Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
Double fertilization is the process found in angiosperms in which out of the two male gametes released inside the embryo sac, one fuses with the egg cell (syngamy) and another fuse with secondary nucleus (triple fusion).
Megasporogenesis is the process of formation of megaspores from the megaspore mother cell.
In the hypodermal region of nucellus towards the micropylar end develops a primary archesporial cell.
Dr. T. Annie Sheron
Annie Sheron
Kakatiya Government College
The Shoot apex is also known as the terminal bud of plants that grows from 0.1-1.0 mm and consists of the apical meristem, developing leaves and the immediate surrounding leaf primordial. The shoot apex is present in both dicot and monocot plants.
Pteridophytes are vascular plants and have leaves (known as fronds), roots and sometimes true stems, and tree ferns have full trunks. Examples include ferns, horsetails and club-mosses. Fronds in the largest species of ferns can reach some six metres in length!
Many ferns from tropical rain forests are epiphytes, which means they only grow on other plant species; their water comes from the damp air or from rainfall running down branches and tree trunks. There are also some purely aquatic ferns such as water fern or water velvet (Salvinia molesta) and mosquito ferns (Azolla species).
Pteridophytes do not have seeds or flowers either, instead they also reproduce via spores.
There are around 13,000 species of Pteridophytes.
Double fertilization is the process found in angiosperms in which out of the two male gametes released inside the embryo sac, one fuses with the egg cell (syngamy) and another fuse with secondary nucleus (triple fusion).
Megasporogenesis is the process of formation of megaspores from the megaspore mother cell.
In the hypodermal region of nucellus towards the micropylar end develops a primary archesporial cell.
Dr. T. Annie Sheron
Annie Sheron
Kakatiya Government College
The Shoot apex is also known as the terminal bud of plants that grows from 0.1-1.0 mm and consists of the apical meristem, developing leaves and the immediate surrounding leaf primordial. The shoot apex is present in both dicot and monocot plants.
Pteridophytes are vascular plants and have leaves (known as fronds), roots and sometimes true stems, and tree ferns have full trunks. Examples include ferns, horsetails and club-mosses. Fronds in the largest species of ferns can reach some six metres in length!
Many ferns from tropical rain forests are epiphytes, which means they only grow on other plant species; their water comes from the damp air or from rainfall running down branches and tree trunks. There are also some purely aquatic ferns such as water fern or water velvet (Salvinia molesta) and mosquito ferns (Azolla species).
Pteridophytes do not have seeds or flowers either, instead they also reproduce via spores.
There are around 13,000 species of Pteridophytes.
This is a slide for complete development in chick ,as chick is a vertebrate so with the help of the development in a chick we can we can understand development in vertebrates .
This topic explains the whole process of growth and development in animal the processes include
Fertilization and incubation
Cleavage
Morula
Blastula
Gastrulation
Notochord And Mesoderm Formation
Neurulation
description of different types of reproductive organs, developmental stages and process of reproduction in Cycas. Various internet sources have been used.
The Slides contains are Female Reproductive part of Flower (Carpels/Pistils), Structure of Ovule, Types of Ovules, Microsporogenesis, Megasporogenesis, Structure of Pollen Grain, Structure of Embryo Sac
This is a Life Cycle of Shpagnum, A good content for Masters Students. (But this content is not made by me...but i thought that this will help many students who are in search for content)
Thank you 😊
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.
This presentation intends to explore the communication of the cell within and others for sustainability along the regulation mechanisms by the cellular neural networks and others to sing the song of the life.
Bioenergetics is an important domain in biology. This presentation has explored ATP production and its optimum utilization in biological systems along with certain theories and experiments to give a bird's eye view of this important issue.
This presentation offers the bird's eye view of the cell as the basic structural and functional unit of life. It also addresses the origin of eukaryotic cells from the prokaryotic cell by the endosymbiotic theory.
This presentation has been intended to offer a bird's eye view about the phylogenetic classification of the plant kingdom in general and the Engler and Prantl system in particular with merits and demerits.
This PPT has been made to explore the plant classification in general and the classification as made by Bentham & Hooker for the classification of the flowering plants. It also offers the history of plant classification along with the merits and demerits of this aforesaid classification.
Energy and the biological systems are joined together and no biological world is almost impossible without ATP. This study material intends to explore the beauty of ATP to drive different biological processes.
This PPT offers a bird's eye view of ICBN and its different rules along with regulations for the naming of plants. It also highlights the history of IBC and its contribution to plant taxonomy.
This presentation intends to offer the basic features of plant metabolism along with the different types of mechanisms to regulate and control the metabolic pathways.
This presentation has been designed to give the foundation of taxonomy in general and Plant Taxonomy in particular as a matter of pleasure to explore the diversity of the plant world.
Sex and sexuality are very common words in biology but para-sexuality is a little bit uncommon, several organisms in general and fungi in particular have the pleasure of sexuality to bring variations by beside sex. This PPT explores the beauty of para-sexuality for the academic fraternity.
Sex life in fungi is not less fascinating than in other organisms. Heterosexuality is a matter of pleasure to explore the diversity of sex in fungi along with its cause and consequences. You can find a pleasure to go through the content.
This PowerPoint wants to explore the bird's eye view of the reproduction of bacteria in general and the genetic recombination of bacteria in particular.
This presentation gives the bird's eye view of bacterial nutrition along with some other issues required to understand bacterial diversity as far as nutrition is concerned.
