▪Introduction
▪Cell theory
▪Whitaker’s kingdomclassification
▪Cell organelles, and their functions
▪Homeostasis
▪Replication and cell Division
▪Tissue differentiation
▪Stem cells and their applications
▪Genetic algorithms
UNIT 1
2.
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Living Organism
• Aliving organism may be defined as a complex unit of
physicochemical materials that is capable of self-regulation,
metabolism, and reproduction.
• Furthermore, a living organism demonstrates the ability to interact with
its environment, grow, move, and adapt.
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What Are themain characteristics of organisms?
Made of cells
Require energy (food)
Reproduce (species)
Maintain homeostasis
Organized
Respond to environment
Grow and develop
Exchange materials with
surroundings (water, wastes, gases)
4.
Concept of evolution
•The process by which different kinds of living organism are believed
to have developed from earlier forms during the history of the earth.
• Evolution is the change in the heritable characteristics of biological
populations over successive generations.
• Jean Baptistae Lamarck (1801)-spontaneous generation of species
according to needs and functionalities of the mutation
• Charles darwin (1859)- Based on survival of the fittest mutations
4
Cell - Basicunit of life
a. Smallest living form
b. Inside the cell some structure transport
c. Metabolize
d. Respire
e. Reproduce (Meiosis)
f. Multiply (Mitosis)
g. Energy producing
h. Keep information
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CELL THEORY
• Suggestedby German scientists Theodor Schwann and Matthias Jakob
Schleiden in 1838
• Matthias Schleiden, a German botanist, and Theodor Schwann, a
British Zoologist formulated the cell theory.
• The cell theory consists of the following information,
• All living things are made of cells
• Cells are the basic unit of structure and function in an organism (basic
unit of life)
• Cells come from the reproduction of existing cells (cell division)
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Prokaryotes
• Nucleoid region(center)
contains the DNA
• Surrounded by cell membrane
& cell wall (peptidoglycan)
• Contain ribosomes (no
membrane) in their cytoplasm
to make proteins
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Eukaryotes
• Cells thathave a nucleus and
membrane-bound organelles
• Includes protists, fungi,
plants, and animals
• More complex type of cells
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Five Kingdoms andtheir chief characteristics
• Unicellular organisms that lack a nucleus and many of the specialized
cell parts, called organelles. Such organisms are said to be prokaryotic
(pro =‘‘before’’; karyotic =‘‘kernel,’’ ‘‘nucleus’’) and consist of
bacteria.
• All of the other kingdoms consist of eukaryotic (eu = ‘‘true’’)
organisms, which have cells that contain a nucleus and a fuller
repertory of organelles.
Five Kingdom and their Classification
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Organelles
• Very small(Microscopic)
• Perform various functions for a cell
• Found in the cytoplasm
• May or may not be membrane-bound
Plant Cell
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Cell or PlasmaMembrane
Outside
of cell
Inside
of cell
(cytoplasm)
Cell
membrane
Proteins
Protein
channel Lipid bilayer
Carbohydrate
chains
• Composed of double layer of phospholipids and proteins
• Surrounds outside of all cells
• Controls what enters or leaves the cell
• Living layer
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• Jelly-like substanceenclosed by
cell membrane
• Provides a medium for chemical
reactions to take place
• Contains organelles to carry out
specific jobs
• Found in all cells
Cytoplasm of a Cell
cytoplasm
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• Controls thenormal
activities of the cell
• Contains the DNA in chromosomes
• Bounded by a
nuclear envelope (membrane)
with pores
• Usually the largest organelle
• Each cell has fixed
number of chromosomes that
carry genes
• Genes control cell characteristics
The Control Organelle - Nucleus
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Nucleolus
• Inside nucleus
•Cell may have 1 to 3 nucleoli
• Disappears when cell divides
• Makes ribosomes that make
proteins
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Cytoskeleton
• Helps cellmaintain cell shape
• Also help move organelles around
• Made of proteins
• Microfilaments are threadlike & made of ACTIN
• Microtubules are tube-like and made of TUBULIN
Cytoskeleton
Microtubules
Microfilaments
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Centrioles
• Found onlyin animal cells
• Paired structures near nucleus
• Made of bundle of microtubules
• Appear during cell division
forming mitotic spindle
• Help to pull chromosome pairs
apart to opposite ends of the cell
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Mitochondrion
(plural = mitochondria)
•“Powerhouse” of the cell
• Generate cellular energy (ATP)
• More active cells like muscle cells have more
mitochondria
• Both plants & animal cells have mitochondria
• Site of cellular respiration (burning glucose)
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Mitochondria
• Surrounded bya double membrane
• Has its own DNA
– Mitochondria come from cytoplasm in the
egg cell during fertilization
– Therefore, you inherit your mitochondria
from your mother!
