1. KILIMANJARO CHRISTIAN MMEDICAL
UNIVERSITY COLLEGE
Faculty of Nursing and Rehabilitation Medicine
Department of Anatomy and Neuroscience
Anatomy Lecture for BSc.Nursing and BSc.Physiotherapy
LECTURE 2 & 3
TOPIC: CELLS
Date: October,2022. GYM – Physiotherapy School
Lecturer: J. S. Kauki, BSc, MSc, on PhD, Email: jskauki@gmail.com.
Office ext. 70 Block C, 3RD Floor, Anatomy dept.
2. Objectives
Define a cell; history of cell, list its general parts and explain
their function
Describe the active and passive processes by which materials
move across plasma membranes
Identify the stages, events and significance of cell division
3. Engage: Cell History
Cytology- study of cells
1665 English Scientist
Robert Hooke
Used a microscope to
examine cork (plant)
Hooke called what he saw
"Cells"
4. Cell History
Robert Brown
discovered the nucleus in
1833.
Matthias Schleiden
German Botanist
Matthias Schleiden
1838
ALL PLANTS "ARE
COMPOSED OF
CELLS".
Theodor Schwann
Also in 1838,
discovered that animals
were made of cells
5. Cell History
Rudolf Virchow
1855, German Physician
" THAT CELLS ONLY COME FROM
OTHER CELLS".
His statement debunked
"Theory of Spontaneous Generation"
6. Cell Theory
The COMBINED
work of Schleiden,
Schwann, and
Virchow make up
the modern
CELL
THEORY.
7. 1. All living things are composed of a cell
or cells.
2. Cells are the basic unit of life.
3. All cells come from preexisting cells.
The Cell Theory states that:
9. Cell Diversity
Cells within the same organism show
Enormous Diversity in:
Size
Shape
Internal Organization
10. Cells are small for 2 Reasons
Reason 1:
Limited in size by the RATIO between their Outer
Surface Area and Their Volume.
A small cell has more SURFACE AREA than a
large cell for a GIVEN VOLUME OF CYTOPLASM.
11. Cells are Small
Reason 2:
THE CELL'S NUCLEUS (THE BRAIN)
CAN ONLY CONTROL A CERTAIN
AMOUNT OF LIVING, ACTIVE
CYTOPLASM.
12. 12
Example of Animal Cell
http://upload.wikimedia.org/wikipedia/commons/2/24/Red_White_Blood_cells.jpg
http://upload.wikimedia.org/wikipedia/commons/e/
e6/Bleeding_finger.jpg
White Blood
Cell
Red
Blood
Cell
Platele
t
Red
Blood
Cells
13. Cell Shape
Diversity of form reflects a
diversity of function.
THE SHAPE OF A CELL
DEPENDS ON ITS
FUNCTION.
16. Cell Types (Review)
Eukaryotic
1. Contains a nucleus and
other membrane bound
organelles.
2. Rod shaped
chromosomes
3. Found in all kingdoms
except the Eubacteria
and Archaebacteria
Prokaryotic
1. Does not contain a
nucleus or other
membrane bound
organelles.
2. Circular chromosome
3. Found only in the
Eubacteria and
Archaebacteria
Kingdoms
20. Cellular Organelles
The Plasma
membrane
The boundary of the
cell.
Composed of three
distinct layers.
Two layers of fat and
one layer of protein.
21. The Nucleus
Brain of Cell
Bordered by a porous
membrane - nuclear
envelope.
Contains thin fibers of DNA
and protein called
Chromatin.
Rod Shaped Chromosomes
Contains a small round
nucleolus
produces ribosomal RNA
which makes ribosomes.
22. Ribosomes
Small non-membrane
bound organelles.
Contain two sub units
Site of protein synthesis.
Protein factory of the cell
Either free floating or
attached to the
Endoplasmic Reticulum.
23. Endoplasmic Reticulum
Complex network of
transport channels.
Two types:
1. Smooth- ribosome
free and functions in
poison detoxification.
2. Rough - contains
ribosomes and
releases newly made
protein from the cell.
24. Golgi Apparatus
A series of flattened
sacs that modifies,
packages, stores,
and transports
materials out of the
cell.
