Download cells.

Unit 6
DNA and the Cell Cycle
UNIT 6 - DNA & THE CELL CYCLE
 The third statement of the Cell Theory states
that all cells come from
Pre-existing cells
____________________________________.
The continuity of life is based on the
reproduction of cells or
Cell division
____________________________.
In most
organisms, cells increase to a certain size
and then divide into two cells. This cycle of
growth and cell division is known as the
Cell Cycle
_________________________.
Cell Cycle
 The cell cycle is defined as the period of time
from the beginning of one
Cell division
_______________________________
to the
______________________________________.
Beginning of the next
This type of cell division is
Asexual
_________________
reproduction. In asexual
reproduction, the genome or
DNA
________________
of the cell is exactly
two
replicated resulting in ________
___________________
cells.
Identical
I. IMPORTANCE OF ASEXUAL
REPRODUCTION (p. 241-243)
A. Single-celled Organisms
Single-celled organisms belonging to
Protista
kingdoms ___________________,
Archaebacteria
______________________,
Eubacteria
_______________,
and
Fungi
____________,
use asexual reproduction
Make new organisms-Reproduce
to______________________________.
B. Multicellular Organisms
 1. Growth & Development – Organisms grow
Cell division
through ___________________________,
rather than unlimited growth of a cell.
 Surface Area to Volume Ratio – As the size of
volume
an object increases, the __________________
increases at a much faster rate than the
Surface area
_____________________;
therefore, the
surface area to volume ratio becomes a
______________
number.
Decreasing
Surface Area to Volume
In a cell, the
Cell membrane
________________________
represents
the surface area and the
cytoplasm
________________________
represents
the volume. At a certain point, a cell can
no longer meet its needs and maintain
homeostasis
_____________________;
therefore, cells
only grow to a certain size.
2. Renewal & Repair
 – Cell division is used to replace cells that die
from normal wear & tear; for example,
Digestive cells
Skin cells
________________
and __________________.
Other types of cells maintain the ability to divide,
but keep it in reserve unless severely damaged;
Liver cells
for example, ___________________________.
Other cells do not appear to divide at all in a
mature human; for example,
Nerve cells
____________________
and
Cardiac muscle cells (heart)
__________________________.
II. CELL CYCLE IN PROKARYOTES
(p. 475)
bacteria
All ______________
undergo a type of
cell division known as
Binary fission
_______________________.
Binary
fission is a less complex, faster process
than eukaryotic cell division because
nucleus
bacteria lack a _________,
Membrane bound organelles
______________________________
and
One (1)
have only ________chromosome
Binary Fission
Pinching in
III. CELL CYCLE IN EUKARYOTES - AN OVERVIEW
(p. 245)
There are two main parts to the eukaryotic cell
cycle:
90%
A. Interphase - Accounts for about ________
of cell cycle. This is the period of time in which a
Normal activities and doing its cell job
cell is carrying out _______________________.
Protein
__________________
synthesis is occurring at
a high rate. The cell’s DNA is in the form of
chromatin
_______________,
long, fine strands of DNA
protein
wrapped in ______________.
M-Phase
 B. M-Phase – Period of time in which cell
division occurs. Consists of two main
events:
Mitosis – Division of the
nucleus
____________________________
Cytokinesis – Division of the
cytoplasm
_________________________
IV.
A CLOSER LOOK AT INTERPHASE
 There are three stages to interphase:
grows
 G1 - Cell ______________,
carries out normal cell
activities such as
Protein synthesis and cellular respiration
_________________________________________.
Period in which _____________
production is highest
Protein
DNA
Synthesis
 S - ______________.
Replication of ___________;
known as the “_________________________”.
Point of No Return
Replication takes place in the _____________________
nucleus
of the cell.
Mitosis
 G2 - Preparation for _____________________.
All organelles
______________________
are replicated in
____________________
cells.
eukaryotic
At the end of interphase . . .
Cell Membrane
Centrioles (replicated)
DNA has been replicated –
a. _____
still in chromatin form.
centrioles
b. ____________
have been
replicated in __________
cells
animal
only. This replication
results in 2 pairs of centrioles,
microtubules
composed of ______________.
_nuclear envelope_
c. The __________________
and nucleolus
_________are still present.
Protein microtubules that
will form spindle fibers
nucleolus
Chromatin
Nuclear envelope
V. A CLOSER LOOK AT MITOSIS (pp. 246-248)
Mitosis, also known as the _M - Phase_,
is described in four stages, but it is a
continuous process.
