Download DNA and Mitosis

I- DNA
A.Using DNA to Make Proteins:
As You grow cells divide producing
new cells. These cells become
specialized organs and grow larger.
B.Your body is made up of many
different proteins.
C.Proteins determine your eye
color, hair color, bone structure,
etc…….
1. Instructions for making proteins are stored in
chromosomes which are made up of DNA
molecules.
2. DNA consist of two long strands forming a
twisted ladder.
a)The double strands in a
molecule are made up of sugars
and phosphates.
b)Nitrogen bases make up the
rungs of the ladder.
•Bases =
~Adenine (A) combines with Thymine (T)
~Guanine (G) combined with Cytosine (C)
~The sequence of three bases is a
chemical code called a codon.
Bases
Handle = Sugars & Phosphates
Codon
c)The DNA molecule is large,
codes for humans are on 46
chromosomes in most cells or
23 pairs.
d)Proteins in cytoplasm use
instruction from the nucleus for
building. The nucleus sends
messengers called RNA
(ribonucleic acid) a single strand of
sugar, phosphates, and bases (DNA
is a double strand)
B Making DNA Copies When cells
reproduce DNA must be copied
exactly. These copies give each new
cell the same instructions as the
original cell.
1) DNA Copies
DNA molecules separate at the bases.
The separated bases pair up with free
bases.
Now we have two DNA molecules that
are identical.
C- Mitosis Notes
Cell division that occurs in a series of
stages, or phases.
1st: INTERPHASE
• Chromosomes are copied
(# doubles)
• Chromosomes appear as
threadlike coils (chromatin)
• Resting Stage or Phase
2nd: PROPHASE
Nuclear Membrane
Starts to Disappear
Spindle fibers
Centrioles
• Mitosis begins (cell begins to divide)
• Centrioles (or poles) appear and begin
to move to opposite ends of cell.
• Spindle fibers form.
3rd: METAPHASE
• Chromatids (Double chromosomes)
attach to the spindle fibers.
• Chromatids line up in the middle of
cell.
4th: ANAPHASE
• Chromatids (Double chromosomes) separate and begin
to move to opposite ends of the cell
5th: TELOPHASE
Nuclear
membrane
• Two new nuclei form.
• Chromosomes appear as chromatin
(threads-like)
• Mitosis ends
6th: CYTOKINESIS
• Cell membrane forms around two
daughter cells - each with its own
nucleus with identical chromosomes
1
2
4
5
3
6
6th: CYTOKINESIS in Plant Cell
cell plate
• Cell membrane forms around two
daughter cells - each with its own
nucleus with identical chromosomes.
• A cell plate forms.
F- Sexual Reproduction in Plants.
1- The flower is the
reproductive organ in a plant.
2- Parts of a Flower
a-Stamen = male contains the anther which
produces pollen grain (male gamete) and
the filament holds up the anther.
3- Pistil = female contains the
~Stigma sticky to catch pollen,
~style tube leading to ovaries,
~ovaries which contain ovules the eggs
(ovum female gamete) of the flower.
D- Sexual Reproduction: Involves the
joining of two special reproductive
cells, one from each parent.
1- These sex cells or gametes have
half the number of chromosomes
as the body cells.
2- Gametes are formed by a special
type of cell division called meiosis.
3- During sexual reproduction the
sperm and egg cell join this is
called fertilization.
a- When they join they form one
cell with a complete set of
chromosomes.
E-Development of the Fertilized Egg: A
Fertilized egg is called a zygote
1-Forms
new identical cell through
the process of mitosis.
2- This process (Differentiation) or
cleavage continues forming more
and more cells.
3- Sexual reproduction leads to
variation in offspring.