Welcome to Class
What is probability?
What is the probability of pulling an Ace out
of a deck of cards?
Agenda
• Finish probability
• Mitosis and Meiosis
Chromosomes
• Chromosome – cell structure that contains DNA (Bio
A)
• Gene – on DNA, controls protein synthesis
• Homologous chromosomes - Chromosomes that
make a pair
– 1 from each parent
• Humans have 46 chromosomes
How do we maintain 46 Chromosomes?
• Produce gametes – sex cells that have half the
number of chromosomes
• Humans have 23 chromosomes per gamete
• Cell with ½ the number of regular chromosomes
(n) is called haploid
• Cell with all chromosome (2n) is called diploid
6 Stages of Mitosis
• Interphase – DNA replicates
• Prophase – Chromosomes condense, spindles
appear, nuclear membrane disappears
• Metaphase – chromosomes attach to spindles,
align in center of cell
• Anaphase – chromosomes move to opposite ends
of cells
• Telophase – nuclear envelope reappears,
chromosome decondense
• Cytokinesis – Cells divide into two cells
Meiosis I
• Interphase – Chromosomes replicate
– Similar to Mitosis!
• Prophase I
– homologous chromosomes pair
• 1 from mom, 1 from dad
– Nuclear envelope breaks down,
spindles form
– Crossing over!
Meiosis I
• Metaphase I
– Homologous chromosomes line up at center
• Anaphase I
– Homologous pairs move to opposite sides of cell
• Telophase I
– Chromosomes uncoil
– Cell divides
Meiosis II
• Prophase II - no DNA replication!!!
– Chromosomes condense
– Spindle fibers appear
• Metaphase II
– Chromosomes line up at center
• Anaphase II
– Chromosomes split and move to opposite sides
• Telophase II
– Nuclei form around chromosomes
– Cells divide
Meiosis
Mitosis
Chromosome Number:
Reduced by half (homologous
Remains the same
pairs separate)
Pairing of Homologues:
Yes
No
Function:
sexual reproduction
Cellular (asexual) Reproduction
(cell division during which the
cell nucleus divides); general
growth and repair of the body
Number of Divisions:
2 nuclear and 2 cytoplasmic
divisions
1 division of the nucleus and 1
Cytokinesis
Number of Cells produced: 4
2
Creates:
Sex cells only: Female egg cells Makes everything other than
or Male sperm cells
sex cells (Somatic Cells)
Occurrence of Crossing
Over:
Yes
No
Produces:
four haploid daughter cells
two diploid daughter cells
Genetically:
different
identical
Meiosis
Mitosis
Two cell divisions
Centrioles appear
Half the original
chromosomes
X
X
X
Homologous
Chromosomes pair up
X
Spindle fibers form
X
Cytokinesis
Four daughter cells
46 Chromosomes at end
X
X
X
X
X
X
• http://biologycorner.com/worksheets/meiosis
_internet.html
Welcome to Class
Define diploid and haploid.
Agenda
• Review mitosis and meiosis
• Compare and contrast mitosis and meiosis
• CH. 10 Study guide
Cytokinesis
Meiosis
Mitosis
Chromosome Number:
Reduced by half (homologous
Remains the same
pairs separate)
Pairing of Homologues:
Yes
No
sexual reproduction
Cellular (asexual) Reproduction
(cell division during which the
cell nucleus divides); general
growth and repair of the body
Function:
Number of Divisions:
2
1
Number of Cells produced:
4
2
Creates:
Sex cells (GAMETES): Female
egg cells or Male sperm cells
Makes “normal” cells(Somatic
Cells)
Occurrence of Crossing
Over:
Yes
No
Produces:
four haploid daughter cells
two diploid daughter cells
Genetically:
different
identical
Meiosis
Mitosis
Two cell divisions
Centrioles appear
Half the original
chromosomes
X
X
X
Homologous
Chromosomes pair up
X
Spindle fibers form
X
Cytokinesis
Four daughter cells
46 Chromosomes at end
X
X
X
X
X
X
Welcome to Class
What are three main differences
between mitosis and meiosis?
Agenda
•
•
•
•
Quiz
Finish Study guide
Traits survey
Mendel
Online Bio Books
• Access Code: CCF2754895
• Glencoe.com
Welcome to Class
What is a trait?
Agenda
• Mitosis/Meiosis Review
– Drawing
• Traits survey
• Mendel
Mitosis/Meiosis Review
1. Number of Cells
– Mitosis creates 2 identical cells
– Meiosis creates 4 individual cells
2. Number of chromosomes
– Mitosis creates cells with 46 chromosomes (2n – diploid)
– Meiosis creates cells with 23 chromosomes (n – haploid)
3. Locations
– Mitosis – somatic (“normal”) cells
– Meiosis – gametes (sex) cells
Drawing Mitosis and Meiosis
1. Interphase
3. Metaphase
2. Prophase
4. Anaphase
5. Telophase/Cytokinesis
1. Prophase I
2. Metaphase I
3. Anaphase I
4. Telophase/Cytokinesis I
3. Anaphase II
1. Prophase II
Cells from
Meiosis I
2. Metaphase II
4. Telophase II
/Cytokinesis II
Importance of Meiosis
• Genetic Variation
Sexual vs. Asexual Reproduction
Asexual
• Organisms inherit all
chromosomes from single
parent
Sexual
• Chromosomes from 2
parents
• Genetic variation
• Genetically identical