Week 11 Flashcards
Cytogenetics is the study of ____________
chromosomes
A chromosome is a single _________
DNA molecule
What is the letters to represent the short arm of a chromosome and the long arm?
Short arm = p for petit
Long arm = q
Attached to the backbone of DNA are nitrogen containing bases • Purines • Pyrimidines what are contained in these bases?
- Purines = (A) adenine, (G) guanine
* Pyrimidines = (C) cytosine, (T) thymidine
Number of chromosomes in dividing somatic cell =
Gametes contain a single copy of each chromosome =
46
23
• Diploid number (2n) = 46 -Created by mitosis
• Haploid number (n) = 23 - Created by meiosis
DNA mutations can be inherited of acquired. What some examples of acquired DNA mutations?
- Radiation
- Toxins
- Diet
- Infection
Some disorders are due to a single altered or missing gene. What is one example of single-gene disorders?
Sickle Cell Anaemia
Are most cancers are genetic or inherited in origin?
genetic
Most are acquired genetic mutations
• The mutation will be present in clones of the abnormal cell line
A gene that has potential to cause cancer is called a __________
Oncogene
What genes protect cells from one step in oncogenic pathway?
Tumour suppressor genes
Chromosome preparation requires cells with inherently high mitotic rate. Where would the sample be most likely taken from?
• Bone marrow
What is added to peripheral blood to stimulate cells to divide in culture?
mitogens
Which mitogens are used to stimulate T cells and B cells?
- Phytohaemaglutinin T cells
* Pokeweed mitogen B cells
What is added to disrupts attachment of chromosome to mitotic spindle and arrests cell division in metaphase?
colcemid
What is added so that the chromosomes spread?
hypotonic KCl
Quinacrine mustard attaches to which parts of the chromosome? tip: this is called Q banding, there is a wide range of other subsequent banding techniques.
Binds to A-T rich parts of chromosome
adenosine and thymine