How does the surface
area to volume ratio
affect a cell?
The larger the surface
area to volume ratio, the
more efficiently the cell
can get nutrients
Why is cell size
limited?
-If cells get too big, their volume
increases faster than surface area;
the cell can’t get nutrients in and
wastes out fast enough
-If cells are too small, the
organelles can’t fit and function
correctly
What are the two
major phases of the
cell cycle?
Interphase and M-phase
What are the 3
phases of
Interphase?
G1, S, and G2
What happens during
G1 of Interphase?
normal growth and
functioning;
organelles are
copied
What happens during
S of Interphase?
DNA is replicated
(copied)
What happens during
G2 of Interphase?
normal growth and
functioning
Why is replication of
DNA and the cell’s
organelles important?
When the cell divides, it
will need to give each
daughter cell all of the
organelles and a full set
of DNA
What are the two
major events that
occur during the Mphase?
Mitosis and
Cytokinesis
What occurs during
the M-phase?
Cell Division
What is mitotic cell
division (mitosis and
cytokinesis)?
When a parent cell
divides into two
identical daughter
cells
What happens during
mitosis?
The parent cell DNA (in
the nucleus) is organized
and divided between the
two new daughter cells
(in two new nuclei)
What happens during
cytokinesis?
How does cytokinesis
occur in plant cells?
How does cytokinesis
occur in animal cells?
The cytoplasm of the
parent cell is divided to
create two daughter
cells
A cell plate grows
between the two cells
and forms a new cell
wall on each side
The cell membrane
pinches inward to form a
cleavage furrow until the
two cells are pinched
apart
Why can’t plant cell
membranes pinch inward
during cytokinesis?
They have a rigid
cell wall.
What is the purpose of
mitosis in unicellular
organisms?
Asexual reproduction:
one organism creates
two new organisms
What is the purpose Replace dying cells or
of mitosis in
help the organism
multicellular
grow
organisms?
Mitosis occurs in what
type of cells?
Somatic (body) cells
What is the most basic
form of DNA?
Double helix
What are the building
blocks (monomers) of
DNA?
nucleotides
What does DNA wrap
around to start
condensing?
Proteins called
histones
What is chromatin?
DNA wrapped around
histones and condensed
into “spaghetti” form
When chromatin coils up
on itself into a supercoil,
what is formed?
Chromosomes
What is half a
chromosome called?
chromatid
A chromosome that has
its copy attached to it
(from the S phase of
Interphase) is made up
of 2 what?
Sister chromatids are
held together at the
what?
Sister chromatids
centromere
What form of DNA is
present during
Interphase?
Chromatin
What form of DNA is
present during mitosis?
chromosomes
What is the role of
spindle fibers during cell
division?
To help organize and
separate the DNA
What do centrioles do
during cell division?
Organize the spindle fibers
Why do cells divide at
different rates?
Some cells need to be
replaced more often than
other types of cells
according to their function
in the body
What are the four phases
of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What happens during
Prophase?
•The nucleolus and nuclear membrane
“break up” and temporarily disappear.
•Chromatin has condensed into
chromosomes, each consists of two
identical sister chromatids
•Centrosomes and Centrioles migrate to
opposite sides of the cell
•Spindle fibers grow from the centrioles
and radiate toward the center of the cell.
What happens during
Metaphase?
Spindle fibers attach to the
chromosomes and help line the
chromosomes up across the center
of the cell on an imaginary line
called the metaphase plate or cell
equator
What happens during
Metaphase?
-The chromosomes line up across the
center of the cell on an imaginary line
called the metaphase plate.
- Microtubules attach to the centromere
of each chromosome from both poles
of the spindle.
What happens during
Anaphase?
What happens during
Telophase?
What is this
phase?
Spindle fibers shorten, breaking
sister chromatids apart to form
separate chromosomes. The
chromosomes are pulled to
opposite ends of the cell
-Chromosomes begin to unwind
back to chromatin.
-The nuclear envelope and
nucleolus reappear in each
daughter cell
-The spindle disappears
Interphase
What is this
phase?
Prophase
What is this
phase?
Metaphase
What is this
phase?
Anaphase
What is this
phase?
Telophase