unit 7: cell division big idea: cell division is the process in the body to create more cells and...
TRANSCRIPT
UNIT 7: Cell Division
BIG IDEA: Cell division is the process in the body to create
more cells and gametes
MITOSIS
Asexual Reproduction
Reproduction with only one parent
offspring are identical to parents
Sexual Reproduction
Requires 2 parentsNew individual is produced by
the union of the nuclei of two specialized cells (sperm & egg)
Chromosome Structure
Inside your nucleus are 3 billion nucleotides of DNA
In order to fit it is coiled and packed into a complicated but organized structure
Chromosome Structure
Histones-Proteins that DNA are wrapped around
Chromosome Structure
Chromatin-Less tightly coiled DNA wrapped around a histone
Chromatid
Chromosome
Chromosomes
Rod shaped structures made up of DNA and histones
Two identical halves are called chromatids Point holding together the chromatids is
called a centromere
Chromosomes
Structure in cells that undergo division and that contain hereditary information of the organism
In mitosis the chromosomes that undergo cellular division are called autosomes
Chromosomes
Draw a chromosome and label the centromere and the chromatids centromere
chromatid
How many chromosomes are present in an autosomal cell?
23 pairs or 46 chromosomes
Refers to DIPLOID: meaning that a cell possesses 2 complete sets of chromosomes
Why are there two sets of chromosomes?
– 1 set is from your mother and 1 set is from your father
– This leads to genetic variation because genetic information on chromosomes from your parents can be different Example: both chromosomes can code for eye color
except one can be for blue eyes and one for green eyes
Blonde Hair Black Hair
Genetic Variation
Why is genetic variation beneficial?
Causes a diverse collection of genes
Increase in survival
CELL CYCLE
Cycle that a cell goes through in order to make new cells
If an organism is unicelluar, than a new organism is created via the cell cycle
Cell Cycle Consists of Two Parts:
Mitosis:– Division of the
nucleus to form two identical nuclei
– REMEMBER: Hereditary material is found in the nucleus
Cytokinesis–Division of the
cytoplasm of the cell after mitosis
INTERPHASE
Interphase
Stage when a cell is between mitotic cycles:
A. G1- cell grows
B. S- DNA replication
C. G2- Organelle replication
MITOSIS
Prophase
Chromosome become visible
Centrioles move to opposite poles of the cells
Microtubules form spindles
Spindle fibers become attached to centromeres
Nuclear membrane disappears
Nucleolus disappears
Prophase:
Metaphase
Chromosomes attach to the microtubule spindles
Chromosomes line up on the equator of the cell
Anaphase
Centromeres double
Chromosomes(sister chromatids) move to opposite poles
Division (cleavage furrow) appears
Telophase
Begins when chromosomes reach the poles
Chromosome uncoil and become invisible
Spindle disappearsNuclear membrane formsNucleioli reappears
Telophase
Cytokinesis in Animal Cells
Begins during late anaphase
Cytoplasm is pinched off by cell membrane
Mitosis & Cytokinesis in Plant Cells
Main events are the same Plants do not have centrioles or
asters Cytokinesis cannot occur by
pinching off of membrane a cell plate forms between the new cells during anaphase or telophase
Cytokinesis
End with two identical daughter cells
Cells that divide rapidly
Plants Animals
Cells that seldom or never divide
Xylem (part of a plant)
Nerve Cells Muscle Cells