Works with the
ribosomes and
Endoplasmic
Reticulum.
25. Lysosomes
Recycling Center
Recycle cellular debris
Membrane bound
organelle containing a
variety of enzymes.
Internal pH is 5.
Help digest food
particles inside or out
side the cell.
26. Quiz
1. List six (6) functions of cell membrane
proteins
2. What is
A. Endocytosis
B. Exocytosis
27. Quiz
List six (6) functions of cell membrane
proteins
Ans: Carriers/ transporters, Ion channels,
Receptors, Enzymes, Identifiers, Markers
What is
A. Endocytosis > Transport into the cell cytoplasm
B. Exocytosis > Transport away from the cell cytoplasm
28. Centrioles
Found only in animal
cells
Paired organelles
found together near the
nucleus, at right angles
to each other.
Role in building cilia
and flagella
Play a role in cellular
reproduction
30. Cytoskeleton
Framework of the cell
Contains small microfilaments and larger
microtubules.
They support the cell, giving it its shape
and help with the movement of its
organelles.
31. Mitochondrion
Double Membranous
It’s the size of a bacterium
Contains its own DNA;
mDNA
Produces high energy
compound ATP
Play important role in
apoptosis
32. Transport of Materials Into and Out of Cells
Kinetic energy transport
Diffusion: A passive process in which a substance (solutes) moves from an area of higher to lower
concentration until equilibrium is reached. Eg. Oxygen and CO2 exchange in the lungs.
Osmosis: A passive process that involves the movement of water molecules across a selectively
permeable membrane from an area of higher water concentration to an area of lower water
concentration until equilibrium is reached.
Transport by transporter proteins
Facilitated diffusion:Passive movement of a substance down its concentration gradient via
transmembrane proteins that act as transporters.
Active transport: An active process in which cell expends energy to move a substance across the
membrane against its concentration gradient through transmembrane proteins that
act as transporters. Eg. Na+ / K+ pumps.
Transport in vesicles: An active process that involves the movement of substances into or out of a cell in
vesicles that bud from the plasma membrane.
Endocytosis: Movement of substances into a cell in vesicles.
Receptor-mediated endocytosis: Ligand–receptor complexes trigger infoldings of a clathrin
coated pit that forms a vesicle containing ligands.
Phagocytosis “Cell eating”: movement of a solid particle into a cell after pseudopods engulf it to
form a phagosome.
Bulk-phase endocytosis “Cell drinking”: movement of extracellular fluid into a cell by infoldings of
plasma membrane to form a vesicle.
Exocytosis: Movement of substances out of a cell in secretory vesicles that fuse with the plasma
membrane and release their contents into the extracellular fluid.
Transcytosis: Movement of a substance through a cell as a result of endocytosis on one side and
exocytosis on the opposite side.
34. 34
Cell Division
All cells are derived from pre-
existing cells
New cells are produced for
growth and to replace damaged or
old cells
Differs in prokaryotes (bacteria)
and eukaryotes (protists, fungi,
plants, & animals)
35. 35
Keeping Cells Identical
The instructions for
making cell parts
are encoded in the
DNA, so each new
cell must get a
complete set of the
DNA molecules
36. 36
DNA Replication
DNA must be
copied or
replicated
before cell
division
Each new cell
will then have an
identical copy of
the DNA
Original DNA
strand
Two new,
identical DNA
strands
39. 39
Prokaryotic Chromosome
The DNA of
prokaryotes
(bacteria) is one,
circular
chromosome
attached to the
inside of the cell
membrane
40. 40
Eukaryotic Chromosomes
All eukaryotic cells store genetic
information in chromosomes
Most eukaryotes have between 10 and
50 chromosomes in their body cells
Human body cells have 46 chromosomes
or 23 identical pairs
41. 41
Eukaryotic Chromosomes
Each chromosome is composed of a
single, tightly coiled DNA molecule
Chromosomes can’t be seen when
cells aren’t dividing and are called
chromatin
42. 42
Compacting DNA into Chromosomes
DNA is
tightly
coiled
around
proteins
called
histones
43. 43
Chromosomes in Dividing Cells
Duplicated
chromosomes are
called
chromatids &
are held
together by the
centromere
Called Sister Chromatids
44. 44
Karyotype
A picture of the
chromosomes from
a human cell
arranged in pairs by
size
First 22 pairs are
called autosomes
Last pair are the
sex chromosomes
XX female or XY
male
45. 45
Boy or Girl?
