Transcript Cell Division

CHROMOSOMES
• Chromosome-before
a cell divides it copies
all the DNA
(replication) and then
coils it into
Chromosomes
CHROMATIDS
• CHROATIDS- One
side of the
chromosome. Each
side is the same.
• (One of the copies of
the DNA)
CENTROMERE
• CENTROMEREPoint where the two
chromatids are
attached to each
other.
HUMANS HAVE 23 PAIRS OF
CHROMOSOMES
KARYOTYPE- A PICTURE OF A HUMANS
CHROMOSOMES ARANGED BY SIZE.
These are used to test for Chromosomal
Disorders in Unborn Babies.
TWO TYPES OF
CHROMOSOMES
• THE FIRST 22 ARE CALLED
AUTOSOMES WHICH ARE THE SAME
FOR BOTH MALES AND FEMALES
• THE LAST PAIR ARE CALLED SEX
CHROMOSOMES AND THEY
DETERMINE GENDER
• XY= MALE
XX= FEMALE
Down
syndrome
(extra 21st)
Cri du chat (Missing
piece of 5th
Chromosome)
Trisome X
(Extra X Chromosome)
Digeorge Syndrome (Missing piece of
22ndchromosome)
DNA REPLICATION
- TAKES PLACE DURING “S” PHASE OF THE CELL CYCLE
3 STEPS
1. ENZYMES “DNA HELICASE” BREAKS HYDROGEN
BONDS TO “UNZIP” THE DNA.
STEP 2ENZYME “DNA POLYMERASE” MOVES ALONG
THE REPLICATION FORKS ADDING NITROGEN BASES
(A,C,T,G)
STEP 3
TWO COMPLETE DNA STRANDS ARE
FORMED. EACH STRAND IS IDENTICAL
The replication process usually takes place
on many segments of the DNA at the same
time. This speeds up the process.
http://www.youtube.com/watch?
v=teV62zrm2P0
http://www.youtube.com/watch?
v=cDlKrLJjRlY&feature=related
INTERPHASE
G1=Growth Phase 1,
Normal cell function
S=Synthesis Phase,
Copy the DNA
G2=Growth Phase 2,
Compress DNA into
Chromosomes,
prepare for cell
division.
MITOSIS
• P= Prophase,
Chromosomes
become visible and
nuclear envelope
breaks down
• M=Metaphase,
Chromosomes line
up in the middle
• A= Anaphase,
Chromosomes get
pulled apart
• cells
Mitosis Continued
• T= Telophase,
Chromosomes bunch
at the poles of the cell
and it begins to split
• Cytokinesis- Two new
daughter cells are
formed and new
cytoplasm is formed
to make two adult
Interphase
• Can be broken into
G1, S and G2
Prophase
• Chromosomes are
formed
• The nuclear envelope
breaks down
Metaphase
• Chromosomes line up
along the “equator” of
the cell
Anaphase
• Chromatids are pulled
apart by the spindle
fibers and move
toward the poles of
the cell.
Telophase
• Chromosomes reach
the poles and the cell
builds a cell
membrane/wall down
the middle of the cell
Cytokinesis
New daughter cells
replace organelles
and grow into new
adult cells which
return to Interphase