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LESSON 6: GENETIC MATERIALS 2. The strands are anti-parallel (run in opposite

direction 5’ to 3’ is parallel to 3’ to 5’
What is Genetic Materials? 3. The two strands are wound round to each
 Is the heredity substance in the cell which other to form a double-helix (not a spiral)
contain specific information of an organism. 4. Two strands are joined together by hydrogen
 The genetic material can be a gene, DNA, bonds between the bases
RNA, a group of genes, DNA and RNA or it 5. The bases therefore form base pairs, which
can just be a fragment of them. are like rungs of a ladder.
 The genetic material can be found depend 6. The base pairs are specific. A only binds to
on the type of organism. T (and T with A), and C only binds to G
(and G with C)
CRITERIA OFGENETIC MATERIALS 7. These are called complimentary base pairs
(or sometimes Watson-Crick base pairs) (A-
T, and G-C)
 Information
8. This means that whatever the sequence of
 Transmission
bases along one strand, the sequence of
 Replication bases on the other strand must be
complimentary to it.
DNA AS GENETIC MATERIALS
TYPES OF DNA
- The genetic material, deoxyribonucleic acid
(dna), The code that controls much of your GENOMIC DNA/NUCLEAR DNA
body’s form and Function. Genes that do not - This genomic DNA is spread across 46
function properly can Cause disease. chromosomes leading to an expression of
genetic traits. This is very useful in the study
DEOXYRIBONUCLEIC ACID (DNA) of congenital abnormalities. However, any
deviation from the normal DNA regulation
- Deoxyribonucleic acid is an extremely long will lead to Malignancies and other
macromolecule that is the main component disorders.
of chromosomes.
- DNA is deoxyribonucleic acid and is MITOCHONDRIAL DNA
contained in your body's cells. It is a double, - mtDNA being derived from the circular
long chain of molecules called nucleotides bacterial genomes-hence mtDNA is a
that tell each cell what proteins to make. double-stranded circular molecule. mtDNA
- DNA is a nucleic acid that contains the is always maternally inherited. Mutations in
genetic instructions for the development and the mtDNA can lead to maternally inherited
function of living things. diseases.
- All known cellular life and viruses contains
DNA FORMS OF DNA
- Main role of DNA in the cell is the long –
term storage of information. A-DNA
- Is a complex molecule that contains all of - It is a right-handed double helix similar to
the information necessary to build and the B-DNA form. Dehydrated DNA takes an
maintain an organism. A form that protects the DNA during
- The three-dimensional (Double Helix) extreme condition such as desiccation.
structure of DNA was discovered in 1953 by Protein binding also removes the solvent
Watson and Crick in Cambridge from DNA and the DNA takes an A form.
MAIN FEATURE OF THE DNA B-DNA
STRUCTURE - This is the most common DNA
conformation and is a right-handed helix.
DEOXYRIBONUCLEIC ACID (DNA) Majority of DNA has a B type conformation
1. DNA is double-stranded and thus has two under normal physiological conditions.
polynucleotide strands alongside each

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Z-DNA 5' cap called 7-methylguanosine, while the 3'

