cell devision and mitosis

1. Cell Cycle
•
The process of cell growth and division in eukaryotes is called cell cycle.
•
This cycle is divided into phases based on what is happening in the cell at
a given time.
•
A cell grows during the G1 phase. During the phase there is chemical
checkpoint that controls whether the divide, delay division or enter the
division stage. When conditions in the cell are right, the G1 checkpoint
will be passed and the cell will enter the synthesis(S) phase.
•
During the S phase DNA replication occurs so that future cells will each
have a complete set of genetic instructions in the DNA.

4. Cell Cycle
•
After DNA replication is complete cells enter the G2 phase, where they
continue to grow and prepare for cell division. At a checkpoint in this phase
the success of DNA replication is assessed; if all is well the cell enter the
mitosis (M) phase.
•
During the M phase, a complex series of events moves the DNA so that a
complete set of genetic instructions will be sent to each daughter cell. The
process of mitosis is assessed at a checkpoint during the M phase.
•
Once this checkpoint is passed, the cell will complete the mitosis as well
begin the cytokinesis(C) phase. Part or all of the C phase overlaps with the
later part of mitosis, so it is not a distinctly separate phase.
•
During the C phase the cytoplasm of the cell is divided and two daughter
cell are created from the original cell. When this process is finished the
daughter cell enter the G1 phase, and the cell cycle is complete.

5. Chromosome
• Chromosome, microscopic structure
within cells that carries the molecule
deoxyribonucleic acid (DNA)—the
hereditary material that influences
the development and characteristics
of each organism.
• A human body cell usually contains 46
chromosomes arranged in 23 pairs.

6. Through research and the development of staining techniques in the
1950's, scientists were for the first time able to view the human
chromosome. Although they appear disorganised within the cell,
scientists have been able to identify them and so have numbered
them from 1-22 in order of size.

8. Eukaryotic Chromosomes
• Located in the nucleus
• Each chromosome consists of a single molecule of DNA and its
associated proteins
The DNA and protein complex found in eukaryotic
chromosomes is called chromatin
1/3 DNA and 2/3 protein
•Complex interactions between proteins and nucleic acids in the
chromosomes regulate gene and chromosomal function

10. Cell division
All complex organisms
originated from a single
fertilised egg.
Every cell in your body
started here, through cell
division the numbers are
increased
Cell then specialise and
change into their various
roles

11. Mitosis and Meiosis
• Mitosis:
-division of somatic (body) cells
• Meiosis
-division of gametes (sex cells)

12. Mitosis
• Mitosis is the process by which new body cell
are produced for:
– Growth
– Replacing damaged or old cells.
This is a complex process requiring different stages

13. Mitosis
• All daughter cells contain the same genetic
information from the original parent cell
from which it was copied.
• Every different type cell in your body
contains the same genes, but only some act
to make the cells specialise – e.g. into nerve
or muscle tissue.

14. Mitosis
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase

15. Interphase
Interesting things happen!
1. Cell preparing to divide
2. Genetic material doubles
•

16. Prophase
Chromosome pair up!
1. Chromosomes thicken and shorten
-become visible
-2 chromatids joined by a centromere
2. Centrioles move to the opposite sides of the
nucleus
3. Nucleolus disappears
4. Nuclear membrane disintegrate
•

18. Metaphase
Chromosomes meet in the middle!
1. Chromosomes arrange at equator of
cell
2. Become attached to spindle fibres by
centromeres
3. Homologous chromosomes do not
associate
•

20. Anaphase
Chromosomes get pulled apart
1. Spindle fibres contract pulling
chromatids to the opposite poles of
the cell
•

21. Telophase
•
1.
2.
3.
4.
5.
Now there are two!
Chromosomes uncoil
Spindle fibres disintegrate
Centrioles replicate
Nucleur membrane forms
Cell divides

24. Meiosis
• 4 daughter cells produced
• Each daughter cell has half the
chromosomes of the parent
• 2 sets of cell division involved

27. Mitochondria
Mitochondria are membrane-enclosed organells distributed through
the cytosol of most eukaryotic cells.
Their main function is the conversion of the potential energy of food
molecules into ATP.
Every type of cell has a different amount of mitochondria.
There are more mitochondria in cells that have to perform lots of
work, for example- your leg muscle cells, heart muscle cells etc.
Other cells need less energy to do their work and have less
mitochondria.

