Presentation on a cell

1. Lesson Plan
 Subject: Basic Anatomy, Physiology and Microbiology
DAPM 101
 Topic: Composite Cell

2. Learning Outcomes
At the end of this unit the learner should be able to:
1.Describe the three major parts of a human cell.
2.Describe the structure and functions of the nucleus.
3.Describe the structure and functions of the cell membrane.
4.Describe the structure and functions of the following cytoplasmic organelles:
 Endoplasmic reticulum
 Ribosomes
 Golgi apparatus
 Mitochondria
 Lysosomes
 Centrosome
 Cilia and flagella

3. Learning Outcomes
 Microfilaments and Microtubules
5.Describe the following processes that are responsible for the movement of
substances through the cell membrane:
 Diffusion
 Facilitated diffusion
 Osmosis
 Filtration
 Active transport
 Pinocytosis
 Phagocytosis

4. Learning Outcomes
6.Describe the following processes of cell division:
 Mitosis
 Meiosis
7.Explain the concept “differentiation”.
8.Identify the chromosome numbers in each of the cells:
 Somatic cell
 Sex cell

5. The three major parts of a human cell
 A cell is the basic unit of structure
and function.
Three major parts of a human cell
Nucleus
 The nucleus is the innermost and is
enclosed by a thin membrane called
the nuclear envelope.
Cytoplasm
 Cytoplasm contains networks of
membranes and organelles
suspended in fluid and may also
contain non-living cellular products.
Cell Membrane
 The cell membrane forms the
outermost limit of a cell.

6. The structure and functions of the nucleus
The structure of the nucleus Functions of the nucleus
 A nucleus is a large, spherical organelle that
contains the genetic material (DNA) that
directs the activities of the cell.
 The nucleus is enclosed in a double-layered
nuclear envelope that has nuclear pores that
control movement of substances between
the nucleus and cytoplasm.
 Chromatin is composed of loosely coiled
fibers of protein and DNA that coil tightly
into chromosomes during cell division.
 Chromatin consists of the cell’s 46
chromosomes.
 A nucleolus is a small, dense body largely
composed of RNA and protein.
 Contains the genetic material
(DNA) that directs the activities of
the cells.

7. The structure and functions of the cell membrane
The structure of a cell membrane Functions of the cell membrane
 The cell membrane forms the
outermost limit of the living material.
 The cell membrane is extremely thin.
 It is flexible and somewhat elastic.
 It acts as a selectively permeable
passageway that controls the
movements of substances between the
cell and its surroundings.
 It includes protein, lipid and
carbohydrate molecules.
 The cell membrane framework is
mainly a double layer of phospholipid
molecules.
 Proteins provide the special
functions of the membrane, as
transporters, receptors, enzymes,
cell surface markers of self and
cellular adhesion molecules.
 Maintains the integrity of the cell.
 Controls the entrance and exit of
substances, allowing some in while
excluding others.
 It allows the cell to receive and
respond to incoming messages, in
a process called signal
transduction.

8. The structure and functions of the cytoplasmic
organelles Page 87 – 97 Hole’s
Endoplasmic Reticulum
Structure of Endoplasmic Reticulum Functions of Endoplasmic Reticulum
 Is a complex organelle composed
of membranous flattened sacs,
cylinders and fluid-filled
bubblelike sacs called vesicles.
 Transports materials within the
cell.
 Provides attachment for
ribosomes.
 Synthesizes lipids.
Ribosomes
Structure of Ribosomes Functions of Ribosomes
 Are tiny, spherical structures
composed of protein and RNA
molecules.
 Synthesize proteins.

9. The structure and functions of the cytoplasmic
organelles Cont
Golgi apparatus
The structure of Golgi apparatus The functions of Golgi apparatus
 Group of flattened, membranous
sacs
 Packages and modifies protein
molecules for transport and
secretion.
Mitochondria
The structure of Mitochondria The functions of Mitochondria
 Membranous sacs with inner
partitions.
 Are elongated, fluid-filled sacs.
 Has two layers, an outer membrane
and an inner membrane.
 Release energy from food
molecules and convert the energy
into a usable form (ATP).

10. The structure and functions of the cytoplasmic
organelles Cont
Lysosomes
The structure of Lysosomes The functions of Lysosomes
 Are small membranous sacs.
 Are the “garbage disposals” of the
cell, where enzymes dismantle
debris.
 The process of a cell’s disposing of
its own trash is called “
autophagy”, which means “eating
self”
Contain enzymes that break down
worn cellular parts or substances that
enter cells.

11. The structure and functions of the cytoplasmic
organelles Cont
Centrosome
The structure of the Centrosome The functions of Centrosome
 It is a non-membranous structure
composed of two rodlike
centrioles.
 A centrosome (central body) is a
structure in the cytoplasm near the
nucleus.
 Helps distribute chromosomes to
new cells during cell division.
 Initiates formation of cilia.

12. The structure and functions of the cytoplasmic
organelles Cont
Cilia
The structure of Cilia Functions of Cilia
 Motile projections attached to
basal bodies beneath the cell
membrane.
 Some cilia propel fluids over cell
surface, other are sensory.
Flagella
The structure of Flagella Functions of Flagella
 Projection attached to a basal body
beneath the cell membrane.
 Enables sperm cell to move.

