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Human Genomics & Genetics > GAG WK5 > Flashcards

GAG WK5 Flashcards

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Biology 101 flashcards
1
Q

What is aneuploidy

A

abnormal number of chromosomes

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2
Q

Why is proper chromosome segregation important

A

it can lead to aneuploidy and lead to developmental disorders

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3
Q

What is crossover recombination

A

forms physical links between homologous chromosomes

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4
Q

What is the purpose of crossover recombination

A

it helps chromosomes stay connected until they are pulled apart (ensures gamete receives 1 chromosome)

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5
Q

What is noncrossover recombination

A

the genetic exchange w/o forming physical links

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6
Q

What is the purpose of noncrossover recombination

A

it helps with chromosome alignment

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7
Q

What are the 4 types of recombination errors

A
  • meiosis I non-disjunction
  • meiosis II non-disjunction
  • reverse segregation
  • precocious sister chromatid separation
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8
Q

What happens in meiosis I non-disjunction

A

both homologous chromosomes go to the same pole (same cell) and fail to segregate

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9
Q

What is the result of meiosis I non-disjunction

A
  • creates 2 types of gametes
  • 2 gametes w/ an extra chromosome (disomic)
  • 2 gametes w/ no copies of those chromosomes (nullosomic)
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10
Q

What happens during meiosis II non-disjunction

A

both sister chromatids go to the same pole (same cell) instead of segregating

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11
Q

What is the result of meiosis II non-disjunction

A
  • creates 4 types of gametes
  • 2 normal gametes
  • 1 gamete w/ an extra chromosome
  • 1 gamete w/ no copies of that chromosome
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12
Q

What happens during precocious sister chromatid separation

A

sister chromatids separate prematurely during meiosis I instead of waiting until meiosis II

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13
Q

What is the result of precocious sister chromatid separation

A
  • one gamete lacks that chromosome entirely
  • one game has an extra chromosome
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14
Q

What is the cause of precocious sister chromatid separation

A
  • Errors in the cohesin proteins that hold sister chromatids together.
  • faulty separase enzyme
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15
Q

What happens during reverse segregation

A
  • sister chromatids are separated in meiosis I
  • homologous chromosomes are segregated in meiosis II
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16
Q

What is the result of reverse segregation

A
  • some gametes may have:
  • an extra chromosome
  • missing chromosome
  • normal chromosome number (if error balances itself out)
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17
Q

What is trisomy

A

cell has 3 copies of chromosome

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18
Q

What is the syndrome associated with trisomy

A

Down Syndrome

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19
Q

What is monosomy

A

cell has 1 copy of chromosome

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20
Q

What is the syndrome associated with monosomy

A

Turner syndrome

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21
Q

What is a genetic marker

A

specific DNA sequence used to determine if mids-segregation happened in meiosis I or II

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22
Q

Why are genetic markers really useful

A
  • genetic markers near centromeres
  • don’t crossover during recombination
  • makes thems reliable
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23
Q

What is the purpose of polar bodies

A
  • researchers can trace back errors in chromosome segregation
  • identify where mis-segregation happened
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24
Q

How are polar bodies useful i DNA analysis

A
  • each polar body contains clues about chromosomal errors
  • each polar body reflects specific stages of meiosis
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25
Q

What is nullosomy

A

a complete loss of one chromosome

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26
Q

Why is nullosomy problematic

A

there is a lack of genetic material for that chromosome

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27
Q

Why is trisomy problematic

A

an imbalance in gene expression because there is additional genetic material

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28
Q

What is a single mutation

A

results in a specific and single phenotype

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29
Q

What is a pleiotropic mutation

A

a single mutation causing diverse effects on phenotype

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30
Q

Why are pleiotropic mutations problematic

A
  • it changes gene expression of multiple genes at the same time
  • results in widespread disruption (ex: can affect heart, eye and liver)
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31
Q

What is sex chromosome aneuploidy

A

adding or losing sex chromosomes

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32
Q

TRUE OR FALSE: Sex chromosome aneuploidy are not survivable

A

FALSE

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33
Q

Name 2 examples of sex chromosome aneuploidy

A
  • Turner Syndrome
  • Klinefelter Syndrome
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34
Q

