BINARY FISSION & THE CELL
CYCLE (INTERPHASE – MITOSIS –
CYTOKINESIS)

Vocab you should know…
 Cellular reproduction: the way that cells reproduce
 Asexual reproduction: reproduction that does not involve the union of gametes; where one parent produces offspring that are genetically identical to it
 Sexual reproduction: reproduction where gametes from two parents unite to form offspring

More vocab…
 Binary fission: division of a prokaryotic cell into two offspring cells
 Mitosis: period of nuclear cell division in which two daughter cells are formed, each containing a complete set of chromosomes
 Interphase: cell growth phase where a cell increases in size, carries on metabolism, and duplicates chromosomes prior to division

More vocab…
 Prophase: 1 st & longest phase of mitosis where chromatin coils into visible chromosomes
 Chromatin: long, tangles strands of DNA found in the eukaryotic cell nucleus during interphase
 Chromosomes: cell structures that carry the genetic material that is copied & passed from generation to generation of cells

More vocab…



Metaphase: short second phase of mitosis where doubled chromosomes move to the equator of the spindle & chromatids are attached by centromeres to a separate spindle fiber
Chromatids: one of the two strands of a chromosome that become visible during meiosis or mitosis
Centromeres: region of the chromosome that holds the two sister chromatids together during mitosis

More vocab…
 Anaphase: phase of mitosis where centromeres split and the chromatid pairs of each chromosome are pulled apart by microbtubules
 Microtubules: thin, hollow cylinders made of protein that provide structural support for eukaryotic cells

More vocab…
 Telophase: final phase of mitosis during which nuclear membranes form around each new set of chromosomes
 Haploid: cell with one of each kind of chromosome (n)
 Diploid: cell with two of each kind of chromosome (2n)

More vocab…
 Cytokinesis: cell process following mitosis in which the cell’s cytoplasm divides & separates into two new daughter cells
 Cell plate: precursor of a new plant cell wall that forms during cell division
& divides the cell into two

CELLULAR
REPRODUCTION - BASICS
 Two basic types:
 Asexual
 Sexual

Prokaryotic Reproduction
 Binary fission

It’s a form of asexual reproduction
 Most prokaryotic cells reproduce this way

Binary Fission

Eukaryotic Cell Reproduction:
The Cell Cycle
 Cell cycle: repeating set of events in the life of a cell, made of 3 phases
 Interphase: time between cell divisions, duplication of DNA & cell parts
 Mitosis: reproduction & division of nucleus
 Cytokinesis: division of cytoplasm & formation of new cells
 Cell Cycle Simulation

INTERPHASE


Longest phase of cell division; divided into 3 phases; After cell division: offspring cells are about ½ the size of the parent cells
G1 phase: cell growth – offspring cells grow to adult size
 S phase: DNA is copied
 G2 phase: cell growth & preparation for division
 Kangaroo rat interphase

Interphase
 Interphase: organelles double in #, DNA replicates, protein synthesis occurs, chromosomes are not visible b/c DNA appears as uncoiled chromatin.

MITOSIS
 Divided into 4 different phases
 Follows interphase
 Is followed by cytokinesis

Mitosis: Prophase, step 1
 Nuclear membrane & nucleolus disappear; chromatin condenses & chromosomes become visible as chromatids; sister chromatids pair up; spindle fibers are assembled.
 Kangaroo rat prophase

Mitosis: Metaphase, step 2
 Sister chromatid pairs line up along the cell's equator; spindle fiber attach to the centromeres holding them together.
 Kangaroo rat metaphase

Mitosis: Anaphase, step 3
 Sister chromatids split apart at the centromere as the spindle fibers shorten and “pull” them toward opposite poles; cleavage furrow appears.
 Kangaroo rat anaphase

Mitosis: Telophase, step 4
 nuclear membrane & nucleoli reform, cleavage furrow deepens; spindle fibers disappear; chromatids uncoil to chromatin.
Kangaroo rat telophase

Cytokinesis; last phase of cell cycle
 Follows mitosis;
 dividing cell separates into 2 diploid daughter cells
 Different in animal and plant cells

Cytokinesis in animal cells
 animal cells lack a cell wall and are surrounded only by a plasma membrane
 Cleavage furrow deepens until the two furrows meet & pinch apart the cytoplasm creating two separate cells
 Cytokinesis real time
 Kangaroo rat cytokinesis

Cytokinesis in Animal Cells

Cytokinesis in plant cells
 plant cells are surrounded by a cell wall in addition to the plasma membrane
 A cell plate is formed along the equator of the cell & separates the cytoplasm into two daughter cells.

Cytokinesis in plant cells

Cellular Reproduction Quiz
1.
2.
3.
What are the two basic types of cellular reproduction?
Binary fission is a type of _________ reproduction.
What are the 3 phases of the cell cycle in eukaryotic reproduction?

Quiz Cont’d
5.
6.
4.
7.
What happens to the DNA during interphase?
What are the 4 phases of mitosis?
During what phases of mitosis do the duplicated chromosomes line up at the equator?
During which phases do the sister chromatids move towards opposite poles?

Quiz Cont’d
8.
9.
During which phase does the nuclear membrane reform?
How many cells are there at the end of cytokinesis?
10.
What is different in plant cell cytokinesis than in animal cell cytokinesis?