CELL REPRODUCTION: MITOSIS
INTERPHASE: DNA replicates
PROPHASE: Chromatin condenses into chromosomes,
centrioles start migrating
METAPHASE: chromosomes align in the equatorial plate of
the cell
ANAPHASE: sisters chromatids are pulled apart
TELOPHASE: nuclear membrane reforms
CYTOKINESIS: Division of the cytoplasm. The two daughter
cells ARE GENETICALLY IDENTICAL TO THE PARENT CELL.
CELL REPRODUCTION
WORKSHOP: MITOSIS
1. Give the correct sequence of the stages of mitosis
and say what happens in each. Do a drawing.
2. During which stage of mitosis does chromatin coil
into chromosomes?
3. At which stage or phase the chromosomes line up
at the equatorial plate of the cell?
4. During which phase sister chromatids pull apart to
form single-stranded chromosomes?
5. The completion of ____________ marks the end
of cell division
CELL REPRODUCTION: MEIOSIS
Interphase: DNA replicates
Prophase I: Chromosomes are formed. Centrioles migrate.
Some DNA sequences are exchanged between
chromosomes.
Metaphase I: same as in mitosis, only that chromosomes pairs
line up on either side of the equatorial plate.
Anaphase I: Chromosomes are separated. Cromatides DON’T
separate.
Telophase I: new nuclear membranes form.
CELL REPRODUCTION: MEIOSIS
Interphase II: chromosomes DON’T replicate
Prophase II: chromosomes condense, nuclear membrane
fragments, centrioles are in opposite sides of the cell.
Metaphase II: chromosomes align in the equatorial plate
Anaphase II: CHROMATIDS separate and begin moving to the
poles of the cell.
Telophase II: nuclear membrane forms.
Cytokinesis: Division of the cytoplasm. There are four daughter
cells with HALF THE NUMBER OF CHROMOSOMES OF THE
INITIAL CELL.
CELL REPRODUCTION
WORKSHOP: MEIOSIS
1. How many divisions undergoes the cell in a meiotic
division?
2. Meiosis results in how many cells? And what is their
condition?
3. Which cells undergo meiosis?
4. When does the exchange of DNA occur?
5. The name of the cells that are produced by meiosis is…
6. Draw the meiosis division. Use colors and mention the
phases the cell is in.
DNA
• The nucleus controls, by chromosomes, all the
activities of the cell
• DNA controls the production of proteins within
the cell.
• These proteins, form the structural units of cells
and control all chemical processes within the
cell.
• Chromosomes are composed of genes, which
are segments of DNA that code for a particular
protein, which in turn codes for a trait.
DNA
DNA: deoxyribonucleic acid (DNA), which has a
double helix spiral-shaped structure. Each side of the
helix has sugar-phosphate molecule.
Nitrogen bases: Adenine (A) pairs with
Thymine (T), and Cytosine (C) pairs with
Guanine (G).
DNA
REPLICATION
Is the process by which DNA makes a copy of itself, and
occurs during interphase, before cell division
Replication is semi-conservative,
because each strand serves as a base or
pattern for the new strand. (Each new
DNA has a new strand and an old one)
DNA
REPLICATION: STEPS
1. DNA helicase (enzyme) unwinds the DNA. The junction
between the unwound part and the open part is called a
replication fork.
DNA
REPLICATION: STEPS
2. DNA polymerase (a protein) adds the
complementary nucleotides and binds the sugars
and phosphates. DNA polymerase travels from the
3' to the 5' end of the template strand.
3. One side is the leading strand - it follows the
helicase as it unwinds. The other side is the
lagging strand - its moving away from the helicase
(in the 5' to 3' direction).
DNA
REPLICATION
RNA
RNA: ribonucleic acid. It has on strand instead of two,
uracil instead of thymine and ribose sugar instead of
deoxyribose sugar.
3 types of RNA:
•mRNA (messenger RNA
•tRNA (transfer RNA)
•rRNA (ribosomal RNA)
DNA and RNA
DNA remains in the nucleus… how are then proteins
made?
In order for the DNA to get its instructions translated into
proteins, it must send its message to the ribosomes,
where proteins are made.
DNA and RNA
TRANSCRIPTION: RNA is made from the DNA. This
process occurs in the nucleus.
The mRNA is small and can pass through the nuclear
membrane. It takes the "message" of the DNA to the
ribosomes, where it is going to be translated into
proteins.
DNA and RNA
TRANSLATION: occurs in the cytoplasm, specifically
on the ribosomes.
The mRNA travels out to the ribosome to carry the
"message" of the DNA. At the ribosome, that massage
will be translated into an amino acid sequence, which is
a protein.
This protein will codify for a specific trait.
GENETIC
CODE
Phe: phenilalanine
Leu: Leucine
Ile: Isoleucine
Met: Methionine
Val: Valine
Ser: Serine
Pro: Proline
Thr: Threonine
Ala: Alanine
Tyr: Tyrosine
His: Histidine
Gln: Glutamine
Asn: Aspargine
Lys: Lysine
Asp: Aspartic Acid
Glu: Glutamic Acid
Cys: Cysteine
Trp: Tryptophan
Arg: Arginine
Gly: Glycine
References
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http://www.cellsalive.com/meiosis.htm
http://www.pbs.org/wgbh/nova/body/how-cells-divide.html
http://www.biologycorner.com/worksheets/DNAcoloring.html
http://www.biologycorner.com/APbiology/DNA/133_replication.html
• http://www.biologycorner.com/bio1/DNA.html
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