Module 2 Flashcards
Nondisjunction?
Failure of chromosomes to separate properly during meiosis.
Aneuploidy?
Abnormal number of a particular chromosome
Deletion?
removal of a chromosomal segment
Inversion?
Reverses a segment within a chromosome
Duplication>
Repeated segment within a chromosome
Translocation?
Removal of a segment from one chromosome to a non-homologous chromosome
Polyploidy?
possession of multiples sets of chromosomes
Disease resulting from nondisjunction?
Down Syndrome, 95% of DS babies have 2 maternal chromosome 21
Diseases resulting from Aneuploidy?
Klinefelter syndrome (XXY) and Turner Syndrom (XO)
Disease resulting from Deletion?
Lejeune Syndrome, tip or short arm of chromosome are deleted
Diseases resulting from translocation?
Myeloid Leukemia, TK overexpression, Familial Down Syndrome
How do chromosome abnormalities and rearrangements occur.
Mutations & Nondisjunction
Explain the effects of odd numbers of chromosomes in meiotic segregation?
An odd number of chromosomes will mean the organism is sterile/infertile as they can not produce viable gametes
Outline the concept of X-inactivation?
X-inactivation occurs in females because they have two copies of the X chromosome, one from each parent. One X chromosome is compacted into a structure calle Barr Body which contains mostly inactive genes. Whether it is the paternal or maternal X chromosome varies randomly from cell to cell. This process happens during embryonic development and is also referred to a lysonization.
What are the birth defects of chromosome abnormalities and rearrangements.?
EMbryo will often die early or have physical abnormalities and a decreased life expectancy
What is gene expression>
The process by which information from a gene is used to synthesis a functional gene product: Protein or non-coding RNA
Define a gene?
A define region of DNA that produces a type of RNA that has some function.
What are gene (DNA) sequences responsible for?
Regulation of the synthesis of RNA
producing RNA
Future processing of RNA
What is the central Dogma of molecular biology?
The process by which DNA is converted to RNA to protein
Transcription?
The synthesis of RNA using a DNA template (MRNA is transcribed from the template strand)
Which DNA strand is transcribed?
Template strand = strand running in the 3-5 prime direction
What occurs during Initiation?
Transcription factors bind to TATA box and other regions of the promotor,
RN pol II binds, forming a transcriptional initiation complex together with the transcription factors,
The two DNA strands seperate and RNA pol II starts mRNA synthesis without the need of a primer.