Flashcards in 2A- Intro to Medical Genetics Deck (37)
What are chromosome disorders?
Entire chromosomes or large segments of them are missing, duplicated or altered
What are single-gene disorders?
Single genes are altered. Classified as autosomal dominant, autosomal recessive or X-linked.
What are multifactorial disorders?
Combination of multiple genetic and environmental causes.
What are mitrochrondrial disorders?
Diseases caused by alteration in the small cytoplasmic mitochondrial chromosome
What has the trend of the genetic disease diagnosis and treatment been like over the past 50 years?
public health improved and genetic diseases became a larger percentage of genetic deaths among children in developing countries
What % of the genome codes functional proteins?
(the rest of the genome sits in unemployed hippy circles chanting that they are the 99%)
What makes up 55% of the genome?
What is dispersive repetitive DNA?
scattered singly throughout the genome. Do not occur in tandem.
What are the 2 forms of dispersive repetitive DNA?
Short Interspersed Elements (SINEs) and Long Interspersed Elements (LINEs)
How long are SINEs?
How long are LINEs?
Can be up to 7000 bp
What is satellite DNA?
repeats are clustered together in certain chromosome locations, where they occur in tandem (the beginning of one repeat occurs immediately adjacent to the end of the another)
What are α-Satellites?
tandem repeats of a 171-bp sequence that can extend to several million base pairs or longer.
Where are α-Satellites found?
Near the centromeres
What are minisatellites?
blocks of tandem repeats (each 14 to 500 bp long) whose total length is much smaller, usually a few thousand base pairs. Vary in length among individuals.
What are microsatellites?
even smaller (1-13 bp long). Vary in length among individuals.
What happens during prophase of mitosis?
chromosomes condense and coil. Sister chromatids attach at centromere. Spindle fibers begin to form from the 2 centrioles on opposite sides of the cell.
What occurs during metaphase of mitosis?
chromosomes are at their most highly condensed state. Clinical diagnosis of chromosome disorders is usually based on metaphase chromosomes. Spindle fibers begin to contract and pull the centromeres.
What occurs during anaphase of mitosis?
Centromere of each chromosome splits allowing the sister chromatids to separate. Chromatids pulled to opposite sides of the cell
What occurs during telophase of mitosis?
new nuclear membranes around 2 sets of 46 chromosomes. Chromosomes begin to decondense. 2 diploid daughter cells formed.
What occurs during the replication division stage (meiosis I)?
two haploid cells are formed from a diploid cell. These are oogonia in females and spermatogonia in males.
What occurs during the interphase I stage of meiosis I?
replication of chromosomal DNA
What occurs during the prophase I stage of meiosis I?
chromatin strands coil and condense
What occurs during the synapsis of prophase I?
homologous chromosomes pair up, side by side, lying together in perfect alignment. Does not occur in mitosis
What occurs during the bivalent stage of prophase I?
chromatids of the 2 chromosomes intertwine. This is 2 chromosomes in a unit
What occurs during the tetrad stage of prophase I?
This is 4 chromatids intertwined in a unit
What occurs during the chiasmata stage of prophase I?
Cross-shaped structures that mark attachments between the homologous chromosomes. This indicates a point where the homologous chromosomes exchange genetic material by crossing over.
What occurs during metaphase I of meiosis I?
Completion of spindle formation and alignment of bivalents which are still attached at the chiasmata
What occurs during anaphase I of meiosis I?
chiasmata disappear and the chromosomes are pulled by the spindle fibers to opposite poles of the cell. Centromeres do not duplicate and divide, so that only half of the original number of chromosomes migrates towards each pole.