Y - Chromosome
X - Chromosome
The Y Chromosome Decides
47. 47
Types of Cell Reproduction
Asexual reproduction involves a
single cell dividing to make 2 new,
identical daughter cells
Mitosis & binary fission are
examples of asexual reproduction
Sexual reproduction involves two
cells (egg & sperm) joining to make
a new cell (zygote) that is NOT
identical to the original cells
Meiosis is an example
48. 48
Cell Division in Prokaryotes
Prokaryotes such as
bacteria divide into 2
identical cells by the
process of binary
fission
Single chromosome
makes a copy of
itself
Cell wall forms
between the
chromosomes dividing
the cell
Parent
cell
2 identical daughter cells
Chromosome
doubles
Cell splits
51. 51
Five Phases of the Cell Cycle
G1 - primary growth phase
S – synthesis; DNA replicated
G2 - secondary growth phase
collectively these 3 stages are
called interphase
M - mitosis
C - cytokinesis
53. 53
Interphase - G1 Stage
1st growth stage after cell
division
Cells mature by making more
cytoplasm & organelles
Cell carries on its normal
metabolic activities
54. 54
Interphase – S Stage
Synthesis stage
DNA is copied or replicated
Two
identical
copies of
DNA
Original
DNA
55. 55
Interphase – G2 Stage
2nd Growth Stage
Occurs after DNA has been copied
All cell structures needed for
division are made (e.g. centrioles)
Both organelles & proteins are
synthesized
56. 56
What’s Happening in Interphase?
What the cell looks like
Animal Cell
What’s occurring
57. 57
Sketch the Cell Cycle
Daughter
Cells
DNA Copied
Cells
Mature
Cells prepare for
Division
Cell Divides into
Identical cells
59. 59
Mitosis
Division of the
nucleus
Also called
karyokinesis
Only occurs in
eukaryotes
Has four stages
Doesn’t occur in
some cells such
as brain cells
61. 61
Early Prophase
Chromatin in nucleus condenses to
form visible chromosomes
Mitotic spindle forms from fibers in
cytoskeleton or centrioles (animal)
Chromosomes
Nucleolus Cytoplasm
Nuclear Membrane
62. 62
Late Prophase
Nuclear membrane & nucleolus are
broken down
Chromosomes continue condensing &
are clearly visible
Spindle fibers called kinetochores
attach to the centromere of each
chromosome
Spindle finishes forming between the
poles of the cell
66. 66
Spindle Fibers
The mitotic spindle form from the
microtubules in plants and
centrioles in animal cells
Polar fibers extend from one pole
of the cell to the opposite pole
Kinetochore fibers extend from the
pole to the centromere of the
chromosome to which they attach
Asters are short fibers radiating
from centrioles
68. 68
Metaphase
Chromosomes, attached to the
kinetochore fibers, move to the center
of the cell
Chromosomes are now lined up at the
equator
Pole of the
Cell
Equator of Cell
75. 75
Telophase
Sister chromatids at opposite
poles
Spindle disassembles
Nuclear envelope forms around
each set of sister chromatids
Nucleolus reappears
CYTOKINESIS occurs
Chromosomes reappear as
chromatin
77. 77
Cytokinesis
Means division of the cytoplasm
Division of cell into two,
identical halves called daughter
cells
In plant cells, cell plate forms
at the equator to divide cell
In animal cells, cleavage furrow
forms to split cell
79. 79
Daughter Cells of Mitosis
Have the same number of
chromosomes as each other and
as the parent cell from which
they were formed
Identical to each other, but
smaller than parent cell
Must grow in size to become
mature cells (G1 of Interphase)
81. 81
Eukaryotic Cell Division
Used for growth and
repair
Produce two new cells
identical to the original
cell
Cells are diploid (2n)
Chromosomes during
Metaphase of mitosis
Prophase Metaphase Anaphase
Telophase
Cytokinesis
82. 82
Identify the Stages
Early, Middle, & Late Prophase
Late Prophase Metaphase Anaphase
Late Anaphase Telophase Telophase &
Cytokinesis
?