What is Turner syndrome

A

only have one X chromosome

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35
Q

What is Klinefelter Syndrome

A

an extra X chromosome in males (XXY)

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36
Q

What is Autosomal Monosomy:

A

loss of a single autosome

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37
Q

What is the main consequence of autosomal monosomy

A

always lethal (except for monosomy X)

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38
Q

Outline the relationship between aneuploidy and occytes and live birth rate

A
  • high aneuploidy rate in oocytes (20%)
  • only a small fraction make it to term (0.3%)
39
Q

What is the chromsome number in Down syndrome

A
  • 47 chromosomes
  • extra chromosome on 21
40
Q

What is the cause of Down Syndrome

A

non-disjunction

41
Q

Outline Edwards Syndrome

A
  • 47 chromosomes & extra on 18
  • cause = maternal non-disjunction
  • low fetal viability
42
Q

Outline Patau Syndrome

A
  • 47 chromsomes & extra on 13
  • lethal
  • cause = maternal non-disjunction
43
Q

Outline XYY syndrome

A
  • 47 chromsomes & extra Y
  • delayed speech and motor skills development
44
Q

What are the features of Klinefelter syndrome

A
  • increased height
  • delayed/incomplete puberty
45
Q

Outline Triple X syndrome

A
  • 47 chromosomes & extra X
  • only in females
  • delayed speech and motor skills development
46
Q

What is the relationship between motor age and aneuploidy

A

As a woman ages, the likelihood of her eggs (oocytes) having chromosomal abnormalities increases

47
Q

What is a proteome

A

complete set of proteins in a cell or organism

48
Q

Why does the proteome vary

A
  • different cells express unique sets of proteins based on their function
  • different mRNA transcripts undergo alternative splicing leads to different protein variant
49
Q

What is the function of mass spectrometry

A

to identify proteins in a sample on a mass scale

50
Q

How does mass spectrometry work

A
  1. proteins are broken down into shorter peptide sequences
  2. peptides are turned into gas (changing their charge)
  3. peptides go through a detector which measures their mass to charge ratio
51
Q

What is the function of gene cloning

A

to copy a specific gene by inserting it into a plasmid

52
Q

How does gene cloning work

A
  1. target gene is inserted into the plasmid and introduced into the bacteria
  2. bacteria replicates, amplifying the gene and producing target proteins
  3. tags can be added to genes for tracking protein
53
Q

What is the function of fluorescent tags in gene cloning

A
  • visualises where the protein is located in the cell
  • tracks protein interactions and helps understand its role
54
Q

What are post-translational modifications

A

polypeptide chains can be cleaved after translation and create multiple protein isoforms from the same mRNA

55
Q

Name an example of post-translational modification

A

cleavage in insulin

56
Q

What are the 3 main processes in insulin cleavage

A
  • signal peptide
  • formation of proinsulin
  • cleavage to active insulin
57
Q

What does signal peptide do in the cleavage of insulin

A
  • signal peptide is added onto precursor protein
  • it directs the precursor protein (pre-proinsulin) to the ER
58
Q

Outline the formation of proinsulin

A
  • in the ER, signal peptide is removed
  • disulfide bonds form between A and B chains
  • allows proper folding and formation of pro-insulin
59
Q

Outline the cleavage to active insulin

A
  • the C chain is removed
  • only A and B chains are held by disulfide bonds
  • mature insulin only consists of those 2 chains
  • they are stable and functional for blood glucose regulation
60
Q

Name an example where proteins cleavage goes wrong/problematic

A
  • BACE overexpression leads to abnormal cleavage of APP into amyloid plaques
  • contributes to Alzheimer’s disease
61
Q

What are the 2 types of post-translation modifications

A
  • glycosylation
  • phosphorylation
62
Q

Outline the process of glycosylation as a type of post-translation modification

A

adds sugar units (glycans) to proteins to create side chains

63
Q

What is the function of glycosylation in post-translation modifications

A

helps localise proteins to specific cell areas & stabilises proteins in bloodstream

64
Q

Outline the process of phosphorylation in post-translation modifications

A

it adds phosphates and changes the protein conformation

65
Q

What is the function of phosphorylation in post-translation modifications

A

activates or deactivates proteins which are involved in transmitting signals in pathways

