INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 1
● Cell Division & Cancer P1
○ Why do cells divide?
■ Unicellular organisms:
● Reproduction
■ Multicellular organisms:
● Development and growth
● Repair
● Reproduction: different kinds of cell division used for sexual vs asexual
reproduction
○ Prokaryotes divide by binary fission:
■
■ DNA replicates
■ Cell elongates
■ Cell splits in half
○ Eukaryotic Cell Cycle
,INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 2
■
■ Interphase (g stands for gap in all of these)
● G0: Non-dividing phase
● G1: Prepare for S phase
● S: DNA replication
● G2: Prepare for M phase (if things have not gone right, and the cell can catch it,
it can stop the transition into m phase)
■ M phase (cell division)
● Mitosis: division of chromosomes
● Cytokinesis: division of cytoplasm
■ Eukaryotic chromosomes:
● Linear, more than 1
● Chromatin (nucleic acid and histone and other proteins that keep it wound up
and condensed) is highly condensed during cell division
● Number of chromosomes has nothing to do with complexity of an organism
■ Chromosome vocabulary:
● Chromosome - molecule made of chromatin
● Sister chromatid - one of two, identical connected pieces of a single
chromosome (after DNA replication)
● Centromere - region where sister chromatids are joined
○ If there are 20 chromosomes in a cell in G1, how many chromatids are there in G2?
■ 5
■ 10
■ 20
■ 30
■ 40
, INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 3
○ If there are 20 chromosomes in a cell in G1, how many chromosomes are there in G2?
■ 5
■ 10
■ 20
■ 30
■ 40
● Cell Division & Cancer P2
○ Mitosis (need to those steps)
○
■ G2 of interphase:
● DNA has already been replicated
● 2 centrosomes (animal cells) - organizing center for mitotic spindles made of
microtubules
, INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 4
●
■ Prophase:
● Chromosomes condense
● Centrosomes move to opposite poles, start radiating microtubules
■ Prometaphase:
● Nuclear envelope breaks down
● Microtubules attach to the chromosomes at kinetochores
■ Metaphase
● Microtubules pull chromosomes to the center of th cell
■ Anaphase
● Sister chromatids separate when centromere splits
● Chromosomes are pulled toward opposite ends of the cell by microtubules
■ Telophase
● Chromosomes decondense
● Nuclear envelopes reform
● Microtubules break down
○ Cytokinesis
■ Cytokinesis in animal cells: contractile ring separates the cytoplasm of the new
daughter cells
■ Cytokinesis in plant cells: cell plate forms a new cell wall between the new daughter
cells
○ During which phase of mitosis do microtubules attach to chromosomes at kinetochores?
■ Anaphase
■ Prometaphase
■ Telophase
■ Metaphase
■ Prophase
○ Which of the following events occurs during anaphase of mitosis?
■ Sister chromatids separate from one another
■ Chromosomes move to center of the cell
■ Chromatin condenses
■ Nuclear envelope breaks down
● Cell Division & Cancer P1
○ Why do cells divide?
■ Unicellular organisms:
● Reproduction
■ Multicellular organisms:
● Development and growth
● Repair
● Reproduction: different kinds of cell division used for sexual vs asexual
reproduction
○ Prokaryotes divide by binary fission:
■
■ DNA replicates
■ Cell elongates
■ Cell splits in half
○ Eukaryotic Cell Cycle
,INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 2
■
■ Interphase (g stands for gap in all of these)
● G0: Non-dividing phase
● G1: Prepare for S phase
● S: DNA replication
● G2: Prepare for M phase (if things have not gone right, and the cell can catch it,
it can stop the transition into m phase)
■ M phase (cell division)
● Mitosis: division of chromosomes
● Cytokinesis: division of cytoplasm
■ Eukaryotic chromosomes:
● Linear, more than 1
● Chromatin (nucleic acid and histone and other proteins that keep it wound up
and condensed) is highly condensed during cell division
● Number of chromosomes has nothing to do with complexity of an organism
■ Chromosome vocabulary:
● Chromosome - molecule made of chromatin
● Sister chromatid - one of two, identical connected pieces of a single
chromosome (after DNA replication)
● Centromere - region where sister chromatids are joined
○ If there are 20 chromosomes in a cell in G1, how many chromatids are there in G2?
■ 5
■ 10
■ 20
■ 30
■ 40
, INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 3
○ If there are 20 chromosomes in a cell in G1, how many chromosomes are there in G2?
■ 5
■ 10
■ 20
■ 30
■ 40
● Cell Division & Cancer P2
○ Mitosis (need to those steps)
○
■ G2 of interphase:
● DNA has already been replicated
● 2 centrosomes (animal cells) - organizing center for mitotic spindles made of
microtubules
, INTRODUCTION TO BIOLOGY (BIO 150) - S 2020 Exam 3 4
●
■ Prophase:
● Chromosomes condense
● Centrosomes move to opposite poles, start radiating microtubules
■ Prometaphase:
● Nuclear envelope breaks down
● Microtubules attach to the chromosomes at kinetochores
■ Metaphase
● Microtubules pull chromosomes to the center of th cell
■ Anaphase
● Sister chromatids separate when centromere splits
● Chromosomes are pulled toward opposite ends of the cell by microtubules
■ Telophase
● Chromosomes decondense
● Nuclear envelopes reform
● Microtubules break down
○ Cytokinesis
■ Cytokinesis in animal cells: contractile ring separates the cytoplasm of the new
daughter cells
■ Cytokinesis in plant cells: cell plate forms a new cell wall between the new daughter
cells
○ During which phase of mitosis do microtubules attach to chromosomes at kinetochores?
■ Anaphase
■ Prometaphase
■ Telophase
■ Metaphase
■ Prophase
○ Which of the following events occurs during anaphase of mitosis?
■ Sister chromatids separate from one another
■ Chromosomes move to center of the cell
■ Chromatin condenses
■ Nuclear envelope breaks down
