Mr. James' - Cell Cycle and Division

Draw and label a BIG chromosome.

UNIT 2: Cell Cycle and

Division

UNIT ESSENTIAL QUESTION:

HOW DO CELLS MAKE MORE

CELLS?

WARM -UP: FOR EACH ORGANISM/PART OF AN ORGANISM, TELL ME WHETHER IT REPRODUCES SEXUALLY, ASEXUALLY OR BOTH.

EXAMPLE: CHICKEN- SEXUALLY

BACTERIA- ASEXUALLY

ESSENTIAL QUESTION: HOW DO MULTICELLULAR ORGANISMS PRODUCE OFFSPRING?

SEAHORSE-

HUMAN

GIANT REDWOOD TREE

STARFISH

CACTUS

KANGAROO

STRAWBERRY

SKIN CELLS IN A HUMAN

when 2 organisms both

contribute to create offspring

http://learn.genetics.utah.edu/content/variation/reproduction/

Sexual

Reproduction

1 parent providing

1/2 the DNA

EQ: How do old cells make new cells?

In sexual reproduction, both

parents contribute to the

genetic makeup of

the offspring

1 offspring

with a full compliment of DNA

New organism has different

DNA than its parents

EQ: How do old cells make new cells?

REFLECTION:

MAKE A 2 COLUMN CHART COMPARING AND CONTRASTING ASEXUAL VS SEXUAL REPRODUCTION.

YOU CAN USE YOUR NOTES & THE BOOK

an organism making an

identical copy of itself

Asexual

Reproduction

mostly occurs with unicellular organisms like bacteria

why does bacteria spread so quickly for organism to organism?

since the parent and offspring have the same DNA, they are CLONES

1 parent passes

on

1 full set of DNA

to offspring

ASEXUAL REPRODUCTION IS HOW CELLS IN A MULTICELLULAR ORGANISM MAKE NEW CELLS

some multicellular organisms use a type of asexual reproduction called budding

Example: Hydra

In asexual reproduction, 1 parent

passes all of it’s genes on to

its offspring.

Two "daughter

cells" that have

the same DNA

as the parent

cell

ESSENTIAL QUESTION: WHAT IS Cell Division?

ESSENTIAL QUESTION: What role do chromosomes play in cell division?

two major parts

of cell division:

DNA is a long chain of nucleotides that are strung together in a specific way.

THE FIRST STAGE, IS DIVISION OF THE NUCLEUS AND EVERYTHING IN IT (DNA)

CENTROMERE

Mitosis

DNA

DNA is the instructions for how

an organism is made.

(Every aspect of that organism)

normally very long and strung

out like spaghetti

Before a cell divides, DNA is copied

END OF SECTION

EACH CHROMATID HAS THE SAME DNA

is the second stage, and is the division of the cytoplasm, the liquidy jelly that holds the organelles, AND the splitting of the cell membrane

Cytokinesis

Chromosomes

is when the DNA coils up into a structure that allows it to split into 2 during cell division

ESSENTIAL QUESTION: What is the life cycle of a cell?

EQ: What role do chromosomes play in cell division?

EQ: What role do chromosomes play in cell division?

CHROMOSOME

When the cell divides, the chromatids separate.

Each new cell gets one chromatid.

Cell cycle

series of stages that

cells go through as

they grow and divide.

Each half of the Chromosome contains identical DNA. Each half is called a

"sister" chromatid

is the period of growth that

occurs between cell divisions.

Interphase

Since each cell gets 1 of the

chromatids, the new cell gets 1 copy of the DNA

Each chromatids are attached at an area called the centromere.

cell spends approx. 90% of its time in interphase.(The first 3 stages of the cycle)

If each new cell gets one copy of the original DNA then each new cell is genetically the same (a clone)

chromatid

Reflection: Draw and label what happen to the chromosome as a cell divides.

After watching the"Replacing Body Parts" Video answer the following questions in complete sentences.

1. What was the most interesting thing in the video and why?

2. What type of cells do they use to "regrow" these body parts?

3. Why can these cells become any type of cell?

ESSENTIAL QUESTION: How do old cells make new cells?

process by which a cell divides into two new identical "daughter" cells

CELL DIVISION

Stages of the Cell Cycle

The Cell Cycle

During G1 (First GROWTH) , the cell

your body produces about 2 trillion

new cells each day

http://science.howstuffworks.com/environmental/life/zoology/reptiles-amphibians/salamander-regrow-body-parts.htm

• goes through rapid growth
• increases in size
• performs normal functions

EQ: WHY ARE STEM CELLS IMPORTANT?

ESSENTIAL QUESTION: WHY ARE STEM CELLS IMPORTANT?

there are two ways that organisms reproduce and

make offspring.

