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1/20/15
Starter:• What is a
chromosome?
1/20/15
133 134Mitosis/Meiosis
ApplicationNotesConnection : WS
Exit: 1. How many chromosomes
do human cells have? 2. Do all humans have the same number of chromosomes in their cells?3. But you were made from one cell from your mom and one cell from your dad, so how is it the same? Shouldn’t you have double the number of chromosomes? 4. Given this information, how many chromosomes do sex cells have?
Mitosis/Meiosis
Practice:Watch Video and write 5 things you learn
JANUARY 20, 2015AGENDA
B. 6 G
STUDENTS WILL RECOGNIZE THE SIGNIFICANCE OF
MEIOSIS TO SEXUAL REPRODUCTION WHILE
READING AND WRITING BY
COMPLETING A WS.
1 Starter2. Practice3. Ws
Date Lecture/ Activity/ Lab Page1/20 Mitosis/Meiosis 133-134
Table of Contents
MITOSIS AND MEIOSIS
Asexual Reproduction Sexual Reproduction• Uses only mitosis• Produces clones—genetically
identical offspring• Fast and effective
reproduction to spread organism
• No diversity
• Combination of two haploid sex cells
• Fertilization: combines genetic information from two separate cells with ½ of the original genetic information of parent organism
• Gametes are from separate parents. (female = egg, male = sperm)
• Zygote (new individual) has two sets of chromosomes, one from each parent
• Process changes diploid cells to haploid gametes—leading to an increase in diversity of offspring
ASEXUAL VS. SEXUAL REPRODUCTION
What is the advantage of an organism that reproduces sexually rather than asexually?An organism that reproduces sexually will have more genetic diversity than one that reproduces asexually.
ASEXUAL VS. SEXUAL REPRODUCTION
MITOSIS AND MEIOSIS Mitosis:
-division of somatic (body) cells
Meiosis-division of gametes (sex cells)
MITOSIS
Interphase
Prophase
Metaphase
Anaphase
Telophase
INTERPHASE Interesting things happen!1. Cell preparing to divide2. Genetic material doubles
PROPHASE ( IN TWO STAGES)
Early: 1. Chromosome pair
up!
2. Chromosomes thicken and shorten
and become visible
3. Two chromatids joined by a centromere
PROPHASE ( IN TWO STAGES)
Late:
1. Centrioles move to the opposite sides of the nucleus
2. Nucleolus disappears
3. Nuclear membrane disintegrate
METAPHASE 1. Chromosomes meet in the middle!2. Chromosomes arrange at equator of
cell Become attached to spindle fibres by
centromeres3. Homologous chromosomes do not
associate
ANAPHASE1. Chromosomes get pulled apart2. Spindle fibres contract pulling
chromatids to the opposite poles of the cell
TELOPHASE Now there are two!1. Chromosomes uncoil2. Spindle fibres disintegrate3. Centrioles replicate4. Nucleur membrane forms5. Cell divides
HOW CAN WE REMEMBER THE STAGES OF MITOSIS?
Interphase Prophase
Metaphase Anaphase Telophase
MEIOSIS Four daughter cells produced Each daughter cell has half the
chromosomes of the parent Two sets of cell division involved Similar to mitosis BUT no synthesis
phase (no DNA replication) Chromatids are NOT identical because
of crossing over (recombination).
1/20/15
Starter:• What is a
chromosome?
1/20/15
133 134Mitosis/Meiosis
ApplicationNotesConnection : WS
Exit: 1. How many chromosomes
do human cells have?
2. Do all humans have the same number of chromosomes in their cells?
3. But you were made from one cell from your mom and one cell from your dad, so how is it the same? Shouldn’t you have double the number of chromosomes? 4. Given this information, how many chromosomes do sex cells have?
Mitosis/Meiosis
Practice:Watch Video and write 5 things you learn
