Mitosis vs. Meiosis

Mitosis vs. Meiosis

asexual vs. sexual reproduction

Cell Cycle

• Interphase: Growth 1 (G1), Synthesis (S - DNA replication), Growth 2 (G2)

• Mitosis (equal division of the nucleus) or Meiosis (division of the nucleus resulting in half the number of chromosomes)

• Cytokinesis: division of the cytoplasm

Closer Look at Mitosis

• Asexual cell reproduction: Makes identical daughter cells

• Happens in somatic cells (any cell except gametes)

• DNA replicated during interphase

• Cell divides once creating 2 identical diploid (2n) daughter cells

Homologous pairs

• In a diploid cell there are 2 copies of each chromosome (2n)

• Homologous pairs have the same genes in the same order, so they will be the same length.

• 1 copy came from the father

• 1 copy came from the mother

• Meiosis: homologous pairs separate (separation divides chromosome number in half = haploid (n) cell)

• Mitosis: no pairing and separation of homologous pairs

Multiple Choice

Why do most cells have a diploid (2n) number of chromosomes?

• meiosis combines pairs of chromosomes

• inherited 1 set of chromosomes from each parent.

Multiple Choice

Which type of cell has homologous pairs?

• haploid cells

• diploid cells

Multiple Choice

No pairing of homologous chromosomes occurs.

• Meiosis

• Mitosis

Closer Look at meiosis

• Sexual cell reproduction: Results in variation (4 genetically unique daughter cells)

• Happens in gametes (produces egg or sperm)

• DNA replicated during interphase

• Cell divides twice producing 4 haploid (n) daughter cells

• Division 1: separates homologous pairs

• Division 2: separates sister chromatids (double stranded to single stranded chromosomes)

Mitosis vs. Meiosis

• Both: Parent cell is diploid (2n) and DNA replication happens during the S phase of interphase before either mitosis or meiosis.

• Mitosis: 1 Division - Sister chromatids separate making 2 identical diploid (2n) daughter cells.

• Meiosis: 2 Divisions - unique haploid (n) daughter cells produced.

Multiple Choice

Occurs throughout an organism's lifetime.

• Meiosis

• Mitosis

Multiple Choice

Chromosome number is halved.

• Meiosis

• Mitosis

Multiple Choice

Four daughter cells are produced.

• Meiosis

• Mitosis

Multiple Choice

Associated with growth and asexual reproduction.

• Meiosis

• Mitosis

Multiple Choice

Daughter cells are identical to parent cell.

• Meiosis

• Mitosis

Multiple Choice

How many cells are created at the end of meiosis?

• 1

• 2

• 3

• 4

Multiple Choice

How many cells are created at the end of mitosis?

• 1

• 2

• 3

• 4

Multiple Choice

How many divisions take place in meiosis?

• 1

• 2

• 3

• 4

Multiple Choice

How many divisions take place in mitosis?

• 1

• 2

• 3

• 4

Multiple Choice

Meiosis occurs in a:

• Sex cell

• Somatic cell

Multiple Choice

Mitosis occurs in a:

• Sex cell

• Somatic cell

Multiple Choice

Produces 2 identical diploid (2n) daughter cells

• mitosis

• meiosis

Multiple Choice

Produces 4 unique haploid (n) daughter cells

• mitosis

• meiosis

Meiosis and Genetic Variation

• Variation is caused during the first division of meiosis.

• Prophase 1 - Crossing Over: homologous pairs exchange pieces (swap gene variations)

• Metaphase 1 to Anaphase 1 - Independent assortment and separation of homologous pairs.

Genetic variation - Random Fertilization

• Meiosis results in unique egg and sperm, which egg combines with which sperm is random.

• The image is tracking 1 gene, and there are 3 possible outcomes in the children.

• Human's have over 20,000 genes

• With the same 2 parents there are millions of possible gene combinations.

Multiple Choice

NORMAL HUMANS HAVE 46 CHROMOSOMES, HOW MANY WILL THE GERM CELLS HAVE AFTER MEIOSIS?

• 46

• 23

• 12

• 92

Multiple Choice

MEIOSIS

• REDUCES THE NUMBER OF CHROMOSOMES BY ONE HALF (1N)

• PRODUCES UNIQUE SEX CELLS

• ALLOWS TRAITS TO BE PASSED TO OFFSPRING

• ALL ARE TRUE

• INCREASE GENETIC VARIATION

Multiple Choice

CROSSING OVER INCREASES

• LIFE SPAN

• GENETIC VARIATION

• THE NUMBER OF OFF-SPRING

• ALL ARE TRUE

Multiple Choice

Which is true for the image?

• INCREASES GENETIC VARIATION

• TAKES PLACE IN PROPHASE I

• CROSSING OVER

• ALL ARE TRUE

Multiple Choice

What is happening in the image?

• Independent assortment of homologous pairs during mitosis

• Independent assortment of sister chromatids during mitosis

• Independent assortment of homologous pairs during the first meiotic division.

• Independent assortment of homologous pairs during the 2nd meiotic division.

Multiple Choice

After meiosis II the daughter cells will contain ____ chromosomes if the original cell contained 78.

• 78

• 39

• 23

• 46