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UNIT OF LIFE
CELL
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Angstrom, A metric unit of length equal to one ten
billionth of a meter .
DISCOVERY OF THE CELL
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History of the cellular studies relies on the development
of technology especially development of microscope.
In 1590 Dutch spectacle makers Zaccharias and Hans
Janssen and developed a complex magnifier by using
several lenses. This was the first microscope.
1632 – 1723: Antonie van Leeuwenhoek teaches himself to grind
lenses, builds a microscope and draws protozoa, from rain water,
and bacteria from his own mouth.
1665: Robert Hooke discovers cells in cork and named them as
cells. Then observed cells in living plant tissue using an early
microscope
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1831: Robert Brown observed nucleus and named it.
Theodor Schwann (1839) and Matthias Jakob Schleiden
(1838) elucidate the principle that plants and animals are
made of cells, concluding that cells are a common unit of
structure and development, and thus founding the cell
theory.
1839: Johannes Purkinge named the jelly like material in the
cell as protoplasm(today cytoplasm)
1853: Rudolph Virchow stated that cells always emerge
from preexisting cells.
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The first electron microscope
prototype was built in 1931 by the
German engineers Ernst Ruska
and Max Knoll. In electron
microscopes electron reflections
are used to determine the
structures.
1953: Watson and Crick made
their first announcement on the
double-helix structure for DNA.
X rays helped them.
1981: Lynn Margulis published
Symbiosis in Cell Evolution
detailing the endosymbiotic
theory.
CELL THEORY
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All organisms are made up of cells
Cells are the structural functional unit of all
organisms.
All cells have cellular activities.
New cells arise from old cells.
Cell needs to survive and reproduce
Nucleus
To survive, organisms need to get
energy
mitochondria
They have to produce new molecules
Ribosome, chloroplast, Endoplasmic
reticulum
They have to destroy harmful materials
Lysosome
They store unnecessary molecules
Vacuole
They package and transport molecules
Golgi body
They are protected by membrane
Cell membrane
They should be supported
Cell skeleton
CYTOPLASM

