Unit 5 Part B Cell Growth, Division and...
Transcript of Unit 5 Part B Cell Growth, Division and...
Unit 5 Part BCell Growth, Division
and Reproduction
Cell Size Are whale cells the same size
as sea stars cells?
Yes!
Cell Size Limitations• Cells that are too big will have difficulty diffusing
materials through the cell.
- Nutrients, water, and air must enter cell at an efficient rate and cells need to remove wastesfrom the cell quickly or else they will build up toxins
• Cytoskeleton cannot support the cell organelles
• Cellular communication decreases and is less efficient
• DNA will a limit a cell’s size
– If cell is too big then DNA cannot make enough proteins to support the cell
It takes moretime for the nutrients to reach the
center of this cell
Large Cell
It takes lesstime for the same nutrients to reach the center of this cell
Smaller cell
Cellular GrowthCopyright © McGraw-Hill Education
Cell Size Limitations
Ratio of surface area to volume
Works
Better
How do cells solve this problem?
As cell size increases too much- it can
lead to death of a cell.
It is important for cells to stay small so
it can function properly by
transporting materials in & out faster.
ANSWER: Cells divide before they
get too big!
CELL CYCLEIS THE SERIES OF EVENTS THAT TAKE PLACE IN A CELLLEADING TO ITS DIVISION AND DUPLICATION(REPLICATION) THAT PRODUCES TWO DAUGHTER CELLS.
G0
The Cell Cycle
Eukaryotic cells divide via
the cell cycle.
Prokaryotic cells divide via
binary fission.
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Cell Division in Prokaryotes (No Nucleus)
Cell Division in Prokaryotes
Prokaryotes such as bacteria divide by theasexual process of binary fission
Parent cell
2 identical daughter cells
Chromosome doubles
Cell splits
Binary Fission
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Advantages for prokaryotes:
• Only requires a single organism to start
• Reproduce quickly and increase in population.
• Less energy usage
Disadvantages:
• All new cells are clones (identical) so the only
source of genetic variation is mutation
The Cell Cycle Process by which a cell
grows and divides toproduce IDENTICAL newcells
All cells go through cell division.
Cells divide before they become too big
Average cycle for a cell is 22 hours.
Cells grow and divide
SO that YOU can grow and reproduce
Human life
cycle
includes
is divided into is divided into
What are the TWO main phases of the cell cycle?
Cell Cycle
MitosisInterphase
G1 phase S phase ProphaseG2 phase Metaphase TelophaseAnaphase
G0 phase
Interphase: LONGEST (90%) phase of the cell cycle (G1 , G0 , S, G2 Phase)
Interphase: G1
1st growth
cell increases size
carries out normal life
activities
Ribosomes makes
proteins
Cell Cycle Phases: G0 G O Phase
Resting phase
No division
Some cells never
leave G O phase
ex. Nerve cells (once it’s
gone- it’s gone)
Some cells never
enter G O phase
ex. Skin cells
(constantly renewed)
G0
Interphase: S – DNA Synthesis
DNA Replication – process
by which DNA is copied
to make 2 identical DNA
molecules.
Double the amount of
chromosomes in cell(you must give new cells a copy of ALL the
instructions)
Interphase: G2G2 phase:
The 2nd growth
Cell prepares to divide
(mitosis)
cell’s organelles are
reproducedex. Mitochondria, vacuole, golgi,
chloroplast
Needed proteins are
produced to build.
Not a part of Interphase
Mitosis –Division of Cell Nucleus
Cytokinesis- Division on the Cytoplasm (2 new cells)
WHERE HAVE SCIENTISTS BEEN?A BRIEF HISTORY
Oswald Avery (1944) Discovered that the
nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next
ERWIN CHARGAFF (1950)
Discovered a relationship in the nitrogenous bases
Adenine (A) = Thymine (T)
Guanine (G) = Cytosine (C)
ALFRED HERSHEY & MARTHA CHASE (1952)
Concluded that the genetic material of the bacteriophage was DNA, not protein.
Used radioactive phosphorous and sulfur.
