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MCS > Day 1, Lecture 3: Genetics: Organization of Human genome > Flashcards

Day 1, Lecture 3: Genetics: Organization of Human genome Flashcards

1
Q

__% of all live born neonates have a significant genetic disease

A

3%

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2
Q

___% of all causes of infant mortality in the U.S. is due to genetic disease

A

20%

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3
Q

____% of all pediatric hospital admissions have a clearly defined genetic disease

A

5-10%

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4
Q

Types of Genetic disease

A
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5
Q

Disease caused by interaction of multiple genes +/- environmental factors

A

Multifactorial/polygenic disease

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6
Q

Cystic fibrosis and Sickle cell disease are examples of what type of genetic disease

A

Single gene defect

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7
Q

Common congenitla defects {NTDs, congential heart disease} are examples of what type of genetic disease

A

Multifactorial/Polygenic Disease

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8
Q

Leber hereditary optic neuropathy (LHON) is an example of what type of genetic disease

A

Mitochondrial Disorders

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9
Q

Nuclear DNA is packaged into _____

A

chromosomes

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10
Q

Only ____% of the entire genome is used for encoding proteins

A

1-2%

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11
Q

How many mitochondrial genes are there

A

37

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12
Q

there are about how many genes in the nuclear genome

A

25,000 genes

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13
Q

what percent of the nuclear genome is genes

A
  • 35%
    • of which only about 5% codes for proteins (about 1-2% of entire genome)
    • of which about 95% is non-coding DNA
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14
Q

What percent of the nuclear genome is extragenic DNA

A
  • About 65%
    • of which about 60% is unique or low copy Number repeat DNA
    • of which about 40% is moderate to highly repetitive DNA
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15
Q

DNA is an _____ double helix

A

anti-parallel

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16
Q

DNA is ___ handed. Explain?

A
  • Right handed
    • turns clockwiss as it goes away from you
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17
Q

How many base pairs are there per turn of the DNA double helix

A

10 base pairs

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18
Q
A
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19
Q

_____ is the repeating unit fo DNA

A
  • Nucleotide
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20
Q
A
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21
Q

DNA replication is ___-conservative

A

semi-conservative

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22
Q
A
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23
Q

DNA is replicated in the ____ direction

A
  • 5’ to 3’
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24
Q

DNA replication is ____-discontinuous. Meaning

A
  • semi-discontinuous.
    • The leading strand is replicated continuously and the lagging strand is replicated discontinuously
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25
Q

Transcription occurs in the _____ direction

A

5’ to 3’ direction (thus it uses the template strand (antisense strand) to make the sense sense strand)

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26
Q

____ is the fundamental unit of DNA packaging

A
  • Nucleosome
    • Nucleosome is made of 8 histone proteins
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27
Q

The nucleosome is the fundamental unit of DNA packaging. It is composed of 8 histone proteins around which ___ bp of DNA is coiled ___ turns

A

146 bp of DNA is coiled 1.75 turns

28
Q

The kinetochore is present at the centromere; and is the site for microtubule spindle attachment for chromosome segregation during cell division

A

kinetochore

29
Q

The central function of the centrosome is to

A

house the kinetochore

30
Q

____ is the most widely used technique for studyign mammalian chromosomes

A

G-banding

31
Q

Aneuploidy

A
  • can’t be divided by 23
    • note that most chromosomal aneuploidies are in the smaller autosomal chromosomes such as chromosome 21
32
Q

Examples of anueploidy

A
  • Trisomy 21 (Down Syndrome): 47, XX, +21
  • Turner Syndrome: 45, X
  • Klinefelter Syndrome: 47, XXY
33
Q

What is Reciprocal Translocation?

A
  • Reciprocal translocations are usually an exchange of material between nonhomologous chromosomes.
  • Estimates of incidence range from about 1 in 500.
  • Such translocations are usually harmless and may be found through prenatal diagnosis.
    • However, carriers of balanced reciprocal translocations have increased risks of creating gametes with unbalanced chromosome translocations, leading to miscarriages or children with abnormalities.
34
Q

Telomere structure and function

A
35
Q

Telomere length is maintained by _____

A

Telomerase

36
Q

Telomeres shorten by ___ bp per cell division (eventually leading to ___)

A

100 bp per cell division (eventually leading to senescence)

37
Q

Major Classes of repetitive DNA

A
38
Q

What is DNA polymorphism?

A
  • if a change in the genetic sequence (at a specific location) is present at a frequency of at least 1% in the population
    • Single nucleotide polymorphism (SNP)
      • Variation at a specific single nucleotide
    • polymorphic microsatellite repeats
    • Copy number variations (CNV)
39
Q

Copy Number Variations (CNV)

A
  • Large segments of DNA
  • ​10kb-5Mb
  • about 12% of the genome (about 1500)
  • a type of polymorphism
  • Deviations from the normal expected chromosomal make up. Microdeletions or micro- duplications detected by chromosomal microarray are such examples. Identied CNVs are classied as known benign, known pathogenic, or of unknown clinical signicance. Copy number variant is now the preferred term over “copy number change.”
40
Q

Epigenetic modification is a mechanism of _____

A
  • genome defense
41
Q

can tandem repeats be polymorphic?

A
  • Yes
    • Single Nucleotide Polymorphism (SNP)
    • Polymporphic microsatellite repeats
    • Copy Number Variations (CNV)
42
Q

Can interspersed repeats transpose

A
  • Yes
    • Ex. L1 repeats and Alu repeats
43
Q

Epigenetic modification of the genome

A
  • Chemical modication of histones determines transcriptional activity of genes- this represents functional organization of the genome
  • DNA is methylated at CpG dinucleotides
44
Q

Euchromatin

A
  • Most of the DNA in interphase nuclei; in extended, active form
  • Open chromatin
  • Acetylated and unmethylated histone tails
  • No DNA methylation
  • at actively expressed genes (functional regulation)
45
Q

Heterochromatin

A
  • Highly condensed, compact, transcriptionally inactive DNA
  • Deacetylated and Methylated histone tails
    • Methylated DNA
    • Seen at repetitive DNA (defense)
      • Constitutive
        • always inactive (1q, 9q, 16q)
      • Facultative
        • either active/ inactive form (X inactivation)
46
Q

The protruding N-Terminal Tails are present on which histones

A
  • H3
  • H4
47
Q

DNA is methylated at ____

A
  • CpG dinucleotides (5’-CG-3’)
    • Methylation at the 5 carbon of cytosine only if it si followed by a guanine in the DNA backbone
    • 70% of the CpG sites in the human genome are methylated
    • 15% of the CpG sites are concentrated in unmethylated CpG
48
Q

___% of the CpG sites in the human genome are methylated

A

70%

49
Q

___% of the CpG sites are concentrated in unmethylated CpG

A

15%

50
Q
A
51
Q
A
52
Q

Gene

A

A unit of heredity. A gene refers to a specific segment of DNA that can be delineated by a start and stop position. Genes typically code for a speci c product (oftentimes a protein molecule).

53
Q

Nucleosome

A

The basic unit of DNA packaging. It comprises a short length of DNA wrapped around a core of histone proteins.

54
Q

Nucleotide

A

The basic unit of DNA and RNA. Nucleotides are

composed of a nitrogenous base, a 5-carbon sugar (either ribose or 2-deoxyribose), and a phosphate group.

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MCS (40 decks)

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