Jelly like fluid filling the cell. It has water, protein,
lipid, carbohydrates, minerals and enzymes. Most of
the cellular reactions occur in the cytoplasm. Some
enzymes produce ATP during breakdown of glucose
in cytoplasm and they also use ATP for this
reaction.(glycolysis)
CELL MEMBRANE
Surrounds the cell . It has 2 layers of
lipid and some protein molecules
within the lipid molecules. Cell
membrane is selective permeable
(semipermeable).
CELL MEMBRANE
The structure is
named as fluid mosaic
model. Lipid gives the
fluidity and flexity.
Proteins have recognition
and transport role. In the
membrane there are
carbohydrates which
recognize foreign
particles.
Ribosomes
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They don’t have membrane. They
are very small organelles. Play
important role in protein
synthesis. Some are free in the
cytoplasm but some are on the
nuclear envelope and
endoplasmic reticulum.
They are made up of proteins
and rRNA
Polysome-many
ribosome
Rough
Endoplasmic
Reticulum
They have membrane.
They are tubular
networks with ribosomes
on them. They play role in
protein synthesis and
protein transport.
Smooth
Endoplasmic
Reticulum
They have membrane. They
are tubular networks but
they don’t have ribosomes.
They play role in lipid
synthesis.
Golgi Body
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They have membrane. They
are flattened sacs and have
important role in package of
synthesized molecules. They
work with endoplasmic
reticulum. Transport or export
synthesized molecules out of
the cell. Modify molecules by
adding groups(glucose,
phosphate, sulphate)
Help formation of cell wall in
plants.
Help formation of lysosomes
Lysosome
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They have membrane. They
contain hydrolytic enzymes.
They are formed by Rough ER
and golgi. They digest foreign
or unnecessary molecules.
Only in animal cells (except
red blood cells)
When they fuse with foreign
molecule they form secondary
lysosome.
Peroxisomes
Membrane enclosed organelles. Contain
catalase enzyme which breaks up H2O2
and form H2O and O2
Vacuoles
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They are fluid filled organelles. They are surrounded by
membrane. They store some food and wastes.
They are very big in old plant cells.
In animal cells they are very small.
Food vacuole, : digests food in one
celled or primitive organisms like
amoeba
Contractile vacuole: throws out
excess water like paramecium
Centrosome(have 2 centrioles)
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2 centrioles form a centrosome. It is important in
cell division.Made up of proteins. It is only found
in animal cells.Can form cilia and flagella.
Mitochondria
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They are double membraned organelles. They
produce energy by breaking down the food and by
using oxygen. This process is called cellular
respiration.
C6H12O6+6O2
6CO2+6H2O+ATP
Plastids
are only found in plant cells.
(Chloroplast (contain chlorophyll–green as spinach
Chromoplasts-(contain xanthophyll, carotene- red,
orange, yellow in carrot,tomatoes
Leucoplasts- colorless in potato(turn to green in sunlight))
Chloroplasts ar large organelles found
only in plant cells. They have double
membrane.
Chloroplasts make photosynthesis.
They use light energy to convert
inorganic (CO2, H2O) molecules into
organic(glucose) molecule.
6CO2+12H2O
C6H12O6+6H2O+6O2
They produce ATP but use it in
dehydration synthesis.
Comparison of mitochondria and
chloroplast
Mitochondria
Produce ATP(not uses
it)
Have DNA, RNA and
ribosomes
Have ETS on cristae
Use Oxygen, produce
carbondioxide
Catabolism
Double membrane
Chloroplasts
Produce and uses ATP
inside.
Have DNA, RNA and
ribosomes
Have ETS on grana
Use carbondioxide,
produce oxygen
Anabolism
Double membrane
Endosymbiosis
Nucleus
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It is the brain of the cell.
It is surrounded by
nuclear envelope(double
membrane). It contains
the genetic material
(DNA) of the organism.
Nuclear membrane(envelope)
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It covers the nucleus. It is double membraned
It has some pores to allow RNA exchange.
Nucleolus
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Some part of the genetic material, which is
specific for rRNA production is condensed and
form nucleolus. So it is important for ribosome
formation.
PROKARYOTE AND EUKARYOTE CELLS
Prokaryote
Nucleus (nuclear
membrane)
Eukaryote
Absent; A single circular Present; Multiple
chromosome
chromosomes
Membrane-enclosed Absent
organelles
Present (mitochondria,
chloroplasts,
endoplasmic reticulum,
Golgi, lysosome, etc.)
Cell wall
Present;
protein+carbohydrate
Absent in animal; if present (plants
& fungi) cellulose
Cell division
Binary fission
Mitosis
Ribosome
Smaller
Larger
Plant and animal cells
Structure
Animal cell
Plant cell
Feature and function
Cell wall
Absent
Present(cellulose)
Support and protection
Cell membrane
Present
Present
Regulation of cellular
transport
Cytoplasm
Present
Present
Jelly like fluid
Nucleus
Present
Present
Controls cell activities
Nucleolus
Present
Present
Ribosome production
Mitochondria
Present
Present
Energy production
Endoplasmic
reticulum
Present
Present
Protein and lipid synthesis
Golgi
Present
Present
Package of molecules
Ribosome
Present
Present
Protein synthesis
Lysosome
Present
Absent
Storage of digestive enzymes
Vacuole
Present (small) Present (big)
Storage of unnecessary
materials
Centriole
Present
Absent
İmportant in cell division
Plastids
Absent
Present
Food production and storage
Chromosomes
The threadlike material is called
chromatin. It condenses during cell
division and form chromosomes.
Each chromosome contains DNA and
protein.
Chromosomes carry genes which code
for the characters.
Humans have 46 chromosomes.
23 pairs of chromosomes.
23 of them come from father and 23 of
them come from mother.
Each pair codes for same trait
(characteristic).They are called
homologous chromosomes.
Sister chromatids are the 2 chromatins after
then DNA replication. Same with each other.
Sister chromatids
DNA
