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)

ch6a celldiv mitosis and cancer f14s

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