A. PROPHASE – In prophase, the
nucleus is preparing to divide. This
includes . . .
A. Prophase –The longest phase of mitosis
Microtubules form Spindle fibers
Sister chromatids
Nucleolus
attach at the 1.______________________
and
Nuclear
envelope
centromere ___________ _____________
disassemble.
DNA
2.Replicated ___________
thickens &
condenses  results in
______________ made up of 2
chromosomes
Sister chromatids
________________
______ held
together at the __________________
centromere
Centrioles
3.________________begin
moving to
opposite poles of the cell.
Microtubules
4. _______________________
form
Spindle
fibers
____________________________.
Specific spindle fibers attach to the
sister chromatids at the
centromere
______________________.
Centrioles
Nuclear envelope
disintegrates
B. METAPHASE-Shortest phase
 In metaphase, the sister chromatids are
Middle or center or equator
organized in the ___________________
of the cell.
Metaphase
centrioles
Kinetochore
microtubules
Spindle fiber
network
Sister chromatids
Spindle fiber
1._____________________
network is fully formed with
centrioles
________________
at
opposite ends.
2.Each
Sister chromatid
_______________________is
attached to a spindle fiber at
kinetochore
the _______________
located
at the
centromere
________________________
3.Sister chromatids align at
equator
the _______________
of the
cell.
C. ANAPHASE
In anaphase, the sister chromatids are
apart
pulled______.
Anaphase
Centrioles
Kinetochore
microtubules
Non-kinetochore
microtubules
Centromeres
1.________________
split.
2.Sister _____________
are
chromatids
pulled apart by
kinetochore
microtubules
_______________________;
move to opposite ends of the
cell.
3.Genetic material is now
known as daughter
chromosomes
_______________________.
4.Cell elongates; prepares for
two new nuclei.
D. Telophase
By the end of telophase…
Telophase
separate
1.Complete and _____________________
set of chromosomes
_____________ at each pole of the
cell.
Spindle fibers
2.__________________disassemble.
Nuclear envelope
3.New _______________________forms
around each group of chromosomes.
chromatin
4.DNA uncoils  _____________________
5.________________
reforms 
nucleolus
ribosomes
___________________ are produced
Protein synthesis resumes  cell
_______________
________________________
Metabolic activity
resumes
Chromosomes
Pinching in
Nuclear
envelope
reforms
E. CYTOKINESIS
 This refers to the actual division of the
cytoplasm
____________________.
Cytokinesis begins during
telophase
______________
and differs in plant versus animal cells
cell wall
because plant cells have a _____________.
 1. Animal Cell – In the final stages of telophase, the
cell membrane
_______________
pinches in. This is referred to as a
__________________
and is due to the action of
Cleavage furrow
____________________.
Invagination
w/microfilaments(actin) This cleavage furrow
deepens until the parent cell is pinched in two, producing
two separate, _________
daughter cells.
identical
Plant Cell Cytokinesis
 2. Plant Cell – There is no cleavage
furrow in plant cells. Instead, during late
vesicles
telophase, _______
from the
Golgi apparatus
_________________
move to the center
cellulose
of the cell where _____________and
other materials they contain come together
cell plate which eventually
to form a_______,
cell wall
develops into a ____________.
CYTOKINESIS
Cell
wall
Cleavage
furrow
Daughter
cells
Animal Cell
Vesicles
Containing
Cellulose
Plant Cell
New cell
wall
Cell plate
New cell
Walls around
New daughter
Cells
Control of the Cell Cycle
VI. CONTROL OF THE CELL CYCLE
(pp. 250-253)
A. Timing of the Cell Cycle
The timing of the cell cycle is regulated by
cyclins
proteins known as _____________
that
bind with enzymes known as
kinases
________________
to form a complex
called ___________________________
Cyclin-dependent kinases
or ___________.
These ____________
CDKs
enzymes
are responsible for monitoring checkpoints
in the cell cycle.
Cell Cycle
If the progression of the cell cycle is too
dying cells are not replaced
slow, ___________________________.
Cell Cycle
If the cell cycle progresses too quickly, the
result is uncontrolled cell growth or
_________.
This is harmful for many
cancer
reasons
If a cell spends all of its time dividing,
It is not doing its cell job
_____________________
Cell Cycle
The rapidly- dividing, nonfunctional cells steal
nutrients
___________________
from healthy,
them to die
functioning cells causing ___________.
The rapid replication of DNA
____ results in a greater
mutations
risk of ___________.
