DNA: Quiz- WE ARE ALL MADE UP OF DNA
• How many nucleotides are in Deoxyribonucleic acid (DNA)?
4 NUCLEOTIDES (A,G=PURINE ; C,T=PYRAMIDINE)
• Where is DNA found? NUCLEUS
• How does DNA methylation change the way exons are transcribed in the lipophorin receptor gene of
• How could researchers distinguish the DNA of African rhinoceros (Diceros bicornis) from Indian
Rhinoceros (Rhinoceros unicornis?)
Probe to catch rhino poacher
Rhinoceros horn—the natural, but politically incorrect version of viagra—can now be protected from
poachers using DNA technology. Scientists at the National Institute of Immunology in India (NII; New
Delhi) have just completed six months of tests on a DNA detection device that has not only been
shown to detect rhino horn but also to tell whether the specimen comes from India or elsewhere. "It
will be a valuable weapon in the hands of conservationists wanting to track down the source of rhino
horn in the illegal market," says Sher Ali, head of NII's molecular genetics laboratory. Ali and his
colleagues have discovered a repetitive 906 base pair DNA sequence that is unique to
India's one-horned rhinoceros (Rhinoceros unicornis). The sequence is not present in the
closely related African double-horned black rhinoceros (Diceros bicornis) or any other
species of rhino. "This distinguishing feature will help identify if a particular horn came
from India or Africa," says Ali. The great Indian one-horned rhino is an endangered species—
currently numbering about 2000—and is confined to three or four protected forests in Assam and West
Bengal in eastern India.
• DNA from poached rhinoceros horn compared to reference samples Lecture 14:
Chromosomes: Quick Quiz
• How many chromosomes do humans have? 46 diploid, 23 haploid
• What is the composition of chromosomes in a skin cell and a sperm cell?
Skin cell- 46 chromosomes, diploid
Sperm cell- 23 chromosomes, haploid
• How does mitosis change the number of chromosomes? In interphase, the DNA is replicated not in
mitosis. Mitosis separate the duplicated chromosmes and put them in each cell. Thus each daughter
cells have the same chromosome number with the original cell.
Polytene chromosomes from salivary gland= 4 chromosomes
Aneuploidy- diploid number is not multiple of haploid number
-chromosome abnormality: missing or extra chromosome
Haplodiploidy- sex determination system
-males are haploid; females are diploid
-eg. Ants and bees
Heterogametic-WZ (female birds)
Homogametic- ZZ (male birds) **Grasshopper- XX(even chromosome #) X(odd chromosome number)
**Zebra fish- region in chromosome 4?-still in research
G1/S phase transition is important because one of the hallmarks of cancer is the loss of normal control
of the transition.
Cytokinesis usually begins while mitosis is still in progress.
In animals: FURROW-contractile ring is made of microfilaments, motor proteins move like draw strings
In plants: CELL PLATE- vesicles in the midpoint plane, extend across, eventually become cell plate
THE F FACTOR AND CONJUGATION
The transfer of genetic material during conjugation:
A. Transfer of the F factor
- NO CHROMOSOMAL DNA IS TRANSFERRED. JUST THE fertility plasmid of (F factor)
B. Transfer of bacterial genes
- F factor integrates with the chromosomal DNA becomes (HfR CELL)
- Recombination during the cross over during the transfer of F+ to F-, conjugating pair
- The recipient remains F- since not all the F factor is transferred.
**The inverted repeat sequence is an IS element on both the F factor and the Bacterial chromosome
that provides the homology needed for the creation of the Hfr strains.
**In a number of bacterial transposons, the inverted repeat sequences are insertion sequences, which
provide the transposase (this is the central region which contains antibiotic resistance) for movement of
the element. These non-IS genes included in transposons are carried along as the TEs move from place
to place. conjugation LECTURE 15
Meiosis and Heredity: Quick Quiz
• How many chromosomes do humans have from their mother? 23 CHROMOSOMES, HAPLOID
• How many sets of chromosomes are in:
A cell during anaphase I? diploid
A cell during anaphase II? haploid
How does meiosis change the number of chromosomes?
* What strain of E. coli caused illness?
Trisomy x female xx+x
Turner’s syndrome x+ 0
Male klinefelter’s xx+y
GENETIC VARIABILITY DURING MEIOSIS;
1. GENETIC RECOMBINATION
2. RANDOM SEGREGATION IN PROMETAPHASE I ANAPHASE I
3. ALTERNATIVE COMBINATION AT MEIOSIS II- RANDOM ASSORTMENT IN
METAPHASE II ANAPHASE II
4. RANDOM FERTILIZATION
TRANSPOSABLE ELEMENTS IN EUKARYOTES
Mapping the alleles by linkage studies produced a surprising result: the map positions changed
frequently, indicating that the alleles could move from place to place in the corn chromosomes.
• Genetic mosaic: Inactivated X-chromosome is cell independent: some cells have inactivated maternal
chromosomes others have inactivated paternal chromosomes EPISTASIS
-gene for the orange fur is on the X chromosome LECTURE 16
Peas: Quick Quiz
• How many phenotypes would you expect among the progeny of the following genetic cross:
• RRYYTT x rryytt ?
• What is the genotype of a pure-breeding purple-flower pea plant? PP
• How does independent assortment explain Mendel’s experimental data with dihybrid crosses in pea
plants? THE COMBINATION OF DIFFERENT ALLELES PAIR INDEPENDENTLY
• Product rule: The probability of two independent events occurring simultaneously is the product of
each of their respective probabilities
• Sum rule: The probability of either of two mutually exclusive events occurring is the sum of their
individual probabilities. LECTURE 17
Pedigrees: Quick Quiz
• How many phenotypes would you expect among the progeny of the follow