Transcript chromosomes - sandsbiochem

CELL GROWTH
& DIVISION
10-1 & 10-2
2 Reasons why cells divide
DNA OVERLOAD
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
2 Reasons why cells divide
Material exchange can’t keep up
2. _____________________
As cell grows bigger demand for
transport across membrane is too
great
Ability to transport of oxygen,
food, waste across cell membrane
depends on _______________
SURFACE AREA
Need for these depends on
CELL VOLUME
___________
As cell grows these DON’T increase at the
same rate
See relationship
between volume and SA
Ratio of Surface Area to Volume in Cells
Section 10-1
Cell Size
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
Go to
Section:
BIGGER CELLS NEED MORE FOOD
and OXYGEN, but CAN’T TRANSPORT
IT FAST ENOUGH or IN BIG
ENOUGH QUANTITIES!
Multicellular organisms grow
mainly by increasing cell number
DNA CAN BE:
SPREAD OUT IN
NON-DIVIDING
CELLS
CHROMATIN
SCRUNCHED UP
IN DIVIDING
CELLS
CHROMOSOMES
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
CHROMATIDS
• ___________________
2 identical arms
• __________________
CENTROMERE
constricted area
holds
chromatids together
HOMOLOGOUS
•__________________
PAIR
2 of each chromosome
(one from mom; one from dad)
HOMOLOGOUS CHROMOSOMES
• SAME SIZE
• SAME SHAPE
• CARRY GENES for the
SAME TRAITS
IDENTICAL
• BUT NOT
______________!
(Don’t have to have the
SAME CHOICES)
CELL DIVISION in PROKARYOTES
Bacteria reproduce using
BINARY FISSION
__________________________________
CELL
CYCLE
______________ =
series of events that cells go
through as they grow and
develop
cells alive cell cycle
CELL CYCLE
INTERPHASE – 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 DIVISION
MITOSIS – Nuclear division
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis – Cytoplasm divides
G0 – cell stops dividing
(Ex: nerve cell)
Figure 10–4 The Cell Cycle
Section 10-2
G1 phase
M phase
S phase
G2 phase
Go to
Section:
INTERPHASE (G1 - S - G2)
In between divisions
Cells are in this phase most of the time
Can see nucleus
DNA spread out as chromatin
Can’t see chromosomes
DNA gets copied (S)
Cell gets ready to divide
PROPHASE
1st dividing phase
DNA scrunches into chromosomes
Centrioles appear in centrosome region
& move to poles
Nuclear membrane & nucleolus disappear
Spindle fibers form & attach to
chromosomes
CENTROSOME
________
region organizes spindle
Spindle MICROTUBULES are part of cytoskeleton
METAPHASE
Chromosomes line up in
middle
___________
ANAPHASE
Centromeres split
apart
Centrioles pull chromatids_______
TELOPHASE (reverse prophase steps)
two nuclei
See ______
Nuclear membrane & nucleolus return
Chromosomes spread out as chromatin
Centrioles disappear
Spindle fibers disappear
CYTOKINESIS
Cytoplasm splits into 2 cells
ANIMAL CELLS pinch cytoplasm in two
with a ______________________
CLEAVAGE FURROW
CYTOKINESIS
Cytoplasm splits into 2 cells
PLANT CELLS can’t pinch because
they have a sturdy ____________
CELL WALL
Plant cells separate cytoplasm by
CELL PLATE
growing a _______________
down the middle.
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Videos
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Animal Cell Mitosis
Animal Cell Cytokinesis
Concept Map
Section 10-2
Cell Cycle
includes
is divided into
Go to
Section:
is divided into
Concept Map
Section 10-2
Cell Cycle
includes
Interphase
M phase
(Mitosis)
is divided into
is divided into
G1 phase
Go to
Section:
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase