1) A reciprocal translocation occurs when pieces of two non-homologous chromosomes are exchanged without loss of genetic material.
2) In a translocation heterozygote, the chromosomes involved in the translocation cannot pair normally during meiosis I. Instead, they form a cross-shaped structure called a quadrivalent.
3) The orientation of the quadrivalent at metaphase I determines whether the gametes will receive normal or unbalanced chromosome complements, with adjacent orientations producing non-functional aneuploid gametes and explaining reduced fertility in translocation heterozygotes.
A chromosome abnormality, disorder, anomaly, aberration, or mutation is a missing, extra, or irregular portion of chromosomal DNA. It can be from an atypical number of chromosomes or a structural abnormality in one or more chromosomes
A chromosome abnormality, disorder, anomaly, aberration, or mutation is a missing, extra, or irregular portion of chromosomal DNA. It can be from an atypical number of chromosomes or a structural abnormality in one or more chromosomes
Structural Chromosomal aberrations (Change in Structure of Chromosome)Asad Afridi
this presentation is about chromosomal aberration especially change in structure of chromosome. different types of structural chromosomal aberrations are also discussed. effects of different aberration are also included.
A complementation test (sometimes called a "cis-trans" test) can be used to test whether the mutations in two strains are in different genes. By taking an example of Benzer's work, complementation has been explained.
Chromosomes are known as hereditary vehicles
They are formed of strands of DNA molecules which contain information for the development of different characteristics and performance of various metabolic activities of the cells
The coordination of various function is brought about through the formation of enzymes which are complex protein molecules
Structural Chromosomal aberrations (Change in Structure of Chromosome)Asad Afridi
this presentation is about chromosomal aberration especially change in structure of chromosome. different types of structural chromosomal aberrations are also discussed. effects of different aberration are also included.
A complementation test (sometimes called a "cis-trans" test) can be used to test whether the mutations in two strains are in different genes. By taking an example of Benzer's work, complementation has been explained.
Chromosomes are known as hereditary vehicles
They are formed of strands of DNA molecules which contain information for the development of different characteristics and performance of various metabolic activities of the cells
The coordination of various function is brought about through the formation of enzymes which are complex protein molecules
Introduction, Types-somatic and germinal; Mechanism of meiotic crossing oversynapsis, duplication of chromosomes, breakage and union, terminalization;
Cytological basis of crossing over - Stern’s experiment in Drosophila; Creighton
and McClintock’s experiment in Maize; Crossing over in Drosophila, Construction
of genetic maps in Drosophila - two point and three-point crosses; Interference and
coincidence.
In metaphase 1 of meiosis, the homologous chromosomes line up side by.pdfinfo961251
In metaphase 1 of meiosis, the homologous chromosomes line up side by side along the equator
so that (a) crossing-over (exchange of DNA regions) can occur between the homologous pairs
and (b) the homologous chromosomes can be pulled to opposite poles during anaphase 1. In
mitosis, by contrast, homologous chromosomes line up single-file along the equator. What
benefits are derived from these two different ways that homologous chromosomes are positioned
at metaphase in meiosis and mitosis?
Solution
The equatorial arrangement of chromosomes make the cell divisions to occur more
symmetrically. This chromosomal alignment is the keyspot of metazoan cell divisions. The
spindle fibers in both mitosis and meiosis relocate the metaphase plates if they are not properly
arranged. Homologous chromosomes functions differently in both mitosis and meiosis. The
homologous chromosomes in mitosis do not pair with eachother like they do in meiosis. They
line up independently at the equatorial plate whereas in meiosis they occur in pairs. The chances
of chromosomes to cross one another by mitotic recombination is very rare..
– Male and female gametes fuse together during fertilization to form a zygote. The chromosome number is halved during the formation of gametes by the process of meiosis. This maintains the chromosome number generations after generations. Meiosis leads to genetic diversity which is very essential for evolution.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
3. Translocation
• It includes all types of unilateral or
bilateral transfer of chromosome
segments from one chromosome to
another non-homologous
chromosome.
• The genetic significance of
translocation is that genes from one
chromosome are transferred to the
another chromosome.
4. Reciprocal Translocation
•When pieces of two non-
homologous chromosomes
are interchanged without any
net loss of genetic material,
the event is referred to as a
reciprocal translocation.
5.
6.
7.
8. FIGURE (a) & (b): Structure and pairing behavior of a reciprocal translocation between
chromosomes. In (b) pairing occurs during the prophase of meiosis I, after the
chromosomes have been duplicated.
Pachytene
configuration
9. • Figure (a) in last slide shows a reciprocal translocation between
two large autosomes.
• These chromosomes have interchanged pieces of their right
arms.
• If a translocation is present in one of the two sets of
chromosomes, this will be a translocation heterozygote.
• In such plants, normal pairing into bivalents is not possible
among chromosomes involved in translocation.
• Due to pairing between homologous segments of
chromosomes, a cross shaped (+) figure involving four
chromosomes will be observed at pachytene of Meiosis-
I.(Figure b of previous slide).
• This pairing configuration is diagnostic of a translocation
heterozygote.
• Cells in which the translocated chromosomes are in
homozygous condition, they do not form this pattern. Instead,
each of the translocated chromosomes pairs smoothly with its
structurally identical partner.
10. This ring quadrivalent (+) of 4
chromosomes at Pachytene of
meiosis-I can have one of
following three orientations at
Metaphase-I
1.Alternate
2.Adjacent-I
3.Adjacent-II
11. In alternate orientation, alternate
chromosomes will be oriented towards
the same pole)
Anaphase-I
Pachytene
configuration
Quadrivalent
12. In adjacent-I orientation, adjacent chromosomes having
non-homologous centromeres will move towards the same
pole.
13. In adjacent-II orientation, adjacent
chromosomes having homologous centromeres
will move towards the same pole.
14. • Alternate disjunction will give functional gametes.
• Adjacent I and adjacent-II disjunctions will form
gametes which would carry duplications and
deficiencies (aneuploid gametes).
• These aneuploid gametes will be non-functional.
• Therefore, in a plant having translocation in
Heterozygous condition, there will be
considerable pollen sterility.
• The production of aneuploid gametes by adjacent
disjunctions explains why translocation
heterozygotes have reduced fertility.
• Translocation heterozygotes are therefore
characterized by low fertility.
15. References
• Snustard, D.P. and Simmons, M.J. (2012).
Principles of Genetics (6th ed.). John Wiley &
Sons, Inc.
• Klug, W.S.; Cummings, M.R.; Spencer, C.A. and
Palladino, M.A. (2012). Concepts of Genetics
(10th ed). Pearson Education, Inc.
• Karp, G. (2010). Cell and Molecular Biology-
concepts and experiments (6th ed.). John
Wiley & Sons, Inc.
