Transcript Cell Growth and Reproduction

CELL GROWTH AND
REPRODUCTION IN
EUKARYOTES
What is a Eukaryotic Cell?
• Cell that HAS nucleus
• Contains double stranded DNA
• Animal and plant cells!!
DNA
• DNA provides the blueprints or instructions for protein
synthesis.
• Cells cannot survive unless there is enough DNA to
support the protein needs of the cell.
Cell Reproduction
• The cell theory states that “all cells come from pre-
existing cells.”
• Cell division is the process by which this happens!
• Cell division results in two cells that are identical to the
original parent cell.
• All organisms grow and change; worn out tissues are
repaired or replaced by newly produced cells!
Before we learn about division, lets
start with the BASICS!
• What is “Genetic Material”? – DNA
• Where do we find DNA? – The cell nucleus
So what the heck is a chromosome?!
• Chromosome- Tightly coiled strands of DNA
• Where are chromosomes found? – THE NUCLEUS!
Parts of the chromosome
Each chromosome has 2
CHROMATIDS
Each chromosome has
1 CENTRIOLE holding both
Chromatids together
How many chromosomes in a cell!?
• Humans have 46 total chromosomes
• 23 pairs of chromosomes
What is MITOSIS?
The process of the
cell dividing ASEXUALLY
Only ONE PARENT is needed
One PARENT CELL
splits into TWO
DAUGHTER CELLS
Both daughter cells have
IDENTICAL DNA to parent cell
Let’s make like hairs and SPLIT
Phase 1: INTERPHASE
• Interphase contains 3 stages!
• 3 stages
• G1 – Cell grows rapidly and protein production is high
• S – Cell copies its chromosomes and DNA synthesis occurs
• G2 – Short growth period in which mitochondria and other
organelles are made and parts needed for cell division (centrioles)
are manufactured
INTERPHASE
Interphase
During this phase, the cell copies its
DNA in preparation for the division.
Phase 2: PROPHASE
1)
PROPHASE – longest phase of mitosis
• Chromatin (DNA strands) coil up into visible
chromosomes
• They look kind of hairy!
• Each chromosome is made of two identical
halves called SISTER CHROMATIDS
• These halves are held together by a
CENTROMERE
PROPHASE
PROPHASE CONTINUED…
• As prophase continues, the nucleus begins to disappear
as the nuclear envelope and the nucleolus disintegrate.
• At this time, the CENTRIOLES begin to migrate to
opposite poles of the cell
• The SPINDLE begins to form between the centrioles.
• “Chromosomes PREPARE for division”
What the heck is a centriole?
A small set of
microtubules
Contain SPINDLE
FIBERS
Centrioles are found
in pairs and travel in
pairs
Centrioles travel to
opposite poles of the
nucleus to begin the
divison process
PROPHASE CONTINUED…
CENTRIOLES
SPINDLE
FIBERS
METAPHASE
1) The chromosomes begin to line up on the midline or
equator of the spindle
2) The spindle fibers of the centrioles become attracted to
the centromeres of chromosomes (middle of
chromosomes
3) “Spindle fibers MEET the centromeres”
METAPHASE
ANAPHASE
3) ANAPHASE – Third
phase of mitosis
• Spindle fibers pull the
chromosomes
• Sister chromatids begin to
separate
• Centromeres split apart
and the chromatids are
pulled apart
• “Split from Annie”
TELOPHASE
• Chromatids are pulled to opposite poles of the cell
• Nucleolus reappears and new nuclear envelope forms around each
new set of chromosomes
• New double membrane begins to form between two new nuclei
TELOPHASE
CYTOKINESIS
• The cell’s cytoplasm
finally divides and the
cell starts to pinch
along the equator of
the cell forming two
new cells!
• “Cytokinesis, division
of cytoplasm”
Overview