mitosis & meiosis · mitosis & meiosis sc.912.l.16.17 compare and contrast mitosis and...
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Mitosis & Meiosis
SC.912.L.16.17 Compare and contrast mitosis and meiosis
and relate to the processes of sexual and asexual
reproduction and their consequences for genetic variation.
1. Students will describe specific events
occurring in each stage of the cell cycle
and/or phases of mitosis, including cytokinesis.
Cell Division: the process of copying and dividing entire cells
The cell grows, prepares for division, and then divides to form new
daughter cells.
Unicellular organisms – allows duplicate using asexual reproduction
Multicellular organisms – allows to grow, develop from single cell to
multicellular, makes other cells to repair and replace worn out cells
Three types: binary fission (bacteria and fungi), mitosis, and meiosis
1. Students will describe specific events
occurring in each stage of the cell cycle
and/or phases of mitosis, including cytokinesis.
Cells divide
through a
process called
the cell cycle
which consists
of interphase,
mitosis, and
cytokinesis.
Note: majority
of the cell
cycle is
Interphase,
while a
smaller
portion is
mitosis/cytoki
nesis.
1. Students will describe specific events
occurring in each stage of the cell cycle
and/or phases of mitosis, including cytokinesis.
Interphase: longest part of the cell
cycle; growth, metabolism, and
preparation for division occurs,
duplicates chromosomes (DNA
Replication)
1. Students will describe specific events
occurring in each stage of the cell cycle
and/or phases of mitosis, including cytokinesis.MITOSIS – division of nucleus of the cell
Prophase: duplicated chromosomes and spindle
fibers appear
Metaphase: duplicated chromosomes line up
randomly in center of cell between spindle fibers
Anaphase: duplicated chromosomes pulled to
opposite ends of cell
Telophase: nuclear membrane forms around
chromosomes at each end of the cell; spindle
fibers disappear; chromosomes disperse
1. Students will describe specific events
occurring in each stage of the cell cycle
and/or phases of mitosis, including cytokinesis.
Cytokinesis: division of plasma membrane; two daughter
cells result with exact genetic information
In plants, a cell plate forms along the center and cuts the
cell in half.
In animals, a cleavage furrow develops to cut the cell in
half.
RESULTS OF MITOSIS:
Two identical daughter cells
Produces and occurs in somatic cells
(body cells)
Diploid = same number of chromosomes as
original cell (humans = 46)
1. Students will describe specific events
occurring in each stage of the cell cycle
and/or phases of mitosis, including cytokinesis.
2. Students will explain how meiosis results in
the formation of haploid gametes or spores.
In meiosis, the cells will also start with interphase.
There are TWO cell divisions instead of one, but the cell only
does interphase ONCE prior to the first cell division.
Meiosis is a reduction division process (chromosome numbers
are divided in half)
Each cell division consists of prophase, metaphase, anaphase,
and telophase
Occurs only in sex cells (gametes) and produces only gametes
(egg and sperm)
First Division: Produces cells containing half # of double stranded
chromosomes
Prophase 1 –
crossing over
occurs
Metaphase 1 –
chromosomes line up in
homologous pairs,
independent
assortment occurs
Anaphase 1 –
chromosomes move towards
each side
Telophase 1 –cells contain
HALF of # of
chromosomes
2. Students will explain how meiosis results
in the formation of haploid gametes or
spores.
2. Students will explain how meiosis results
in the formation of haploid gametes or
spores.
Crossing over: genes are essentially “switching”
places on chromosomes in prophase I
Independent assortment: the genes randomly
move towards ends of cell in metaphase I
THESE BOTH RESULT IN GENETIC VARIATION!
Second Division: Results in formation of four cells, each
haploid (half the number of original chromosomes)
(humans = 23)
2. Students will explain how meiosis results in
the formation of haploid gametes or spores.
RESULTS OF MEIOSIS:
Four unique daughter cells
Unique due to genetic variation such as crossing over and independent assortment
Produces and occurs in gametes (sex cells)
Haploid = half number of chromosomes as original cell (humans = 23)
Sex cells combine during sexual reproduction to produce a diploid individual
2. Students will explain how meiosis results in
the formation of haploid gametes or spores.
3. Students will compare and contrast
sexual and asexual reproduction.
SEXUAL REPRODUCTION
Pattern of reproduction that involves the
production and fusion of haploid sex cells
Haploid sperm from father fertilizes haploid
egg from mother to make a diploid zygote
3. Students will compare and contrast
sexual and asexual reproduction.
ASEXUAL REPRODUCTION
A single parent produces one or more
identical offspring by dividing into two cells.
Diploid cells are clones of parent cell.
DNA Replication
SC.912.L.16.3 Describe the basic process of DNA replication
and how it relates to the transmission and conservation of
the genetic information.
1. Students will describe the process of DNA replication
and its role in the conservation and transmission of
genetic information.
DNA Replication: DNA must replicate during the cell cycle (in both mitosis and meiosis) in
order for genetic information to be passed
on to daughter cells
Semi-Conservative: the new daughter cells will have one strand of parent DNA and one
strand of new DNA
2. Students will explain the basic process of
transcription and/or translation and their roles in
the expression of genes.
DNA Replication occurs in two steps:
1. TRANSCRIPTION:
DNA helicase unzips and unwinds the double helix; RNA primase inserts
RNA into each strand as a “place holder”
Base pairs must match! A U (because this is RNA) and C G!
DNA polymerase then adds the appropriate matching nucleotide
Again, base pairs must match! A T (because now we are adding
DNA) and C G
2. DNA ligase links the two strands of DNA together and proofreads to be
sure base pairs are matched correctly
2. Students will explain the basic process of
transcription and/or translation and their roles in
the expression of genes.
Each strand
of parent
DNA makes
TWO strands
of daughter
cell DNA!
2. Students will explain the basic process of
transcription and/or translation and their roles in
the expression of genes.
Practice matching this strand of DNA to its parent strand of DNA:
2. Students will explain the basic process of
transcription and/or translation and their
roles in the expression of genes.
Practice matching this strand of DNA to its parent strand of RNA:
U U U
2. Students will explain the basic process of transcription
and/or translation and their roles in the expression of
genes.
After DNA Replication has began, the process of Protein Synthesis
simultaneously begins:
Once the first stage of transcription has occurred (DNA base
pairs matching with RNA base pairs), the RNA is then sent out of
the nucleus and moves towards to ribosome through a process
called TRANSLATION.
Once in the ribosome, the RNA strand is converted to amino
acids (building blocks of proteins) through the use of codons.
2. Students will explain the basic process of transcription
and/or translation and their roles in the expression of
genes.
You must be able to
read a codon table:
AUG – UCA – CAA ???
Met – Ser - Gin
3. Students will describe gene and chromosomal
mutations.
Sometimes the process of DNA replication will
become flawed, resulting in mutations.
Mutations: changes in the genetic code
Passed from one cell to new cells
Transmitted to offspring if it occurs in sex cells
Most will have no effect
3. Students will describe gene and chromosomal
mutations.
Gene Mutation: change in a single gene
Chromosome Mutation: change in many genes
Can be spontaneous or caused by
environmental mutagens (radiation, chemicals,
etc)