Unit 3: Genetics
• The Cell Cycle + DNA structure/function
• Mitosis and Meiosis
• Mendelian Genetics (aka - fun with Punnett squares)
• DNA replication
http://photoblog.nbcnews.com/_news/2013/06/07/18831654-fashion-photographer-focuseson-those-with-genetic-conditions-to-reframe-beauty?chromedomain=rockcenter&lite
Today’s Agenda
• The Cell Cycle + DNA structure/function
• Mitosis and Meiosis
• Mendelian Genetics (aka - fun with Punnett squares)
• DNA replication
The Cell Cycle
Chapter 12
Where are we going?
The biological basis of heredity
molecular
chromosomal
cellular
Where are we going?
The biological basis of heredity
molecular
chromosomal
cellular:
 how you get 2
cells from one
 how you make a
cell from two
gametes
Where are we going?
The biological basis of heredity
molecular
chromosomal:
 the organization
of genetic material
cellular
Where are we going?
The biological basis of heredity
molecular:
 the biochemical basis
of information storage
chromosomal
cellular
Outline
A. A Cell’s Life: Cell Cycle and Mitosis
1. The functions of mitotic cell division
2. When cells are not dividing: interphase
3. The mitotic phase
(tomorrow)
www.biologycorner.com;
1. The functions of mitotic cell division
1) What are the functions of mitotic cell division?
•
The vast majority of cells in the adult body are not dividing!
•
To renew naturally used-up cells.
•
To replace cells after injury.
•
During DEVELOPMENT
•
During reproduction of single-celled organisms
Cell division is fundamental to life as we know it
1. The functions of mitotic cell division
What happens when cell division goes WRONG?
1. The functions of mitotic cell division
What happens when cell division goes WRONG?
 cancer = uncontrolled cell division
1. The functions of mitotic cell division
Cancers
Lymph
vessel
Tumor
Blood
vessel
Glandular
tissue
1 A tumor grows
from a single
cancer cell.
2 Cancer cells
invade neighboring tissue.
3
Cancer
cell
Metastati
c
tumor
Cancer cells spread
4 Cancer cells may
to other parts of
the body.
survive and
establish a new
tumor in another
part of the body.
1. The functions of mitotic cell division
So, how can our bodies have
this, without getting that??
Normal Growth
Cancer
A difficult line to
walk for our cells
Nearly ALL
problems in
biology involve
tradeoffs
http://upload.wikimedia.org/wikipedia/commons/4/4d/Forain_-_The_tightrope_walker.jpg, 10/18/10
The balance in cell division:
Make sure everything is where it should be before you leap!
nickshell1983.wordpress.com
1. The functions of mitotic cell division
Two major problems to solve in cell division:
1.
The actual feat of cell division (MITOSIS):
• take one cell
• make two out of it
• both new cells need to have EVERYTHING that the original cell
had
1.
Only getting cell division WHEN and WHERE it is beneficial to the
organism  REGULATION
Outline
A. A Cell’s Life: Cell Cycle and Mitosis
1. The functions of cell division
2. When cells are not dividing: interphase
3. The mitotic phase (tomorrow)
2. Interphase
Overview
Cell cycle = from the time a cell is formed (from the
division of its parent cell), to the time it undergoes its
own division into two cells
2. Interphase
Overview
G
0
most of the
time
INTERPHASE
G
1=
growth
“Gap
1”
S
synthesis
G
2=
growth
“Gap
2”
Phases and Stages within the Cell Cycle
phases of cell cycle
INTERPHASE
G1 Phase (1st gap)
Prophase
MITOTIC PHASE
S Phase (synthesis)
Prometaphase
G2 phase (2nd gap)
Metaphase
stages of mitosis
Anaphase
Mitosis +
Cytokinesis
Telophase
cytokinesis
3. Mitotic Phase
Overview
Mitotic Phase (M phase)
• Actual cell division
• Occurs in two parts:
• Mitosis- Division of nucleus and nuclear
material
• Cytokinesis- Division of rest of cell
5 Minute Break
© Carli Davidson
Today’s Agenda
• The Cell Cycle + DNA structure/function
• Mitosis and Meiosis
• Mendelian Genetics (aka - fun with Punnett squares)
• DNA replication
3. Mitotic Phase
Overview
The organization of genetic
material in your cells
cell
nucleus
3. Mitotic Phase
The organization of genetic
material in your cells
cell
nucleus
multiple
chromosomes
Overview
3. Mitotic Phase
Overview
The organization of genetic
material in animal cells
cell
(DNA molecule)
nucleus
+
multiple
chromosomes
Chromodisorder.org
accessory proteins
Getting to know
DNA
Chapters 16
and 20
wikipedia.org
Figure 16.7
Figure 16.21
But, what is DNA, exactly?
