Cell Division and Mitosis

Chapter 8

11/19-11/21

Complete photo graph Review for exam Essay question topics Begin cell repro Ppoint Not an old persons disease case

study Cell Energy Exam on Friday

Review Topics

Photo vs Cellular resp. (location, products)

Heat lost Define Respiration vs Cellular resp Equation What actually “carries” the energy? Stages in order What is oxidative Phosphorylation?

Locations of stages Oxygen or no oxygen Net gains pH at the end What makes your muscles sore? What if your Mito’s couldn’t

complete the process?

Essay 1 Making energy at different time

frames. Essay 2 Heterotroph, Autotroph, Aerobic,

Anaerobic, Eukaryote,Prokaryote

HOMEWORK

12/2 Pre/post,Read pages 126-129

Math moments

If you made $ 30,000 per hour, what would you make in a day?

If you were given $ 8.00 per year from the year you were born what would you have now? What would you have when you are 75 years old?

Science Moments

If you lost 30,000 skin cells per hour, what would you lose in a day?

If you lost 8.00 lbs. of skin per year from the year you were born how many lbs. would you have lost by now? How much would you have lost when you are 75 years old?

Like Begets Like….

Buzz Words

Genes Chromosomes Asexual Sexual Generation Cell division Reproduction

Why is it necessary for cells to divide?

DNA overload To improve material exchange

Surface area to volume

Cell Size

Surface Area (length x width x 6)

Volume (length x width x height)

Ratio of Surface Area to Volume

Ratio of Surface Area to Volume in Cells

Section 10-1

Understanding Cell Division

What instructions are necessary for inheritance?

How are those instructions duplicated for distribution into daughter cells?

By what mechanisms are instructions parceled out to daughter cells?

Reproduction

Parents produce a new generation of cells or multicelled individuals like themselves

Parents must provide daughter cells with hereditary instructions, encoded in DNA, and enough metabolic machinery to start up their own operation

Like begets like..

Division Mechanisms

Eukaryotic organisms

Mitosis

Meiosis

Prokaryotic organisms

Prokaryotic fission (Binary fission)

Roles of Mitosis

Multicelled organisms

Growth

Cell replacement

Some protistans, fungi, plants,

animals

Asexual reproduction EXPLAIN!!!

Chromosome A DNA molecule & attached proteins Duplicated in preparation for mitosis When the chromosomes are just a mass of fibers it is called

a Chromatin

one chromosome (unduplicated)

one chromosome (duplicated)

Chromosome Number

Sum total of chromosomes in a cell Somatic cells

Chromosome number is diploid (2n) Two of each type of chromosome

Gametes Chromosome number is haploid (n) One of each chromosome type

Human Chromosome Number

Diploid chromosome number (n) = 46

Two sets of 23 chromosomes each One set from father One set from mother

Mitosis produces cells with 46 chromosomes--two of each type

Lots of DNA

Stretched out, the DNA from one human somatic cell would be more than two meters long

A single line of DNA from a salamander cell would extend for ten meters

Organization of Chromosomes

DNA and proteinsarranged as cylindrical fiber

DNA

histone

one nucleosome

Cell Cycle

Cycle starts when a new cell forms

During cycle, cell increases in mass and duplicates its chromosomes

Cycle ends when the new cell divides

Fig. 8.4, p. 130

Interphase

Usually longest part of the cycle

Cell increases in mass

Number of cytoplasmic components

doubles

DNA is duplicated

Stages of Interphase

G1 Interval or gap after cell division

S Time of DNA synthesis (replication)

G2 Interval or gap after DNA replication

Control of the Cycle

Once S begins, the cycle

automatically runs through G2 and

mitosis

The cycle has a built-in molecular

brake in G1

Cancer involves a loss of control

over the cycle, malfunction of the

“brakes”

Stopping the Cycle

Some cells normally stop in

interphase

Neurons in human brain

Arrested cells do not divide

Adverse conditions can stop cycle

Nutrient-deprived amoebas get stuck in

interphase

Cell Cycle Regulators

Cyclin (protein) regulate the timing of the cell cycle

Cancer cells do not respond to these “signals”

This results in masses called tumors

A sample of cytoplasm is removed from a cell in mitosis.

The sample is injected into a second cell in G2

of interphase.

As a result, the second cell enters mitosis.

 Effect of Cyclins

Skin Cancer

Asymmetrical, Borders, Color, Diameter, Elevation

Essay Question 1

Compare and contrast mitosis and meiosis. Pay extra attention to crossing over, number of daughter cells and chromosome number. Based on your comparison, explain how these two processes play an important role in reproduction and evolution.

List and describe the main events of the cell cycle.

Mitosis

Period of nuclear division Usually followed by cytoplasmic

division Four stages:

Prophase

Metaphase

Anaphase

Telophase

nucleusplasmamembrane

pair of centrioles

chromosomesnuclear envelope

CELL AT INTERPHASE EARLY PROPHASE LATE PROPHASE

TRANSITION TO METAPASE

Fig. 8.7a, p. 132

The cell duplicates its

DNA, prepares for

nuclear division

Mitosis begins. The DNA and its

associated proteins have started to

condense. The two chromosomes

color-coded purple were inherited

from the female parent. The other

two (blue) are their counterparts.,

inherited from the male parent.