ROSALIND FRANKLIN (1952)
Took an x-ray of the DNA structure so the patterns could be seen.
The x-rays show that DNA is twisted around each other like a helix and has two strands.
(1953)Watson and Crick proposed that DNA is made up of 2 chains of nucleotides held together
by nitrogenous bases & that the 2 strands are twisted together in a shape called a double helix.
Deoxyribonucleic Acid (DNA)
Words related to DNA:
Nucleic Acids
Chromosome
Chromatin
Chromosomal
Genetic material
Hereditary information
Genes
Alleles
Function of DNA:The master copy of an organism’s information
code that contains the instructions (blueprint) used to make proteins
Determines how an organism looks and acts(traits)
Protein
Coiled (twisted) DNA
Gene
Trait
DNA StructureA gene is a section of DNA that codes for a
protein.
Each unique gene has a unique sequence of bases.
This unique sequence of bases will code for the production of a unique protein.
It is these proteins and combination of proteins that give us different physical traits .
DNA StructureDeoxyriboNucleic Acid
The DNA shape looks like a twisted ladder and is called a Double Helix.
DNA is a polymer made up of millions of tiny monomers (subunits) called nucleotides.
Each nucleotide has 3 parts:1. Phosphate group2. Deoxyribose sugar3. 1 of 4 Nitrogenous bases
Draw and Label a nucleotide.
Phosphate
DeoxyriboseSugar
NitrogenousBase
Nucleotides
The phosphate (P) and deoxyribose sugar (S) form the outside of the DNA molecule.
S P S P S P S P S P S P S P S P S P S
P S P S P S P S P S P S P S P S P S P S
N N N N N N N N N N
Nucleotides
The nitrogenous bases form the inside of the DNA molecule.
There are four types of nitrogenous bases.
S P S P S P S P S P S P S P S P S P S
P S P S P S P S P S P S P S P S P S P S
N N N N N N N N N N
Nucleotides
A
Adenine (Purine)
T
Thymine (Pyrimidine)
G
Guanine(Purine)
C
Cytosine(Pyrimidine)
Nucleotides Each base will only bond with one other specific
base held together with hydrogen bonds.
Adenine (A)
Thymine (T)
A = T
Cytosine (C)
Guanine (G)
C = G
Form a base pair.
Form a base pair.
If there are 5 A’s, how many T’s are
there?___________5
If there are 82 G’s, how many C’s
are there?________82
Because of the
hydrogen bonds,
Adenine can only
bond with Thymine
& Guanine can only
bond with Cytosine
*A purine is always paired with a
pyrimidine.
Thymine
Adenine
Cytosine
Guanine
This is known as
COMPLEMENTARY base pairing
G
G
A
T
T
A
A
C
T
G
C
A
T
C
DNA StructureBecause of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.
A G G - C T C - A A G - T C C - T A G
T C C - G A G - T T C - A G G - A T C
DNA VIDEO: what is it and how does it work
DNA Replication (to copy) DNA has to be copied before new
cells can be made in cell division.
DNA Replication happens during the S phase or synthesis phase of the cell cycle
All new cells have to
be given a complete
set of DNA instructions!
Without replication, new cells would NOT have a complete set of DNA instructions & the organism would not function.
DNA ReplicationReplication is semi-conservative (one strand
is old, one strand new)
This is to help prevent mistakes (mutations) in DNA.
Think* You want to copy of Mickey Mouse. Is it easier to draw or trace?
Semi-Conservative= Tracing!
General Process of DNA ReplicationStep 1: Separation of strands.
DNA has to unwind and unzip.
DNA separates in the middle (weak hydrogen bonds).
Helicase is the enzyme speeds the breaking of hydrogen bonds.
Step 2: Base pairing & Bonding of bases
The free floating bases in the cytoplasm will attach to bases to the exposed DNA.
Step 2: Base pairing & bonding
Remember bases bond A=T , C=G.
