Transcript Cell Growth and Reproduction

Cell Growth and Reproduction
Cell Size Limitations
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How does a cell receive
materials and expel its
wastes?
Through the plasma membrane
This means that no part of the
cell can be too far away
Mitochondria of a cell 20 cm
wide would have to wait
months
Surface Area to Volume Ratio
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The more volume = more
cytoplasm
= more energy
requirements
Volume increases much
greater than surface area
If a cell a cell were to
double; it would require 8X
as much nutrients
Cell Reproduction
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Recall cell theory
One cell becomes two
Chromosomes – structures
which contain DNA and are
carriers of genetic material
that is copied and passed
from generation to
generation
Cell Reproduction cont…
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Most of time as chromatin
Chromatin – long strands of
DNA wrapped around
proteins
Condenses before cell
division
Cell division follows a
pattern or cycle
Chromosomes
The Cell Cycle
Events that occur in the life
of a cell
Includes 3 major stages:
 Interphase
 Mitosis
 Cytokinesis
Interphase
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Most of the cell cycle is in
what stage?
3 parts
G1- rapid growth and metabolic
activity
S – DNA synthesis and
replication
G2 – Cell prepares for division
Mitosis
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Cells undergo division
when they get to a certain
size
Continuous process
Stages are named for ease
of identification
Steps of Mitosis
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Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Prophase
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Chromatin condenses into
chromosomes
Two halves called sister
chromatids are held
together by contromere
Nucleus disentegrates
Centrioles go to poles
Spindle forms
Prophase
Metaphase
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Chromosomes pulled by
spindle fibers at the
centromeres
Sister chromatids lined up
in the middle
Single file
Metaphase
Anaphase
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Centromeres split
Sister chromatids pulled
apart by spindle fibers
Pulled to opposite sides
Anaphase
Telophase
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Chromatids reach opposite
poles
Chromosomes unwind
Spindle breaks down
Nuclear membrane and
nucleolus reappear
Telophase
Cytokinesis
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Dividing the cytoplasm
between the two new
daughter cells
Cleavage furrow in animal
cells
Cell plate in plant cells
Cytokinesis in Animals
Cytokinesis in Plants
Mitosis in Onion Cell
Mitosis in Whitefish
In mitosis, the two double
copies of the DNA attached to
the spindle fibers are known
as __________.
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a.
b.
c.
d.
centromeres
chromatids
centrioles
nucleoli
During which phase do most
cells spend the most time?
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a.
b.
c.
d.
prophase
metaphase
anaphase
interphase
If a cell has 20 chromosomes,
how many chromosomes will
be present in the daughter
cells?
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a.
b.
c.
d.
5
20
10
30
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List the stages of the Cell
Cycle in order
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Name one stage of
Interphase