The control of gene expression

Question 1

What is insertion?

Answer 1

when a nucleotide is randomly inserted into a DNA sequence
affects function of the polypeptide due to causing a frameshift
causes Huntington’s disease

Question 2

What is deletion?

Answer 2

when a nucleotide is randomly deleted in a DNA sequence
affects function of the polypeptide due to causing a frameshift
causes Cystic fibrosis

Question 3

What is substitution?

Answer 3

where a DNA nucleotide is swapped for a different one
It is:
silent - doesn’t alter amino acid sequence
missense - alters a single amino acid
nonsense - can create a premature stop codon
causes sickle-cell anaemia

Question 4

What is inversion?

Answer 4

when a single gene is cut in 2 places, inverted 180 degrees and re-joined
results in a non- functional protein
causes haemophilia A

Question 5

What is duplication?

Answer 5

where one or more nucleotides are duplicated in a DNA sequence
original gene is not gene
causes Charcot-Marie tooth disease

Question 6

What is translocation?

Answer 6

when a section of a chromosome is added to another chromosome that isn’t its homologous partner
Philadelphia chromosome that’s found in leukaemia cancer

Question 7

What is genomics?

Answer 7

the study of the whole set of genetic information in the form
of the DNA base sequences that occur in the cells of organisms of a
particular species

Question 8

What is a genome?

Answer 8

the complete set of genetic information contained within an organism / cell

Question 9

What is a proteome?

Answer 9

the full range of proteins that the cell can produce

Question 10

Why is determining the proteome of a simple organism easy?

Answer 10

-They have just one, circular piece of DNA that is not associated with histones
-There are no non-coding portions of DNA which are typical of eukaryotic cells

Question 11

Why is determining the proteome of a complex organism difficult?

Answer 11

-There are many non-coding genes
-Many genes have a role regulating other genes
-Individuals (except identical twins) have different base sequences on their DNA, therefore mapped DNA will differ, slightly, from everyone else’s DNA

Question 12

What is the Human genome
project?

Answer 12

International research initiative with the primary goal of mapping and
sequencing the entire human genome.
It aimed to determine the order of all the nucleotide bases in human DNA, identify all the genes, and understand their functions.
The project, which began in 1990, was officially completed in
2003.

Question 13

How were the sections of the human genome cloned in the
Human Genome Project?

Answer 13

introduced into bacteria, allowing the fragments to be
cloned and amplified.
The amplified DNA was then sequenced and pieced together using computational techniques.

Question 14

What advances have been made as a result of
publishing the research of the Human Genome Project?

Answer 14

-Identification of genes linked to diseases: such as cystic fibrosis,
Huntington’s disease, and certain cancers.
-Advances in personalized medicine: Development of targeted therapies based on individual genetic profiles.
-Biotechnology advancements: Use of genomic data in drug development and agricultural improvements.
-Evolutionary insights: Understanding human evolutionary history and comparing genomes across species.

Question 15

What is recombinant DNA (rDNA)?

Answer 15

where fragments of foreign DNA are inserted into other sections of DNA

Question 16

What is genetic engineering?

Answer 16

an area of research that studies the design and construction of different biological pathways, organisms and devices, as well as the redesigning of existing natural biological systems

Question 17

Describe the steps of genetic engineering:

Answer 17

• Identification of the DNA fragment or gene
• Isolation of the desired DNA fragment
• Multiplication of the DNA fragment (using polymerase chain reaction - PCR)
• Transfer into the organism using a vector (e.g. plasmids, viruses, liposomes)
• Cloning-Identification of the cells with the new DNA fragment (by using a marker), which is then cloned

Question 18

What is needed to modify an organism?

Answer 18

Enzymes (restriction endonucleases, ligase and reverse transcriptase)

Vectors - used to deliver DNA fragments into a cell (eg. plasmids, viruses and liposomes)

Markers - genes that code for identifiable substances that can be tracked (eg. GFP - green fluorescent protein which fluoresces under
UV light or GUS - β-glucuronidase enzyme which transforms colourless or non-fluorescent substrates into products that are coloured or fluorescent)