- Z-DNA is a left-handed DNA where the end is polyadenylated. A poly(A) tail, which
double helix winds to the left in a zig-zag is a sequence of adenine nucleotides, is
pattern. It was discovered by Andres Wang added to the transcript during the process
and Alexander Rich. It is found ahead of the known as polyadenylation.
start site of a gene and hence, is believed to
play some role in gene regulation tRNA
- The RNA molecules known as tRNAs
RIBONUCLEIC ACID (RNA) convert mRNA into proteins. A 3' acceptor
site, 5' terminal phosphate, D arm, T arm,
- RNA stands for ribonucleic acid, which is a and anticodon arm make up their cloverleaf
long, single-stranded chain of cells that structure. With the aid of aminoacyl-tRNA
processes protein. synthetase, a tRNA's main job is to transport
- The main function of RNA is to carry amino acids to a ribosome complex on its 3'
information of amino acid sequence from acceptor site. To create proteins, enzymes
the genes to where proteins are assembled called aminoacyl-tRNA synthetases attach
on ribosomes in the cytoplasm. the proper amino acid to a free tRNA. An
- Most living things, including viruses, aminoacyl-tRNA is a tRNA that has been
contain the chemical ribonucleic acid bonded by an amino acid. The mRNA
(RNA). Nucleotides, which are ribose sugars codon, a group of three nucleotides that
joined to nitrogenous bases and phosphate codes for an amino acid, determines the kind
groups, are the building blocks of DNA. of amino acid that is present on a tRNA. The
Adenine, guanine, uracil, and cytosine are location of the anticodon, which is
some examples of nitrogenous bases. The complementary to an mRNA codon and
majority of RNA is single-stranded, determines which amino acid to carry, is on
although some unique RNA viruses are the anticodon arm of the tRNA. Through
double-stranded. The length and structure of their function as cytochrome c scavengers,
the RNA molecule might vary. Many human tRNAs control apoptosis as well.
diseases can be brought on by RNA viruses,
which have RNA as their genetic material rRNA
rather than DNA. DNA is converted into - Ribosomes, which are necessary for protein
RNA by transcription, and RNA is synthesis, are created by rRNA. There are
converted into proteins through translation. two ribosomal subunits: a large and a small
Eukaryotes and prokaryotes have different one. A prokaryotic 70S ribosome is made up
methods and mechanisms for RNA of the small 30S and large 50S ribosomal
production. subunits. The 40S and 60S subunits combine
to generate an 80S ribosome in eukaryotes.
TYPES OF RNA The ribosomes have three sites for binding
aminoacyl-tRNAs and joining amino acids
mRNA to form polypeptides: the exit (E), peptidyl
- The genetic code needed to generate (P), and acceptor (A) sites
proteins is found in mRNA, which is
produced from DNA. Prokaryotic mRNA DNA VS RNA
doesn't need to be translated; it can start
synthesizing proteins right away. A newly RNA DNA
generated RNA transcript in eukaryotes is Single-stranded molecule Double-stranded molecule
referred to as a pre-mRNA and needs to go which has a shorter chain that has a long chain of
through maturation to become an mRNA. of nucleotides nucleotides
Introns and exons, which are referred to as NITROGENOUS BASES: NITROGENOUS BASES:
coding and non-coding sections, - Adenine - Adenine
respectively, are found in pre-mRNA. The - Guanine - Guanine
exons are linked together and the introns are - Cytosine - Cytosine
spliced during the processing of premRNA. - Uracil - Thymine
The 5' end of the RNA transcript receives a

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Smaller with hundreds of Much larger than RNA

nucleotides. with millions of
nucleotides
DNA is synthesized from DNA is self-replicating
DNA
RNA contains the sugar DNA contains the slightly
ribose different sugar deoxyribose
Has nucleobase Has thymine
The RNA helix geometry is The DNA helix geometry
in the form of A. It is more is in the form of B and can
resistant to damage by be damaged by exposure of
ultra-violet rays. ultra-violet rays.
RNA is to create proteins The instructions required
via translation. for a creature to grow,
endure, and reproduce are
encoded in its DNA.
RNA is present in cytosol DNA is in the nucleus, and
and ribosomes, sometimes some are present in
in nucleus too. mitochondria.

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LESSON 7: CHROMOSOMES chromosomes have a banded structure that

unambiguously identifies each chromosome
 a threadlike structure of nucleic acids and of a karyotype.
protein found in the nucleus of most living
cells, carrying genetic information in the KARYOTYPE OF MALE
form of genes.
 A very long DNA molecule and associated - The human haploid genome contains
proteins, that carry portions of the hereditary 3,000,000,000 DNA nucleotide pairs,
information of an organism divided among 22 pairs of autosomes and
 Mendelian Genetics one pair of sex chromosome

XX-XY DETERMINATION SYTEM CHROMOSOMAL ABNORMALITIES

- The male is the heterogametic sex in - Errors in mitosis and meiosis occur; meiosis
organisms such as humans and mammals, can result in chromosomal abnormalities in
producing gametes with either an X or a Y daughter cells can leading to spontaneous
chromosome. The female's gametes are all abnormalities if those cells proceed forming
X. As a result, the sperm class determines zygote.
the sex of the offspring. - Estimate that 50% of conceptions lost and
- Two of the chromosomes (the X and the Y 50% of those losses are due to chromosomal
chromosome) determine your sex as male or abnormalities
female when you are born. They are called - Chromosomal defects accounts for 7% of
sex chromosomes: major birth defects.
o Females have 2 X chromosomes. - Individual gene account for about 8%.
o Males have 1 X and 1 Y
chromosome. NON-DISJUNCTION AND ANEUPLOIDY
- Any human cell contain 46 (somatic) or 23
CELL DIVISION (germ) chromosomes. This normal state is
called euploidy. Any variations on this
MITOSIS creates abnormality called aneuploidy.
- Mitosis is a process where a single cell Aneuploidy will cause birth defects or
divides into two identical daughter cells (cell spontaneous abortion.
division). - Aneuploidy results from germ cell having
- Mitosis is divided into five phases: three sets of same chromosomes (trisomy) or
Interphase, Prophase, Metaphase, Anaphase, one set (monosomy).
Telophase - Occurring due to nondisjunction errors
during meiosis I or II.
MEIOSIS
- Meiosis is a process where a single cell TYPES OF CHROMOSOMAL
divides twice to produce four cells ABNORMALITIES
containing half the original amount
- of genetic information. These cells are our A. Numerical - it involves the loss and / or gain of a
sex cells – sperm in males, eggs in females whole chromosome or chromosomes
- Meiosis I: Interphase, Prophase I, B. Structural - it involves changes in the structure of
Metaphase I, Anaphase I, Telophase I one or more chromosomes.
- Meiosis II: Prophase II, Metaphase II, a. Constitutional
Anaphase II, Telophase ii b. Acquired