28. Mitochondria
•
Double membrane
with shelf-like cristae
•
Matrix: Substance located in
space
formed
by
inner
membrane.
•
Provide most of the cell’s ATP via
aerobic cellular respiration
•
Mitochondrial enzymes catalyze
series of oxidation reactions that
provide about 95% of cell’s
energy supply
•
Each mitochondrion has a DNA
molecule, allowing it to produce
its own enzymes and replicate
copies of itself.
structure

29. The Mighty
Mitochondrion!
Powerhouse of
the Cell
ATP

30. Mitochondria
1)
2)
3)
4)
5)
TCA cycle
Fatty acid oxidation
Amino acid oxidation
Gluconeogenesis
Synthesis of organelle protein

31. Proteins
Amino
acids
Outer Membrane: Freely permeable to
small molecules and ions
Inner Membrane: impermeable to most
small molecules and ions, including H+
Contains:
•Respiratory electron carriers (complexes IIV)
•ATP Synthase
•Other membrane transporters
Fats
Sugars
Glycerol
Glycolysis
Glucose
Glyceraldehyde-3-
NH3
Matrix Contains:
•Pyruvate dehydrogenase complex
•Citric acid cycle enzyme
•Fatty acid β-oxidation enzymes
•Amino acid oxidation enzymes
•DNA
•Ribosomes
•Many other enzymes
•ATP, ADP, Pi, Mg+2, Ca+2, K+
•Many Soluble metabolic intermediates
Carbohydrates
P
Pyruvate
Acetyl CoA
Citric
acid
cycle
Oxidative
phosphorylation
Fatty
acids

32. Electron shuttles
span membrane
CYTOSOL
2 NADH
Glycolysis
Glucose
2
Pyruvate
MITOCHONDRIO
N
2 NADH
or
2 FADH2
6 NADH
2 NADH
2
Acetyl
CoA
+ 2 ATP
Citric
acid
cycle
+ 2 ATP
Maximum per glucose:
2 FADH2
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ about 32 or 34 ATP
About
36 or 38 ATP
Rodney-464 page

33. Chloroplast
•
Largest organelles of plants
and algae
•
Vary in size and shape
•
Function: Photosynthesis
•
Inner membrane system
– Grana
• thylakoids
– Stroma
• Calvin cycle
• sugar synthesis
•
Genome
•
Has its own protein
synthesizing enzymes
Converts light energy to chemical energy (sugars)

34. Chloroplasts

35. Chloroplast
Granum
Stroma
Outer
membrane
Inner
membrane
Thylakoid
lumen
Do not post photos on Internet
Thylakoid
membrane
1 µm

36. CO2
H2O
Light
NADP+
ADP
+ P
i
Light
Reactions
Calvin
Cycle
ATP
NADPH
Chloroplast
O2
[CH2O]
(sugar)

37. Mitochondria
Chloroplast
Aerobic respiration
Mitochondria (all eukaryotic cells)
Photosynthesis
Chloroplasts (some plant and algal cells)
Light
CO2
Glucose +
O2
ATP
CO2
+
Respiration
H2O
H2O
+ ATP
O2 + Glucose
Photosynthesis

38. Chloroplasts
1)
Photosynthesis
2)
Fatty acid synthesis
3)
Complex lipid synthesis
4)
Synthesis of some amino acids
5)
Synthesis of organelle protein
6)
Calvin cycle
7)
Light reaction
8)
Reduction of nitrate and sulphate
9)
Part of photorespiration