Practise IB Biology HL D1.3 by classifying mutations, predicting molecular consequences and evaluating gene knockout and CRISPR evidence.
Duchenne muscular dystrophy (DMD) is a sex-linked genetic disorder caused by a recessive allele resulting from mutations in the X-linked dystrophin gene. This causes the degeneration of cardiac and skeletal muscle. These mutations can include deletions, insertions and base substitution mutations.
Distinguish between deletion and insertion mutations.
Explain ways in which CRISPR-Cas9 gene editing could be used to change the mutated dystrophin protein produced.
Outline the effects of a base substitution mutation in the case of sickle-cell anemia.
In a hypothetical study, new DNA sequence changes occur in both unexposed cells and cells exposed to ultraviolet radiation, with a higher frequency in the exposed group.
Which explanation is consistent with the causes of gene mutation?
Only radiation causes mutations; changes in the unexposed cells cannot be mutations.
Ultraviolet radiation directs cells to make only changes that improve their survival.
Replication errors can cause mutations, but external factors cannot affect mutation frequency.
Internal replication or repair errors can cause mutations, and a mutagen can increase their frequency.
Duchenne muscular dystrophy (DMD) is a sex-linked genetic disorder caused by a recessive allele resulting from mutations in the X-linked dystrophin gene. This causes the degeneration of cardiac and skeletal muscle. These mutations can include deletions, insertions and base substitution mutations.
Distinguish between deletion and insertion mutations.
What causes variation in both sexually and asexually reproducing organisms?
Mutations
Polygenic inheritance
Crossing over
Independent assortment
Knockout organisms are used as models in research. The p53 knockout mouse is named after p53, a gene which codes for a protein that normally suppresses the growth of cancerous tumours.
How could scientists use p53 knockout mice in cancer research?
To extract tumour suppressor protein from p53 knockout mice for cancer treatments
To obtain functional copies of the p53 gene to use in gene replacement therapy
To investigate the effect of new anti-cancer drugs on mouse tumours
To study the effect of mutations on the expression of the p53 gene
Duchenne muscular dystrophy (DMD) is a sex-linked genetic disorder caused by a recessive allele resulting from mutations in the X-linked dystrophin gene. This causes the degeneration of cardiac and skeletal muscle. These mutations can include deletions, insertions and base substitution mutations.
Explain ways in which CRISPR-Cas9 gene editing could be used to change the mutated dystrophin protein produced.
Golden rice (Oryza sativa, GR) is the generic name given to genetically modified rice that produces beta-carotene (provitamin A). Golden rice was created by transforming rice with the gene coding for the PSY protein (phytoene synthase) from daffodil (Narcissus pseudonarcissus) or from corn (Zea mays).
The picture shows variations of rice.
A White wild-type rice
B Yellow Golden rice expressing the gene coding for PSY from daffodil
C Orange Golden rice expressing the gene coding for PSY from corn
A bioinformatics analysis was performed on the protein PSY transcribed from the gene from corn and from daffodil to obtain the sequence alignment.
On the alignment, identify the longest part of the sequence where the consecutive amino acids are the same.