Download Cell Division and Genetic material

4.1 Cell Division and Genetic Material
SBI3U
Genetics:
The study of how genetic
information is passed from
one generation to the next.
Recall: Cell Theory
1) All living things are composed of one or
more cells
2) Cells are the smallest units of living
organisms
3) New cells come only from pre-existing cells
by cell division
DNA Structure
 DNA is the genetic information
that an individual inherits from
his/her parents.
 DNA is double stranded and is
called a double helix
 During cell division (mitosis), DNA is
replicated so that each new cell
(daughter cell) receives an identical
copy of the genetic information from
parent cells
DNA Structure
DNA is made up of
many nucleotides
joined together as a
chain.
This chain is known as
polynucleotide.
DNA Structure
Made up of 3 main
parts
1)Phosphate group:
-Binds to the
deoxyribose
(phosphodiester bond) to
form the backbone of
the DNA
2)Nitrogenous base:
-Carbon ring (s)
-bound to the sugar
(A,C,T,G)
3)Pentose Sugar:
-5 carbon ring
-Deoxyribose
The Deoxyribose sugar on the
DNA does not have an oxygen on
the 5th carbon.
RNA has a ribose sugar, which has
an oxygen atom on the 5th
carbon..
Nitrogenous Bases:
1) Pyrimidine:
- Cytosine, Thymine and
Uracil( only in RNA)
2) Purine:
- 2 ring structure
- Adenine & Guanine
Complementary base-pairing:
Adenine – Thymine
Guanine - Cytosine
U
DNA Structure
Genome: Complete DNA
sequence of an organism.
Test your Understanding….
Complementary Base Pairing
What would the complementary strand be?
A T T C G A A CT
a) T A A G G T C A G
b) T A A G C T T G A
c) G C C A T G G T C
Recall: Key
Terms
Chromatin:
uncoiled,
uncondensed
DNA
Chromosome:
coiled DNA
(many strands
of chromatin)
Video
https://www.youtube.com/watch?v=xUrlreMaUrs
The Cell Cycle
5-6 hours
3 main stages:
Interphase, Mitosis, Cytokinesis
10 – 12 hours
4-6 hours
Less than 1 hour
Which phase does the cell spend most of its time?
The Cell Cycle

Process of growth and cell division for somatic
cells ( body cells)
 One complete cycle produces 2 new daughter
cells
One cycle takes approx. 12-24 hours
Function = Growth, Repair & Maintenance of
cells
INTERPHASE
 Stage where the cell grows and makes copies of genetic information
and prepares the cell for division.
3 Stages
 G1 (First Growth Phase) : synthesizes new molecules
 S (Synthesis Phase): DNA is copied and in the form
of chromatin.
 G2 (Second Growth Phase): synthesizes more
proteins that prepare for cell division.
MITOSIS
 The copied genetic material separates and prepares for the
separation of two new daughter cells.
 The splitting of genetic information allows each new
daughter cell to have identical genetic information.
 Subdivided into 4 main phases: Prophase, Metaphase, Anaphase,
Telophase ( PMAT)
4 stages of
Mitosis
1) Prophase
 Chromatin condenses into
chromosome
 The chromosome arms are sister
chromatids and are joined at the
center by the centromere.
 Nuclear membrane breaks down
and nucleus disappears.
 Spindle fibres are formed and
migrate to opposite poles
2) Metaphase
 Spindle fibers attach to the
centromere of the sister
chromatids
 The sister chromatids line
up at the equator of the cell
forming a metaphase plate.
3) Anaphase
 Each centromere separates,
causing the sister
chromatids to separate.
 Each chromatid migrates to
the opposite pole.
 One complete set of
chromosomes is now on
both poles of the cell.
4) Telophase
 Chromosomes unwind into
chromatin
 Spindle fibers break down
 Nuclear membrane forms around
the new set of chromosomes
Cleavage Furrow
 Nucleolus forms within each new
nucleus.
CYTOKINESIS
 Process of nuclear division
 The cytoplasm divides and creates two new
daughter cells
 The microfilaments on the cytoskeleton of the
cell wall pinch and separate the cytoplasm.
 The cytoplasm divides equally between the two
cells.
Cytokinesis in Plant Cells
 Have a cell wall that is rigid
 A cell plate forms between
the two nuclei and separates
the two daughter cells.
 A new cell wall then forms
around the cell plate.
HOMEWORK
 Read & Make notes pgs. 160-165
 Complete Pg. 164 Q# 1-4, 6