DNA with proteins
chromatin structure DNA replication
Chromosome
The threadlike material is called chromatin. It
condenses during cell division and form
chromosomes.
Cell life cycle
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Cells should produce new cells by dividing.
But during reproduction or formation of new
cells, The genetic material should be kept
untouched.
Cells undergo 2 types of division. Mitosis and
meiosis.
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Mitosis is the process of making new body cells.
Meiosis is the type of cell division that creates egg
and sperm cells(gametes).
Cell life cycle and Mitosis
The series of events from one cell division to the next
is called cell cycle.
In the life cycle of a cell:
1. Cell grows (G1)
2. Decide to divide and
replicate DNA (S)
3. Prepare for division(G2)
4. Divide
This cycle occurs in every
cell but not in nerve and
muscle cells. They stay
at G1 phase, never
divide.
Mitosis
Mitosis is important in:
 Repair and regeneration.
 Growth
 Mitosis is a fundamental process for life. During
mitosis, a cell duplicates all of its contents, including
its chromosomes, and splits to form two identical
daughter cells.
As a result of the mitosis:
 2 new cells are formed
 New cells have same genetic material and
chromosome number with mother cell.
 The genetic material and chromosome number of the
new cells are same.
Mitosis
Interphase: Resting period of the cell.
http://www.whfreeman.com/thelifewire6e/content/ch09/ani0901mov1.html
Cell carries out normal activities. In S
http://www.sumanasinc.com/webcontent/anisamples/biology/biology.html
phase DNA of the cell replicates itself.
2 sister chromatids are formed.
 Prophase: nuclear membrane
disappears. Centrioles go to the
opposite poles.
 Metaphase: Chromosomes with sister
chromatids stay in the middle of the
cell (equator). Spindle fibers are
formed.
 Anaphase: Sister chromatids
separate from each other and go to
the opposite poles with the help of the
spindle fibers.
 Telophase: Chromatids reach to the
poles and nuclear membrane is
formed . Spindle fibers disappear.
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1. A cell with 4 chromosomes undergoes 1 mitotic
division.a. How many cells will form? b.How many
chromosomes does each cell contain?
2 cells with 4 chromosomes
2. A cell with 4 chromosomes undergoes 3 mitotic
division.a. How many cells will form at the end?
b.How many chromosomes does each cell
contain?
23 = 2 x 2 x 2 = 8 cells with 4 chromosomes
3. At the end of the successive mitotic divisions
256 cells are formed. How many mitotic divisions
occured?
2x2x2x2x2x2x2x2= 256 28 = 256
8 divisions
Meiosis
http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html
Meiosis is important in:
 formation of gametes (sperm, egg)
 reducing chromosome number
 genetic variation
As a result of the meiosis:
 4 new cells are formed
 New cells can have different genetic makeup from the
mother cell
 New cells have half of the chromosome number of the
mother cell.(n)
 The genetic makeup of the new cells can be different
from each other.
Meiosis
http://www.whfreeman.com/thelifewire6e/con_index.htm?09
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Interphase:
DNA replicates
itself
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Prophase I:
2 Homologous
chromosomes
(tetrad)
exchange genes
(crossing over)
Prophase II: The chromosomes
become shorter and thicker.
Metaphase I: Homologous chromosomes
(tetrad) line up in the middle of the cell(equator).Metaphase II: Spindle fibers attach to
the chromatids of the chromosomes.
Spindle fibers attach to the chromosomes.
Anaphase II: Sister chromatids of the
Anaphase I: Homologous chromosomes
separate from eachother and go to the opposite chromosomes are separated and go to
the opposite poles of the cells.
poles.
Telophase II: Totally 4 cells are formed.
Telophase I: Chromosomes reach to the
Each cell can have a different genetic
opposite poles. Two cells are formed . The
chromosome number is reduced by meiosis I. make up and half of chromosome
number
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What should we know about meiosis I?
Crossing over(gene exchange)between homologous
chromosomes occurs in Meiosis I (Prophase). Genetic
variation occurs .
Homologous chromosomes are separated from each other in
meiosis I, chromosome number is reduced by half in Meiosis I.
Homologous chromosomes line randomly in Metaphase I.
Causes variation.
What should we know about meiosis II?
Sister chromatids are separated from each other in Meiosis II.
(similar to mitosis)
Mitosis and meiosis
MITOSIS
MEIOSIS
1. takes place in body cells.
1. takes place in germ cells and forms sex
cells.
2. No crossing over (gene Exchange)
2. crossing over can happen between
homologous chromosomes.(Tetrad
forms)
3. It has 1 cycle of the phases (1 division)
3. It has 2 cycle of phases (2 division)
4. Produces 2 cells
4. Produces 4 cells
5. newly formed cells have the same
chromosome number of the parent
cell(2n)
5. Newly formed cells have the half of the
chromosome number of the parent cell
(n)
6. The genetic make up of the newly
formed cells are same with each other
and with the parent cell
6. The genetic make up of the newly
formed cells can be different from
each other and from the parent cell
7. Only sister chromatids separarte.
7. Homologous chromosomes separate at
the 1st division, sister chromatids
separarte in the 2nd division.
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A
A
B
b
If this cell undergoes meiosis, draw the genetic
makeup uf the new cells? 2n= 2
If there is no crossing over
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at the end of 1 st part of meiosis
A
A
B
b
If there is crossing over,
between A-B and A-b
A
A
b
B
n=1
Homologous chromosomes separated and went to
opposite 2 cells (chr number is halved)
crossing over doesn’t change the gene
combination
n=1
At the end of the 2nd part of the meiosis
A
A
A
A
A
A
A
A
B
B
b
b
b
b
B
B
n=1
Sister chromatids are separated and went to the
opposite to cells
Sister chromatids are separated and
went to the opposite to cells

