website/email
http://mscwan.wordpress.com
mscwan2@gmail.com
1
TEST: Tues. February 7th
• identifying organelles and their functions
• DNA structure (nucleotide base pairing)
• protein synthesis (only at depth of textbook)
• types of mutations (addition, deletion,
substitution; positive, negative, neutral)
• causes of mutations (mutagens)
• how gene therapy works
2
TEST: Tues. February 7th
• Questions?
3
recap
• mutagens cause mutations in DNA
• mutations = change in genetic
sequence  proteins not made
properly
4
recap
• positive = beneficial to survival
• negative = detrimental to survival
• neutral = no effect on survival
5
recap
• addition = insertion of an extra base
• TACTGC  TACCTGC
• deletion = removal of a base
• TACTGC  TACTC
• substitution = switching of a base
• TACTGC  TAATGC
6
recap
• gene therapy is a highly experimental
procedure to correct mutations
• insertion of healthy gene into cold
virus, which carries the gene to target
cells
• cell must activate healthy gene to
synthesize correct amounts of the
healthy protein
7
mitosis & cancer
30 January 2012
8
9
question
• How does each cell in the body get a
complete set of DNA when a cell
divides?
10
which stage?
• longest stage of the cell cycle
interphase
11
which stage?
• spindle fibres pull chromosomes into a
line
metaphase
12
which stage?
• nuclear membrane breaks down
prophase
13
which stage?
• spindle fibres contract and shorten
anaphase
14
which stage?
• condensation of chromatin into visible
chromosomes
prophase
15
which stage?
• individual chromosomes not visible
interphase
16
which stage?
• nucleolus disappears
prophase
17
which stage?
• growth and DNA replication occurs
interphase
18
which stage?
• spindle forms
prophase
19
which stage?
• nuclear membranes start to re-form
telophase
20
which stage?
• spindle attaches to centromere
prophase
21
which stage?
• chromosomes aligned at cell equator
metaphase
22
which stage?
• spindle fibres start to disappear
telophase
23
which stage?
• sister chromatids pulled to opposite
poles of the cell
anaphase
24
which stage?
• cell membrane pinches to divide
cytoplasm and organelles
cytokinesis
25
which stage?
• one set of chromosomes at each pole
of the cell
telophase
26
which stage?
• centromere pulled apart
anaphase
27
which stage?
• DNA loosely coiled so it can be
transcribed into RNA
interphase
28
which stage?
• nucleolus reappears
telophase
29
which stage?
• shortest stage of mitosis
anaphase
30
*
31
32
• “In Cell Division” song
• http://www.youtube.com/watch?v=Il
V9hExXZnM
question & discussion
• Nina spent all summer tanning on the
beach without any sunscreen. After
feeling poorly for several months, she
went to see a doctor, who told her
that she had metastatic melanoma,
and that there were tumours growing
on her internal organs. How did she
get cancer? How did it spread from
her skin to her organs?
34
checkpoints
35
cancer
• loss of cell cycle control (mutation in
gene that codes for a checkpoint
protein)
• may lead to uncontrollable cell division
36
cancer
37
cancer
38
cancer
• cancerous cells release chemicals that
cause blood vessels to branch into
tumour
• nutrients delivered, tumour grows
• cancerous cells may break away and
be carried to other locations where
they form a new tumour
39
cancer (extra)
30 January 2012
general facts
• leading cause of death worldwide
• lung, stomach, liver, colon and breast cancer
cause the most cancer deaths each yr.
• most frequent types of cancer differ
between men and women.
• About 30% of cancer deaths due to the five
leading behavioural and dietary risks: high
body mass index, low fruit and vegetable
intake, lack of physical activity, tobacco use,
alcohol use.
general facts
• In the US, direct medical costs (total
of all health expenditures): $102.8
billion
UV damage
• “…key reaction on the DNA molecule
that is linked to sunburn happens
with astounding speed - in less than
one picosecond.”
• one picosecond = one trillionth of a
second (10-12 seconds)
43
http://www.scienceagogo.com/news/20070101164743data_trunc_sys.shtml
UV damage
• “Badly damaged cells
simply die - the effect
that gives sunburn its
sting.”
• “… chronic damage
creates mutations
that lead to diseases
such as skin cancer.”
http://www.scienceagogo.com/news/20070101164743data_trunc_sys.shtml
UV damage
• “UV-B light causes crosslinking between
adjacent cytosine and thymine bases
creating pyrimidine dimers. This is
called direct DNA damage.
• UV-A light creates mostly free radicals.
The damage caused by free radicals is
called indirect DNA damage.”
http://en.wikipedia.org/wiki/DNA_repair#Types_of_damage
free radicals
• atom or group of atoms with an odd
(unpaired) number of electrons
• highly reactive
• Cl2
UV
Cl∙ + Cl∙
free radicals
• as molecules react with oxygen in
cellular respiration, they become free
radicals, which are highly unstable
and highly reactive
• free radical goes around cell,
‘stealing’ electrons from stable
molecules, rendering them unstable
free radicals
• antioxidants
eating grilled red meat cancer?
• The Nature of Things
• “Myth or Science?”
• original air date: November 24, 2011
• http://www.cbc.ca/video/#/Shows/The_
Nature_of_Things/1242300217/ID=2170
768762