Quiz (notes from Monday)
Quiz A, part 2
# 1 = just the bottom
(ACG)
# 2 = only 1!
# 3 = whole thing
#4 = many!
Quiz B, part 2
# 1 = many!
# 2 = whole thing
# 3 = only 1!
#4 = just the bottom
(ACG)
Both Versions, Part 3
› Don’t worry about the start codon!
April 14, 2010 Bellringers

What are the two main types of
mutations we discussed?

How are these mutations different?

What are examples of each?
 What
are the two main types of mutations
we discussed?
› Frameshift
› Point/Substitution
 How
are these mutations different?
› Frameshift – changes reading frame for
amino acids
› Point- changes only one base, may or
may not change amino acids
 What
are examples of each?
› Frameshift – insertion/deletion of
base
› Point – nonsense (makes an early
stop codon), missense (changes 1
amino acid)
How do little elephants grow up to be BIG
elephants?
The process of asexual cell
reproduction (called mitosis) begins
after a sperm fertilizes an egg.
Body cells are DIPLOID
They have 2 copies of
each chromosome, one
from mom and one
from dad
Cell Division
All the cells DNA
is found in the
cell nucleus in
structures called
chromosomes
Cell Division
When cells
divide, the
chromosomes
appear, divide
and separate
Cell Division
Two new cells
form with
identical
chromosomes to
the original cell
46
46
46
Somatic cells: body cells
(non-reproductive cells)
Every one of the billions of
cells that make up the
human body have 46
chromosomes (23 pairs) in
their nuclei.
Cell Division
46
What will be the result of this
cell dividing by MITOSIS ?
?
46
• The cell divides
ONCE
• TWO identical cells
form
• Daughter cells
have SAME
number of
chromosomes as
parent
Cells that are not somatic cells are called
Sex Cells (Gametes)

These are HAPLOID, they only have one
copy of each chromosome
› Each gamete will meet with another gamete to
make a new diploid organism

They do NOT go through the process of
mitosis to divide.
More about chromosomes
chromatid
centromere
Chromosomes
consist of a
chromatid and
centromere
More about chromosomes
chromatid
chromatid
centromere
When cells divide,
chromosomes appear
as 2 chromatids and a
centromere holding
them together.
These are called SISTER CHROMATIDS.
They are EXACTLY alike.
3 main stages
1. INTERPHASE
2. MITOSIS
3. CYTOKINESIS
• Enzymes control the cell cycle and check the cell as it goes thru
each stage. If there is a problem, the cell will not be allowed to
continue in the cycle until the problem is fixed.
• Sometimes these enzymes get messed up and cell division
becomes uncontrollable. This is called cancer.
Occurs before mitosis (cell division)
 3 parts

› G1 = Gap 1 = GROWTH
Normal cell functions (protein being made!)
Organelles multiply
= Synthesis = DNA replicates
This creates the SISTER CHROMATIDS (exact copies of
DNA strand)
› G2 = Gap 2 = final preparations for mitosis


› S

Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Animated Mitosis Cycle
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
•
Chromatin (DNA) coils and chromosomes
become visible
• Easier to move DNA if it is condensed!
• Sister Chromatids form X shape
•
Centrioles appear and begin to move to
opposite ends (poles) of the cell.
• Animal cells only!
•
Spindle fibers appear from centrioles
•
Nuclear envelope and nucleolus disappear
by end of this phase.
Animal Cell
Plant Cell
Spindle fibers
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromosomes line up in center
•
Spindle fibers attach to centromeres
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
•
Centromeres split
Chromatids separate and begin to move to
opposite ends of the cell.
Cell membrane pinches in SLIGHTLY
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Spindle fibers break down
•
Nuclear membrane forms around two new
nuclei.
•
Chromosomes unwind (now called chromatin)
• One copy of each chromatid in each daughter cell
Nuclei
Nuclei
Chromatin
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Cytoplasm and organelles are separated
•
Cell membrane pinches in center to create
two daughter cells – each with its own
nucleus with identical chromosomes.
• In plants a “cell plate” forms between the cells,
this becomes the cell wall
Daughter cells:
genetically
identical to
parent cell!
MITOSIS
Original Cell Divides
to form TWO new
cells with the SAME
number of
chromosomes
These daughter cells
are genetically
identical to the
parent and each
other.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
35
http://www.cellsalive.com/mitosis.htm
Where does - All cells
it happen? - Eukaryotes: nucleus
- Prokaryotes: cytoplasm
- to prepare the cell for
mitosis
Why
and
- to make daughter cells
when
with the exact same DNA
does it
as old cells
happen?
- happens during
Interphase (S = synthesis)
1. enzymes help DNA
unwind and unzip
How
does
it
happen?
2. other enzymes help free nucleotides
attach to the appropriate bases
(A-T, C-G)
DNA replication #1
3. Two identical DNA strands are made
DNA replication #2
You are creating a flip book to show mitosis is a CONTINUOUS process as
opposed to separate steps with no in between.
1. Start by drawing the END of each phase
2. Then, draw inside the cells to show how the cell gets from interphase to
the end of prophase, from prophase to the end of metaphase, etc.
3. You MUST include the following in your diagrams (in appropriate phases)
• 2 sets of chromosomes (each a different color)
• Total of 4 chromosomes, each daughter cell should have 2 of
each color!
• Nuclear membrane
• Centrioles
• Spindle fibers
• Cell membrane
• Nucleolus
• At least 1 other organelle (mitochondria, ER, etc)
4. Lastly, on the back of your drawings, write a couple notes describing
what your picture is showing!
5. Cut out each page, put them in order, and staple one side. Flip through
it to see mitosis!