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EMS Genetics > Genome Anatomy > Flashcards

Genome Anatomy Flashcards

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1
Q

what is genome anatomy?

A

genome anatomy is how the genome is organised and how it functions

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2
Q

how is almost all heritable information written and how is it organised?

A

in DNA sequences

3x10^9 nucleotides from father and mother and there is 750 megabytes of uncompressed date

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3
Q

where is other information found?

A

in chromatin features such as in epigenetics

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4
Q

where do data storage errors arise from?

A

genetic pathologies (genome goes wrong and genetic disease results) and this is why error correction methods (ensure that the DNA is copied correctly) are important

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5
Q

what is epigenetics?

A

changes in the genome that influence the genome and are not included in the DNA code

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6
Q

what is the difference between DNA and RNA?

A

the presence and absence of the hydroyxl group on the second carbon atom

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7
Q

what is the effect of the chemical groups on the carbon atoms?

A

this changes the stability of the molecule - RNA is less stable as the breakage is faster in the phosphodiester bond (intramolecular nucleophilic attack)

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8
Q

which direction are DNA sequences written in?

A

5’-3’ direction which is the direction that DNA and RNA are synthesised in

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9
Q

what determines the sequences?

A

the order of purine and pyrimidine bases sticking out the side of the chain

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10
Q

at which end do new nucleotides get added?

A

3’ end

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11
Q

how are strands arranged and how are they matched?

A

they are antiparallel and matched by base pairing

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12
Q

Abb(ns) nt and bp are what?

A

these are shorthand loosely interchangeable terms for DNA sequences

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13
Q

how is shorthand usually written?

A

with the sense strands (which can also relate to antisense as well)

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14
Q

in DNA replication what happens on the antisense (lagging) strand?

A

Okazaki fragments are found

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15
Q

how do they replicate?

A

they unwind the structure using a helicase and then synthesise a complimentary daughter strand

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16
Q

how long is DNA in one chromosome?

A

around 9 cm

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17
Q

what are chromosomes?

A

they are the packages in which the DNA is organised as it must fit into the nucleus

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18
Q

how many nucleotides are wrapped around histone proteins?

A

around 200

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19
Q

what order is standard karyotype?

A

largest to smallest

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20
Q

what does diploidy refer to?

A

diploidy is the human genome and means that we get one gene from mother and one from father

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21
Q

what is the centromere?

A

the centromere is where the chromosomes are attached to the spindle during cell division

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22
Q

what is found at the end of the chromosomes?

A

at the end of each arm of the chromosome (p being short and q long) there is a telomere - Ptel and Qtel are different

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23
Q

what is the telomeric repeat sequence?

A

TTAGGG and includes specialised replication machinery with telomerase and TERT

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24
Q

what happens in somatic cell division?

A

the telomeres shorter and therefore telomerase is inactive in somatic cells - there is a finite number of cell divisions until senescence known as ageing. Telomerase is only active in germ cells

25
Q

what happens in a cancerous mechanism?

A

TERT reactivates

26
Q

how does the end of the chromosome work?

A

it is single stranded and loops back round in a complex structure to stabilise the chromosome

27
Q

in the chromosome ideogram how can abnormal chromosomes be identified?

A

stretching of chromosomes determines the visibility of bands and therefore when there are abnormal chromosomes they are shown up in bands

28
Q

what does 2n=46 mean

A

the chromosome complement is diploid therefore n = 23 and 2n = 46.

29
Q

what does haploinsufficiency mean?

A

haploinsufficiency is when 2 copies are needed and one is insufficient - dosage is important in these genes - the exception is the X chromosome

30
Q

what are psudomonal regions?

A

information that is shared with the X and the Y regions

31
Q

why are males hemizygous?

A

they only have one X chromsome and therefore only have one copy of many genes that are only found on the X chromosome

32
Q

what happens to chromosomes after replication?

A

each chromosome becomes sister chromatids - 4n

33
Q

what is the Y chromosome composed of compared to X?

A

the Y has the pseudomonal regions and then mostly heterochromatin, the X has the pseudomonal regions and the X unique genes

34
Q

how much of the human genome is non coding?

A

> 90% - short and long non coding genes

35
Q

how many protein coding genes are there?

A

around 20,000 with an average size of 50-100kb and average mRNA of 2kb

36
Q

what are three different sequences classes and examples?

A

single copy sequences such as genes
repetitive sequences such as Alu repeats - interspersed repeats
satellite DNA such as heterochromatin and large blocks of repetitive sequence

37
Q

describe mitochondrial genomes?

A

circular, not linear: this is an endosymbiotic remnant

cytoplasmic not nuclear due to maternal inheritance from oocyte

38
Q

what do the genes in mitochondria do?

A

they encode for mitochondrial roles such as components of oxidative phosphorylation

39
Q

how are mitochondrial pathologies inherited?

A

maternally

40
Q

what is a gene?

A

it is a functional unit of DNA

41
Q

what is the term used to describe the copying of DNA into RNA?

A

transcription. Translation is when RNA is turned into a protein.

42
Q

what are the components of genes?

A

introns, exons and regulatory sequences (promtores, enhancers and locus control regions)

43
Q

where is the DNA transported to after splicing?

A

after splicing the DNA is transported into the cytoplasm

44
Q

which regions gets removed in splicing?

A

the intronic region

45
Q

what is the term for when exons are spliced together in different orders or creating different proteins?

A

alternative splicing

46
Q

what happens to the genome through evolution?

A

duplication and divergence

47
Q

what does duplication produce?

A

two random arrangements of genes

48
Q

what do mutations lead to?

A

mutations over millions of years lead to two random arrangements of genes diverging and producing different functions

49
Q

what are pseudogenes?

A

they look the same as normal genes but they contain errors and are therefore non functional

50
Q

what are processed genes?

A

intronless copies of other genes that are usually remote from parent genes. They occur via reverse transcription and reintegration. They will occasional remain functional but most are non functional

51
Q

what are the classifications of repetitive DNA?

A

interspersed repeats (scattered around the genome) and satellite DNA

52
Q

where is satellite DNA found?

A

satellite DNA is found with large blocks at the centromeres and heterochromatin chromosomal regions

53
Q

what are simple tandemly repeated sequences?

A

there are many types - centromere repeats and chromosome specific

54
Q

what does polymorphic relate to?

A

polymorphic means that the blocks of satellite DNA may vary in size

55
Q

what type of satellite DNA is found at centromeres?

A

alphoid DNA - 171bp repeat unit. It is required for the assembly of the centromere and making it unique

56
Q

what type of variation does alphoid DNA show?

A

it shows chromosome specific sequence variation

57
Q

what is an alu repeat?

A

it i a SINE - short interspersed nuclear element that has a role in the generation of molecular pathology

58
Q

how are alu repeats dispersed?

A

retrotransposition

EMS Genetics (19 decks)

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