the cell cycle - mr. curtis' biology site€¦ · mitosis • 1.) part of the cell cycle when...
TRANSCRIPT
The Cell Cycle
Biology
Standards you are responsible
for mastering. • SB1a: Explain the role of cell organelles
for both prokaryotic and eukaryotic cells,
including the cell membrane, in
maintaining homeostasis and cell
reproduction.
• SB2b: Explain the role of DNA in storing
and transmitting cellular information.
The next two slides aren’t for
the notes…just pay attention.
• A Question for you…
– Cells need to be small.
• That’s a fact.
• But, WHY do they need to be small?
• Why is it better to have many small cells
than just a couple of big cells?
Ok, good.
• So, how do organisms get more cells and
prevent cells from getting too large??
• Cell Division.
Two main reasons why cells divide:
• 1.) To prevent DNA overload if the cell
grows too big, there will be an information
crisis.
• 2.) Bigger is not better if the cell grows
too large, it would take too long for
nutrients and wastes to travel through the
cell.
Cell Division
• A.) the cell divides forming 2 daughter
cells before growing too big.
B.) solves the problems of:
1.) Information crisis
2.) Increasing size
Cell Division
• A.) Chromosomes:
1.) pass on genetic information
2.) made of DNA and proteins
3.) every organism has a specific number of
chromosomes. (Humans = 46)
4.) are only visible during cell division
5.) are replicated BEFORE cell division
a.) chromatids 2 identical “sister”
parts of a duplicated chromosome.
1.) are attached at the centromere
Chromosome
Chromosome
The Cell Cycle
• 1.) The cell cycle is a series of events that
the cell goes through as it grows and
divides.
2.) During the cell cycle, the cell grows,
prepares for division, and divides to
form two daughter cells.
The 2 phases of the cell cycle
• A.) Interphase
• B.) Cell Division Mitosis & cytokinesis
Interphase -NOT A PART OF MITOSIS; NOT CELL DIVISION!
• 1.) contains the G-1, S, and G-2 phases.
• 2.) G-1 phase the cells grow in size and make new molecules and organelles.
• 3.) S phase chromosomes are replicated
• 4.) G-2 phase shortest phase, molecules & organelles needed for cell division are made.
Cell Cycle
Interphase
Interphase
Mitosis
• 1.) part of the cell cycle when the chromosomes separate from each other and the cell splits in half.
• 2.) This is how somatic cells reproduce.• Somatic cells are normal body cells (i.e., not sperm and egg)
• 3.) Mitosis has 4 phases:• Prophase - Nucleus breaks down, chromosomes become thick
(visible) and pair up.
• Metaphase - Chromosomes line up in the middle of the cell
• Anaphase - Chromosomes move to the opposite ends of the cell
• Telophase - Chromosomes unwind (become invisible) and nucleus reforms.
Prophase – more info…
• 1.) The chromatin condenses to form
chromosomes (DNA is visible)
• 2.) Centrioles separate and the spindle
fiber forms.• A.) spindle fiber helps to separate the
chromosomes.
• 3.) The nuclear envelope breaks down
Prophase
Prophase
Prophase
Prophase –
Draw This in the Box…
Nuclear Membrane
Spindle Fibers
Centriole
Cell Membrane
Metaphase …more info
• 1.) Chromosomes line up at the equator of
the cell.
• 2.) Each chromosome is connected to a
spindle fiber at its centromere.
Metaphase
Metaphase
Metaphase
Metaphase –
Draw this in the box
Anaphase …more info
• 1.) The sister chromatids separate into
individual chromosomes and are moved to
the opposite ends of the cell.
Anaphase
Anaphase
Anaphase
Anaphase –
Draw this in the box…
Telophase…more info
• 1.) Chromosomes gather at opposite ends
of the cell.
• 2.) chromosomes lose their shape
• 3.) Two new nuclear envelopes form.
Telophase
Telophase
Telophase
Telophase –
Draw this in the box…
Cytokinesis
- Starts during Telophase• 1.) Cytoplasm divides separating the two
identical nuclei.
• 2.) in animals the cell membrane is
pulled inward until the cytoplasm is
pinched into 2 almost equal parts.
• 3.) in plants a cell plate forms half way
between the two new nuclei.
Animal Cell Cytokinesis
Cleavage furrow
Contractile ring of
microfilamentsDaughter cells
100 µm
(a) Cleavage of an animal cell (SEM)Figure 12.9 A
Plant cell cytokinesis
Daughter cells
1 µmVesicles
forming
cell plate
Wall of
patent cell Cell plateNew cell wall
(b) Cell plate formation in a plant cell (SEM)Figure 12.9 B
End result of Mitosis
• 2 genetically identical daughter cells.
Review Questions
Review 1
• During which part of interphase is the DNA
copied?
• A.) G1
• B.) S
• C.) G2
• D.) Mitosis
Review 2
• Which stage in a cell’s life cycle is the
longest?
• A.) mitosis
• B.) metaphase
• C.) interphase
• D.) cytokinesis
3
• Which of the following is the correct name
of DNA when it is uncoiled (not in a
chromosome form)?
• A.) Chromatid
• B.) Chromatin
• C.) Chromosome
• D.) Spindle Fiber
4
• If a cell has 32 chromosomes in G1 of
interphase, how many chromosomes will
each daughter cell have after mitosis &
cytokinesis?
• A.) 16
• B.) 32
• C.) 64
• D.) 128
5
• During which stage of mitosis do the
chromosomes line up at the equator of the
cell?
• A.) prophase
• B.) metaphase
• C.) anaphase
• D.) telophase
6
• Each side of a copied chromosome is
called:
• A.) a chromosome
• B.) a sister chromatid
• C.) chromatin
• D.) centromere
7
• The part of a copied chromosome where
the two sides are linked together is called
the:
• A.) centriole
• B.) centromere
• C.) chromatid
• D.) spindle fiber
8
• During which stage of mitosis do the sister
chromatids separate?
• A.) prophase
• B.) metaphase
• C.) anaphase
• D.) telophase
9
• Division of the nucleus is called:
• A.) interphase
• B.) cell cycle
• C.) mitosis
• D.) cytokinesis
10
• Division of the cytoplasm is called:
• A.) interphase
• B.) cell cycle
• C.) mitosis
• D.) cytokinesis
11
• What organelle has the job of pulling on
the spindle fibers to separate the
chromatids?
• A.) DNA
• B.) ribosome
• C.) centromere
• D.) centriole