BIOL 3333 1st Edition Lecture 18Current LectureWhat are miRNA’s distinguished by?- 60-120 ribonucleotide-long segments of reverse sequence complimentarily- this will snap back spontaneously into hairpin stem-loop structures What happens to pri-miRNA’s immediately after transcription?- they are recognized by enzyme which crops out pre-miRNA stem loops from larger RNA What happens to Pre-miRNA’s in the cytoplasm?- they undergo active transport from nucleus to cytoplasm- they are then recognized by the enzyme “Dicer”What does the Dicer do to the pre-miRNA?- it reduced it into a short-lived miRNA:miRNA duplex which si released and picked up by RISCMicro-RNA Processing:How does miRNA cleave the mRNA?- if miRNA and its target mRNA contains perfectly complementary sequencesWhat does RNase do to the cleavage product?- it degrades the cleavage product rapidlyWhat is Aneuploidy?- additions or losses of parts of the genome These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.What is a trisomic chromosome complement?2n+1What is a monosomic chromosome complement?- 2n-1What is Turner Syndrome?- a syndrome with a frequency of about 1/5000 in female births- the most frequent abnormality sees spontaneous abortuses What are the characteristics of Turner Syndrome (45,x)?- short stature- webbed neck, arms held at a characteristic angle- prepubescent secondary sex characteristics- sterile- usually normal intelligence- may show some space/form blindnessWhat is Klinefelter Syndrome (47, XXY)?- a syndrome with a frequency of about 1/1000 male birthsWhat are the characteristics of Klinefelter syndrome? - taller than normal- enlarged breasts - gynecosmastia (20 percent of those affected)- usually sterile- often depressed intelligence What is Double Y Syndrome (47, XYY)?- a syndrome with a frequency of about 1/1000 male birthsWhat are the characteristics of Double Y Syndrome?- tend to be tall- normally fertile- offspring will be normal- associated with violent behavior - slightly depressed intelligence What is Triplo-X (Trisomy X) Syndrome (47 XXX)?- a syndrome with a frequency of about 1/1000- most individuals are difficult to determine phenotypically What are the characteristics of Triplo-X syndrome?- most individuals are phenotypically normal- the frequency of mild retardation is slightly higher than 46 XX females - not usually associated with sterility In most cases, what does autosomal aneuploidy lead to?- fetal inviability*all autosomal monosomies lead to inviability*few autosomal trisomies are observedWhat is Downsyndrome (47, 21+)?- the most common of the autosomal aneuplodies - it has a frequency of 1/800 birthsWhat are the characteristics of Down Syndrome?- hypotonia; lax musculature- epicanthic eyefolds - slanting eyes- large tongue, small arched palate- unusual dematoglyphics (ridges, palm creases)- congenital heart defects- mental retardationWhat happens to the risk of down syndrome as the mothers age increases?- the risk of down syndrome increases as wellWhat is trisomy 13?- Patau Syndrome- has a frequency of about 2/10000 birthsWhat are the characteristics of Patau Syndrome (Trisomy 13)?- cleft lip and palate- cardiac abnormalities- polydactyly (additional digits)- severe mental retardation- death usually by 3 monthsWhat is trisomy 18? - Edwards syndrome - frequcnry of about 2-3/10000 births- about 80 percent of which are female What are the characteristics of Edwards syndrome (Trisomy 18)?- multuple congenital problems - often cardiac problems- low-set, malformed ears- severe mental retardation- death usually occurs within the first 6 monthsWhat is Clastogen?- a substance that can introduce chromosome breakageFound in:- chemicals- ionizing radiation- some virusesWhat is a reciprocal translocation?- breaks and fusions that occur in non homologous chromosomes but that do not affect gene expression What is a balanced translocation?- no loss of gene function- translocated genes are now accosted with different linkage groupsWhat types of chromosomes will be non-viable?- acentric and dicentric chromosomes What does adjacent segregation cause?- gene duplications and deficiencies in gametesWhat is a Protooncogene?- a normal cell gene, involved in the control of normal cell growth and proliferation (cell cycle control, transcription factor, DNA repair gene).What is an Oncogene?- a mutated/de regulated gene whose inappropriate expression leads to CANCERWhat is a Tumor Supressor Gene?- one in which the loss of gene function can lead to cancer- the Rb protein is important in cell cycle control*loss of Rb protein has same effect as inactivation and stimulates