Agenda for the day
1.
2.
3.
4.
Types of cells – Somatic vs. Gamete
Steps of the cell cycle
Mitosis – defined
Mitosis lab
Focus for the day
• Today, we will discuss the importance of
mitosis and how it relates to cell reproduction.
• I will sequence the steps of the cell cycle,
particularly mitosis, using a laboratory
exercise.
Cells
WHAT’S THE DIFFERENCE?
 Living cells are divided into two types:
 Eukaryotic (Plant & Animal cells)
 Prokaryotic (Bacteria)
Prokaryotic Cells
• Prokaryotic cells do not have a membrane
bound nucleus. Instead, their genetic material
is in a circular loop in a region referred to as
the nucleoid.
PROKARYOTIC
 Prokar yotic
 These cells are simple in structure
 No structured nucleus
 Exist as single-celled organisms
 Bacteria is both helpful and harmful to us and the environment .
 Example: Bacterial cells
 Structure:
Capsule (bacterial cells only)
Cell wall
Chromosomes
Cytoplasm
Flagellum (bacterial cells only)
Inner membrane
Outer membrane
Pili (bacterial cells only)
Ribosomes
• Members of the kingdoms Archaebacteria
(ancient bacteria) and Eubacteria (true
bacteria) have prokaryotic cells.
• Most bacteria come in one of three basic
shapes: spirilla (spiral), bacilli (rod), and cocci
(round).
BACTERIAL CELL
( P ROKA RYOTIC )
 Unique parts of the bacterial cell
 Capsule - Protects the bacterial cell and serves as a barrier against
phagocytosis by white blood cells.
 Flagellum – “Mobility”. Flagella are long appendages which rotate by means
of a "motor" located just under the cytoplasmic membrane. Bacteria may
have one, a few, or many flagella in different positions on the cell.
 Pili - These hollow, hair-like structures allow bacteria to attach to other cells.
• More complicated organisms have cells which
have more structural integrity with a defined
nucleus.
• Members of the kingdoms Protista, Fungi,
Plantae (plants), and Animalia (animals) all
have eukaryotic cells.
EUKARYOTIC
 Eukar yotic
 These cells tend to be larger than the cells of bacteria (prokaryotic)
 Have a defined nucleus
 Found in organisms made up of many cells
 Example: Plant and Animal cells
 Structure:
Cell Membrane
Cell Wall (plant cells only)
Centrosome
Centriole (animal cells only)
Chloroplast (plant cells only)
Cytoplasm
Cytoskeleton
Cytosol
Golgi
Lysosome
Mitochondria
Nucleus
Nucleolus
Peroxisome
Reticulum
Ribosomes
Rough Endoplasmic
Secretory Vesicle
Smooth Endoplasmic
Vacuole
PLANT CELL
( E UKA RYOTIC )
 Unique parts of the plant cell
 Cell wall – a feature of plants cells that functions like stiff lattice-like
wall which helps plant cells maintain their structure and shape
 Chloroplast – a feature of plant cells that allows plants to do
photosynthesis and make their own glucose from sunlight, water and
carbon dioxide
SIMILARITIES
Similarities
DESCRIPTION
1. DNA/ Chromosomes
2. Cell membrane
3. Structures to produce
energy for cell- Cell
Respiration
4. Structures that make
proteins and enzymes for
the cell
5. Cytoplasm
Bacterial Cells
Yes
Yes
No-occurs
near cell
membrane
Plant Cells
Animal Cells
Yes
Yes
Yes
Yes
Yes- in organelle Yes- in organelle
called
called
mitochondrion
mitochondrion
Yes-poly(many)
ribosomes
Yesendoplasmic
reticulum
(organelle)
Yesendoplasmic
reticulum
(organelle)
Yes
Yes
Yes
DIFFERENCES
Differences
DESCRIPTION
1. Cell Wall
2. Nucleus-nuclear membrane
3. Fimbria-DNA transfer
4. Vacuoles
5. Chloroplasts (organelles) (for
photosynthesis)
6. Flagella-mobility
7. Capsule
Bacterial Cells
Yes
No
Some
No
Yes-blue-green
bacteria has a
green pigment
that makes its
own food.
Yes
Some
Plant
Cells
Animal
Cells
Yes
Yes
No
Yes
No
Yes
No
Yes
Yes
No
No
No
No
No
Types of cells in the body
• 1. Somatic Cells
• 2. Gametes
Somatic Cells
• Somatic cells can be defined as any cells other
than gametes, germ, or undifferentiated stem cell
which make up the entire body.
• Somatic stem are natural cells which are found in
the bodies of all multicellular organisms.
• Somatic cells are undifferentiated and are not
dedicated to a particular type of tissue
permanently.
Somatic cells perform two major
functions:
• Replacing dying cells, especially in the
epidermis where the requirement is
continuous
• Repairing the damaged tissue, mostly when
the body has faced the onslaught of trauma
and disease
Gametes
• Gametes, also known as germ cells or sex
cells, are spermatozoon (sperm cells) or ovum
(egg cells) which result from the process of
meiosis.
