-HOMOLOGOUS chromosomes, it is?

A

translocation

246
Q

When there is a recombination mistake between similar sequences within a chromosome, it is?

A

inversion or deletion

247
Q

When there is a recombination mistake between tandemly repeated sequences on HOMOLOGOUS chromosomes, it is?

A

duplication or deletion

248
Q

What are the phenotypic effects of the multiple genetic steps required for a normal somatic cell to become a malignant tumor? (TLDR: HALLMARKS OF CANCER) (HINT: 11)

A
  1. self-sufficiency in growth signals
  2. insensitivity to anti-growth signals
  3. tissue invasion and metastasis
  4. limitless replicative potential
  5. sustained angiogenesis
  6. evading apoptosis
  7. avoiding immune destruction
  8. tumor-promoting inflammation
  9. genome instability + mutation
  10. deregulating cellular energetics
  11. tumor cells can evolve resistance to chemotherapy drugs

***each of these phenotypic steps requires at least ONE genetic “step”/mtuation

249
Q

Explain “self-sufficiency in growth signal.”

A

CANCER CELL GROWS OUT OF CONTROL IN AN UNREGULATED FASHION (doesn’t wait for permission signals from other cells)

***requirement to become successful cancer

250
Q

Cell division (growth) is normally a ________ ___________ _________.

A

highly regulated process

251
Q

Stem cells receive permission from other cells to divide. This permission comes in the form of _________ __________ released by _________ _________.

A

growth factors released by other cells

252
Q

Many components of growth control are ___________________.

A

proto-oncogenes

253
Q

Mutations can turn _______________ into _______________ (cancer-causing genes).

A

proto-oncogenes into oncogenes

254
Q

Describe the steps of the normal growth-control pathway.

A
  1. growth factor attaches to receptor on cell
  2. signaling enzymes dispatched to cell nucleus
  3. signal reaches nucleus, activates transcription factors
  4. activates cell proliferation
255
Q

Oncogenes activate ______ ________.

A

cell proliferation

256
Q

Mutated alleles (_________) tell the cells to grow and divide all the time, even when there’s ____ _______________ ____________.

A

oncogene

no permission signal

257
Q

When mutated, oncogenes contribute to _______. Their normal, wild-type function is? This wild-type allele is called?

A

cancer

normal, wild-type function is to regulate cell division

wild-type allele name: proto-oncogenes

258
Q

Cancer-causing mutations are (dominant/recessive).

A

DOMINANT

259
Q

What are FOUR possible oncogene-creating mutation?

A
  1. cell makes its own growth factor
  2. receptor “thinks” it’s bound to GF when it’s not
  3. signaling enzymes think they are receiving “go” signal from GF
  4. transcription factors are OVEREXPRESSED; turn on their target genes regardless of upstream regulation
260
Q

Explain “insensitivity to anti-growth signal.”

A

loss of both wild type alleles of one or more tumor suppressor genes

***requirement to become successful cancer

261
Q

Tumor suppressor genes are _____________ of ____________ _________.

A

guardian of genome integrity

262
Q

If there is a mutation in the tumor suppressor genes, what happens?

A

MUTATIONS/REARRANGEMENTS ACCUMULATE

263
Q

Cancer-causing mutations in tumor suppressor genes are typically (dominant/recessive).

A

RECESSIVE

264
Q

If there is a mutation in the tumor suppressor genes, what happens to the GENE PRODUCT aka protein?

A

gene product isn’t made or doesn’t function at all

–> loss-of-function/null alleles

265
Q

Cancers ___________ to new regions in the body.

A

metastasize

266
Q

What is metastasis?

A

process in which tumor spreads to a distant organ or tissue

267
Q

___% of cancer deaths are due to cancers spreading throughout the body.

A

> 90%

268
Q

Cancer is ____ _______ disease, but _____.

A

not one, many

269
Q

In different tissues, ___________ ________ must be mutated in order for a cell to become cancerous.

A

different genes

270
Q

What gene is mutated in approx. 50% of human tumors?

A

p53

271
Q
A
272
Q

What signaling pathway is mutated in many different types of tumors?

A

RAS/MAPK pathway

273
Q

True or False: A predisposition to some types of cancer can also be inherited.

A

TRUE

274
Q

About ___-___% of all cancers are attributable to the inheritance of an allele that resulted in greatly increased cancer risk.

A

5-10%

275
Q

Inherited cancer syndromes are typically _________ _________.

A

autosomal dominant

276
Q

For inherited cancer syndromes, each of an affected person’s cells now contains…?

A

one of the steps in a multistep cancer pathway

277
Q

For inherited cancer syndromes, the other mutations required for tumorigenesis and tumor progression still occur _______.

A

somatically

278
Q

In smokers who get lung cancer most of the mutations are ________, but _______________ mutations still play a role.

A

induced, spontaneous

279
Q

Cancer is a _________ disease of _________ cells.

A

genetic, somatic

280
Q

A key characteristic of cancer is the…?

A

loss of growth control

281
Q

(One/Multipple) mutation(s) is/are required for cancer to develop. Most of these mutations are __________/________?

A

MULTIPLE

spontaneous/random

282
Q

Oncogenes (mutated) are usually…

A

GAIN OF FUNCTION

283
Q

Mutated tumor suppressor genes are usually…

A

LOSS OF FUNCTION

284
Q

(T/F) Cancer is a single disease.

A

FALSE

285
Q

(T/F) Cancer is many different diseases.

A

TRUE

286
Q

(T/F) Genetics are involved for inherited cancer predisposition syndromes.

A

TRUE

Bio 97 (4 decks)

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