• Folded inner membrane called cristae
(increases surface area for more chemical
reactions)
• Interior called matrix
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Endoplasmic Reticulum -ER
• Network of hollow membrane tubules
• Connects to nuclear envelope & cell membrane
• Functions in synthesis of cell products & transport
Two kinds of ER ---Rough & Smooth
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Rough Endoplasmic Reticulum(Rough ER)
• Has ribosomes on its surface
• Makes membrane proteins and proteins for
export out of cell
• Proteins are made by ribosomes on ER surface
• They are then threaded into the interior of the
Rough ER to be modified and transported
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Smooth Endoplasmic Reticulum
•Smooth ER lacks ribosomes on its surface
• Is attached to the ends of rough ER
• Makes cell products that are used inside
the cell
• Makes membrane lipids (steroids)
• Regulates calcium (muscle cells)
• Destroys toxic substances (Liver)
Includes nuclear membrane
connected to ER connected
to cell membrane (transport)
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Ribosomes
• Made ofproteins and rRNA
• “Protein factories” for cell
• Join amino acids to make proteins
• Process called protein synthesis
• Can be attached to Rough ER OR Be free (unattached) in
the cytoplasm
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Golgi Bodies
• Stacksof flattened sacs
• Have a shipping side (trans face) and
receiving side (cis face)
• Receive proteins made by ER
• Transport vesicles with modified
proteins pinch off the ends
Transport
vesicle
CIS
TRANS
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Golgi Bodies
Look likea stack of pancakes
Modify, sort, & package molecules from ER for storage or transport
out of the cell.
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Lysosomes
• Contain digestiveenzymes
• Break down food, bacteria, and worn-out cell parts for cells
• Programmed for cell death (Autolysis)
• Lyse (break open) & release enzymes to break down & recycle cell
parts)
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Vacuoles
• Fluid filledsacks for storage
• Small or absent in animal cells
• Plant cells have a large Central
Vacuole
• No vacuoles in bacterial cells
• In plants, they store Cell Sap
• Includes storage of sugars, proteins,
minerals, lipids, wastes, salts, water,
and enzymes
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Chloroplasts
• Found onlyin producers (organisms containing chlorophyll)
• Use energy from sunlight to make own food (glucose)
• Energy from sun stored in the Chemical Bonds of Sugars
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Surrounded by doublemembrane
Outer membrane smooth
Inner membrane modified into sacs called thylakoids
Thylakoids in stacks called Grana & interconnected
Stroma – gel like material surrounding thylakoids
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Chloroplasts
• Contains itsown DNA
• Contains enzymes & pigments for Photosynthesis
• Never in animal or bacterial cells
• Photosynthesis – food making process
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The Cell Cycle
•Mitosis and meiosis are single steps in cell cycle
• G1, S, G2, and M phases
– Cells not in process of dividing are in G0 phase
– Chromosomes are duplicated in preparation for the next round of
division during Interphase
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Control of theCell Cycle
• The stimuli for entering the cell cycle is in the form of growth factors
and cytokines that are capable of inducing mitotic divisions
• The cell cycle is highly regulated
– Proteins whose concentrations rise & fall in a controlled manner
• Cyclin and cyclin-dependent kinases (cdk)
• p53 and pRb
• Inhibitors of cdk
• Internal checkpoints & guardians monitor cell health
• Errors in this process can lead to uncontrollable growth and cancer
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• Cell cyclecontrol is
focused at 3 places:
• G1 checkpoint
• G2 checkpoint
• M checkpoint
– Before S phase (DNA
synthesis)
– At transition between
G2 and M phase
Control of the Cell Cycle
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DNA replication-Binary fission
Daughtercells are identical copies
(1) (2) (3)
(4) (5) (6)
Chromosome Plasma membrane
Neither mitosis nor meiosis occurs in prokaryotes
42.