• They are haploid, meaning that each cell
contains only half of the complement of
chromosomes and genetic material needed to
encode (and essentially create) an individual.
• Two gametes merge to produce a single
diploid cell, the zygote, which will contain the
complete number of chromosomes needed
for life.
Haploid Vs. Diploid
• Haploid = n
• Diploid = 2n
• Diploid cells (2N) have two complete sets of
chromosomes (one from the mom and one
from the dad). The body cells of animals are
diploid.
• Haploid cells have one complete set of
chromosomes. In animals, gametes (sperm
and eggs) are haploid.
Diploid
Examples
Organisms
Cell Division and Growth
About:
Haploid
Spermatogonium cell
Human sex cells (sperm and
ova).
Humans and most animal
Algae and fungi are
cells are diploid organisms. examples of organisms that
are mostly haploid during
their life cycle. Male bees,
wasps, and ants are also
haploid.
During the process of
Haploid cells are the result
reproduction, haploid cells
of the process of meiosis, a
(male and female) unite to
type of cell division in which
form a diploid zygote, which diploid cells divide to give
divides by mitosis to give rise rise to haploid germ cells.
to more diploid cells.
Diploid cells contain two
complete sets of
chromosomes
Haploid cells have half the
number of chromosomes (n)
as diploid – i.e., a haploid
cell contains only one
complete set of
chromosomes.
Specialized cells
Epithelial, Muscle, and Bone cells
• Epithelial cells are attached to one another.
Special devices (intercellular junctions,
tonofilaments) provide for structural integrity
of the epithelium. There are several types of
cell junctions.
Cell Junctions:
• Adhering junctions
• Tight (occluding) junctions
• Gap junctions
Muscle cells
• 1. Skeletal muscle
• 2. Cardiac muscle
• 3. Smooth muscle
• http://www.youtube.com/watch?v=PJDrR3sZP
ZU
Bone Cells
• Osteoclasts are large cells that dissolve the
bone. They come from the bone marrow and
are related to white blood cells.
• Osteoblasts are the cells that form new
bone. They also come from the bone
marrow and are related to structural
cells. They have only one nucleus.
Osteoblasts work in teams to build
bone.
• Osteocytes make up the structure of existing
bone. They also come from osteoblasts.
• http://www.youtube.com/watch?v=78RBpWS
Ol08
Cell Differentiation
• Cell differentiation is the development of a
generic cell into a cell with a specific function,
which is directed by various triggers.
• This differentiation is essential for cell
renewal and embryonic development; it
occurs numerous times in the development of
a single-celled zygote into a multi-cellular
organism with many different cell types.
• It is also essential for cellular turnover, the
continuous maintenance of most multicellular organisms.
• Through differentiation, a cell drastically
changes its size, shape, membrane potential,
metabolic activity, and responsiveness.
What is (and is not) mitosis?
Mitosis is nuclear division plus cytokinesis, and
produces two identical daughter cells during
prophase, **prometaphase, metaphase, anaphase,
and telophase. Interphase is often included in
discussions of mitosis, but interphase is technically not
part of mitosis, but rather encompasses stages G1, S,
and G2 of the cell cycle.
**Prometaphase is often times considered part of
prophase.
G1 phase: Metabolic
changes prepare the cell for
division. At a certain point
(the restriction point) the
cell is committed to division
and moves into the S
phase.
S phase: DNA synthesis
replicates the genetic
material. One chromosome
now consists of two sister
chromatids.
G2 phase: Metabolic
changes assemble the
cytoplasmic materials
necessary for mitosis and
cytokinesis.
M phase: A nuclear division
(mitosis) followed by a cell
division (cytokinesis).
The Cell Cycle
Interphase
• Interphase consists of the G1, S, and G2
phase.
Cell Division
• Mitosis
• Mitosis is the division of a SOMATIC cell
Mitosis
• can be defined as nuclear
division plus cytokinesis. The
process produces two identical
daughter cells through
prophase, prometaphase,
metaphase, anaphase, and
telophase.
Prior to Mitosis (G2)
The cell is engaged in metabolic activity and preparing
for mitosis (the next four phases that lead up to and
include nuclear division). Chromosomes are not
clearly discernible in the nucleus, although a dark
spot called the nucleolus may be visible. The cell may
contain a pair of centrioles (or microtubule
organizing centers in plants) both of which are
organizational sites for microtubules.
Prophase
Chromatin in the nucleus
begins to condense and
becomes visible in the light
microscope as
chromosomes. The
nucleolus disappears.
Centrioles begin moving to
opposite ends of the cell
and fibers extend from the
centromeres. Some fibers
cross the cell to form the
mitotic spindle.
Prometaphase
The nuclear membrane
dissolves, marking the
beginning of prometaphase.
Proteins attach to the
centromeres creating the
kinetochores. Microtubules
attach at the kinetochores and
the chromosomes begin
moving.
