Powers Cell Cycle and Mitosis Notes

5.1 The Cell Cycle and Mitosis Notes
10.1

KEY CONCEPT

Cells have distinct phases of growth, reproduction,
and normal functions.

5.1 The Cell Cycle

•In most cases, living things grow by producing more
cells
• On average, the cells of an adult organisms are not
bigger than those of an infant organisms, there are just
more of them
• In order for organisms to maintain a consistency
(homeostasis) between new and old cells, an
organizational systems must be in place
• Scientists call the system that has evolved the Cell
Cycle
• The cell cycle is a regular pattern of growth, DNA
replication, and cell division.

10.1

5.1 The Cell Cycle

10.1

5.1 The Cell Cycle

• The 2 main stages of the cell cycle are:

1. Interphase:

○ The entire time that the cells needs to prepare for cell

division

○ Largest portion of Cell Cycle

- Gap 1 (G1): cell growth and normal functions
- DNA synthesis (S): copies DNA
- Gap 2 (G2): additional growth and prepare for division

2. Cell Division/Mitosis (M):

○ Includes division of the cell nucleus (mitosis) and

division of the cell cytoplasm (cytokinesis)

• Cell division occurs only if the cell is large enough and

the DNA is undamaged.

10.1

Multiple Choice

During what phase of the cell cycle does the cell prepare for mitosis?

• G1 phase

• S phase

• G2 phase

• M phase

Multiple Choice

The cell spends most of it's life in ________________.

• mitosis

• cytokinesis

• Interphase

• None of the above

Multiple Choice

What is a series of events a cell goes through as they grow and divide?

• Cell Division

• Cell Cycle

• Cytokinesis

• Mitosis

5.1 The Cell Cycle

10.1

Multiple Choice

During what phase of the cell cycle is DNA replicated?

• G1 phase

• S phase

• G2 phase

• M phase

Multiple Choice

During which stage of the cell cycle does mitosis and cytokinesis occur?

• Interphase

• S phase

• M phase

• G1 phase

5.1 The Cell Cycle

Key Concept: Cells divide at different rates.

• The rate of cell division varies with the need for those

types of cells.

• Some cells are unlikely to divide (G0).

10.1

5.1 The Cell Cycle

• Cell size is limited. Cells MUST be small.

• Volume increases faster than surface area.
• Cells need LARGE surface area but SMALL volume
• Large S.A. – easy for things to travel in and out of cell
• Small volume – quick diffusion (travel time) for things inside

of cell

10.1

5.1 The Cell Cycle

• Surface area must allow for adequate

exchange of materials.

– Cell growth is coordinated with

division.

– Cells that must be large have

unique shapes.

10.1

5.1 The Cell Cycle

KEY CONCEPT

Cells divide during mitosis and cytokinesis.

10.2

5.1 The Cell Cycle

• Mitosis

• All of your body cells will do mitosis because:

– Growth (from infant to adult)
– Replace dead or damaged cells
– Injury (cut skin)

• Some organisms will use mitosis to reproduce

ASEXUALLY

• The end result of cell division (sometimes referred to

as mitosis) are 2 cells that are genetically identical

10.2

5.1 The Cell Cycle

• Chromosomes condense at the start of mitosis.

• DNA wraps around proteins (histones) that condense it.

DNA double

helix

DNA and
histones

Chromatin

Supercoiled

DNA

10.2

5.1 The Cell Cycle

• DNA plus proteins is called chromatin.
• Chromatin is loosely coiled/
condensed
• A chromosome is very tightly

coiled/condensed

• One half of a duplicated

chromosome is a chromatid.

• Sister chromatids are held

together at the centromere.

• Sister chromatids are EXACTLY

THE SAME (product of DNA
Replication)

Condensed, duplicated chromosome

chromatid

telomere

centromere

telomere

10.2

Multiple Choice

Chromosomes are made of

• DNA

• RNT

• WWE

• DMA

Multiple Choice

Segments of DNA are called _______________________

• Genes

• Alleles

• Traits

• Chromosomes

Multiple Choice

The traits of an organism are passed to its offspring on small coded strands of DNA material called

• meiosis

• recessive traits

• genes

• heredity

Mitosis in Detail

● For the cell to maintain homeostasis, it needs a

complete copy of the genetic material (DNA)

● Interphase (G1, S, G2) is the copying of the DNA

and organelles

● Mitosis is the division of the DNA into 2 equal

parts (daughter cells), one complete copy for
each new cell

● Occurs in somatic (body) cells for growth,

repair/replacement of old/damaged cells

● Mitosis starts with 1 Diploid cell, and ends with 2

Diploid cells that are identical copies of the Parent
(original) cell.

