Download - Ch6a CellDiv Mitosis and Cancer F14s

8/10/2019 Ch6a CellDiv Mitosis and Cancer F14s

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Cell Division: Overview

The Cell Cycle and Mitosis

Cancer

Cell Division, Mitosis, and

Cancer (Ch. 6 part 1)


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Learning Objectives: Overview

Identify the three different types of celldivisionand the functions of each


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Cell Division: Three Types

Binary fission

Used for asexual reproduction

Mitosis, Meiosis

Asexual reproduction:


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Prokaryotes reproduce by binary fission

Circular parent

chromosome

Parent cell

divides;

duplicate

chromosomes

separate

Duplicate

chromosomes

Genetically

identical

daughter cells


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FUNCTIONS OF MITOSIS

Early human embryo

LM

ColorizedTEM

Red blood cells

Mitosis produces duplicate cells

Used for many functions in eukaryotes


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Sea starsLM

Amoeba African Violet

FUNCTIONS OF MITOSIS, continued


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Meiosis:

Two

parents

FERTILIZATION

Sperm cell

Offspring

(has mixture

of genes from

2 parents)

Egg cellGametes

MEIOSIS

Each gamete

has only half the

parents DNA


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Learning Objectives:

Cell Cycle and Mitosis

Name the 2 main phases of the cell cycleand describe the events that occur in each

Distinguish between the terms chromatin,

sister chromatid, centromere, chromosome List the 4 main stages of mitosisin order,

and describe the events that occur in each

Distinguish mitosis from cytokinesis


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G1

S

G2

M

The Cell Cycle regulates the

growth and mitotic division

of eukaryotic cellsInterphase:

Mitotic (M)

phase:


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DNA replication during Interphase

produces identical sister chromat ids

one DNA molecule

two identical DNA molecules(= )

The chromatids stayjoined together at the:

repl icat ion

one chromosome Still have only one

chromosome!


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The M Phase includes two distinct

events: mitosis & cytokinesis

Mitosis:

4 subphases

G2

M

Cytokinesis:


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Duplicated chromosome

(sister chromatids

joined at centromere) TEM

Coiled fiber

Looped regions

Centromere

DNA in

condensed form

DNA in form

of chromatinDuring the

M phase, the

chromosomes

are condensed

and visible


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Distinct chromosomes

seen during cell division

LM

DNA in form of chromatin


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Mitosis begins with Prophase

Nuclear

envelope

Plasma

membrane

Chromosome consisting

of two sister chromatids

Spindle

microtubules

Fragments of

nuclear envelopecentrosome

Centromere

centrosomes

Chromatin

PROPHASEINTERPHASE

1)

2)

3)

Mitotic spindle: cage of

microtubulesradiating

from centrosomesat

opposite poles of cell


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Metaphase and Anaphase ensure an

orderly division of chromosomes

Anaphase:

ANAPHASEMETAPHASE

Spindle Daughter chromosomes

Metaphase:

Spindle fibers aid chromosome movements

sister

chromatids


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Telophase is the last stage of Mitosis

and overlaps with Cytokinesis

Cytokinesis: two new daughter cells formed through

division of cytoplasm and other organelles

Telophase:

1)

2)

3)

Cleavage

furrowNuclear

envelope

forming


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Learning Objectives: Cancer

Define cancer, and explain how cancer isrelated to the cell cycle and mutations

Explain how age and inherited cancer

genes increase a persons cancer risk Describe several ways in which personal

habits and individual choices can affect a

persons risk of developing cancers Explain why chemotherapyoften has

unpleasant side effects


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Cancer

Leading causes of

death in the U.S.:

1. Heart disease (25%)

2. Cancer (23%)

Lifetime risk of cancer (U.S.):

Uncontrolled celldivision produces

tumorsthat can disrupt

vital organ functions


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Conversion to a cancerous cell

usually requires multiple mutations

Explains:

1mutation

Normal cell Cancerous cell

4mutations

3mutations

2mutations

Chromosomes

New cancer diagnoses per year (U.S.):

Age 50+ : 15 per 1000 people

Age


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Inherited cancer genes

1mutation

Gamete-

producing

cell (normal)

Chromosomes

gamete

(e.g., egg cell)

All cells in offspring

will have the mutation


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Many environmental and lifestyle

factors increase cancer risk

Carcinogens

UV and other high-energy radiation

Tobacco chemicals

Alcohol (liver cancer) Viruses

Disrupt cell cycle regulator

genes or proteins


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Many cancer treatments act to

inhibit cell division

Side effects of

chemotherapy

hair root cells

cells lining

digestive tract

bone marrow cells(give rise to red and

white blood cells)