A
a
B
b
If this cell undergoes meiosis, draw
the genetic makeup uf the new cells?
2n= 2

If there is no crossing over
at the end of 1 st part of meiosis
at the end of 1 st part of meiosis
a
A
Homologous chromosomes separated and went to
opposite 2 cells (chr number is halved)
B
A
B
a
b
B
n=1
a
b
New genetic makeup is formed as a result of
crossing over
At the end of the 2nd part of the meiosis
At the end of the 2nd part of the meiosis
A
A
n=1
b
B
If there is crossing over
a
A
A
a
b
b
b
B
n=1
Sister chromatids are separated and went to the
opposite to cells
a
B
n=1
Sister chromatids are separated and went to the
opposite to cells
Changes in chromosome number, DNA amount
and volume of cell
A
B
D
C
A cell undergoes some cell divisions and
fertilization. Can you find them by looking at the
graphic?
Mitosis
Meiosis
fertilization
A
B
D
C
A gamete cell of an organism has 14
chromosomes? What is the chromosome number
in stomach cells?
 N= 14
2n= 28
If an animal has 7+Y chromosome in one sperm cell, What
will be the number of autosomes and gonosomes in kidney
cells?
14 + XY
What are the reasons of genetic variation in
meiosis?
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Crossing over(gene exchange)between homologous
chromosomes occurs in Meiosis I (Prophase). Genetic
variation occurs
Homologous chromosomes line randomly in Metaphase I.
Causes variation.
Mutations during meiosis also cause variation.
Nondisjunction
Normal meiosis
Failure of separation of
homologous chromosomes or
separartion of sister chromatids
Transport across membrane
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Cell membrane is semipermeable. Some
small molecules can pass the cell membrane
easily but some molecules can not pass. Cell
should take needed materials from the
outside of the cell and send some secretions
out of the cell.
According to the properties of the materials,
cells use different ways to take in or give out
molecules.
Transport mechanisms
Mechanisms that
don’t need energy
1. Passive Diffusion
Mechanisms
that need energy
1. Active transport
2. Facilitated
Diffusion
2. Endocytosis
3. Osmosis
3. Exocytosis
1. PASSIVE DIFFUSION
Diffusion is the movement of molecules from a
region of high concentration to low concentration.
 When you put a drop of ink into the water , ink
molecules diffuse within the water.
 When you open a parfume bottle, the smell diffuses.
 Small molecules
move in that way.
Oxygen,
Carbondioxide, urea
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Important!
Concentration gradient, temperature, size of
the molecules effect the diffusion rate.
2. Facilitated diffusion
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It is the movement of molecules from high
concentration to low concentration through
the membrane with the help of a protein.
Ex. Glucose, fructose, galactose
3. OSMOSIS
Experiment of cellular transport
1
• Peel the potatoes
• Cut it half and make a
hollow in the centre.
(Don’t damage the
potato)
• Put 2 halves in to the
water.
• Dry the hollows and put
one tablespoon of sugar
inside one of the
potatoes.
Sugar gets wet because
of osmosis. Water enters
the inner part of the potato
2
• Peel the potatoes
• Cut same size of
rectangular sticks from
potato.
• Note the sizes of the
sticks(measure the
length.
• Label the petridishes
as the concentration,
then put 1 potato piece
to each petri. Put the
sugar solutions to each
petri.
• Wait for 10 min. Then
note the size of the
sticks(measure the
length..
Potato stick in distilled water will
take in water.
But other sticks will lose water
3
• Tie one side of the
tubing
• Pour starch solution
into the tubing
• Tie the other side
• Put the sausage with
starch into the lugol
solution
Sausag
Lugol(iodine
) solution
e
tubing
with
starch
Lugol enters the sausage
tubing and starch
becomes black. But
starch can’t pass the
membrane.
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a HYPOTONIC (= hypoosmotic) solution is
one which has relatively more water
molecules (and fewer solutes) than a
HYPERTONIC (= hyperosmotic) solution.
ISOTONIC (isoosmotic) solutions have equal
concentrations of solutes.
Important!
Osmotic pressure is important for the movement of
water.
Osmotic pressure is the ability to take water.
If it is high in one area , that area can take in
water.This means that the solute concentration of
that area is high.
Osmotic pressure is high=solute concentration is high=
water concentration is low= ability to take water is
high
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Plasmolysis:Plasmolysis is the loss of water from
the cell by osmosis. If the concentration of the cell is
lower than the outside(solute is low, water is high),
water moves out of the cell. Cell shrinks.
Deplasmolysis: is the gain of water from the outside
by osmosis. If the cell has higher concentration than
the outside, water moves in and plasmolyzed cell
swells.
Turgor: is the force(pressure) exerted to the cell wall
of the cell.
1. Which of the organelles can increase the
osmotic pressure of the cell?
a.
Lysosome b. centrosome c. ribosome
d. nucleus
e. mitochondria
2. Compare the osmotic pressures of the
following cells?
A
B
1. ACTIVE TRANSPORT
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In diffusion and osmosis, no energy is used.
But in some cases to transport molecules
across membranes, we use energy . This
process is called active transport.
Active transport is the movement of
molecules from low concentration to hıgh
concentration.
1. ACTIVE TRANSPORT
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During active transport molecules are carried
from low concentration to high concentration.
ATTENTION!!! (in diffusion molecules flow
from high concentration to low concentration
BUT in active transport they are carried from
low concentration to high concentration)
This transport is very hard so cell spends
ATP(energy) .
Active transport carries small molecules that
are hard to pass.
Example. Na + / K+ pump
The movement of Na and K molecules across
membrane from low concentration to high concentration.
A