Multiple Choice

What is chromatin?

• The little protein balls that DNA is wrapped around.

• The structure which holds two chromatids together.

• The beads-on-a-string form of DNA in the nucleus of a non-dividing cell.

• The most subtle color of blue-green.

5.1 The Cell Cycle

The phases of mitosis include:
- Prophase
- Metaphase
- Anaphase
- Telophase

10.2

Multiple Choice

The correct sequence of mitosis:

• metaphase, anaphase, telophase, prophase

• prophase, metaphase, anaphase, telophase

• prophase, anaphase, metaphase, telophase

• telophase, metaphase, prophase, anaphase

Prophase

●1st and longest phase of mitosis

●Chromosomes become visible as
the chromatin condenses

●Spindle fibers form from
centrioles

●Centrioles take their position on
opposite sides of the cell

●Nuclear membrane breaks down

Metaphase

● The shortest phase of mitosis.
● Chromosomes line up across

the middle of the cell.

● Spindle fibers connect the

centromere of each sister
chromatid to the poles of the
cell.

● “Meet in the middle”

Anaphase

●Chromosomes split apart as spindles pull them apart towards the ends of the
cell

●Chromosomes continue to separate until they have formed 2 groups at the
poles of the spindle

●Cell elongates

Telophase

●Nuclear membrane forms around each new cluster of chromosomes in order
to form new nuclei, one for each cell

Multiple Choice

Which phase is this in?

• Prophase

• Metaphase

• Anaphase

• Telephase

Multiple Choice

Which phase is this in?

• Prophase

• Metaphase

• Anaphase

• Telephase

Multiple Choice

Which phase is this in?

• Prophase

• Interphase

• Anaphase

• Cytokinesis

Multiple Choice

Which phase is this in?

• Prophase

• Metaphase

• Anaphase

• Telephase

Telophase continued...

● Telophase ends with

cytokinesis by
“pinching” inward

● This is the final division

of cytoplasm between
the 2 new identical cells

● Animal cells use a

cleavage furrow

● Plant cells use a cell

plate because of their
cell wall

Plant vs. Animal Cell Division

Reorder

Reorder the following

• Prophase

• Metaphase

• Anaphase

• Telephase

• cytokenises

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

5.1 The Cell Cycle

KEY CONCEPT

Many organisms reproduce by cell division.

5.1 The Cell Cycle

• Binary fission is similar in function to mitosis.

• Asexual reproduction is the creation of offspring from a

single parent.
– Binary fission produces two daughter cells genetically

identical to the parent cell.

– Binary fission occurs in

prokaryotes.

parent cell

DNA
duplicates

cell begins
to divide

daughter
cells

5.1 The Cell Cycle

• Some eukaryotes reproduce through mitosis.

• Budding forms a new organism from a small projection

growing on the surface of the parent.

bud

Hydra

Yeast

5.1 The Cell Cycle

• Fragmentation is the

splitting of the parent into
pieces that each grow into a
new organism.

• Vegetative reproduction

forms a new plant from the
modification of a stem or
underground structure on
the parent plant.

5.1 The Cell Cycle

• Environment determines what form of reproduction is most

advantageous.

– Asexual reproduction is

an advantage in
consistently favorable
conditions.

– Sexual reproduction is

an advantage in
changing conditions.

Multiple Choice

What type of asexual reproduction is illustrated in the diagram?

• binary fission

• budding

• sporulation

• regeneration

Multiple Choice

What type of asexual reproduction is illustrated in the diagram?

• binary fission

• budding

• sporulation

• regeneration

Multiple Choice

A cell with 46 chromosomes divides by mitosis, how many chromosomes will be present in the resulting daughter cells?

• 92

• 46

• 23

• 12

5.1 The Cell Cycle

• Let’s Practice!!