CELL GROWTH & DIVISION 10-1 & 10-2. 2 Reasons why cells divide 1. _____________________ As cell...

CELL GROWTH & DIVISION10-1 & 10-2

2 Reasons why cells divide

1. _____________________As cell grows bigger demand on DNA“genetic library” becomes too great

Ex: Small town library has 1000 books. As town grows and more people borrow books, there may be a waiting list to read the most popular titles

DNA OVERLOAD

2 Reasons why cells divide

2. _____________________As cell grows bigger demand for transport across membrane is too great

Material exchange can’t keep up

Ability to transport of oxygen, food, waste across cell membrane depends on _______________

Need for these depends on ___________

SURFACE AREA

CELL VOLUME

As cell grows these DON’T increase at the same rate

See relationshipbetween volume and SA

https://smartsite.ucdavis.edu/access/content/user/00002950/bis10v/media/ch03/area_volume.html

Go to Section:

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

BIGGER CELLS NEED MORE FOODand OXYGEN, but CAN’T

TRANSPORTIT FAST ENOUGH or IN BIGENOUGH QUANTITIES!

Multicellular organisms grow mainly by increasing cell number

SPREAD OUT INNON-DIVIDING CELLS

SCRUNCHED UPIN DIVIDINGCELLS

CHROMATIN CHROMOSOMES

DNA CAN BE:

DNA in PROKARYOTES

• BACTERIAL DNA is CIRCULAR• HAVE ONE CHROMOSOME• NO NUCLEUS;

ATTACHED TO CELL MEMBRANE

DNA in EUKARYOTES(Plants & Animals)

• DNA is ROD-SHAPED CHROMOSOMES• MANY PAIRS• FOUND IN NUCLEUS

Chromosome structure

• ___________________ 2 identical arms

• __________________ constricted area

holds chromatids together

•__________________ PAIR 2 of each chromosome(one from mom; one from dad)

CHROMATIDS

CENTROMERE

HOMOLOGOUS

HOMOLOGOUS CHROMOSOMES

• SAME SIZE• SAME SHAPE• CARRY GENES for the

SAME TRAITS• BUT ______________! (Don’t have to have

the SAME CHOICES)

NOT IDENTICAL

CELL DIVISION in PROKARYOTES

Bacteria reproduce using__________________________________ BINARY FISSION

______________ =series of events that cells go through as they grow and develop

cells alive cell cycle

CELL CYCLE

http://www.cellsalive.com/cell_cycle.htm

CELL CYCLEINTERPHASE – non-dividing phase G1- Grow bigger

Cell is “doing its job” DNA is spread out as

chromatin

S - Synthesis (copy DNA)& chromosomal proteins

G2- Grow bigger, make organelles &

molecules needed for cell division

CELL DIVISIONMITOSIS – Nuclear division Prophase Metaphase

AnaphaseTelophaseCytokinesis – Cytoplasm divides

G0 – cell stops dividing (Ex: nerve cell)

Go to Section:

M phase

G2 phase

S phase

G1 phase

Figure 10–4 The Cell Cycle

Section 10-2

INTERPHASE (G1 - S - G2)

In between divisionsCells are in this phase most of the timeCan see nucleus DNA spread out as chromatin

Can’t see chromosomes DNA gets copied (S)

Cell gets ready to divide

PROPHASE1st dividing phase

Spindle fibers form & attach to chromosomes

Nuclear membrane & nucleolus disappear

DNA scrunches into chromosomes

Centrioles appear in centrosome region & move to poles

________ region organizes spindle

Spindle MICROTUBULES are part of cytoskeleton

CENTROSOME

METAPHASE

Chromosomes line up in ___________middle

ANAPHASECentromeres splitCentrioles pull chromatids_______apart

TELOPHASE (reverse prophase steps)

See ______ nuclei

Nuclear membrane & nucleolus returnChromosomes spread out as chromatinCentrioles disappear

Spindle fibers disappear

two

CYTOKINESISCytoplasm splits into 2 cells

ANIMAL CELLS pinch cytoplasm in two with a ______________________CLEAVAGE FURROW

CYTOKINESISCytoplasm splits into 2 cellsPLANT CELLS can’t pinch because they have a sturdy ____________

Plant cells separate cytoplasm by growing a _______________ down the middle.

CELL PLATE

CELL WALL

Go to Section:

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Section 10-2

Figure 10–5 Mitosis and Cytokinesis

Videos

Click a hyperlink to choose a video.

Animal Cell Mitosis Animal Cell Cytokinesis

Go to Section:

includes

is divided into is divided into

Concept Map

Section 10-2

Cell Cycle

Go to Section:

includes

is divided into is divided into

Concept Map

Section 10-2

Cell Cycle

M phase (Mitosis)

Interphase

G1 phase S phase ProphaseG2 phase Metaphase TelophaseAnaphase

CELL GROWTH & DIVISION 10-1 & 10-2. 2 Reasons why cells divide 1. _____________________ As cell...

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