Chapter 4
Chapter 4
Section 1

Allows us to grow.

Replaces worn out cells.
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One-celled organisms reproduce this way.

Organisms formation

Growth and Development

Death


The time it takes to complete the
cell cycle differs depending on
whether you are referring to a plant,
animals or humans.
Interphase is the longest part of
the cell cycle.

Hereditary material is copied

Preparation for cell division

Nerve and Muscle cells no longer divide, they
are always in interphase

http://www.youtube.com/watch?
v=s4PaOz7eWS8&feature=related


Why is hereditary material copied
prior to dividing?
Each of the two new cells will get a
complete copy of hereditary
material
to carry out life functions


Process in which the nucleus divides to form
two identical nuclei.
Each new nucleus is identical to the original
nucleus.

Prophase

Metaphase

Anaphase

Telophase


It is a structure in the nucleus that contains
hereditary material.
During interphase the chromosomes duplicate.

These are duplicated chromosome coils that are
tightly coiled into two thickened identical
strands.



Found at opposite ends of the cell.
Between the centrioles, spindle fibers form that
stretch across the cell.
Plant cell also form spindle fibers, but do not
have centrioles.

Chromatids are held together at a region called
a centromere.


Pairs of Chromatids are fully visible.
Nucleus and Nucleolus membrane
disintegrates.


The pairs of chromatids line up across the
center of the cell.
Centromere of each pair usually becomes
attached to two spindle fibers-one from each
side of the cell.



Each centromere divides, spindle fibers shorten
Each pair of chromatids separates, the
chromatids begin to move to opposite sides of
the cell
Separated chromatids are now called
chromosomes.

Spindle fibers start to disappear.

Chromosomes start to uncoil.

New nucleus forms.

http://www.stolaf.edu/people
/giannini/flashanimat/celldivi
sion/crome3.swf

http://www.cellsalive.com/mitosis.htm


Animal cells- cell membrane pinches in the
middle, and the cytoplasm divides.
Plant cells- the appearance of a cell plate
indicated that the cytoplasm is being divided.
Division of the Nucleus

Produces two new nuclei that are identical.



Every cell in our bodies, except sex cells, has
a nucleus with 46 chromosomes.
Every cell in our body has the same identical
46 chromosomes.
Every cell has the same hereditary material.

We grow and develop through the process of
cell division.

Replaces worn out cells.

Replaces damaged cells.


A new organism is produced from one
organism.
Hereditary material is identical to that of the
parent organism.

Fission

Budding

Regeneration


Asexual reproduction in eukarytic cells
happens through cell division.
An example is a sweet potato growing in a jar
of water.

Mitosis is the division of the nucleus.

Bacteria do not have a nucleus.

Bacteria reproduces asexually by fission.



Budding is made possible by cell division.
Regeneration is the process that uses cell
division to regrow body parts.
A whole new organism can grow from each
piece.
 Compare
the DNA in one of
your brain cells to the DNA in
one of your heart cells.

https://www.youtube.com/watch?v=XROMX
TrklmQ
 The
DNA is identical.

Egg and Sperm come together.

Formed in reproductive organs.


Sperms found in male reproductive organs.
Eggs found in the female reproductive organs.



Fertilization- the joining of an egg and sperm.
Zygote- it is the cell that forms when the egg
and sperm join.
Come from two different organisms of the
same species.




Body cells- Far outnumber sex cells
Typical cell has 46 chromosomes
23 pairs of chromosomes
Cells that have pairs of similar chromosomes
are said to be diploid.

Sex cells do not have pairs of chromosomes.
Have half the number of chromosomes

Egg and sperm have 23 single chromosomes.




Produces haploid sex cells.
Most animals would not survive with a double
set of chromosomes.
2 haploid cell combine which produces one
diploid zygote.


During meiosis, two divisions of the nucleus
occurs.
Called meiosis I and meiosis II.


Before meiosis begins, each chromosome is
duplicated
Steps are Prophase I, Metaphase I, Anaphase I
and Telophase I

Each duplicated chromosome comes near its
duplicated mate.
Difference
 In mitosis, they do not come near each other.



The pairs of duplicated chromosomes line up
in the center of the cell.
The centromere of each chromotid pair
becomes attached to one spindle fiber.
Difference
In mitosis, the centromere splits and each become
attached to a spindle fiber.

The two pairs of chromatids of each similar
pair move to opposite ends of the cell.


Difference
The chromatids do not separate in anaphase
one as they do during mitosis


The cytoplasm divides, and two new cells
form.
Each new cell has one duplicated chromosome
from each similar pair.

Prophase II

Metaphase II

Anaphase II

Telophase II


Two cells now begin meiosis II
The duplicated chromosomes and spindle
fibers reappear in each new cell.


The duplicated chromosomes move to the
center of the cell.
Difference from Metaphase I
Each centromere now attaches to two spindle
fibers instead of one.



The centromere divides.
Chromatids separate and move to opposite
ends of the cell.
Each chromatid is now a separate chromosome.

Compare what happens to
chromosomes during Anaphase I
and Anaphase II ?


