aim: why and how do cells divide. dn: compare and contrast sexual and asexual reproduction. hw:...
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AIM: Why and how do cells divide.
DN: Compare and Contrast Sexual and Asexual Reproduction.
HW: Castle Learning due Monday
Compare the size of these organisms
Vs.
Vs.
Do these organisms have different size cells?
No How do organisms get so big?
CellDivision
Why do cells divide rather than grow in size?
XXXX
XXXX
XXXX
XXXX
XXXX+
DNA “Overload”
DNA Library
Small Town
City
Nucleus (DNA) loses control over the Cell as it grows larger!!
Exchange of Materials
Cell Membrane
4 small cells have more surface area than 1 big cell•More cell membrane – less cytoplasm
Surface area
Rate of Exchange Increases
Surface AreaSmall particles have a relatively larger surface
area than large particles.
What will melt first?
Ice Cube Ice Chips
Vs.
Why?The smaller chips have more surfacearea.
Smaller cells have more surface area and can exchange materials across membrane more efficiently.
What is Cell Division?
One cell divides into 2 new daughter cells
Size?
What happens to the chromosomes before a cell divides?
They need to replicate
• What does replication mean?
• To make an exact copy of the chromosome.
Chromosomes Replicate before the cell divides
1 Chromosome
2 Chromatids
Centromere
When do cells divide?
Organism Growth
What tissues in our body needto undergo a lot of cell division?
Skin Stomach
Bone Why?
y?
What is Mitosis?
Mitosis is the process that divides the cell’s nucleus into two, each with a complete set of genetic material from the parent’s cell
What are the phases of the Cell Cycle?
Centriole
Interphase
Stages of Mitosis:
Prophase:
1)The chromosomes becomevi sible.
2)The centrioles separate and Spindle fibers begin to form.
3)The nuclear membrane breaks down.
Centriole
Spindle FibersNuclear
Membrane
Stages of Mitosis:
Metaphase:
1)The chromosomes line up across the center of the cell.
2)Each chromosome is connected to a spindle fiber at the centromere.
Stages of Mitosis:Anaphase:
1)The spindle fibers separate
the chromatids into individual
chromosomes and are they
are moved apart.
Stages of Mitosis:Telophase:
1)The chromosomes gather at opposite
ends of the cell.
2) Two new nuclear membranes form.
3)The chromosomes lose their distinctshapes.
Cytokinesis:
The cytoplasm pinches and two cells are formed.
What is the end result of Mitosis?
46X 46X + 46X
Chromosome Number?
Parent Daughter Cell Daughter Cell
Is the genetic material of the daughter cells identical to the parent?
The same number ofchromosomes is maintainedfrom one generation to thenext.
YES
Mitosis Phases
Prophase Metaphase Anaphase
TelophaseCytokinesis
Plant Cells vs. Animal Cells
Which are plant cells and which are animal cells?
Cell Wall
Animal CellsPlant Cells
Plant Cell vs. Animal Cell Mitosis
In plants, a Cell Plate forms across the middle of the cell.
In an animal cell, the cytoplasm pinches off.
What process is this?
CytokinesisHow is plant cytokinesis different than animal cell cytokinesis?
Which phase are these cells in?
Prophase Anaphase
What phase are these cells in?
Metaphase
Telophase