Transcript The Cell Cycle - HomeworkNOW.com

The Cell
Cycle
Brought to you by:
Today’s Lesson
Is brought to you by the letter
And the numbers
C
23 and 46
Important Vocabulary
• Chromatin: Long, tangled strands of DNA found
in the cell nucleus during Interphase
• Chromosomes: Structures that carry the genetic
material that is copied and passed from generation
to generation of cells. Humans have 23 pairs of
chromosomes; 46 total chromosomes
• Chromatids: Chromosomes duplicate during S
phase and are attached by a centromere. The two
copies are called chromatids.
Chromatids & Centromere
Vocab. Continued . . .
• Centromere: Cell structure that joins the two
chromatids.
• Homologous Chromosomes: Paired
chromosomes with genes for the same traits,
structure and function. Humans have 23
Homologous Chromosomes.
• Parent Cell: Original cell in interphase, before
division occurs.
• Daughter Cell: Cells produced from parent cell
at the end of the cell cycle.
Cell Cycle
• Made up of 3 Phases
– Interphase
– Mitosis
– Cytokenesis
Interphase
•
•
•
•
Cell spends 90% of its lifetime in interphase
G1 phase: cell grows
S phase: DNA (chromosomes) replicate
G2 phase: cell prepares to divide
Mitosis
• Occurs AFTER interphase is finished
• Consists of 4 phases:
–
–
–
–
Prophase
Metaphase
Anaphase
Telophase
Prophase
• Early – chromatin coil up
and become chromosomes.
Each crhomosomes is made
up of 2 identical parts called
chromatids joined by a
centromere
• Mid – nuclear envelope
begins to disappear
• Late – nuclear envelope
gone and centrioles move
towards poles as spindles
form.
Metaphase
• Early – centrioles at
poles and spindle fibers
attach to centromeres of
chromosomes
• Mid – chromosomes in
the process of lining up
along the equator of the
cell
• Late – chromosomes
lined up along equator of
cell.
Anaphase
• Early – Centromeres
split apart as spindles
bring chromatid pairs
towards opposite poles
• Mid – chromatids
moving closer to
opposite poles
• Late – chromatids at
opposite poles
Telophase
• Early – Nuclear
envelope begins to
form
• Late – 2 distinct
daughter cells are
formed
Can you guess what
my favorite phase is?
Telly – phase!
Cytokenesis
• Cytoplasm divides
• IN PLANTS: cell plate forms between cells,
cell membrane forms around each side of
cell plate, and cell wall forms around
membrane
• IN ANIMALS: cell membrane pinches off
between old and new cell, creating 2
separate cells
Let’s count how many
daughter cells come from
1 parent cell!
1. . . . 2. . . . . 2 daughter
cells!