Organisation of Prokaryotic and Eukaryotic Genome

Question 1

Genome

Answer 1

Genome refers to a complete set of genetic material in a particular cellular component.

Question 2

Control element

Answer 2

Control elements are non-coding DNA segments that transcription factors bind to in order to regulate transcription - includes promoters, enhancers, silencers.

Question 3

Telomere

Answer 3

Telomeres are nucleotide sequences found at both ends of eukaryotic chromosomes.

Question 4

Centromere

Answer 4

Centromeres are constricted regions on chromosomes where spindle fibres (kinetochore microtubules) attach to during nuclear division.

Question 5

Regulatory gene

Answer 5

A regulatory gene is a gene that regulates the expression of one or more structural genes by controlling the production of a protein which regulates their frequency of transcription - includes introns, promoters, enhancers and silencers.

Question 6

Gene amplification

Answer 6

Gene amplification refers to the replication of a specific gene multiple times to create more copies of that gene.

Question 7

Proximal control elements

Answer 7

Proximal control elements are non-coding DNA that usually lie directly upstream of the transcription start-site. They are bound by general transcription factors.

Question 8

Distal control elements

Answer 8

Distal control elements are non-coding DNA that can be located thousands of nucleotides upstream or downstream of the gene, or even within an intron. They are bound by specific transcription factors.

Question 9

Transcription factors

Answer 9

Transcription factors are proteins that can recognise and bind to a specific sequence of nucleotides on DNA and recruit other proteins to exert an effect on the frequency of transcription of the gene controlled.

Question 10

Capping

Answer 10

Capping involves the addition of a 7-methylguanosine nucleotide to 5’ end of pre-mRNA.

Question 11

Splicing

Answer 11

Splicing is a process during which introns are excised and exons are joined together / spliced together by a spliceosome.

Question 12

Cancer

Answer 12

Cancer is a group of diseases characterised by uncontrolled cell division and spread of abnormal cells.

Question 13

Proto-oncogene

Answer 13

Proto-oncogenes are normal cellular genes which codes for proteins that are involved in regulation of cell growth and proliferation.

Question 14

Tumour suppressor gene

Answer 14

Tumour suppressor genes are normal cellular genes that code for products which inhibit cell division and helps to prevent uncontrolled cell division.

Question 15

Gain-in-function mutation

Answer 15

A mutation that causes a gene to be expressed in a cell / at a time when it is not normally expressed. Gene products of proto-oncogenes become hyperactive / resistant to degradation / are produced in excessive amounts.

Question 16

Loss-in-function mutations

Answer 16

A mutation that causes a gene product to be non-functional. Gene products of tumour suppressor genes are defective and cannot activate other genes.