? ? ?
? ? ?
83. 83
Uncontrolled Mitosis
If mitosis is not
controlled, unlimited
cell division occurs
causing cancerous
tumors
Oncogenes are special
proteins that
increase the chance
that a normal cell
develops into a tumor
cell
Cancer cells
85. 85
Facts About Meiosis
Preceded by interphase which
includes chromosome replication
Two meiotic divisions --- Meiosis I
and Meiosis II
Called Reduction- division
Original cell is diploid (2n)
Four daughter cells produced that
are monoploid (1n)
86. 86
Facts About Meiosis
Daughter cells contain half the
number of chromosomes as the
original cell
Produces gametes (eggs & sperm)
Occurs in the testes in males
(Spermatogenesis)
Occurs in the ovaries in females
(Oogenesis)
87. 87
Start with 46 double stranded
chromosomes (2n)
After 1 division - 23 double stranded
chromosomes (n)
After 2nd division - 23 single stranded
chromosomes (n)
Occurs in our germ cells that produce
gametes
More Meiosis Facts
88. 88
Why Do we Need Meiosis?
It is the fundamental basis of
sexual reproduction
Two haploid (1n) gametes are
brought together through
fertilization to form a diploid (2n)
zygote
90. 90
Replication of Chromosomes
Replication is the
process of
duplicating a
chromosome
Occurs prior to
division
Replicated copies
are called sister
chromatids
Held together at
centromere
Occurs in
Interphase
91. 91
A Replicated Chromosome
Homologs
(same genes, different
alleles)
Sister
Chromatids
(same genes,
same alleles)
Gene X
Homologs separate in meiosis I and therefore different
alleles separate.
92. 92
Meiosis Forms Haploid Gametes
Meiosis must reduce the chromosome number
by half
Fertilization then restores the 2n number
from mom from dad child
meiosis reduces
genetic content
too
much!
The right
number!
93. 93
Meiosis: Two Part Cell Division
Homologs
separate
Sister
chromatids
separate
Diploid
Meiosis
I
Meiosis
II
Diploid
Haploid
94. 94
Meiosis I: Reduction Division
Nucleus Spindle
fibers Nuclear
envelope
Early Prophase
I
(Chromosome
number
doubled)
Late
Prophase I
Metaphase I
Anaphase I Telophase I
(diploid)
103. 103
Meiosis II
Only one homolog of each
chromosome is present in
the cell.
Meiosis II produces gametes with
one copy of each chromosome and thus one
copy of each gene.
Sister chromatids carry
identical genetic
information.
Gene X
104. 104
Meiosis II: Reducing Chromosome
Number
Prophase II
Metaphase II
Anaphase II
Telophase II
4 Identical
haploid cells
109. 109
Results of Meiosis
Gametes (egg & sperm) form
Four haploid cells with one
copy of each chromosome
One allele of each gene
Different combinations of
alleles for different genes
along the chromosome
111. 111
Spermatogenesis
Occurs in the
testes
Two divisions
produce 4
spermatids
Spermatids mature
into sperm
Men produce about
250,000,000
sperm per day
114. 114
Oogenesis
Occurs in the ovaries
Two divisions produce 3 polar
bodies that die and 1 egg
Polar bodies die because of
unequal division of cytoplasm
Immature egg called oocyte
Starting at puberty, one oocyte
matures into an ovum (egg)
every 28 days
118. 118
Mitosis Meiosis
Number of
divisions
1
2
Number of
daughter cells
2 4
Genetically
identical?
Yes No
Chromosome # Same as parent Half of parent
Where Somatic cells Germ cells
When Throughout life At sexual maturity
Role
Growth and
repair
Sexual reproduction
Comparison of Divisions
119. In conclusion, we managed to:
Define a cell; history of cell, list its general parts and
explain their function
Describe the active and passive processes by which
materials move across plasma membranes
Define a gene; explain its role in protein synthesis
Identify the stages, events and significance of cell
division