Free nucleotides continue to pair up until the entire double strand of DNA has been copied
DNA polymerase is the enzyme that builds and joins the nucleotides
DNA is made out of an original strand with a new strand. This is called semi-conservative.
Step 3: Results of replication.
Replication produces 2 IDENTICAL molecules
of DNA. The polymers will twist back up. Now
new daughter cells can be made!
Whew- end of S phase
BACK TO THE CELL CYCLE!!!
Mitosis and Cytokinesis
Mitosis OverviewShortest phase of Cell Cycle
A eukaryotic cell divides to produce two daughter cells that are genetically identical to the parent cell.
Daughter cells have the SAME number of chromosomes as the parent cell
Parent cell
Mitosis – is divided into 4 phases
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
Prophase PREPARE
Centrioles move to the opposite sides
Spindle fibers form
Visible chromatids (DNA)
Nuclear envelope breaks down
Sister Chromatids are held
together by a Centromere
Metaphase MIDDLE
The sister chromatids line up across the
MIDDLE (equator) of the cell
*no more nucleus
Sister chromatids is connected to a spindle
fiber at its centromere.
Anaphase AWAY
Sister chromatids separate and move
AWAY from each other.
What happens if the chromatids break? Mutations!
Telophase TWO
The chromosomes move to opposite sides of
the cell .
Two new nuclear membranes will form
around the sets of chromosomes.
*nucleus reforms in each cell
MITOSIS IS OVER!*remember only PMAT for mitosis
M-Phase continues with CYTOKINESIS
Cytokinesis CUT
Cell membrane CUTS
inward to create 2 cells
Each cell has its own
nucleus with identical
chromosomes
CYTOKINESIS IN PLANT CELLS
Cell plate forms prior to the cell wall
appearing
MitosisLet's watch the whole process now.
Source: http://highered.mcgraw-hill.com/olc/dl/120073/bio14.swf
*many of these stages overlap when occurring –
constant process
Identify the different stages of the cell cycle:
I Passed My Algebra Test Corrections
•Interphase
•Prophase
•Metaphase
•Anaphase
•Telophase
•Cytokinesis
(Two Identical Daughter Cells)
(New Cell)
PUT in ALL together: Cell Cycle
MITOSIS (ASEXUAL) Video- stop at 4:03
Parent Cell has 4 chromosomes
Chromosomes replicate = 8
chromosomes
Cell divides producing 2 identical
daughter cells each with
4 chromosomes
EUKARYOTIC REPRODUCTIONMITOSIS (ASEXUAL)
If the Parent Cell has 16
chromosomes instead of 4
How many chromosomes would
you have after replication?
How many chromosomes would
each Daughter Cell have?
32 chromosomes
16 chromosomes
CELL CYCLE: WHAT STAGE OF INTERPHASE IS A?WHAT STAGE IS B?
Video Review Amoeba sisters: Mitosis
Regulating the Cell Cycle
Cell growth and cell division are carefully
controlled inside an organism.
Most nerve and muscle cells do not divide once
they have developed (G0 phase)
Cells that make blood, skin, and hair divide
rapidly throughout life
Regulating the Cell CycleCell division is controlled by:
Cyclins regulates timing of cell division
Regulator Proteins including growth factors
Apoptosis: when a cell is programmed to die
What happens if cell division is NOT regulated???
Cell Cycle Disorder: CANCER Cancer - the uncontrolled division (mitosis) of
cells (cells can’t stop making more cells; divides
rapidly)
Due to mutation in DNA
Cells lose the ability to control their growth rate
Cells no longer respond to signals that regulate
growth of most cells.
Cell Cycle Disorder: CANCER Cancer cells form masses of cells called tumors and
cause damage to other cells and tissues
a. Benign tumor: does not spread to surrounding
healthy tissue
b. Malignant tumor: invade and destroy other tissue
(*move)
Tumor in liver
Causes of Cancer
• Surgery
• Radiation
• Chemotherapy
Treatment of Cancer
• Smoking
• Radiation exposure
• Defective genes
• Viral infections
Cell cycle and Cancer Amoeba SISTERS: Cell Cycle and Cancer