1) Plants have meristematic tissues that allow for indeterminate growth, including apical meristems at the tips of roots and shoots that initiate primary growth.
2) There are three primary meristem types - protoderm, procambium, and ground meristem - that give rise to the primary plant body.
3) Meristematic cells later differentiate into various cell types like parenchyma, collenchyma, and sclerenchyma cells that make up the different plant tissues.
This subject is designed to enhance the understanding of the principles and concepts in the study of biology, particularly heredity and variation, and the diversity of living organisms, their structure, function, and evolution
This subject is designed to enhance the understanding of the principles and concepts in the study of biology, particularly heredity and variation, and the diversity of living organisms, their structure, function, and evolution
Introduction to Life Science and The Theories on the Origin of LifeSimple ABbieC
I. Introduction to Life Science
II. The Concept of Life
III. Characteristics of Life
IV. Theories on the Origin of Life
V. Unifying Themes in the Study of Life
Introduction to Life Science and The Theories on the Origin of LifeSimple ABbieC
I. Introduction to Life Science
II. The Concept of Life
III. Characteristics of Life
IV. Theories on the Origin of Life
V. Unifying Themes in the Study of Life
A plant has two organ systems: 1) the shoot system, and 2) the root system. The shoot system is above ground and includes the organs such as leaves, buds, stems, flowers (if the plant has any), and fruits (if the plant has any). The root system includes those parts of the plant below ground, such as the roots, tubers, and rhizomes.
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.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
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.
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 .
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
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.
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.
4. Meristems
-enables plants to have
indeterminate growth
Apical meristems –tip of roots
and shoots
-initiate primary growth in the
length of roots and shoots
Primary Plant Body
Lateral/Secondary Meristem
Secondary Growth
4
12. Outer protective
covering (physical
damage desiccation)
Begins as parenchyma
cells then modifies
Helps control the
exchange of gases and
water vapor
Epidermis
Periderm
Cuticle
12
15. Makes up the plant’s bulk
Cortex
-between dermal and
vascular tissues
*storage of food
Pith
-between phloem and
xylem
-soft spongy parenchyma
cells
*nutrient storage and
transport
http://extension.oregonstate.edu/mg/botany/im
ages/fig3-big.gif
http://en.wikipedia.org/wiki/Pith
15
17. Raven, P.H. , Evert, R.F. and Eichhorn, S.E. 1999.
Biology of Plants 6th Ed. W.H. Freeman and Co.
Worth Publishers, USA. 944 pp.
Nabors, M.W. 2004. Botany an Introductory
Approach. Pearson Education South Asia Pte.
Ltd. 626pp.
Diola, A., Dy., D., Ilano, A., Inoc, D.C., Oquinena,
K., Parilla, R., Tambuli, A. and Yee, J. 2010.
Natural Science 1 (Biological Sciences) Lecture
Notes. University of San carlos, 126 pp.
Starr, C. 2003. Biology: Concepts and
Applications, 5th ed. Brooks/Cole, USA. 799 pp.
17
Editor's Notes
Shoot System – upper part
Stem- supports upright growth; conduction of substances
Leaves –photosynthesis
Flowers –reproductive structure that attracts pollinators
Root System – specialized; penetrates soil (except for few); spread downward and sideward
Function: absorb water and dissolved nutriets; anchorage; stores food
Primary plant body –produced by shoot and root apical meristem
Primary meristems –regions of cell growth
Protoderm –produces the primary dermal tissue system or epidermis
Procambium –produces the primary vascular system (phloem, xylem)
Ground system –produces the ground or fundamental tissue system (neither conducting and dermal tissues)
Lateral meristem –makes plants woody; causes thickening of stems and roots
Secondary growth –growth in thickness produced by lateral meristems
Meristematic Cells –unspecialized cells that can divide indefinitely to produce new cells
Meristems –regions that produce new growth
Initials –meristematic cells that remain within meristems as sources of new growth; one of the daughter cells
Derivative –other daughter cell that is pushed out of the meristem divides or begins elongation and differentiation
Differentiation –process where an unspecialized cell becomes a specialized cell
with secondary walls hardened by lignin
-more expensive to produce (cellulose making up the secondary walls)
-less common in smaller plants
-typically dead in maturity
*provides rigid support
Types:
Fibers
Sclereids (stone cells) –rockhard and inflexible (nutshell and fruit pits); gritty sand-like structures (pears
Vascular plants –with highly organized and efficient vascular tissues consist of cells joined into tubes that transport water and nutrients throughout the plant’s body; majority of plants; evolved from algae-like ancestors
Epidermis –one layer of dismal tissue (first year of growth)
Periderm –replaces epidermis of stems and roots for plants that live more than one growing season
Trichome –hair like extensions, dermal cells that modify
Cuticle –layer of wax and fatty acids (cutin) found outside the cell wall helps to limit water loss
Epidermis –one layer of dismal tissue (first year of growth)
Periderm –replaces epidermis of stems and roots for plants that live more than one growing season
Trichome –hair like extensions, dermal cells that modify
Cuticle –layer of wax and fatty acids (cutin) found outside the cell wall helps to limit water loss
Vascular tissue system –continuous system of tissues that conduct water minerals and food
Xylem –brings water and nutrients from the roots to the other parts
Phloem –moves sugars and other organic nutrients from leaves to the other parts
Sap –contents transported by xylem and phloem
Tracheids –long cells with tapered ends; first water conducting cells to evolve in vascular plants align with each other to form continuous water conducting system
Pits –thin regions n primary walls of tracheids; aligns with pits of adjacent tracheids
Vessel elements –water conducting cells that transport water and minerals more rapidly; dead at maturity
Sieve Tube Members /Elements –alive and active at maturity; brings organic nutrients from the leaves to other parts; believed to be arising from the meristem others think they are highly defirrentiated form of parenchyma
Sap –contents transported by xylem and phloem
Vessel elements –water conducting cells that transport water and minerals more rapidly; dead at maturity
Sieve Tube Members /Elements –alive and active at maturity; brings organic nutrients from the leaves to other parts; believed to be arising from the meristem others think they are highly defirrentiated form of parenchyma
Sieve plates-cell walls with membrane-lined pores that allow materials from cell to cell
Companion cell –cell that shares its nucleus to the siee tube members which do not have nucleus at maturity
Callose –carbohydrate molecule formed by sieve tube members when damaged; around the components of cell wall in its sieve plates
Sieve cell –primitive type of water conducting cell in non-flowering plants
In most dicots:
Cortex- region between the vascular bundles and the epidermis
Pith – center of the stem; inside the ring of vascular bundle