low

B
high

Na ions are very low in
concentration in part A
(outside of the cell).
And Na ions are high in
concentration in part B
(inside the cell)
If cell wants to take more
Na, then it has to take
more Na only by ACTIVE
TRANSPORT.
2. Endocytosis
Endocytosis is a way for cell to take in
large particles by engulfing . Cell spends ATP.
Cell membrane gets smaller by engulfing.
Phagocytosis is the intake of solid
particles.(not in plants)
Pinocytosis is the intake of liquid
molecules.
3. Exocytosis
Exocytosis is a way for cell to throw out
big particles, cell membrane gets larger.
It is the opposite of endocytosis. Cell
spends ATP.
Question
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Pressure
OP
AF
OP= Osmotic pressure
AF= absorption force
TP= Turgor pressure
TP
Which one is true?
t1
time
I. It will take in water as long as osmotic pressure is larger
than turgor pressure.

II. At t1 cell is in the turgor stage.
III. As the osmotic pressure decreases, force of
absorption increases
Metabolism
needs
energy(ATP)
METABOLISM
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All chemical activities within the cell are called
metabolic activities or metabolism of the organism.
There are two kinds of metabolic activities.
Anabolism or the anabolic reactions are synthesis
reactions. They produce polymers. For example
formation of proteins, polypeptides.Water is formed.
Needs energy.
Catabolism or catabolic reactions are the breakdown
reactions. They produce monomers. For example
formation of amino acids from proteins,
monosaccharides from carbohydrates. Water is used.
Multicellularity

an early step in the evolution of multicellular organisms was the
association of unicellular organisms to form colonies. The
simplest way of achieving this is for daughter cells to remain
together after each cell division. In Volvox the individual cells
forming a colony are connected by fine cytoplasmic bridges so
that the beating of their flagella is coordinated to propel the entire
colony along like a rolling ball. Within the Volvox colony there is
some division of labor among cells, with a small number of cells
being specialized for reproduction and serving as precursors of
new colonies. The other cells are so dependent on one another
that they cannot live in isolation, and the organism dies if the
colony is disrupted


http://www.mhhe.com/biosci/esp/2001_gbio/d
efault.htm#ok biology 1 subjects
http://w3.dwm.ks.edu.tw/bio/activelearner/05/
ch5c1.html soru
Prophase

nuclear membrane disappears. If it is an animal
cell, Centrioles go to the opposite poles. Don’t
forget there is no centriole in plant cells.
Metaphase

Chromosomes with sister chromatids stay in the
middle of the cell (equator). Spindle fibers are
formed.
Anaphase

Sister chromatids separate from each other
and go to the opposite poles with the help of
the spindle fibers.
Telophase


Chromatids reach to the poles and nuclear
membrane is formed . Spindle fibers disappear.
Karyokinesis(division of nucleus) ends.
Cytokinesis (division of cytoplasm) ends. If it is
an animal cell cytokinesis is by burrowing.
If it is a plant cell cytokinesis is by formation of
cell plate. Cell plate derives from golgi body.
Interphase

Resting period of the cell. Cell carries out normal
activities. In S phase DNA of the cell replicates
itself. 2 sister chromatids are formed.

Each organism has 2 pairs of chromosomes.
One set comes from mother and other comes
from father.Each pair codes for same trait
(characteristic- eye color).They are called
homologous chromosomes.But they can be
different.