Metaphase
Spindle fibers align the
chromosomes along the middle
of the cell nucleus. This line is
referred to as the metaphase
plate. This organization helps to
ensure that in the next phase,
when the chromosomes are
separated, each new nucleus will
receive one copy of each
chromosome.
Anaphase
The paired chromosomes
separate at the kinetochores
and move to opposite sides of
the cell. Motion results from a
combination of kinetochore
movement along the spindle
microtubules and through the
physical interaction of polar
microtubules.
Telophase
• Chromatids arrive at opposite
poles of cell, and new membranes
form around the daughter nuclei.
The chromosomes disperse and
are no longer visible under the
light microscope. The spindle
fibers disperse, and cytokinesis or
the partitioning of the cell may
also begin during this stage.
Cytokinesis
In animal cells,
cytokinesis results
when a fiber ring
composed of a protein
called actin around the
center of the cell
contracts pinching the
cell into two daughter
cells, each with one
nucleus. In plant cells,
the rigid wall requires
that a cell plate be
synthesized between
the two daughter cells.
Mitosis
• https://www.youtube.com/watch?v=C6hn3sA
0ip0
Oreo Lab Instructions
• In groups of 3:
• You will get 6 oreo cookies, 3 toothpicks, and
some sprinkles.
• Determine which color sprinkles represent the
mitotic structures inside the cell. You will
need to modify the sprinkles to represent
smaller structures (like centrioles). The filling
represents the cytoplasm.
• Each oreo represents a stage of the cell cycle:
IPMATC
Meiosis
Meiosis
• Meiosis is a process which stands alone,
separate from the cell cycle, even though the
process of mitosis occurs within meiosis. This
process (unlike mitosis), is necessary for
sexual reproduction and results in a total of
four daughter cells, each of which are
different from the parent cell.
• The cell's chromosomes replicate and form pairs in
meiosis. In a process called crossing over, each pair
exchanges chromosomal material to enhance genetic
variation. The cell then follows division steps similar
to mitosis to form two daughter cells. These two
daughter cells, in turn, undergo cell division to create
a total of four new sex cells, each with only half the
chromosomal makeup of the parent cell, and each
with the unique assortment of genetic information.
• So when a male sex cell and a female sex cell
combine during sexual reproduction, a new
cell with the normal number of chromosomes
is created. This new cell will divide repeatedly
by mitosis until a complete new individual is
formed.
Prophase 1
• DNA replication precedes the start of meiosis
I. During prophase I, homologous
chromosomes pair and form synapses, a step
unique to meiosis. The paired chromosomes
are called bivalents, and the formation of
chiasmata caused by genetic recombination
becomes apparent.
• Chromosomal condensation allows these to
be viewed in the microscope. Note that the
bivalent has two chromosomes and four
chromatids, with one chromosome coming
from each parent.
Prophase 1
Prometaphase 1
• The nuclear membrane disappears. One
kinetochore forms per chromosome rather
than one per chromatid, and the
chromosomes attached to spindle fibers begin
to move.
Metaphase 1
• Bivalents, each composed of two
chromosomes (four chromatids), align at the
metaphase plate.
The orientation is random, with either
parental homologue on a side. This means
that there is a 50-50 chance for the daughter
cells to get either the mother's or father's
homologue for each chromosome.
Anaphase 1
• Chiasmata separate. Chromosomes, each with
two chromatids, move to separate poles. Each
of the daughter cells is now haploid (23
chromosomes), but each chromosome has
two chromatids.
Telophase 1
• Nuclear envelopes may reform, or the cell may
quickly start meiosis II.
Prophase 2
Metaphase 2 and Anaphase 2
Telophase 2 and Cytokinesis
Meiosis
• http://www.youtube.com/watch?v=qCLmR9YY7o
Organism Levels
• 1. Chemical Level: The smallest microscopic
units of matter that have the properties of an
element. They combine with covalent bonds
to form molecules such as molecular oxygen
(O2), glucose (C6H12O6), or methane (CH4).
• 2. The Cellular Level: The smallest unit of life.
Cells have various sizes, shapes, and
properties that allow them to carry out
specialized functions.
• 3. Tissue Level: A tissue is a group of cells
having a common structure and function.
There are four types of tissue: muscle,
epithelia, nervous, and connective.
• Connective: Fibrous, nonliving: gives shape to
organs and holds them in place
• Muscle: Most active tissue – smooth, skeletal,
cardiac
• Nervous: Central and peripheral
• Epithelial: provides a barrier of protection
• 4. Organ Level: Two or more tissues working
for a common function develop an organ. All
four tissue types combine to form skin, the
largest organ in the body, or the cochlea in the
ear, the smallest organ of all.
• 5. Organ System Level: Organs work together
for a common function. The organ systems
include the integumentary, skeletal, muscular,
nervous, endocrine, cardiovascular, lymphatic,
respiratory, digestive, urinary, and
reproductive systems.
• 6. Organismal Level: The organismal level
(whole animal), includes all the organ systems
that work together to maintain homeostasis.