How Cells Reproduce

Chapter 8

Have you ever wondered…

How you grow from one cell to billions?

How your cuts heal? Hair grows?

How some animals regenerate lost parts?

The Answer Is _______!!!

FUN FACT: ___________________ ______________________

Rudolph Virchow came up with this great idea in 1858.

Its importance is hugeIf you start as one cell

and end up with millions… that means there is a lot of cellular division happening…

In that case lets study it!

The process of division depends on who you are and what you want…

Prokaryote: All are unicellular so any _________ is __________

and all reproduction is asexual (called binary fission)

Eukaryote: Unicellular ones… all reproduction is asexual but

they use mitosis Multicellular

________ for repair, increasing size, and replacement of damaged cells

______ for sexual reproduction… making egg and sperm

Asexual Reproduction

Like a Xerox machine.DNA comes only from

one parent making variation dependent on ______ _______and __________

Organisms can be only asexual or both depending on the circumstanceRegenerationBudding (cactus)Mitosis (we’ll come

back to it)

Before we can get to Mitosis we need to start with the chromosome…

For the majority of DNA’s life it exists as _______… chromosomes + protein associated, loosely packed

When a cell is going to divide the DNA packs up tightly into ______________.

Cell cycle… INTERPHASEA cell is undergoing

changes at all timesEvery moment of a cells life

________ ________ is called INTERPHASE

In this time it gets prepared to divideMakes proteins, lipids,

carbohydrates and organelles. Grows, metabolizes etc (___ or gap 1)

____________ its DNA (S phase)

Prepares for mitosis(__ or gap 2)

Not all cells are destined to divideSome cells, like adult

_______ will _____ _____ __ living life but not ready to divide

Some cells, like skin cells, are _____ _______ though the cell cycle

At the end of G1, G2, and during division there are _________, like stop lights, that must be ‘green’ for the cell to continue though the

cycle.More on this later!

Duplicating DNA (S-Phase)

Before it divides it has to duplicate…

Each chromosome makes a Xerox so that it has a _____ of chromatids (we call them _______ _________)

They are joined by a __________ and when the cell divides each new cell grabs its chromatid by the centromere

** NOTE… it’s a chromosome before and after division… when its doubled its called sister chromatids

M phase-- MITOSISAfter interphase…Nuclear Division

P__________ (one and two) M__________ A__________ T__________

Before cytoplasm division (c____________)

Prophase

Early prophaseTime when chromosomes appearNucleolus disappears

Late prophaseNuclear membrane breaks apartMicrotubules grab the centromere

making a structure called the kinetochore

Chromosomes begin to move

Centriole

Metaphase

Spindle fibers line the chromosomes up at the metaphase plate… all ready to break apart

Anaphase

Sister chromatids break apart and move to opposite poles (sides)

Make little A looking things… remember A for Anaphase!

The other spindle fibers (that are not forming kinetochores push apart to elongate the cell)

TelophaseReversal of prophase… the nuclear

membrane, then nucleolus reappearThe chromosomes go back to chromatinAs the cell begins cytokinesis a cleavage

furrow forms

BUT WE’RE NOT DONE… cytokinesisOnce nuclear division

is over the cytoplasm must be divided

This splits up the _________, _______, _____ and _______… everything but the DNA

Accomplished by the spindle fibers

Affecting cell division

Cells will grow more or less based on their surroundings_________ _______ is

when cells won’t grow unless with other cells that are the same.

________ ______ is when cells stop dividing once they reach their max capacity (like a full room)

Growth factor: when one cell makes and secretes a protein that tells other cells to divide

Check-points of Mitosis

What happens if cell division gets out of control?

So what do we do to stop it? Cell cycle control system 3 major check points

G1G2 M

Each go ahead sends the cell further into dividing

Non- dividing cells such as muscle and nerve receive stop signals at the _____ phase.

If a cell is damaged it will not have the proper signal to divide and thus will abort its reproduction… the mechanism of this is called signal transduction

When Mitosis gets out of control

Cells that undergo uncontrolled division are tumor cells

Their divisions cause them to pile up making a tumor

The tumor can be malignant or benignbenign means the cells are

okay… like a molemalignant means the cells kill

the good tissue as they go and can break off or metastasize to other cells

Cancer Nomenclature

Each cancer is named from where it originatedCarcinoma: from the covering

or lining (epithelium) either in the gut or on the skin (includes lung)

Sarcoma: supportive tissue, bone or muscle

Leukemia: of the blood or blood forming tissues

Lymphoma: lymph or lymphatic organs (spleen)

Cancer Treatments

Treatments:Surgery: cut out as much

of the tumor as possibleRadiation therapy exposes

a localized area to large amounts of radiation which halt cell division in the area

Chemotherapy supplies a poison to the whole individual slowing cell divisionit works better…but it

also effects many normal cells