Bacteria
Reproduction
• Asexual, throughbinary fission
• No true sexual reproduction, since neither mitosis nor
meiosis exist in prokaryotes
• Horizontal transfer of genetic material
DNA
cell wall
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Transformation -Uptake of genetic material from the environment
Transduction - Transfer of genetic material between prokaryotes by viruses
Conjugation - Direct transfer of genetic material from one prokaryote to another
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Mitosis
Four phases –
a.Prophase: chromosomes condense, spindle apparatus forms,
nuclear envelope breaks down
b. Metaphase: chromosomes line up at equator of cell
c. Anaphase: sister chromatids separate
d. Telophase: new nuclear envelopes form, chromosomes
unwind
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(d) Anaphase: Sister
chromatids
haveseparated, and one set
has moved toward each pole.
(a) Interphase in a seed cell: The
chromosomes (blue) are in the
thin, extended state and appear
as a mass in the center of the
cell. The spindle microtubules
(red) extend outward from the
nucleus to all parts of the cell.
(b) Late prophase: The
chromosomes (blue) have
condensed and attached to
the spindle microtubules (red).
(e) Telophase: The
chromosomes have gathered
into two clusters, one at the
site of each future nucleus.
(c) Metaphase: The chromosomes
have moved to the equator of the
cell.
(f) Resumption of interphase: The
chromosomes are relaxing again
into their extended state. The spindle
microtubules are disappearing,
and the microtubules of the two
daughter cells are rearranging into
the interphase pattern.
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Parent Cell
Chromosomes have
beenreplicated
Daughter Cells
Each cell has the same genetic
makeup as the parent cell
Mitosis
Each new nucleus is genetically identical to the parent nucleus
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Mitosis or SomaticCell Division
• A cell divides producing two genetically identical
daughter cells.
• New cells are produced for growth or repair of
aging or damaged tissues.
• For asexual reproduction
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Interphase
• The stagebetween two successive cell divisions.
• Prior to mitosis, thin strands of DNA in a cell thicken into chromosomes,
which then duplicate
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Early Prophase
• Thecentrioles divide and with the asters, move apart
• The nuclear membrane begins to disintegrate
Late Prophase
• The centrioles and asters are pushed to the opposite poles of the cell.
• Spindle fibers extend between the poles
• The nuclear membrane and nucleolus have almost disappeared
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Metaphase
• Nuclear membranedisappears completely
• The double chromosomes, their centromeres attached to the spindle
fibers, align at the metaphase plate, midline of the cell.
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Early Anaphase
• Thecentromeres split half moving to one pole and half to the other pole
Late Anaphase
• The chromosomes have almost reached to their respective poles.
• The cell membrane begins to contract at the midline.
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Telophase
• The cellmembrane completes contraction, closing over to split the cell
in two.
• Nuclear membrane form around the chromatin masses within each new
daughter cell.
Mitosis completed
There are now two cells, with structures and chromosomes identical to
each other and the original cell
Once Telophase completes,
the cell divides at a stage
called CYTOKINESIS where
two daughter cells form
completely.
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Meiosis
Characteristics of meiosis-
Occurs in sex cells (germ cells) and produces
gametes.
