Cell growth and division pp presention
-
Upload
narsglance -
Category
Education
-
view
916 -
download
0
description
Transcript of Cell growth and division pp presention
Cell Growth and Division
Cell Division is the Cell’s way of Reproducing itself
Reproduction
IS A LIFE PROCESS MORE OF THE SAME UNIT IS FORMED NOT ESSENTIAL FOR SURVIVAL IS A NEED TO PERPETUATE SPECIES
CHAPTER OBJECTIVES
At the end of lecture discussion, the learners are expected to:
Explain Cell Reproduction at
the molecular level, with
emphasis of the role of DNA
and Chromosomes
Describe the limits to cell growth.
Identify the types of cells in the body
of an organism.
Name and describe the sequence of
stages in Mitosis and Meiosis.
Describe the chromosamal changes
in Mitosis and Meiosis.
Give the significance of cell division.
Trace the formation of sperm and egg cells through the process of spermatogenesis and oogenesis.
Cell Growth & Reproduction
Review of Terms
DNA
Chromatids
Histones
Helix
Chromosome
Chromatin
Nucleosomes
DNA Replication
DNA possesses a
remarkable ability
to create copies of
its own structure
DNA Replication cont’
REPLICATION
Occurs as the
double strand of
DNA unzips at
certain points
(synthesis stage)
Limits of Cell Growth
Cells of human adult are no larger than human babies. Cells eat and defecate Cells know to adapt Cells growth and division rate vary.
Sometimes cell growth and division become
uncontrollable (cancer cells)
CELLS OF THE HUMAN BODY
Somatic CellsDiploid number (2N) or complete set of (46) Chromosomes
Ex.Skin CellsLung Cellsetc.
Reproductive CellsHaploid number (N) or half (23) number of chromosomes.
Ex.Sperm CellEgg Cell
Assessment Break
Explain the limits of Cell Growth.
Why do cells divide?
Distinguish between
Somatic and Germ Cells
Haploid and Diploid
MITOSIS
Mitosis is the
first step in
growth and
differentiation
of somatic
cells.
During Mitosis Chromosomes duplicate and daughter cells receives the
same amount of chromosomal
material as the parent cell.
MITOSIS cont’
Interphase
G1 ~ Presynthetic
S ~ Synthetic Phase
G2 ~ Postsynthetic stage
Interphase
( not a phase of Mitosis)
Growth occurs as organelles double (G1)Chromosomes (DNA) duplicates (S)Growth occurs as cell prepares to divide (G2)
The Major Events of Cell Division
KARYOKINESIS
SPLITTING OF THE NUCLEUSINSIDE NUCLEAR EVENTS OF THE CELL
CYTOKINESIS
CYTOPLASMIC DIVISIONOUTSIDE NUCLEAR EVENTS OF THE CELL
Mitosis
Phases of Mitosis Mitosis begins after Interphase
Stages/Phases
Prophase
Metaphase
Anaphase
Telophase
ProphaseEarly ProphaseCentrioles move to the poles of the cellChromosomes appear as long, this threadsNucleus becomes less distinct
Nuclear membrane is still visibleAsters are formed
ProphaseMiddle Prophase
Centrioles begin to organize spindle fibersSister chromatids are formed with the centromere as point of attachment
ProphaseLate ProphaseCentrioles are
nearly at the opposite sides of the nucleus
Nuclear membrane slowly desintegrates
Nucleulus is no longer visible
Chromosome move toward the equator
Spindle fibers attach to the centromere of each chromosome
Metaphase Nuclear membrane has completely disappearedThe centromere of each double-stranded chromosome is attached to a spindle fiber at the equator
Centrioles are at the opposite ends of the polesChromosomes line up at the center forming metaphase plate
Anaphase
Early AnaphaseSister
chromatids separate and begin moving toward opposite poles of the cell
Sister chromatids start to move toward the poles, seemingly being pulled by the thread or fibers
Anaphase
Late AnaphaseTwo sets of new,
single stranded chromosomes start to migrate near their respective poles
Cytokinesis begins
A slight cleavage furrow in the cell membrane begins to form in the region of the equator
Telophase
New nuclear membrane starts to form in each new cellChromosomes become longer, thinner and less distinctThe nucleus reappears
Centrioles are replicatedCytokineseis is nearly completeSpindle fibers and asters disappearThe cleavage furrow deepens and the cell finally divide onto two parts
2nd Interphase: 2 cell stage
o Nuclear membrane are complete in each cells
o Chromosomes are no longer visible
o Cytokinesis is complete
o Two new daughter cells are formed, each with a complete set of materials as the parent cell
The process of Mitosis
Occur in less than an hour or longer ( some in just 23 minutes)
Brain cells do not dived when mature
Most frequent/fast in human embryo formation
Assessment Break
Define Mitosis. Why is it important?
What are the stages of mitosis?
What body cells are involved in mitotic process?
When is the process of mitosis faster? Slower?
Meiosis
A cell division forming reproductive cells
OogenesisSpermatogenesis
Occurs in two cycles of division
Meiosis Dissected: Stages
Meiosis involves two
consecutive divisions
It involves “Crossing
Over” or the exchange of DNA traits
1st & 2nd Meiotic Division
Parent Sex Cells
Chromosomes duplicate
Crossing over
1st Cell division(2 daughter
cells)
2 daughter cells
Chromosomes pair up
Chromosomes separate
2nd Cell Division) Cell divides into 4 sex cells with haploid
chromosomes
Mitosis VS Meiosis
Gametogenesis
Meiosis only happens when your body is ready to produce
reproductive cells
Spermatgenesis ~ formation of sperm cells
Oogenesis ~ formation of egg cells
Spermatogenesis
The formation of
male gametes
An example of Meiosis
Oogenesis
Formation of Female Gamete
An example of Meiosis
SPERMATOGENESIS VS OOGENESIS
Assessment Break
Define meiosis. How is it different from mitosis?How many cells are formed after the first cell division in meiosis? After the second division?What is gametogenesis?Compare and contrast spermatogenesis and oogenesis.