66
Q

Name 2 ways post-translational modifications can be detected

A
  • Western Blots
  • mass spectrometry
67
Q

How do western blots detect post-translational modifications

A
  • they use antibodies designed to recognise specific modifications
68
Q

How does mass spectrometry detect post-translational modifications

A
  • by detecting mass or charge shifts in protein fragments
  • can use antibodies or fluorescent tags
69
Q

What is ubiquitination

A

a post-translation protein modification where a small protein (ubiquitin) is attached to lysine residues on other proteins

70
Q

What is the function of ubiquitination

A

tags proteins for degradation but can also change the protein’s activity + location + stability

71
Q

What is the Ubiquitin-Proteasome System

A

a system of enzymes (E1, E2, E3) that add chains of ubiquitin to the protein marking it for breakdown by the proteasome

72
Q

What is the proteasome

A

large protein complex where degraded proteins are processed

73
Q

How does the Ubiquitin-Proteasome System degrade proteins

A
  • cap proteins remove ubiquitin tags, unfold proteins and use ATP to guide the protein into the proteasome core
  • they have a cylindrical core that contains enzymes that cleave the proteins into short peptides
74
Q

What happens after the proteins are broken down by the proteasome

A

proteins are broken into smaller pieces for reuse or disposal by the cell

75
Q

What is the Purpose of Ubiquitination and Proteasome-Mediated Degradation

A
  • maintains protein quality by removing degraded or misfolded proteins
  • regulates protein levels
76
Q

What is the function of CDKs

A

regulate cell cycle and promote cell division

77
Q

What are cyclins

A
  • proteins that activate CDK
  • Each cyclin pairs with specific CDKs to regulate distinct phases of the cell cycle
78
Q

Why do certain cyclin-CDK complexes add ubiquitin tags to themselves and other proteins

A
  • regulates protein expression
  • ensures proper cell cycle progression
79
Q

What happens when mutations disrupt ubiquitination machinery in cancer?

A

can lead to rapid cell proliferation, genomic instability, and cancer development

80
Q

What are the consequences of rapid cell proliferation caused by disrupted ubiquitination?

A

uncontrolled growth of cells

81
Q

How does genomic instability contribute to cancer?

A

It increases mutations and errors in DNA replication.

82
Q

How does altered signalling contribute to tumorigenesis?

A

t promotes cancer development.

83
Q

What are the main steps in ubiquitination profiling?

A
  1. Capture methods: Isolating ubiquitinated proteins using beads or antibodies.
  2. Analysis: Fragmentation and mass spectrometry to identify ubiquitination levels.
84
Q

What is the purpose of ubiquitination profiling in cancer research?

A
  • understand ubiquitination’s role in cancer progression
  • identify potential therapeutic targets
85
Q

What is lysosomal degradation?

A

A protein breakdown process where lysosomal enzymes degrade proteins, organelles, or pathogens

86
Q

What is the function of lysosomal enzymes?

A

to break down proteins and nucleic acids

87
Q

How does lysosomal degradation differ from ubiquitination-mediated protein breakdown?

A
  • Lysosomal degradation involves enzymatic digestion within lysosomes
  • ubiquitination tags proteins for degradation by the proteasome
88
Q

What happens when lysosomes become leaky with age?

A

Lysosomal contents can escape, causing significant cellular damage.

89
Q

What are stress granules?

A

membraneless organelles that form in response to cellular stress, storing RNA and proteins to provide temporary protection

90
Q

Can stress granules permanently fix lysosomal leaks?

A

No, they temporarily seal lysosomal leaks but are not permanent solutions

91
Q

How does lysosomal dysfunction contribute to ageing?

A

By impairing cellular function and triggering stress responses

92
Q

How is lysosomal dysfunction linked to neurodegenerative diseases?

A

Accumulation of damaged proteins disrupts neuronal function, contributing to diseases like Alzheimer’s and Parkinson’s

93
Q

Why is the combination of lysosomal dysfunction and persistent stress granules harmful?

A

It exacerbates cellular damage, promoting ageing and neurodegenerative disease progression.

Human Genomics & Genetics (7 decks)

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