A reduction division resulting in haploid cells.
Involves two sequential divisions resulting in four
cells.
Produces cells that are genetically different because
of genetic recombination (crossing-over).
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Meiosis produces gametesfor sexual reproduction
• Multiplies number of cells but also reduces chromosome
number in each daughter cell to exactly half the number
present before meiosis
• Daughter cells get 1 member of each homologous pair, i.e. 1
allele for each gene
• Mitosis produces 2 daughter cells
• Meiosis produces 4 daughter cells
• All body cells in humans are diploid, except gametes
• Cells with 1 member of each homologous pair are haploid
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Cell Differentiation
• Theprocess of altering the pattern of gene expression and thus becoming a cell of
a particular type is called cell differentiation.
• Presence of chemicals (or other influences) starts altering the decisions as to
which genes will be turned on or off.
• The zygote is a totipotent cell - its daughter cells can become any cell type. As the
development proceeds, some of the cells become pluripotent - they can become
many, but not all cell types.
• Later on, the specificity narrows down further and a particular stem cell can turn
into only a very limited number of cell types, e.g., a few types of blood cells, but
not bone or brain cells or anything else. That is why embryonic stem cell research
is much more promising than the adult stem cell research.
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Homeostasis
Definition : Maintenanceof the relative stability of the physical and chemical aspects of the
internal environment within a range compatible with cellular function.
Maintaining a constant internal environment with all that the cells need to survive (O2, glucose,
minerals, ions, and waste removal) is necessary for individual cells. The processes by which
the body regulates its internal environment are referred to as homeostasis.
Components : 1) sensor
2) afferent pathway
3) integration center or comparator
4) efferent pathway
5) effector organ(s)
• Physiological control systems are the nervous system, endocrine system, and immune system
through feedback mechanisms.
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• Stimulus (Changein environment)
↓
• Receptor (detects the change)
↓
• Afferent Signal (body to brain)
↓
• Control Center (Brain / Hypothalamus)
↓
• Efferent Signal (brain to body)
↓
• Effector Organs(muscles / glands / organs)
↓
• Response (restores normal condition)
Homeostatic Pathway
82.
Nervous System
• Thenervous system maintains homeostasis by controlling and
regulating the other parts of the body.
– A deviation from a normal set point acts as a stimulus to a
receptor, which sends nerve impulses to a regulating center in the
brain. The brain directs an effector to act in such a way that an
adaptive response takes place.
• The nervous system has two major portions: the central nervous
system and the peripheral nervous system.
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Extrinsic homeostatic systems
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• Regulating centersare located in the central nervous system,
consisting of the brain and spinal cord.
– The hypothalamus is a portion of the brain particularly
concerned with homeostasis; it influences the action of the
medulla oblongata, a lower part of the brain, the autonomic
nervous system, and the pituitary gland.
• The peripheral nervous system consists of the spinal nerves. The
autonomic nervous system is a part of peripheral nervous system
and contains motor neurons that control internal organs. It has two
divisions, the sympathetic and parasympathetic systems.
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• The endocrinesystem consists of glands which secrete special
compounds called hormones into the bloodstream.
• Each hormone has an effect on one or more target tissues. In this way
the endocrine system regulates the metabolism and development of most
body cells and body systems.
• For e.g. the endocrine system has sex hormones that can activate
sebaceous glands, development of mammary glands, alter dermal blood
flow, and release lipids from adipocytes etc. besides governing
reproduction.
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Endocrine System
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• In themuscular system, hormones adjust muscle metabolism, energy
production, and growth.
• In the nervous system, hormones affect neural metabolism, regulate
fluid/electrolyte balance and help with reproductive hormones that
influence CNS (central nervous system), development and behaviors.
• In the cardiovascular system, hormones regulate heart rate and blood
pressure.
• Hormones also have anti-inflammatory effects and control the
lymphatic system.