CELLS FOUND IN THE EARLIEST STAGES OF DEVELOPMENT

EMBRYONIC STEM CELLS

CELLS THAT ARE UNSPECIALIZED.

THEY HAVE NO SPECIFIC JOB

STEM CELLS

ARE NOT SPECIALIZED, SO CAN BECOME ANY TYPE OF CELL IN THE BODY

THIS MEANS AS AN ORGANISM DEVELOPS, STEM CELLS BECOME DIFFERENTIATED

1

Interphase

SINCE THEY CAN BECOME ANY TYPE OF CELL, STEM CELLS CAN BE USED TO REPLACE OR REPAIR DAMAGED OR DESTROYED CELLS/TISSUE

G1

STEM CELL RESEARCH

During the cell cycle:

• a cell grows
• copies its DNA
• prepares for division
• divides to form two daughter cells, each of which begins the cycle again

STEM CELLS WILL BECOME ALL THE DIFFERENT TYPES OF CELLS FOUND IN MULTICELLULAR ORGANISM

REFLECTION: ANSWER THE FOLLOWING QUESTIONS AT THE BOTTOM OF THIS SECTION OF NOTES. USE COMPLETE SENTENCES

The G2 Phase (Second Growth Phase):

During the S (copying stage) phase,

• Centrioles duplicate to help with division

• DNA synthesis takes place (DNA is copied)

• Cell checks to make sure DNA was copied correctly

• Once G2 is complete, the cell is ready to start the M phase—Mitosis

At the end of S phase the cell has twice the normal amount of DNA (same as saying twice as many chromosomes)

1. DURING INTERPHASE (G1, S AND G2 STAGES),

WHAT ARE THE TWO IMPORTANT THINGS HAPPENNING IN THE CELL.

2. WHY DOES CELL CHECK TO MAKE SURE THE DNA WAS COPIED CORRECTLY? (HINT: WHAT MIGHT HAPPEN TO THE CELL IF THE DNA SEQUENCE IS WRONG)

Interphase

G1

Interphase

G1

G2

S phase

Cytokinesis: Splitting the cell

Phases of Mitosis

Is the last part of telophase

Chromosomes gather at opposite ends (poles)

of the cell and begin to uncoil

Centromeres split

The cytoplasm and membrane pinches in half.

A new nuclear membrane reforms around each cluster of chromosomes.

Telophase:

4th phase of

cell division

The sister chromatids separate into individual chromosomes.

Cytokinesis:

last part of

cell division

DNA begins to look like spaghetti again

Anaphase:

3rd phase of

cell division

Spindle fibers break down and disappear

Each daughter cell has:

• own nucleus

• identical set of chromosomes (DNA)

Each copy moves APART to opposite poles of the cell

Cell begins to pinch in the middle (animal cell only)

In plants, a structure known as the cell plate forms midway between the two new nuclei.

Telophase in Plants

the cell plate will harden and become a new cell wall

When it finishes forming, you have

2 identical plant cells.

Cell plate

Cell wall

DRAW THIS DIAGRAM IN YOUR NOTES

ESSENTIAL QUESTION: HOW DOES A CELL DIVIDE PERFECTLY?

EQ: HOW DOES A CELL DIVIDE PERFECTLY?

Mitosis (M Phase)

Mitosis

THE CELL CYCLE

Biologists divide the events of mitosis into four phases: (PMAT)

• Prophase
• Metaphase
• Anaphase
• Telophase

Spindle

forming

Centriole

Phases of Mitosis

Centriole

Spindle Fiber

Chromosomes

(paired chromatids)

Centromere

The chromosomes line up in the MIDDLE of the cell.

• DNA (already copied) condenses into chromosomes, becomes visible.

Metaphase:

2nd phase of cell division

• The nuclear membrane breaks down.

Prophase:

1st phase of

cell division

Spindle fibers connect to the

centromere of each chromosome and to centriole at each pole.

• Spindle fibers start to form and centrioles move to opposite sides of cell (poles)

10-2

Cytokinesis usually occurs

• at the same time as telophase.
• after telophase.
• during interphase.
• during anaphase

The series of events that cells go through as they grow and divide is called

• the cell cycle.
• mitosis.
• interphase.
• cytokinesis.

The phase of mitosis during which the chromosomes line up across the center of the cell is

• prophase.
• metaphase.
• anaphase.
• telophase.

10-2

DNA replication takes place during the

• S phase of the cell cycle.
• G1 phase of the cell cycle.
• G2 phase of the cell cycle.
• M phase of the cell cycle.

During mitosis, “sister” chromatids separate from one another during

• telophase.
• interphase.
• anaphase.
• metaphase.