BIONOTES ( CELL CYCLE, CELL DIVISION AND the body.

These contrast with benign tumors, which

CELLULAR TRANSPORT) do not spread.
CELL CYCLE  METASTASIS- the development of
 The sequence of events from the time a cell first secondary malignant growths at a distance from a
arises as a result of cell division until the time when primary site of cancer.
that cell divides itself.
 Arise-divides Proto-oncogenes
 2 PERIODS OF CELL CYCLE
A. Interphase  The genes that code for the positive cell cycle
B. Mitotic phase regulators,
- period of growth and DNA replication between cell divisions  Are normal genes that, when mutated in certain
ways, become oncogenes, genes that cause a cell
-it is the longest phase in cell cycle
to become cancerous.
THREE PHASES OF INTERPHASE
1. G1 Phase Tumor suppressor genes
 Cell increases in size
 DNA replication or separation of sister  are segments of DNA that code for negative
chromatids will not occur in this phase. regulator proteins, the type of regulators that, when
 Active metabolic activity activated, can prevent the cell from undergoing
2. S Phase uncontrolled division.
 Replication of DNA  A cell that carries a mutated form of a
 Two sister strands of DNA called chromatids negative regulator might not be able to halt
are produced the cell cycle if there is a problem.
3. G2 Phase  Are similar to brakes in a vehicle:
 Organelles double malfunctioning brakes can contribute to a car
 New cytoplasm forms crash. Mutated p53 genes have been
 All other structures needed for mitosis identified in more than one-half of all human
form tumor cells and it can increase cell division.
THE CHECKPOINTS  Retinoblastoma protein (Rb) is a tumor
Checkpoints help ensure that cell cycle events occur in the suppressor that inhibits cell division.
correct order.  A mutation in the BRCA1 gene, a tumor
suppressor, can increase the risk of breast
cancer.

Cell division
 occurs every after interphase.
In eukaryotic cells, these types
of cell division occur: mitosis
and meiosis.
Somatic cells have 46 chromosomes and are diploid
Gametes have half as many chromosomes as found in
somatic cells.