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• Negative feedback: a control system that causes the value of a
physiological measurement to change in the direction opposite to
the initial deviation from set point.
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• Positive feedback: a control system that causes the value of a
physiological measurement to change in the same direction as the
initial deviation from set point.
Genetic Algorithms
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Genetic algorithms(GA) in programming, simulate the process of
natural selection which means those species who can adapt to changes
in their environment are able to survive and reproduce and go to next
generation. In simple words, they simulate “survival of the fittest” among
individual of consecutive generation for solving a problem. Genetic
algorithms are based on an analogy with genetic structure and behavior
of chromosomes of the population.
90.
Following is thefoundation of GAs based on this analogy –
1. Individual in population compete for resources and mate
2. Those individuals who are successful (fittest) then mate to create
more offspring than others
3. Genes from “fittest” parent propagate throughout the generation, that
is sometimes parents create offspring which is better than either
parent.
4. Thus each successive generation is more suited for their environment.
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• Gene representsa single solution to a problem
• chromosome (individual) is composed of several genes or multiple
similar solutions.
• population of individuals are maintained within search space - all
solutions to the problem
The whole algorithm can be summarized as –
‾ Randomly initialize n populations
‾ Determine fitness of population
‾ Until convergence repeat:
a) Select parents from population
b) Crossover and generate new population
c) Perform mutation on new population
d) Calculate fitness for new population
Components of a search space in Genetic algorithm
93.
The Fitness score
•The GAs maintains the population of n individuals (chromosome/solutions)
along with their fitness scores.
• The individuals having better fitness scores are given more chance to reproduce
than others.
• The individuals with better fitness scores are selected who mate and
produce better offspring by combining chromosomes of parents.
• Always the new generation of solutions will have better fitness than the parent
population.
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94.
Operators for GA
•The Algorithm uses certain
biological concepts as operators
to find better solutions
• Cross Over
• Mutation
• Selection ( best fitness score in
previous generation)
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Crossover
Mutation
95.
Uses of GA
•Genetic Algorithms are primarily used in optimization problems of
various kinds, but they are frequently used in other application areas.
• Optimization − Genetic Algorithms are most commonly used in
optimization problems wherein we have to maximize or minimize a
given objective function value under a given set of constraints.
• DNAAnalysis − GAs have been used to determine the structure of DNA
using spectrometric data about the sample.
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• Neural Networks− GAs are also used to train neural networks,
particularly recurrent neural networks.
• Parallelization − GAs also have very good parallel capabilities,
and prove to be very effective means in solving certain problems,
and also provide a good area for research.
97.
Advantages of GA
•Does not require any derivative information (which may not be
available for many real-world problems).
• Is faster and more efficient as compared to the traditional methods.
• Provides a list of “good” solutions and not just a single solution.
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Disadvantages of GA
•GAs are not suited for all problems, especially problems which are
simple and for which derivative information is available.
• Fitness value is calculated repeatedly which might be
computationally expensive.
• Being stochastic, there are no guarantees on the optimality or the
quality of the solution.
#47 Figure: 10-07
Title:
The cell cycle in a plant cell.
Caption:
Interphase and mitosis in the African blood lily. The chromosomes are stained bluish-purple, and the spindle microtubules are stained pink to red. Compare these micrographs with the drawings of mitosis in an animal cell shown in Figure 10-8. (Each micrograph is of a different single cell that has been fixed and stained at a particular stage of mitosis. Only chromosomes and microtubules have been stained.)
#48 Figure: 10-08a
Title:
The cell cycle in an animal cell: late interphase.
Caption:
The cell cycle in an animal cell.
#57 Figure: 10-11a
Title:
The details of meiotic cell division: prophase I.
Caption:
In these diagrams, two pairs of homologous chromosomes are shown, large and small. The yellow chromosomes are from one parent and the violet chromosomes are from the other parent. Note that each daughter cell contains one member of each pair of parental homologous chromosomes.