This presentation explores the food value of mushrooms along with the long-term and short-term storage procedures. It also offers a detailed account of the nutrients that remain present in the edible mushrooms.
If you want to explore the role of Cyanobacteria in soil fertility in general & Azolla-Anabena association in particular, you can visit this PowerPoint Presentation.
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.
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.
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.
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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
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Monitor common gases, weather parameters, particulates.
1. PLANT EMBRYOLOGY
Welcome to the development of Dicot & Monocot Embryo
By
N.Sannigrahi, Associate Professor of Botany
Nistarini College, Purulia(W.B) India
2. EMBRYO-DICOT & MONOCOT
• The plant embryo, sometimes called the seed embryo, is the part of a seed or bud
that contains the earliest forms of a plant's roots, stem and leaves. The embryo
develops after a fertilized adult plant flowers, and is generally contained within a
seed or bud. It acts as a sort of "starter kit" for the plant: When conditions are
right for the seed to grow, the embryo 'activates' and begins germination,
eventually becoming a seedling when it grows out of its container.After
fertilization, the fertilized egg is called zygote or oospore which develops into an
embryo. The oospore before it actually enters into the process undergoes a period
of rest which may vary from few hours to few months. Generally the zygote
(oospore) divides immediately after the first division of the primary endosperm
nucleus.
• Unlike gymnosperms where the early stages of the development show free
nuclear divisions the first division of zygote is always followed by wall-
formation resulting in a two-celled pro-embryo. Practically there are no
fundamental differences in the early stages of the development of the embryos of
monocots and dicots.
4. DICOT EMBRYO
• According to Soueges, the mode of origin of the four-celled pro-embryo and the
contribution made by each of these cells makes the base for the classification of the
embryonal type. However, Schnarf (1929), Johansen (1945) and Maheshwari (1950)
have recognized five main types of embryos in dicotyledons. For the first time Hanstein
(1870) worked out the details of the development of embryo in Capsella bursa- pastoris,
a member of Crucifeae.
• The oospore divides transversely forming two cells, a terminal cell and basal cell. The
cell towards the micropylar end of the embryo sac is the suspensor cell (i.e., basal cell)
and the other one makes to the embryo .cell (i.e., terminal cell). The terminal cell by
subsequent divisions gives rise to the embryo while the basal cell contributes the
formation of suspensor.
• The terminal cell divides by a vertical division forming a 4-celled 1-shaped embryo. In
certain plants the basal cell also forms the hypocotyl (i.e., the root end of the embryo) in
addition of suspensor. The terminal cells of the four-celled pro-embryo divide vertically
at right angle to the first vertical wall forming four cells. Now each of the four cells
divides transversely forming the octant stage (8-celled) of the embryo.
6. STAGES OF DEVELOPMENT
• The four cells next to the suspensor are termed the hypo-basal or posterior
octants while the remaining four cells make the epibasal or anterior octants.
The epibasal octants give rise to plumule and the cotyledons, whereas the
hybobasal octants give rise to the hypocotyl with the exception of its tip.
Now all the eight cells of the octant divide periclinally forming outer and
inner cells.
• The outer cells divide further by anticlinal division forming a peripheral
layer of epidermal cells, the dermatogen. The inner cells divide by
longitudinal and transverse divisions forming periblem beneath the
dermatogen and plerome in the central region. The cells of periblem give
rise to the cortex while that of plerome form the stele.
• At the time of the development of the octant stage of embryo the two basal
cells divide transversely forming a 6-10 celled filament, the suspensor
7. STAGES
• which attains its maximum development by the time embryo attains globular
stage.
• The suspensor pushes the embryo cells down into the endosperm.
• The distal cell of the suspensor is much larger than the other cells and acts as a
haustorium. The lowermost cell of the suspensor is known as hypophysis. By
further divisions, the hypophysis gives rise to the embryonic root and root cap.
• With the continuous growth, the embryo becomes heart-shaped which is made up
of two primordia of cotyledons. The mature embryo consists of a short axis and
two cotyledons. Each cotyledon appears on either side of the hypocotyl. In most
of dicotyledons, the general course of embryogenesis is followed as seen in
Capsella bursa-pastoris.
9. DEVELOPMENTAL STAGES
• There is no essential difference between the monocotyledons and the
dicotyledons regarding the early cell divisions of the proembryo, but the mature
embryos are quite different in two groups. Here the embryogeny of Sagittaria
sagittifolia has been given as one of the examples.
• The zygote divides transversely forming the terminal cell and the basal cell. The
basal cell, which is the larger and lies towards the micropylar end, does not
divide again but becomes transformed directly into a large vesicular cell. The
terminal cell divides transversely forming the two cells. of these, the lower cell
divides vertically forming a pair of juxtaposed cells, and the middle cell divides
transversely into two cells.
• In the next stage, the two cells once again divide vertically forming quadrants.
The cell next to the quadrants also divides vertically and the cell next to the upper
vesicular divides several times transversely. The quadrants now divide
transversely forming the octants, the eight cells being arranged in two tiers of
four cells each. With the result of periclinal division, the dermatogen is formed.
10. DEVELOPMENTAL STAGES
• Later the periblem and plerome are
also differentiated. All these regions,
formed from the octants develop into
a s i n g l e t e r m i n a l c o t y l e d o n
afterwards. The lowermost cell L of
the three-celled suspensor divides
vertically to form the plumule or stem
tip. The cells R form radicle. The
upper 3-6 cells contribute to the
formation of suspensor.
• Stages in the development of a typical
monocot embryo in Sagittaria
