organisation of the human genome

Question 1

genome

Answer 1

is the total amount of DNA in an organism that contains an entire set of genetic information of the organism

Question 2

what are the 2 kinds of genomes

Answer 2

nuclear genome and mitochondrial genome

Question 3

nuclear genome

Answer 3

has introns, is 1.1% coding, has repetitive sequences, has 23/24 linear chromosomes, has a low gene density, follows mendelian inheritance

Question 4

mitochondrial genome

Answer 4

is small, circular, 93% coding, no introns, no repetitive sequences, no recombination events, is highly compact

Question 5

the heavy strand in mDNA is

Answer 5

is rich in G

Question 6

the light strand in mDNA is

Answer 6

rich in C

Question 7

gene forests

Answer 7

are high gene density areas

Question 8

gene deserts

Answer 8

are low gene density areas

Question 9

traits of the C value paradox

Answer 9

• it represents the DNA content of the haploid genome
• there is no correlation between complexity and size of DNA
• there is a minimum C value needed to make organisms of increased complexity
• closely related organisms can vary widely in the quantity of DNA of their genome

Question 10

how much of DNA is genic? extragenic?

Answer 10

genic: 20-30%
extragenic: 70-80%

Question 11

multigene families are a consequence of

Answer 11

Gene duplication

Question 12

what are the 5 main mechanisms of gene duplication

Answer 12

• tandem gene duplication
• duplicative transposition
• gene duplication by ancestral fusion
• large scale sub genomic duplications
• whole genome duplication

Question 13

what are the advantages of DNA sequence duplication

Answer 13

• more dosage

- novel genetic variants

Question 14

tandem gene duplication

Answer 14

is when there is crossing over between misaligned chromatids resulting in one gene with a tandem duplication and one lost gene

Question 15

homologous genes

Answer 15

is a gene related to a second gene by descent from a common ancestral DNA sequence

Question 16

orthologous genes

Answer 16

are genes in different species that evolve from a common ancestral gene by speciation, they retain the same function over evolution

Question 17

paralogous genes

Answer 17

are genes related by duplication within a genome, they evolve new functions

Question 18

gene family

Answer 18

a set of genes with structure and sequence similarities

Question 19

how do new genes arise?

Answer 19

during evolution from repetitive duplication events of ancestral gene followed by partial divergency due to random mutations

Question 20

psuedogene

Answer 20

is a genomic sequence that shows a high level of sequence similarity with a functional gene but is not itself functional

Question 21

how can pseudogenes form

Answer 21

• duplication followed by mutation: are non processed pseudogenes with introns
• retrotransposition: are processed pseudogenes, no introns, come from reverse transcriptase

Question 22

retrogenes

Answer 22

are active copies of a gene without introns

Question 23

what are the 2 functions of reverse transcriptase

Answer 23

• DNA polymerase activity

- RNase H activity

Question 24

in what arder is the globin gene cluster organized and how does it work

Answer 24

epsilon-gamma-delta-beta. their expression is controlled by a locus control region LCR is upstream the entire gene set

Question 25

large scale subgenomic duplication

Answer 25

arise as a result of chromosomal translocation