Chromosomes continue to

condense. New

microtubules become

assembled. They move one

of the two pairs of centrioles

to the opposite end of the

cell. The nuclear envelope

starts to break up.

Now microtubules penentrate

the nuclear region. Collectively,

they form a bipolar spindle

apparatus. Many of the spindle

microtubules become attatched

to the two sister chromatids of

each chromosome.

MITOSIS

METAPHASE ANAPHASE TELOPHASE INTERPHASE

Fig. 8.7b, p. 133

All chromosomes have become

lined up at the spindle equator.

At this stage of mitosis (and of

the cell cycle), they are most

tightly condensed

Attachments between the

two sister chromatids of each

chromosome break. The two

are separate chromosomes,

which microtubules move to

opposite spindle pores.

There are two clusters

of chromosomes, which

decondense. Patches of

new membrane fuse to form

a new nuclear envelope.

Mitosis is completed.

Now there are two

daughter cells. Each

is diploid; its nucleus

has two of each type

of chromosome, just

like the parent cell.

Longest Phase

The Spindle Apparatus

Consists of two distinct sets of

microtubules

Each set extends from one of the cell

poles

Two sets overlap at spindle equator

Moves chromosomes during mitosis

Spindle Apparatus

one spindle pole

one of the condensed chromosomes

spindle equator

microtubules organized as a spindle apparatus

one spindle pole

Stages of Mitosis

Prophase

Metaphase

Anaphase

Telophase

Early Prophase - Mitosis Begins

Duplicated chromosomes begin to condense

Late Prophase

New microtubules are assembled

One centriole pair is moved toward opposite pole of spindle

Nuclear envelope starts to break up

Transition to Metaphase

Spindle formsSpindle microtubules become attached to the two sister chromatids of each chromosome

Metaphase

All chromosomes are lined up at the spindle equator

Chromosomes are maximally condensed

Anaphase

Sister chromatids of each chromosome are pulled apart

Once separated, each chromatid is a chromosome

Telophase

Chromosomes decondense

Two nuclear membranes form, one around each set of unduplicated chromosomes

Results of Mitosis

Two daughter nuclei

Each with same chromosome number as parent cell

Chromosomes in unduplicated form

Metaphase

Prophase

Prophase

Interphase

Anaphase

Telophase

Cytoplasmic Division

Usually occurs between late

anaphase and end of telophase

Two mechanisms

Cell plate formation (plants)

Cleavage (animals)

Cytokinesis

Cell Plate Formation

Animal Cell Division

Essay Question #2

Describe how cancer cells are different from other cells and how they form. Based on these differences, explain why cancer is so difficult to cure and explain how tumors form.

Essay question 3

You have been introduced to a variety of abnormalities found in the human based on the number and location of chromosomes. Choose one of these” syndromes” and illustrate its karyotype. In addition, explain in detail the genetic condition as well as the biological features affected by it.

There is a single bacterium in a bottle at 11:00 pm, and it is a type that doubles once every minute. The bottle will be completely full of bacteria at 12:00 midnight - exactly one hour.

In your opinion, what percentage of the bottle will be full when the bottle starts to look full? For what amount of time between 11:00 and 12:00 would they have plenty of room to grow and spread out? If you were a lab researcher, in the lab, at what time between 1:00 and midnight might you look at the bottle and think, "I'd better get a bigger container for those bacteria!"

Culturing Cells

Growing cells in culture allows researchers to investigate processes and test treatments without danger to patients

Most cells cannot be grown in culture

HeLa Cells

Line of human cancer cells that can be grown in culture

Descendents of tumor cells from a woman named Henrietta Lacks

Lacks died at 31, but her cells continue to live and divide in labs around the world

Regulating the Cell Cycle

Pre-Natal Tests - help to determine if an at risk baby is healthy

Sex chromosomes

Human Karyotype

Sex Chromosomes

Female with Turner Syndrome (XO)

Klinefelder Syndrome

Klinefelter’s Syndrome

47, XXY

Klinefelter Syndrome (XXY)

Down Syndrome (trisomy 21),

47,XY,+21.

47: the total number of chromosomes (46 is normal).

XY: the sex chromosomes (male).

+21: designates the extra chromosome as a 21.

Down Syndrome

Gene Therapy - an absent or faulty gene is replaced by a working gene

Has not been very successful

Normal hemoglobin gene

Bone marrow cell

Chromosomes

Genetically engineered virus

Nucleus

Bone marrow

Figure 14-21 Gene Therapy

Cloning

A donor cell is taken from a sheep’s udder. Donor

Nucleus

These two cells are fused using an electric shock.

Fused Cell

The fused cell begins dividing normally.

EmbryoThe embryo is placed in the uterus of a foster mother.Foster

Mother

The embryo develops normally into a lamb—Dolly

Cloned Lamb

Egg Cell

An egg cell is taken from an adult female sheep.

The nucleus of the egg cell is removed.

Figure 13-13 Cloning of the First Mammal

Stem Cells

1. What phase ?

2. What phase ?

3. What phase ?

4. What phase ?

5. What is the longest phase of the cell cycle ?

6. What is the longest phase of

mitosis?

7. List (in order) the phases of

mitosis

8. List two outcomes of Interphase

9. How many chromosomes do you have in you

sex cells ?

10. Name the phase

BONUS

Name and explain two reasons why cells must divide