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DNA is located in
chromosomes
What is a genome?
collective genetic information of an organism
What nature of the gene was discovered in 1865?
discrete units of inheritance by Gregor Mendel
What nature of the gene was discovered in the 1880s?
chromosomes
what nature if the gene was discovered in 1903
homologous chromosomes
what nature of the genes was discovered from 1909 to 1911?
Crossing over during Meiosis
what nature of the gene was discovered from 1911 to 1913?
Genes are mapped in order along the length of chromosomes
what nature of the gene was doscovered mfrom 1944 to 1952?
DNA as genetic material
what nature of the gene was discovered during 1953?
DNA structure
Mendel's work on garden peas became the foundation for:
genetics
Why did mendel chose garden peas in his work?
they have clearly definable 2 alternative traits
Mendel's experiment on his pea plants gave rise to:
Laws of Inheritance
Characteristics of organisms are governed by units of inheritance called
genes
What is an allele
2 forms of a gene that controls each trait
what is a gamete?
reproductive cell containing one gne for each trait
how many alleles are inherited?
2; 1 from each parent
what are the 4 concepts of geen as a unit of inheritance?
Characteristics of oraganisms are governed by units of inheritance 2. A reproductive cel called gametre contains one gene for each trait 3. 2 pairs of genes are segregated during gamete formation 4. Genes controlling different traits segregate independently of each other.
How was chromosomes first discovered?
in dividing cells under the light microscope
What happens to chromosomes during cell division?
they divide equally into two daughter cells
Before cell divion, chromosomeese are
already doubled
What is a homologous chromosomes?
one of the two pairs of chromatids that forms chromosomes
what happens to the homologous chromosomes during meiosis?
they associate to form a BIVALENT; then separate into different cells
to what concept in genes is the chromosmal behavior be correlated wityh
Mendelian Laws of Inheritance
genes on the same chromosome do not:
assort independently
the genes on the same chromosome are part of the same:
linkage group
the locations of the traits Mendel observed are
part of the same linkage group
Why is drosophilia used as a genetic tool?
they have 4 pairs of homologous chromosomes, they can mutate (from red eyes to white), easier to access and lays egg quickly, have shortwer life span
Linkage between alleles on the same chromosme is
incomplete
when can maternal and patrnal chromosomese can exchange pieces?
during crossing over or geentic recombination
what is a homolog/ homologue?
gene inherited in two species from a common ancestor
what is a chiasmata?
points where homologues are crossed
percentage of recombination between a pair of genes is:
constant
percentage of recombination between diffferent pair of genes can be
different
Positions of genes along a chromosome can be
mapped
what happens to the frequency of recombination when the distance increases?
frequency of recombination increases also
what are polytene chromosomes?
these are single chromosome found in cells that can undergo in consecutive genome replicatipon without breaking the nuclear envelope
how are polytene chromosomes formed?
when chromatids of diploid nuclei chromosomes duplicate successively during S-PHASE without segregation, the cable-like structure products are compacted to form one giant chromosome
function of puffs in polytene chromosome
visualization of gene expresion
siginifaincance of polytene chromosomes
observing specific band related to individual genes
building block of DNA
nucleotide
parts of a nuclotide
phosphate group, deoxyribose sugar, nitrogenous base
two types of nitrogenous bases?
purine, pyrimindine
Purine
Adenine Guanine
Pyrimidine
Cytosine Thymine
polarized structures of nucleotides have ends called
5' and 3'
what links the sugar and phosphates in the DNA
3' , 5'- phosphodiester bonds
Chargaff rules were established after
base composition analysis A=T and C=G
What is the structure of DNA based on the Watson-Crick proposal
double helix
DNA has ___ chains of nucleotides
two
The two chains of DNA are
antiparallel
what is the meaning of antiparallel?
run I opposite directions
the sugar-phosphate background in DNA is located at the ___, while the bases are _____
outside of the molecule; inside the helix
what holds the DNA chain at their bases?
hydrogen bonds
the DNA molecular has __ and __ grooves
major and minor
what is the major groove?