STAINED CHROMOSOMES TRISOMY 21

- Chromosomes are stained with A-T (G - Trisomy of chromosome 21 is known as

bands) and G-C (R bands) base pair specific Down syndrome.
dyes. When they are stained, the mitotic

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- People with this condition have varying CHARACTERISTICS

degree of mental capability ranging from - Deletion have been diagnosed with
profound deficits to nearly full social developmental delay or autistic
functioning with accommodation. characteristics. Other people with the
16p11.2 deletion have no related health or
CHACTERISTICS OF TRISOMY 21 behavioral issues, therefore the deletion may
- Growth Delays go undetected
- Immune system problems
- Flattened facial features CAUSES AND INHERITANCE
- Epicanthal folds of the eyes - People with deletion 16 karyotype syndrome
lack a sequence of around 600,000 DNA
Risk of trisomy 21 (and all non-disjunct ion events) building units (base pairs), sometimes
increases with maternal age. known as 600 kilobases (kb), on
chromosome 16.
DELETION 10 - Affected persons usually have no family
history of the ailment, but they can pass it on
-Chromosome 10, distal trisomy 10q is a to their offspring. There have been several
chromosomal disease in which the end reports of inherited 16p11.2 deletions. Other
(distal) section of one chromosome 10 (10q) family members may be affected in inherited
appears three times (trisomy) rather than situations.
twice in body cells.
DIAGNOSIS OF DELETION 10 TRANSLOCATION 2:15
- The illness is distinguished by abnormally
slow growth both before and after birth; - In individuals with Chromosome 15, Distal
(hypotonia); mild to severe intellectual Trisomy 15q, an extremely rare
incapacity; and mild to severe delays in the chromosomal disorder, the end (distal)
acquisition of skills requiring coordination portion of the long arm (q) of chromosome
of mental and physical processes. 15 (15q) is duplicated (trisomic).

CHARACTERISTICS OF DELETION 10 SIGNS AND SYMPTHOMS

- Affected newborns and children may also - The disorder is characterized by growth
have (craniofacial) malformations; hand delays before and/or after birth (prenatal
and/or foot problems; and/or skeletal, heart and/or postnatal growth retardation); mental
(cardiac), kidney (renal), and/ or breathing retardation; and/or distinctive malformations
(pulmonary) abnormalities. of the head and facial (craniofacial) area.

DELETION 16 KAYOTYPES CAUSES OF TRANSLOCATION (2:15)

- The duplication of the distal portion of
- 16p11.2 deletion syndrome is characterized chromosome 15q is responsible for the
by developmental delay and intellectual symptoms and physical features that
impairment. Most have at least some characterize this disorder. The range and
characteristics of autism spectrum disorders. severity of associated abnormalities may
These disorders are distinguished by depend upon the exact length and location of
impaired communication and socializing the duplicated portion of chromosome 15q.
abilities, as well as delayed speech and AFFECTED POPPULATION
language development. - Chromosome 15, Distal Trisomy 15q is an
- Expressive language abilities (vocabulary extremely rare chromosomal disorder that is
and speech production) are often more thought to affect males approximately twice
severely impacted than receptive language as often as females.
skills in 16p11.2 deletion syndrome (the
ability to understand speech). Recurrent INVERSIONS
seizures occur in some patients with this - A portion of the chromosome has broken
condition (epilepsy) off, turned upside down and reattached,
therefore the genetic material is inverted.