B. Stem Cells
 B. Stem Cells
undifferentiated cells that
Stem cells are ____________
have the ability to _____________.
reproduce forever Stem
cells that can give rise to many types of
pluripotent
cells are said to be _________.
Stem Cells
Although stem cells are found in certain
locations in adults, most research involves
embryonic
the use of ____________
stem cells, due
to the fact they are considered to be
immortal
“___________”
and capable of unlimited
specialization. Scientists hope that stem
cells may be used as implants to replace
______________________________,
but
Damaged tissues and organs
legal
there are many _______
and __________
ethical
concerns.
C. Number of Cell Division per Cell
Each cell is programmed to divide a
certain number of times, and then it will
not divide again. This is monitored by
telomeres a series of DNA ________
nucleotides
________,
found at the tips of each __________.
chromosome
Number of Cell Divisions per Cell
S of the cell cycle,
 As DNA is replicated
__________ in __
the telomeres shorten. Once they reach a
critical length, the DNA does not replicate again,
and the cell does not _______________.
divide
________________
and _____________
Cancer cells
stem cells
produce an enzyme known as _____________,
telomerase
which restores the chromosomes back to their
original length, thereby theoretically making the
cell capable of ______________
cell division.
unlimited
A CLOSER LOOK AT DNA & REPLICATION
 I. DNA – THE DISCOVERY OF THE MOLECULE OF
INHERITANCE (pp. 287-294)
 DNA contains the ________________
Genetic code and the
_______________________________
for a cell.
Working instructions
Scientists in the early 1900s realized that inheritance
was dependent on __________
found on
genes
chromosomes
____________________
and that chromosomes were
DNA
composed of ___________
and __________________.
protein
It wasn’t until the 1940s that scientists established
_______
DNA as the molecule of inheritance, and still another
15 years passed before the structure of DNA was
discovered.
A. Griffith (1928)
 Discovered that bacteria can take up genetic
material from environment in a process known
transformation
as _____________________.
 Performed experiments with _____________
mice
Pneumococcus
and bacteria known as ___________________.
Mixed harmless living bacteria with dead
______________________
Pathogenic
(deadly) bacteria and injected them
into mice.
Mice died.
Griffith’s Experiment
B. Avery, et.al. (1944)
 Set up experiments to identify “transforming
substance” discovered by Griffith
 Used enzymes that destroyed carbohydrates,
lipids, proteins, and RNA . . . transformation still
occurred. Used an enzyme that destroyed DNA,
Transformation did not occur, mice survived
_________________________________.
DNA
 Concluded that ______
stores and transmits the
genetic information from one generation of an
organism to the next.
 Scientific community did not completely accept
their conclusion
Avery’s Experiment
C. Hershey & Chase
(1952)
bacteriophagewhich
 Used a virus known as a ____________
bacteria
 infects _________.
DNA
protein
 Viruses are composed of _______and
____________;
host cell in order to replicate.
require a ______
 Hershey & Chase recognized that virus must inject its
genetic material into the bacterial cell for replication to
take place.
isotopes
 Used labeled ________ to determine whether DNA or
protein was injected into bacterium.
 Hershey & Chase concluded that the genetic material of
DNA
the bacteriophage was ________________.
Hershey and Chase’s Experiment
D. Watson & Crick
(1953)
 Used molecular models to solve the 3dimensional structure of DNA
 “Borrowed” an x-ray of DNA taken by
Rosalind Franklin to solve the puzzle
________________
Double Helix
 Proposed a ______________
structure with a
deoxyribose
backbone of alternating ________________
and
phosphate
Nitrogen bases
______________with
____________________
paired in the middle
Rosalind
Franklin
Died at age 37 from cancer,
probably caused by all her
exposure to radiation from
the x-ray diffraction technique.
Did not receive the Nobel
Prize.
Watson and Crick (Won Nobel Prize)
Facts I would want to know!