How is it managed in our cells?
What happens to DNA during the cell cycle?
1. DNA = the molecule of heredity
Why is DNA so important?
DNA directs the program that takes raw materials (sugars, fats, amino acids,
etc.) and turns them into YOU
DNA is also how we pass this program to our descendants
News.bbc.co.uk
1. DNA = the molecule of heredity
Reminder:
A nucleic acid is a polymer of
made of nucleotide monomers
DNA is deoxyribonucleic acid
1. DNA = the molecule of heredity
 The sugar and phosphate
group are the SAME for all
DNA nucleotides
The base is what varies
 the sequence of
nucleotides with different
bases forms the code
containing all hereditary
information
1. DNA = the molecule of heredity
In DNA:
• Only 4 nitrogenous bases
• Only 4 possible nucleotides
Different sequences of these
nucleotides make up the
different genetic code of
every living organism
26 letters in alphabet = 230,000 (or 1 million, or 3
million...) English words alone
4 nucleotides = billions of unique individuals of
thousands of species
1. DNA = the molecule of heredity
DNA Structure:
1.
2.
DNA is a double stranded molecule
The two strands are complementary, and together wind around in the form
of a double helix
1. DNA = the molecule of heredity
1950:
Erwin Chargaff
looking at chemical composition of DNA in any
particular species:
% adenine (A) = % thymine (T)
% guanine (G) = % cytosine (C)
These equalities are known as “Chargaff’s Rule”
wikipedia.org
Example: Human DNA
30% of nucleotides are A, and 30% are T...
...and likewise 20% G and 20% C
1. DNA = the molecule of heredity
Building evidence about the structure of DNA
+ unpublished, internal
report written by Franklin
Figure 16.6
In an UNPUBLISHED REPORT, Franklin postulated that
1.DNA had a sugar-phosphate backbone,
2.around the outside of a double stranded molecule,
3.with nitrogenous bases arranged in the middle
1. DNA = the molecule of heredity
The famous (or infamous?) discovery of the structure of DNA
+ unpublished, internal
report written by Franklin
photos: wikipedia.org; Figure 16.6
Maurice Wilkins
James Watson
Francis Crick
1. DNA = the molecule of heredity
Watson and Crick built models of a double helix to conform to the X-rays and
chemistry of DNA
1. DNA = the molecule of heredity
The DNA Double Helix
1. DNA = the molecule of heredity
The strands of DNA run in
an antiparallel manner
• the phosphate group in a
single nucleotide is
attached to the 5’ carbon
atom of the sugar
LG 22,24
1. DNA = the molecule of heredity
The strands of DNA run in
an antiparallel manner
• adjacent nucleotides are
linked phosphate to 3’
carbon atom  This
forms the “backbone”
1. DNA = the molecule of heredity
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Figure 16.8
DNA and Chromosomes
Figure 16.21
3. Mitotic Phase
Overview
accomplished when?
 S phase of interphase
accomplished
when?
 Mitotic phase
Figure 12.4, p. 230
3. Mitotic Phase
Overview
No. of Chromosomes?
1
1
2
Figure 12.4, p. 230
3. Mitotic Phase
Overview
Remember:
If they’re hooked
together, they’re 1
chromosome!
Today’s Exit Ticket
phases of cell cycle
MITOTIC PHASE
G2 phase (2nd gap)
What happens:
What happens:
What happens:
What happens: