V L5: Organisation of the human genome

Question 1

is Genome size and gene content the same in every species?

Answer 1

no it varies a lot

Question 2

How big is a Haploid human genome ?

Answer 2

3.1 x 10^9 nucleotides

Question 3

Name three parts of a chromosome and their loccation ?

Answer 3

centromere - middle
telomere - bottom
chromatid - bottom length

Question 4

what is a centromere?

Answer 4

Constricted region, required for segregation of daughter chromosomes.

Question 5

what is a telomere?

Answer 5

Region located at the ends of chromosomes, that protect the end of the chromosome.

Question 6

where does the o allele have a DNA base detection?

Answer 6

in exon 6

Question 7

what does the DNA base detection in the O allele cause?

Answer 7

a reading frame shift, leading to a truncated protein lacking the catalytic domain. (Frame shift mutation)

Question 8

A allele produces _________ leading to addition of __________ to the existing O/H _____.

Answer 8

A- transferase
N-acetylgalactosamine
antigen

Question 9

B allele produces _______ , leading to addition of ____ to the existing O/H antigen.

Answer 9

B-transferase

galactose

Question 10

what does RNA splicing do?

Answer 10

RNA splicing remove unwanted introns from the mRNA transcript.

Question 11

what happens after introns are removed from the mRNA transcript ?

Answer 11

The remaining exonic segments are joined to produce a shorter RNA product.

Question 12

what happens once a shorter RNA product has been produced?

Answer 12

A specialised nucleotide guanine is added. This is known as 5ʹ capping.

Question 13

After transcription 3ʹ cleavage reaction what happens?

Answer 13

enzyme adds adenylate (polyadenylation), produces a poly (A) tail.

Question 14

which part of the final mRNA molecule is translated?

Answer 14

Only a central segment

Question 15

One pre-mRNA =

Answer 15

different proteins

Question 16

what percentage of a gene is repeated sequence?

Answer 16

46%

Question 17

what can be found as part of the unique sequence?

Answer 17

Genes (Exons) < 2%
Introns/UTRs 
Pseudogenes
Gene fragments/truncated genes
Unique low copy non-repetitive DNA

Question 18

Genes can…

Answer 18

appear in clusters
share common sequence motifs
are present in multiple copies

Question 19

what is a Pseudogenes?

Answer 19

Pseudogenes appear to have arisen by insertion of processed mRNA and are no longer functional

Question 20

What are the 2 types of Pseudogenes?

Answer 20

Conventional (gene relic)

Processed

Question 21

what causes conventional Pseudogenes?

Answer 21

caused by a single point mutation causing a non-functional gene that over time will degrade.

Question 22

what are processed Pseudogenes?

Answer 22

believed to be processed mRNAs that have been converted to DNA by reverse transcription and re-incorporated into the genome

Question 23

are processed Pseudogenes usually found in clusters?

Answer 23

yes

Question 24

what causes a gene fragment?

Answer 24

Genes can become damaged over time leaving remnants of the original gene behind

Question 25

what are the 2 types of repeated sequences?

Answer 25

Genome wide interspersed DNA (transposons)

- Tandemly repeated DNA (simple sequence repeats)

Question 26

Genome wide interspersed DNA is present as what?

Answer 26

multiple copies interspersed throughout the genome

Question 27

How does Genome wide interspersed DNA propogate?

Answer 27

via an RNA intermediate (retro-elements) or by DNA transposition

Question 28

Genome wide interspersed DNA may be autonomous or non- autonomous. true or false?

Answer 28

true

Question 29

Genome wide interspersed DNA is mobile? true or false?

Answer 29

True, move from one site to another

Question 30

whats a LINE?

Answer 30

Long Interspersed Nuclear Element

Question 31

whats a SINE?

Answer 31

Short Interspersed Nuclear Element

Question 32

whats satellite DNA?

Answer 32

tandem arrays of 5-200 bp repeat units, 100s kb in length, associated with centromeres, 90% AT

Question 33

what is Mini-satellite DNA ?

Answer 33

tandem arrays up to 20kb with repeat units of up to 6-100bp associated with telomeres

Question 34

what is Micro-satellite DNA ?

Answer 34

tandem array of 1-6 bp repeat unit, up to 150bp

very common in genome, prone to mutation so very useful for genetic profiling

Question 35

what are some classes of satellites?

Answer 35

Several classes of satellite DNA:
Alphoid (α)satellite DNA 
Beta (β) satellite DNA
Satellite 1
Satellite 2
Satellite 3

Question 36

Mini-satellites with similar sequences are found. where?

Answer 36

multiple locations within the genome

Question 37

why are mini satellites useful?

Answer 37

hybridising a mini-satellite probe to restriction digested DNA on a Southern blot will pick up multiple bands
- every person has a different pattern of bands

Question 38

when were micro satellites introduced into forensic casework?

Answer 38

mid 90s

Question 39

what are microsatellites also known as?

Answer 39

STRs

Question 40

Microsatellites are used how?

Answer 40

Typically use tetranucleotide repeats (4 bp).

Question 41

Micro and mini-satellites are prone to expansion and contraction at _____.

Answer 41

meiosis

Question 42

what used to be used to look at the differences in DNA sequence ?

Answer 42

ultracentrifugation

Re-association kinetics

Question 43

what current methods are used to classify specific DNA sequences?

Answer 43

Amplification of specific DNA

Detection of specific DNA using hybridisation

Question 44

what happens in a buoyant density study?

Answer 44

• genomic DNA has a GC content of about 40% and forms the main band
• repetitive sequence have very different GC contents and form satellite bands