the oxygen molecule in the deoxyribose ring is always pointed up in the correct orientation 5' to 3'
what is the minor groove?
the oxygen molecule in the deoxyribose ring is always pointed down in the correct orientation 5' to 3'
the two chains in DNA are ___ to each other
complementary
The 3 importance of the Watson-Crick proposal?
storage of genetic information 2. reolication of inheritance 3. expresion of the genetic message
what is supercoiling?
it is the coiling of the DNA in favor of many complex cell processes to take plaxce
when the DNA is more compact than its relaxed counterpart, it is then considered to be
supercoiled
an underwound DNA is ____ supercoiled while an overwound DNA is ___ supercoiled
negatively; positively
an underwould molecule assumes a _____
negatively supercoiled conformation
what does negative supercoiling does to the DNA in cell nucleus?
it makes the DNA fit
what enxyme changes the DNA supercoiling?
topoisomerase
function of type II topoisomerase?
change supercoiled state by CREATING A TRANSIENT BREAK IN ONE STRAND OF THE DUPLEX
function of type I topoisomerase?
make atransient break in both ends of the DNA duplex
what is denaturation in DNA
its ability to separate into two strands
what is renaturation or reanneling?
it happens when a single-stranded DNA molecules reassocites
some of the products of the discovery of renaturation?
development of nucleic acid hybridization
what is nucleic acid hybridization?
complementary strands of nuclic acids from different sources can form hybrid molecules
Three classes of DNA reannealing and their sequence in increasing Cot
Highly repeated, moderately repeated, Nonrepeated
How many percent does highly repeated DNA sequences can represent the total DNA
1 to 10 %
what is a satellite DNA
short sequences; tend to evolve rapidly
what is a minisatellite DNA and its function
unstable; variable in population; basis of DNA fingerprinting
process of DNA fingerprinting
Restriction endonucleases digest the DNA and DNA fragments are separated via gel electrophoresis
what is microsatellite DNA and its functiom
shortest sequences in small clusters; detect genetic disorder
what happenes during Fluorescent in situ hybridization
DNA probe that is hybridized into chromosomes are used to determine position of satellite sequences
the process of Fluorescent in situ hybridization
fluorescent probes are generated towards a specific DNA sequence 2. Probed hybridize with DNA 3. Fluorescent spots determines gene/DNA location
what are the 2 types of moderately repeated DNA sequences
repeated DNA sequences with coding functions 2. repeated DNA sequences without coding fucntions
examples of repeated DNA sequence woth coding functions
genes for RIBSOSOMAL RNA and HISTONES
what products does repeated dna sequence without coding functions have
none. They do not have any gene product
repeated dna sequence without coding functions have 2 classes:
SINEs or LINEs
what are trinucleotide repeats
they causes mutations in repeating unit of 3 nucleotides
when trinucleotide repeats occur the mutant alleles are
highly unstable
when trinucleotide repeats occur what happens to the number of repeating units
increase when the gene is passed from parent to offspring
Type I diseases in expanision of trinucleotide repeats, which are all nuerodegeneratic disorders result from
expansion of CAG trinucleotides
huntington's disease is caused by __ and from what gene
36 glutamine repeats in the huntingtin gene
the expanded glutamine repeats in huntington's disease are toxic to
brain cell
the type II diseases classified under the expansio of triucleotide sequence are present in
gene parts that do not code for an amino acid
what is polyploidization
whole genome replication; occurs when offspring receive more than 2 pairs of chromosomes
what is the function of the unequal crossing over of duplicated genes
generate changes in gene number
gne duplication happens within?
a portion of a single chromosome
how does gene duplication occur
unequal crossing over between misalogned homologous chromosomes
gene duplication played a major role in
evolution of multigene families
what genes are part of the globin genes?
myoglobin, hemoglobin, leghemoglobin
how was globin genes derived
duplication, gene fusion, divergence
what are pseudogenes
nonfunctional sequences that resembles globin genes
what is transposition
genetic elements moves within a chromosome
what are transposable elements
mobile elements that can move in the chromosome
funciton of the enzyme tranposase
facilitate insertion of transposons to the target site
Note
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