II. STRUCTURE OF DNA
Slide 51
Deoxyribonucleic acidis a ________
Nucleic acid made up
______________
nucleotide monomers. Each DNA
of _________
nucleotide is composed of:
_______
Deoxyribose (5-carbon sugar)
_________________________
Phosphate group
_________________________
Nitrogen Base
_________________________
Structure of DNA
covalent bonds hold the
 Strong, stable ________
components of each nucleotide together.
covalent
 In addition, nucleotides form strong __________
bonds with other nucleotides, resulting in a long
strand of nucleotides.
hydrogen bonding
 Double helix created by ________
Nitrogen bases
between ________________________
 The diameter of DNA is uniform due to specific
pairing of nitrogen bases
Structure of DNA
Purines – double-ringed nitrogen bases
guanine
____________
adenine
____________
Pyrimidines - single-ringed nitrogen bases
cytosine
___________
thymine
___________
(And Uracil)
Purines and Pyrimidines
Purines
__________
always base pairs with a
pyrimidine
____________,
specifically …
thymine
Adenine
_______________
base pairs with ______________
cytosine
Guanine
_______________
base pairs with ______________
Structure of DNA
Watson
Crick
________
and ________
determined this
diameter
structurally because the ___________
of DNA
is uniform.
Chargaff
___________
determined this chemically. His
chemical analysis of DNA from many different
organisms always showed that the % of
thymineand the % of guanine
adenine = % ________
cytosine
= the % _________.
These findings are
Chargaff’s rules
known as ______________.
Structure of DNA
The two strands of nucleotides are
Anti-parallel that is, they run opposite to
__________;
each other.
Pattern and _______
number of
It is the _______
nucleotides that makes each gene unique.
Deoxyribonucleic Acid
adenine
covalent bond
cytosine
deoxyribose
guanine
hydrogen bond
nitrogen bases
nucleotide
phosphate group
purines
pyrimidines
thymine
5’ end
3’ end
III. DNA REPLICATION
(pp. 295-299)
Cell division
 Prior to ___________,
the DNA must
__________________.
replicate
This occurs in __
S of
interphase
_____________________.
 During this part of the cell cycle, DNA is in the
chromatin
form of ______________.
DNA can replicate
Chargaff’s base pairing rules
itself exactly due to _____________________.
nucleus
Replication occurs in the _________
of the cell
and requires the participation of
enzymes
 several _____________________.
Replication may be summarized in the following steps:
Helicase
 DNA is “unzipped” by the enzyme, __________.
hydrogen
Helicase breaks the ______________________
Nitrogen bases
bonds between the _____________________.
The point where the unzipping begins is known
Origin of replication
as the ____________________________.
The
continuation of the unzipping is called the
Replication fork
_________________________________.
This
occurs in several places in each
chromosome
__________________,
much like a
Broken zipper
__________________________________.
DNA Replication
Single stranded binding proteins
_________________________________
hold the separated DNA strands apart.
topoisomerase
Another enzyme, ___________________
helicase
moves ahead of the _________________
to relieve tension in the double helix as it
is being unzipped.
Topoisomerase
DNA Replication
DNA polymerase
 The enzyme, ________________ adds nucleotides to
both sides of the DNA molecule according to
Base-pairing rules
_________________________
rules; however, DNA
polymerase has two restrictions:
5’ – 3’
 It can only add nucleotides in a __________
direction.
 It can only add nucleotides to an existing strand.
 Before DNA polymerase begins moving in nucleotides,
RNA
Primer
an __________
________________
must be put in
place. Eventually this primer is removed and replaced
with DNA nucleotides.
DNA Replication
 The two sides of the DNA molecule are
replicated differently because nucleotides can
5’ – 3’ direction:
only be added in a ______
One side of the DNA molecule is being replicated in the
Replication fork
same direction as the __________________________.
leading
This is known as the _______________________
strand. Nucleotides are moved in by
DNA polymerase
5’ – 3’
_____________________
in a _______________
direction as the DNA is unzipped.
Okazaki Fragments
 On the other side of the DNA molecule, nucleotides are added
away
________________
from the replication fork. This is known as
Lagging
the _____________________
strand. Short segments of
nucleotides are synthesized, each with a new
RNA primer
_____________________,
as the DNA is unzipped. These short
Okazaki ________.
fragments
segments are known as ________________
ligase
Eventually, another enzyme known as __________________
Okazaki
“glues” together the _____________
fragments to create a
continuous strand of nucleotides.
DNA polymerase
 Another type of _________________
proofreads the
mutation
replicated DNA to minimize the chance of ___________.
Okazaki Fragment
Replication Fork
DNA Replication
identical
 The result is two ____________DNA
molecules,
each new DNA consists of one
original
_________________
strand and one
new strand. This is known as the
________
________________
Semi-conservative model of replication.
 These two identical DNA molecules are the
Sister chromatids
____________________
that proceed through
mitosis
______.
 Once replication has been completed, the cell
G2 and then, ________________
prophase
moves into ___
of
mitosis
________________.