Anaphase I: duplicated chromosome pairs
separate and move to opposite ends of the cell.
Anaphase II: chromatids separate and move to
opposite ends of the cell.



Spindle fibers disappear.
Nuclear membrane forms around each new
nucleus at each end of the cell.
When meiosis is finished, the cytoplasm
divides.

http://www.stolaf.edu/people
/giannini/flashanimat/celldivi
sion/meiosis.swf

Two cells form

Meiosis II, both of these cells form two cells.

The two divisions of the nucleus results in four cells.

Produces four cells with 23 unpaired chromosomes.


Can produce sex cells with the wrong number
of chromosomes.
Organisms with the wrong number of
chromosomes may not grow normally.
 How
many chromosomes are
in a sex cell?
 Sex
cells, the egg and sperm,
contain 23 single
chromosomes.
 Compare
and contrast the
steps of meiosis I and meiosis
II.

Prophase I and Prophase II:
In prophase I, the duplicated
chromosomes approach each other.
 In prophase II, the duplicated
chromosomes and spindle fibers
reappear.


Metaphase I and Metaphase II:

In Metaphase I, pairs of duplicated chromosomes
line up in the center of the cell and attach to one
spindle fiber.

In Metaphase II, each centromere now attaches to
two spindle fibers after the duplicated
chromosomes move to the center of the cell.

Anaphase I and Anaphase II:

In anaphase I, the two pairs of
chromatids of each similar pair move
away to opposite ends of the cell.

In anaphase II, the centomere divides
and the chromatids separate and
move to opposite ends of the cell.

Telophase I and Telophase II:
 In
telophase I, the cytoplasm
divides, and two new cells form.
 In
telophase II, the cytoplasm of
the two cells divides and four
new cells form.

Deoxyribonucleic acid

Genetic code is stored in hereditary material.

Hereditary material of all your body cells is the
same.




Rosalind Franklin discovered that DNA is
two chains of molecules in a spiral form.
Watson and Crick
Each side of the ladder is made up of sugarphosphate molecules.
Each molecule consists of the sugar
deoxyribose and a phosphate group.




The rungs of the ladder are made up of
nitrogen bases:
Adenine, Guanine, Cytosine, Thymine
Cytosine = Guanine
Adenine = Thymine
http://www.youtube.com/watch?v=qy8dk5iS1f0


Bases will only bond with the correct
partner.
http://science.howstuffworks.com/cell6.ht
m



The amount of DNA in the nucleus is doubled.
The two sides of the DNA unwind and
separate.
Each side then becomes a pattern for a new
side to form.



The amount of DNA in the nucleus is doubled.
The two sides of the DNA unwind and
separate.
Each side then becomes a pattern for a new
side to form.



The amount of DNA in the nucleus is doubled.
The two sides of the DNA unwind and
separate.
Each side then becomes a pattern for a new
side to form.


DNA in our cells store the instructions for
making proteins.
The proteins made determine your
characteristics such as hair color, your
height, and how things taste.

Nucleus
Chromosomes
DNA wrapped around
proteins
Genes are
composed of
DNA




Each chromosome contains 100’s or 1000’s
of genes.
Proteins are made of chains of amino acids.
Genes determine the order of the amino
acids.
Different order makes a different protein.

Proteins are manufactured on the ribosomes.

Ribosomes are located in the cytoplasm.

Genes are in the nucleus.

Proteins are made in the cytoplasm.

Codes for making protein carried from the
nucleus to the cytoplasm via
RNA.

RNA is made in the nucleus on a DNA pattern
RNA is also a twisted ladder

RNA has the base uracil instead of thymine


Messenger RNA

Ribosomal RNA

Transfer RNA


DNA in the nucleus is used to make the
mRNA.
mRNA carries the code from the nucleus to
the cytoplasm.

mRNA
cytoplasm
Three nitrogen bases on
the mRNA
temporarily match with
three Nitrogen bases
on the tRNA
Ribosomes attach
to mRNA
tRNA in cytoplasm
bring
Amino acids to
Ribosomes


The amino acids which are attached to the
tRNA molecules form bonds. This is the
beginning of a protein.
The code carried on the mRNA directs the
order in which the amino acids bond.


The ribosome moves along the mRNA.
New tRNA molecules with amino acids
match up and add amino acids to the
protein molecule.
http://www.youtube.com/watch?v=NJxobgkPEAo

http://www.wisconline.com/objects/index_tj.asp?objid=AP13
02
http://www.youtube.com/watch?v=NJxobgkPEAo


Each cell in a multicellular organism uses only
some of the thousands of genes that it has to
make proteins.
Cells must be able to control genes by turning
some off and some on.
 Why
is it necessary for cells to
regulate gene function?


Different cells in our bodies have different
functions. Therefore, depending on the cells
function, different proteins are necessary to
carry on a specific function.
The genes you inherit dictate what proteins are
made in different cells.



Mistakes when DNA is copied
Proteins made from the instructions may not be
made correctly
Any permanent change in the DNA sequence

http://www.youtube.com/watch?v=35ncSrJO
wME&feature=related