Download Cell Cycle

Asexual Cell
Reproduction
“Chapter 17”
General Outcomes
„
In this unit you will…
„
Describe the processes of mitosis and meiosis.
„
Explain the basic rules and processes associated
with transmission of genetic characteristics.
„
Explain classical genetics at a molecular level.
Curriculum Outcomes
Key Terms
The Importance of Cell Division
„ Imagine
what you would look like if you
peeled your back after a sun burn and
new cells did not replace the dead skin
cells.
„ Without
cell division scratches would
never heal.
„ If
your red blood cells did not divide you
would die.
Cell Cycle
Cell Cycle
Cell Cycle
„ Cells
reproduce to make new cells.
The process for making new cells is
called the cell cycle.
„ New
cells are produced by the cell
cycle.
„
Principles of Mitosis
„
Cell theory states that all living things are made up of one or more
cells.
„
Cells are formed from preexisting cells by cell division.
„
Binary fission – is a form of asecual reproduction in which one cell
divides into two equal cells.
„
Division involves two phases: division of nuclear material
division of cytoplasm
„
Mitosis – is a type of cell division in which daughter cells receive
the same number of chromosomes as the parent cell.
„
Cytokinesis – the division of cytoplasm
Chromosome Structure
„
Chromosomes contain both DNA and a number of proteins.
„
Combination of DNA and proteins is called chromatin.
„
As a cell moves through the cell cycle, chromosomes may either be
uncondensed or condensed.
„
Uncondensed are long, thin strands that cannot be seen under a
microscope.
„
Condensed can be seen under a microscope, can be unduplicated or
duplicated.
„
Duplicated – the original is attached to its copy by a centromere.
while attached the two chromosomes are called
sister chromatids (contain identical genetic material)
Unduplicated and Duplicated
Chromosomes
Mitosis
„
During interphase a cell's DNA is doubled.
„
At metaphase the DNA is organized into a
doubled chromosome made of two
chromatids.
„
What will happen to the two chromatids at
the end of the cell cycle?
„
Each chromatid becomes a chromosome in
daughter cells of the original cell. Cells
produced by mitosis have identical
chromosomes.
„
The chromosomes are now single
chromosomes.
„
What is the difference between a single
chromosome and a double chromosome?
Stages of Cell Division
“Interphase”
„
Interphase – describes the processes of cell activity
between divisions.
„
Most cells spend their time in this phase.
„
Cell grows, and carries out chemical activities that
sustain life during this period.
„
Cells make proteins to repair damage, move nutrients.
„
Single strands become double strands.
“Prophase”
„
First phase of cell division.
„
Contents of nucleus become visible (chromosomes
shorten + thicken)
„
Centrioles - Small bodies that separate and move to
opposite poles. (provide attachment for spindle fibers)
„
Spindle fibers – are protein structures that guide
chromosomes during cell division.
„
Chromosomes consist of two chromatids held together
by a centromere.
“Metaphase”
„
Second phase
„
Chromosomes composed of sister chromatids move
toward the center of the cell.
„
This area is called the equatorial plate (imaginary line
that divides the cell and its chromosomes)
„
Chromosomes appear are dark thick masses attached to
spindle fibers.
„
Chromatids become intertwined.
“Anaphase”
„ Third
phase
„ Centromeres
divide and chromatids move
to opposite poles of the cell.
„ Same
number of single-stranded
chromosomes will be found at each pole.
“Telophase”
„
Last phase
„
Chromosomes reach opposite poles of the cell
„
They begin to lengthen and intertwine.
„
Spindle fibers dissolve and nuclear membrane begins to
form around each mass of chromatin.
„
Telophase is followed by the division of the cyctoplasm.
“Cytoplasm Division”
„
Once chromosomes have moved to opposite
poles, the cytoplasm begins to divide.
„
Cytokinesis – or division of the cytoplasm,
appears to be separate from nuclear division.
„
Division of the cytoplasm must provide
organelles for each newly established cell.
Mitosis
Mitosis
Summary
QUIZ
Identify the stage of the cell
cycle.
Identify the stage of the cell
cycle.
Identify the stage of the cell
cycle.
Identify the stage of the cell
cycle.
Homework
„ Review
Questions
„ Page 434 Questions 1 - 6
Cloning
„ Process
of forming identical offspring from
a single cell or tissue in the parent organ.
Plant Cloning
Plant Cloning Technology
„ 1958
Fredrick Stewart revealed that he
had produced a plant from a single carrot
cell.
„ Many
plants like orchids are produced
from clones
„ Not
all plants can be cloned grass and
legume families cannot.
Lab
Plant Cloning
Animal Cloning Technology
„
Robert Biggs and Thomas King investigated
nuclear transplants in frogs.
„
Extracted nucleus from an unfertilized egg with
a glass tube.
„
The egg cell with the transplanted nucleus
began to divide.
„
Dolly the sheep was another example of this
Animal Cloning
Animal Cloning
Animal Cloning
Dolly
Summary
Homework
„ Review
Questions
„ Page 440 Questions 7 -12
„ Page 443 Questions 13 -17