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- Chromosome 7, Partial Monosomy 7p is a

IDEOGRAM rare chromosomal disorder that appears to
- Ideograms provide a schematic affect males and females in relatively equal
representation of chromosomes. They are numbers. More than 30 cases have been
used to show the relative size of the reported in the medical literature
chromosomes and their characteristic
banding patterns. DELETION 13

DELETION 7 - Chromosome 13, Partial Monosomy 13q is a

rare chromosomal disorder in which a
- Chromosome 7, Partial Monosomy 7p is a portion of the long arm (q) of chromosome
rare chromosomal disorder characterized by 13 is missing (deleted or monosomic). The
deletion (monosomy) of a portion of the range and severity of symptoms may vary
short arm (p) of chromosome 7 (7p). greatly, depending upon the exact size and
- Associated symptoms and findings may be location of the deletion on 13q.
variable and may depend on the specific size
and location of the deleted segment of 7p.
- However, in many cases, there is early
closure of the fibrous joints (cranial sutures) SIGN AND SYMPTOMS
between certain bones of the skull - Partial Monosomy 13q is usually apparent at
(craniosynostosis), resulting in an birth and may be characterized by low birth
abnormally shaped head. weight, malformations of the head and facial
(craniofacial) area, abnormalities of the
SIGNS AND SYMPTHOMS eyes, defects of the hands and/or feet,
- the symptoms and physical findings genital malformations in affected males,
associated with Chromosome 7, Partial and/or additional physical abnormalities.
Monosomy 7p may vary in range and Affected infants and children may also
severity from case to case. However, many exhibit delays in the acquisition of skills
affected individuals have growth delays requiring the coordination of mental and
before and after birth (prenatal and postnatal muscular activity (psychomotor retardation)
growth retardation). The syndrome may also as well as varying degrees of intellectual
be associated with varying degrees of disability.
psychomotor retardation and mental
retardation; however, as noted earlier, some AFFECTED POPULATION
affected individuals may have normal - Chromosome 13, Partial Monosomy 13q
intelligence. appears to affect females slightly more
frequently than males. Although rare,
CAUSES deletions involving chromosome 13q are
- In individuals with Chromosome 7, Partial among the most commonly observed
Monosomy 7p, there is deletion monosomies. Since the disorder was
(monosomy) of a portion of the short arm originally reported in 1963, more than 125
(p) of chromosome 7. In most cases, cases have been recorded in the medical
Chromosome 7, Partial Monosomy 7p literature.
appears to be caused by spontaneous (de
novo) errors during early embryonic CAUSES OF DELETION 13
development that occur for unknown - Chromosomes are found in the nucleus of all
reasons. In such instances, the parents of the body cells. They carry the genetic
affected child usually have normal characteristics of each individual. Pairs of
chromosomes and a relatively low risk of human chromosomes are numbered from 1
having another child with the chromosomal through 22, with an unequal 23rd pair of X
abnormality. and Y chromosomes for males and two X
chromosomes for females. Each
AFFECTED POPPULATION chromosome has a short arm designated as

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“p” and a long arm identified by the letter recombination are a dicentric 13;14 and the
“q”. small, short arm recombination product,
which lacks a centromere. This latter,
acentric chromosome fragment is usually
lost in subsequent cell replications and
divisions.
DELETION 14

- Chromosome 14q deletion is a chromosome

abnormality that occurs when there is a
missing (deleted) copy of genetic material
on the long arm (q) of chromosome 14. The
severity of the condition and the signs and
symptoms depend on the size and location
of the deletion and which genes are
involved.

SIGN & SYMTOMS

- Features that often occur in people with
chromosome 14q deletion include
developmental delay, intellectual disability,
behavioral problems and distinctive facial
features. Chromosome testing of both
parents can provide more information on
whether or not the deletion was inherited. In
most cases, parents do not have any
chromosomal anomaly.

TREATMENT & INHERITANCE

- However, sometimes one parent is found to
have a balanced translocation, where a piece
of a chromosome has broken off and
attached to another one with no gain or loss
of genetic material.
- The balanced translocation normally does
not cause any signs or symptoms, but it
increases the risk for having an affected
child with a chromosomal anomaly like a
deletion. Treatment is based on the signs and
symptoms present in each person.

DICENTRIC 13;14

- Diagram of the creation of a Robertsonian

translocation involving chromosome 13
(purple) and chromosome 14 (orange).
These ideograms (dark and light bands)
represent the G-banding pattern of the
respective chromosomes. The light
horizontal line (far left and far right)
indicates the positions of the centromeres.
- When breakage and reunion occur in the
short arms of each (indicated by the
lightening bolt), the resultant products of

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