Chromosomal Aberrations Flashcards
1
Q
Fly experiment crossing over
A
- Bred fly with 2 chromosomes with marks on them, in addition to the genes they were following (carnation and bar eye), break in X chromosome (easy to spot), other chromosome has a little piece of Y chromosome stuck (hook)
- If crossing over–> then you can get B+ gene linked with carnation, and B linked with car+, see hook associated with the broken part
–> demonstrates that chromosomes have broken and reattached (see broken chromosome with hook)
2
Q
polytene chromosomes
A
- In salivary grands
- Go through rounds of replication to amplify numbers of genes used in salivary secretions
- Microscope- see giant fat chromosomes, each has 1000 copies of DNA–> shows a characteristic banding pattern
- chromocenter- middle protein stuck
- Homologous pairs are also paired up
- *can see chromosomal aberrations in polytene chromosomes
3
Q
salivary gland of drosophila
A
polytene chromosomes can be seen
4
Q
Large Scale Chromosomal Mutations/Aberrations (4)
A
- inversion- chunk cut off and inverted
- translocation- like crossing over, genetic information reciprocal exchange,
- deletion- missing a region (forms a loop- can be seen in flies under microscope)
- duplication- 2 copies of genes
5
Q
spontaneous abortions
A
- sometimes chromosomal aberration
- all fertilized eggs–> fair percentage never implants/lost early on- kinds of spontaneous abortions that women may not be aware of (happens so early)
6
Q
2 types of chromosomal inversion
A
- paracentric- does not include centromere, not always a problem, except for in meiosis–> get one chromatid with no centromere and one with 2 centromeres (won’t get hooked up to spindle”
- paricentric- includes the centromere- get crossing over and have some chromosomes that are larger than others, effects occur during reproduction (not life)–> low fertility
7
Q
Translocation consequences (reciprocal)
A
- Swap between nonhomologous chromosoes
- When it tries to separate pairs, can be pulled in different ways
8
Q
translocation- Philadelphia Chromosome, Chronic Myelogenous Leukemia (CML), Down syndrome
A
- Break near the end of 21 and near the other end of 14
- big sections join together, and little sections join together (little often gets lost)
- -> messes with dosage
- Sometimes little part of 21 sticks in places–> down syndrome with 2 normal 21s and a small extra piece
9
Q
oncogene
A
- More than 90% of patients with chronic myelogenous leukemia show this
- translocation
- Right in the middle of types of genes that are coding for tyrosine kinase enzyme (switches around phosphate groups)
10
Q
asexual bacteria
A
- do not exchange genes when replicating/reproducing, do not form gamete
- exchange information
1. Conjugation- Exchange of genes via an F plasmid, grows pilus, sticks onto second one, creates tube, F plasmid transfers to other bacteria
2. Transformation- An acquisition of naked DNA, picks it up from environment
3. Transduction- Acquiring DNA sequences from a viral infection, bacteriophage,
11
Q
Virus
A
- considered a non-living biological entity
- Has genetic material plus a protein coat of various types
- No cytoplasm, no independent replication
- Requires a cellular host
12
Q
epigenetic mechanism
A
- histone tails can become modified in some ways
- Could be methyl groups, acetyl groups, phosphates, ubiquitination
- Controls the packing of nucleosomes- has an important affect on whether genes in that vicinity will be expressed or not
- Important when development is occurring in the differentiation process
ex. Methyl groups are important for packing DNA more tightly (like in heterochromatin)
ex. in skin cells- skin genes are on, liver genes pushed to heterochromatin - Recent years- evidence that epigenetics might be important for one generation to the next
NO epigenetic marks in egg/sperm, so they can develop ALL possible kinds of tissues
13
Q
Possible multigenerational effects for epigenetics
A
- inject pesticide into female rat
- Discovered that offspring of the exposed rat, had low sperm count–> had interfered with development of testes (could still reproduce)
- In F3–> every one of these offspring, still had poorly developed testes
- -> seems more Lamarckian- passing acquired characteristic
ex. starvation in Overkalix, Sweden
14
Q
starvation in Overkalix, Sweden
A
- effect is produced by epigenetic marks
- storm that wipes out crops–> starvation
medical- kept records–> noticed that if you had a paternal grandmother that had gone through one of these starvation period- then you (granddaughter) would have a greater risk of CVD