 It is also known as G1 checkpoint, G2 checkpoint The eukaryotic chromosomes can fit inside the nucleus even
and Spindle fiber or Mitosis checkpoint. though it is too long because the DNA remains coiled around
 If the M checkpoint is not cleared then the proteins to form nucleosomes.
Anaphase stage will be blocked.
 If there is severe damage of the cells then will Mitosis
undergo cell death or APOPTOSIS-it is a type of  is a cellular process wherein
programmed cell death that occurs only in
two nuclei and two cells are
multicellular organisms.
produced due to the division of
the original nucleus, each of
CANCER which contains the same
 is a group of diseases involving abnormal cell growth chromosome number as the
with the potential to invade or spread to other parts of parent cell.
  is divided into four stages karyokinesis.
namely:prophase, metaphase,  Cytoplasmic division called
anaphase, and telophase. cytokinesis occurs concurrently,
splitting the cell into two.
 2 TYPES OF MITOSIS MEIOSIS
A. Karyokinesis or nuclear
 is a special type of cell division of germ cells in sexually-
division- division takes place in
reproducing organisms that produces the gametes, the
the nucleus. sperm or egg cells. It involves two rounds of division
that ultimately
B. Cytokinesis- division takes result in four cells each with only one copy of each
place in the cytoplasm. chromosome (haploid)
 involves two divisions MEIOSIS I and MEIOSIS II.
Meiosis I.
 is a reduction division phase (diploid
- haploid).
 There are two daughter cells
produced after Meiosis 1, each
Prophase Stage daughter cell is carrying haploid
number of chromosomes.
 The repeated coiling of chromosomes
occurs resulted to its thicker and  This consists of four stages, namely,
prophase I, metaphase I, anaphase
shorter structure. These are made up
I, and telophase I.
of two sister chromatids that are
identical to each because of the Prophase I Stage
 Meiosis starts with this stage and
replication of DNA during the S
includes the following substages:
phase.
leptotene, zygotene, pachytene,
 The two chromatids are still attached at the
diplotene, and diakinesis.
centromere.
 The nuclear membrane breaks down. A.Substage 1: Leptotene
 Each chromosome is made up of
Metaphase Stage sister chromatids. These are long
threadlike structures which result
 Chromosomes align at the equatorial plane. from the replication of DNA during
 Each spindle fiber from both the Synthesis or S phase of the cell
centrosomes connects to each cycle.
chromosome through its kinetochore. B.Substage 2: Zygotene
 The homologous chromosomes start
Anaphase Stage to pair off through the process known
 Spindle fibers begin to contract and as synapsis. Pairs of chromosomes
become shorter. Continued that are similar in size and shape
contraction causes the separation of are called homologous
the genetically identical sister chromosomes or tetrads.
chromatids. C. Substage 3: Pachytene
 Centromeres divide.  The repeated coiling of chromosomes
 The single chromatids move towards the occurs resulting to its contraction and
opposite poles. thickening making the homologous
pair of chromosomes to be very
Telophase Stage close to each other. At this stage, the
 The chromosomes are now at the opposing process called crossing over
poles of the spindle. happens. T h e c o n s e q u e n c e o f
 The microtubules disappear. crossing over is the genetic
Two sets of chromosomes are variation.
surrounded by new nuclear C.Substage 4: Diplotene
membranes, completing the nuclear  The two homologous chromosomes
division process known as forming a tetrad begin to repel one
 another and move apart. They are
held only by the chiasma. CELL TRANSPORT
D. Substage 5: Diakinesis Phospholipids- are the foundation of all biological
 This is the last stage of meiosis membranes.
prophase 1. Diakinesis stage is Lipid bilayer- is formed through the interaction of
characterized by chiasmata between the nonpolar (hydrophobic or water fearing)
terminalization. After diakinesis, the phospholipid tails and (hydrophilic or water loving )
dividing cell enters metaphase. phospholipid heads.
Meiosis II. Phospholipids and proteins –are the major structural
components of cell membrane.
 The second meiotic division forms A protein should be amphipathic in order to become
four daughter cells, each carrying an integral protein.
haploid number of chromosomes.
FLUID MOSAIC MODEL
This consists of the following -phospholipids can move laterally along the plane of
stages, namely, prophase II, the membrane.
- maintaining the integrity of a fluid mosaic membrane is the
metaphase II, Anaphase II, and important function for the glycolipids and glycoproteins in
telophase II. animal cell membranes.
Prophase II Stage
 Chromosomes (chromatids) condense to form
metaphase chromosomes. TWO TYPES OF CELLULAR TRANSPORT
 Nuclear membrane dissolves and nucleolus 1. PASSIVE TRANSPORT
disappears.  Cell doesn’t use energy
 Centrosomes move towards each pole of the  It includes diffusion, facilitated diffusion and
cell. osmosis
 Molecules spread out from an area of high
Metaphase II Stage concentration to an area of low concentration.
DIFFUSION
 Spindle fibers attach to chromatids at the - Random movement of particles from an area
kinetochores. of high concentration to an area of low
 Chromosomes line up concentration.
at the equatorial plane. - It continues until the molecules are evenly
(Single alignment of spaced (equilibrium)
chromosomes). FACILITATED DIFFUSION
- Diffusion of specific particles through carrier
proteins found in the membrane.
- Carrier proteins they select only certain
Anaphase II Stage molecules to cross the membrane. Changes
shape as it transfers materials across the
 Spindle fibers shortened and separated the
membrane
sister chromatids.
 Chromatids that are now called
- Channel protein acts like pore in membranes
chromosomes move towards each so that small molecules can pass through.
pole of the cell. OSMOSIS
Telophase II Stage -diffusion of water through a selectively
 Single-stranded chromosomes decondense. permeable membrane.
 Nuclear membrane and nucleolus reforms. - plays an important role in homeostasis
 Cytoplasm divides (cytokinesis). hypertonic solution
Four haploid (n) daughter cells are formed. -has a higher concentration of solute than another
DISEASES/ABNORMAL CONDITIONS solution, meaning water will flow into it.
Aneuploidy, the presence of an abnormal number of -cell will shrink and die
chromosomes can result from errors in meiosis. hypotonic solution
Down syndrome, a genetic disorder characterized by extra -has a lower concentration of solute than another
chromosome 21, is caused by aneuploidy during meiosis. solution, meaning water will flow out of it.
-cells swell and burst (ex. Blood)
 to the outside of the cell.
Isotonic solution –equal solute and solution.
2. ACTIVE TRANSPORT – requires energy or ATP ENDOCYTOSIS
2 TYPES OF ACTIVE TRANSPORT A. PHAGOCYTOSIS It engulfs the solid material
A. PRIMARY forming phagocytic vesicle
B. SECONDARY -cell eating
3. BULK TRANSPORT B. PINOCYTOSIS. It occurs when the plasma
A. ENDOCYTOSIS- The process of capturing a membrane folds inward to form a channel allowing dissolved
substance or particle from outside the cell by engulfing it with substances to enter the cell.
the cell membrane.

B. EXOCYTOSIS. Describes the process of vesicles

fusing with the plasma membrane and releasing their contents
Prayer for Preparation to Study
Lord, I know you are with me and love me.
Give me peace of mind as I prepare for this time of study.
Help me to focus on my books and notes,
keep me from all distractions so that I will make the best use
of this time that is available to me.
Give me insight that I might understand what I am studying,
and help me to remember it when the time comes.
Above all, I thank you for the ability to be able to study
and for the many gifts and talents you have given me.
Help me always to use them in such a way
that they honor you and do justice to myself. AMEN