13. The structure and functions of the cytoplasmic
organelles Cont
Microfilaments and Microtubules
The structure of Microfilaments and
Microtubules
Functions of Microfilaments and
Microtubules
 Microfilaments are tiny rods of the
protein actin that form meshworks
or bundles and provide cellular
motility.
 Are threadlike structures in the
cytoplasm.
 Microtubules are long, slender
tubes with diameters two or three
times greater than those of
microfilaments.
 Support cytoplasm.
 Help move substances and
organelles within the cytoplasm.

14. The processes that are responsible for the movement of
substances through the cell membrane Page 101 – 106
Hole’s
 Diffusion
 Diffusion is due to the random movement of atoms, molecules or ions in air
or solution.
 Diffusion is movement of atoms, molecules or ions from regions of higher
concentration toward regions of lower concentration.
 It exchanges oxygen and carbon dioxide in the body.
 Facilitated diffusion
 Facilitated diffusion uses protein channels or carrier molecules in the cell
membrane.
 This process moves substances such as ions, sugars and amino acids from
regions of higher concentration to regions of lower concentration.

15. The processes that are responsible for the movement of
substances through the cell membrane
 Osmosis
 Osmosis is a process in which water molecules move through a selectively
permeable membrane toward the solution with greater osmotic pressure,
lifting a volume of water.
 A solution is isotonic when it contains the same concentration of dissolved
particles as the cell contents.
 Cells lose water when placed in hypertonic solutions and gain water when
placed in hypotonic solutions.
 Filtration
 In filtration, molecules move through a membrane from regions of higher
hydrostatic pressure toward regions of lower hydrostatic pressure.

16. The processes that are responsible for the movement of
substances through the cell membrane
 Active transport
 Active transport moves molecules or ions from regions of lower
concentration to regions of higher concentration.
 It requires ATP and carrier molecules in the cell membrane.
 Pinocytosis
 In pinocytosis, a cell membrane engulfs tiny droplets of liquids.
 Phagocytosis
 In phagocytosis, a cell membrane engulfs solid particles.

17. Processes of cell division
 Mitosis
 Mitosis occurs all over the body in somatic cells and produces two daughter
cells from an original cell.
 Mitosis consist of one cell division.
 These new cells are genetically identical.
 Mitosis produces Diploid cells (2n) (46 chromosomes).
 The 46 chromosomes are actually 2 sets of 23 chromosomes, with one set
inherited from each parent.
 Mitosis is a continuous process, but it is described in stages that indicate the
sequence of major events. The stages are, Prophase, Metaphase, Anaphase
and Telophase.

18. Processes of cell division
Major Events in Mitosis
Stage Major Events
Prophase  Chromatin condenses into chromosomes.
 Centrioles move to opposite sides of cytoplasm.
 Nuclear membrane & nucleolus disperse.
 Microtubules assemble & associate with centrioles & the two
sister chromatids making up each chromosome.
Metaphase  Spindle fibers from the centrioles attach to the centromeres of
the sister chromatids of each chromosome.
 Chromosomes align midway between the centrioles.

19. Processes of cell division
Major Events in Mitosis
Stage Major Events
Anaphase  Centromeres separate and sister chromatids move apart, with
each chromatid now an individual chromosome.
 Spindle fibers shorten and pull these new individual
chromosomes toward the centrioles.
Telophase  Chromosomes elongate and form chromatin threads.
 Nuclear membranes form around each chromosome set.
 Nucleoli form.
 Microtubules break down.

20. Processes of cell division
 Meiosis
 Meiosis occurs only in the cells that give rise to sex cells or reproductive cells
of a gonads in order to form gametes (sperm and oocyte).
 Meiosis consist of two stages of cell division, meiosis I and meiosis II.
 Meiosis produces Haploid cells (n) (23 chromosomes).
 Haploid are reproductive cells called gametes.
 Gametes are cells that transmit genetic information from the parents to their
offspring.
 In humans, this gametes takes the form of a sperm and egg cell.
 During fertilization the sets of chromosomes will combine to give one diploid
cell (2n), which are a combination of a genetic material from the mother and
father.
 In this way, when a sperm fertilizes an egg, the total number of 46
chromosomes is restored.

21. Differentiation
 A process in development in which unspecialized cells or tissues are
systemically modified and altered to achieve specific and characteristic
physical forms, physiologic functions and chemical properties.
 Differentiation is the process by which cells develop different structures and
functions.

22. The chromosome numbers in each of the cells
Somatic cell Sex cell
 46 Chromosomes (2 sets of
chromosomes; 1 set from each
parent)
 Represented by “2n” chromosome
number
 All somatic cells
 Created by Mitosis
 23 Chromosomes (1 set of
chromosomes)
 Represented by “n” chromosome
number
 Gametes only
 Created by Meiosis

23. Summary
 The three major parts of a human cell.
 The structure and functions of the endoplasmic organelles.
 The processes responsible for the movement of substances through the cell
membrane.
 The process of cell division.
 Chromosome numbers in Somatic cell and Sex cell.

24. Assessment
1.Name three major parts of a human cell.
2.Define the following concepts:
 Diffusion
 Pinocytosis
 Phagocytosis
3.Name two processes of cell division.
4.Name the stages of Mitosis.
5.Identify the chromosome numbers in each of the cells:
 Somatic cell
 Sex cell

25. The End
Thank You