Download 16-17 Mitosis Activity intro

Mitosis Activity intro
Interphase
• Divided into 3 phases:
• G1 = 1st Gap (Growth)
• cell doing its “everyday job”
• cell grows
• S = DNA Synthesis
• copies chromosomes
• G2 = 2nd Gap (Growth)
• prepares for division
• cell grows (more)
• produces organelles,
proteins, membranes
G0
green = key features
Interphase
• Nucleus well-defined
• DNA loosely packed in long
chromatin fibers
• Prepares for mitosis
• replicates chromosome
• DNA & proteins
• produces proteins &
organelles
S phase: Copying / Replicating DNA
• Synthesis phase of Interphase
• dividing cell replicates DNA
• must separate DNA copies correctly to 2
daughter cells
• human cell duplicates ~3 meters DNA
• each daughter cell gets complete
identical copy
• error rate = ~1 per 100 million bases
• 3 billion base pairs in mammalian genome
• ~30 errors per cell cycle
• mutations (to somatic (body) cells)
ACTGGTCAGGCAATGTC
Organizing DNA
•DNA is organized in
chromosomes
DNA
histones
chromatin
double stranded chromosome
duplicated mitotic chromosome
• GENOME=
cell’s genetic
information
Prokaryotes genome – single
circular loop of DNA
Eukaryotes - several DNA
molecules in multiple
chromosome bundles
• Every eukaryotic
species has
characteristic number
of chromosomes in
each cell nucleus
~Human SOMATIC
cells (body cells) have
46 chromosomes (two
sets of 23; one from
each parent).
~Human GAMETES (sperm or eggs) have one set (23
chromosomes); ½ number in somatic cells
- made of CHROMATIN (DNA + associated proteins)
PROTEINS maintain shape and control gene activity
- one long, linear DNA made up of 100’s-1000’s of genes
- spread out as CHROMATIN in NONDIVIDING cells; allows access to
info
- condensed as CHROMOSOMES in DIVIDING cells; allows easier
transport
Duplicated chromosomes made up of:
-TWO IDENTICAL SISTER CHROMATID ARMS
- TELOMERES-region at ends of arms; prevent degradation
- Region where chromatids are most closely attached = CENTROMERE
- KINETOCHORES-proteins in centromere region where microtubules attach
- Once chromatids separate in anaphase ~ considered individual
chromosomes
Duplicated chromosomes made up of:
-TWO IDENTICAL SISTER CHROMATID ARMS
- TELOMERES-region at ends of arms; prevent
degradation
- Region where chromatids are most closely
attached = CENTROMERE
- KINETOCHORES-proteins in centromere region
where microtubules attach
- Once chromatids separate in anaphase ~
considered individual chromosomes
homologous = “same information”
Chromosome with 1
chromatid
Chromosomes have this
structure before and after
mitosis
One chromosome after
replication.
Replicated Chromosomes
have 2 identical sister
chromatids per
chromosome.
Homologous Pair of
Chromosomes
Overview of cell cycle
interphase
prophase
I.P.M.A.T.
Twilight Mitosis Clip
(pro-metaphase)
cytokinesis
metaphase
anaphase
telophase
Mitosis in whitefish blastula
Mitosis in plant cell
onion root tip
double-stranded mitotic human
chromosomes
• After DNA duplication, chromatin condenses
• coiling & folding to make a smaller package
Copying DNA & packaging it…
mitotic chromosome
DNA
chromatin