10/8/2013
Bio 10: Intro to Biology
Instructor: Paul Nagami
Laney College
October 9, 2013
Agenda
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Administrative Stuff
Binary Fission
Adjusted Lecture Schedule
DNA and Chromosomes
Mitosis
Which Cells Undergo Mitosis?
Mitosis and Cancer
Wrap-up
What Do You Already Know?
(Image of bacteria
dividing. Source:
http://www2.estrellamo
untain.edu/faculty/farab
ee/biobk/69091a.jpg)
Do all living things
have cells that
divide? Why would
cells need to
divide?
Write down your
answer and
reasoning on your
index card.
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Functions of Cell Division
(Figure source: Figure 8.1 in the text –
shows division of kidney cells, embryo
cells, and amoeba.)
Replace
lost/dead
cells
Allow
growth
Reproduce
(make
offspring)
Cell Division: Any time a cell divides into two new cells
Asexual Reproduction: Makes exact copies
All Living Organisms Need to
Divide
In eukaryotes, the process of division is
mitosis or meiosis, depending on how it
happens. We’ll learn about mitosis today.
In prokaryotes, cell
division is called binary
fission, and is simpler!
(Image shows
binary fission
of a bacterium)
Binary fission: Copy
bacterial DNA, then divide
(Figure source:
cell in half. That’s it!
http://gleesonbiology.pbworks.com/f/1159266492/
binary%20fission.JPG)
Adjusted Lecture Schedule
• 10/9: Mitosis (Chapter 8)
• 10/11: Meiosis and Inheritance (Chapter 8,
Chapter 9)
• 10/16: DNA Function (Chapter 9, Chapter 10)
• 10/18: DNA Function, part 2 (Chapter 10)
(Second Essay Outline Due)
• 10/23:Controlling How DNA is Read (Chapter 11)
• 10/25: DNA, Populations, and Evolution (Ch 13)
• 10/30, 11/1: Lab Exam 2
• 10/30: Lecture Exam 2
• 11/1: Second Essay Due
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Why Do Offspring Resemble Their
Parents?
This is obviously a
hoax. But how do we
know for sure?
(Image: Hoax
headline: Woman
gives birth to
puppies)
For centuries, people
told stories about
humans giving birth
to other species.
Why do organisms only give rise to similar
organisms? What carries the information that
makes a puppy different from a human baby?
DNA: The ‘Recipe’ of Life
DNA carries instructions for how and where to make
RNA. RNA carries instructions to make proteins.
Gene = piece of DNA that codes for mRNA.
Image: Central
Dogma – DNA codes
for RNA, which
codes for protein
Almost every cell in
your body has the
same DNA! But
different parts of the
DNA are “turned on”
in different cells.
(Figure source: http://katiephd.com/wp-content/uploads/2011/01/central-dogma.jpg)
Every cell in your body contain 3 meters of DNA!
How is this possible if your cells are so small?
How DNA Is Organized
(Image:
Chromosomes
stained in a
plant cell.)
Eukaryotic DNA is packaged
into chromosomes.
Chromosomes consist of
DNA wound tightly around
packaging proteins, like
string on a spool.
(Figure source: Fig. 8.3 in text)
Your genome consists
of all of your
chromosomes put
together!
How many chromosomes do most people have?
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An analogy…
Image: A bookshelf with 46 books
arranged in pairs. Each pair of
books shares a number, but the
number is shown in a bold font for
one book and a script font for the
other.
Your genome is
like a bookshelf
full of books!
These books represent the 46
chromosomes in a human cell,
numbered 1 – 22 (in pairs), plus the
sex chromosomes.
Each pair of chromosomes consists
of one version inherited from the
mother, and one inherited from the
father.
By this analogy,
what do the books
represent?
How many books
are in the genome
for most people?
What are the
sentences in the
books?
Why We Need Mitosis
Mitosis makes two eukaryotic cells out of one.
Why is it harder to copy a
eukaryotic cell than it is to copy
a prokaryotic cell?
We need to copy every single
chromosome before mitosis
even begins…
Then we need to make sure that both resulting cells
have exactly one copy of every chromosome.
And all of those chromosomes have to be in the
nucleus of the cell!
Are Cells Always Undergoing
Mitosis?
Image: Figure
8.6 in text,
showing the
cell cycle with
interphase
and mitosis.
Even dividing cells spend
most of their time in
interphase.
Interphase is not mitosis;
it is when cells are not
dividing.
Chromosomes
are copied
during
interphase.
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Stages of Mitosis (Whiteboard)
Animal vs. Plant Mitosis
Image: Figure 8.8 in the text, showing the
difference in cytokinesis between plant
and animal cells
(Text, figure 8.8)
Do All of Your Cells Undergo
Mitosis?
Almost all of the cells in your body came from
mitosis. (Exception: Eggs, sperm)
However, most of the cells in your body have
stopped dividing!
This is a good thing! When cells that are not
supposed to divide do so, the result is cancer.
Image: The development and metastasis
of a tumor, figure 8.29 in the text.
(Figure 8.29 in text)
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Review!
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