Figure 9.20 The catabolism of various molecules from food
Figure 9.17 ATP yield per molecule of glucose at each stage of cellular respiration
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
Class 3-cell division & mito
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.
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.
• 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.
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.
• Located in the nucleus
• Each chromosome consists of a single molecule of DNA and its
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
All complex organisms
originated from a single
Every cell in your body
started here, through cell
division the numbers are
Cell then specialise and
change into their various
Mitosis and Meiosis
-division of somatic (body) cells
-division of gametes (sex cells)
• Mitosis is the process by which new body cell
are produced for:
– Replacing damaged or old cells.
This is a complex process requiring different stages
• 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.
Interesting things happen!
1. Cell preparing to divide
2. Genetic material doubles
Chromosome pair up!
1. Chromosomes thicken and shorten
-2 chromatids joined by a centromere
2. Centrioles move to the opposite sides of the
3. Nucleolus disappears
4. Nuclear membrane disintegrate
Chromosomes meet in the middle!
1. Chromosomes arrange at equator of
2. Become attached to spindle fibres by
3. Homologous chromosomes do not
Chromosomes get pulled apart
1. Spindle fibres contract pulling
chromatids to the opposite poles of
Now there are two!
Spindle fibres disintegrate
Nucleur membrane forms
• 4 daughter cells produced
• Each daughter cell has half the
chromosomes of the parent
• 2 sets of cell division involved
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
with shelf-like cristae
Matrix: Substance located in
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
Each mitochondrion has a DNA
molecule, allowing it to produce
its own enzymes and replicate
copies of itself.
Fatty acid oxidation
Amino acid oxidation
Synthesis of organelle protein
Outer Membrane: Freely permeable to
small molecules and ions
Inner Membrane: impermeable to most
small molecules and ions, including H+
•Respiratory electron carriers (complexes IIV)
•Other membrane transporters
•Pyruvate dehydrogenase complex
•Citric acid cycle enzyme
•Fatty acid β-oxidation enzymes
•Amino acid oxidation enzymes
•Many other enzymes
•ATP, ADP, Pi, Mg+2, Ca+2, K+
•Many Soluble metabolic intermediates
+ 2 ATP
+ 2 ATP
Maximum per glucose:
+ about 32 or 34 ATP
36 or 38 ATP
Largest organelles of plants
Vary in size and shape
Inner membrane system
• Calvin cycle
• sugar synthesis
Has its own protein
Converts light energy to chemical energy (sugars)
Do not post photos on Internet
Mitochondria (all eukaryotic cells)
Chloroplasts (some plant and algal cells)
O2 + Glucose
Fatty acid synthesis
Complex lipid synthesis
Synthesis of some amino acids
Synthesis of organelle protein
Reduction of nitrate and sulphate
Part of photorespiration