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.

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.

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.

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.

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 chromatin1/3 DNA and 2/3 protein

•Complex interactions between proteins and nucleic acids in the chromosomes regulate gene and chromosomal function

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

Mitosis and Meiosis

• Mitosis:-division of somatic (body) cells

• Meiosis-division of gametes (sex cells)

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

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.

Mitosis

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase

Interphase

• Interesting things happen!1. Cell preparing to divide2. Genetic material doubles

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 disappears4. Nuclear membrane disintegrate

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

Anaphase

• Chromosomes get pulled apart1. Spindle fibres contract pulling

chromatids to the opposite poles of the cell

Telophase

• Now there are two!1. Chromosomes uncoil2. Spindle fibres disintegrate3. Centrioles replicate4. Nucleur membrane forms5. Cell divides

Meiosis

• 4 daughter cells produced• Each daughter cell has half the

chromosomes of the parent• 2 sets of cell division involved

http://www.youtube.com/watch?v=oHH4JxGxC0s

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.

Mitochondria • Double membrane structure 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.

The MightyMitochondrion! Powerhouse of

the Cell

ATP

Mitochondria

1) TCA cycle2) Fatty acid oxidation3) Amino acid oxidation4) Gluconeogenesis5) Synthesis of organelle protein

Proteins Carbohydrates

Aminoacids

Sugars

Fats

Glycerol Fattyacids

Glycolysis

Glucose

Glyceraldehyde-3-

Pyruvate

P

NH3

Acetyl CoA

Citricacidcycle

Oxidativephosphorylation

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 I-IV)•ATP Synthase•Other membrane transporters

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

Maximum per glucose: About36 or 38 ATP

+ 2 ATP+ 2 ATP + about 32 or 34 ATP

Oxidativephosphorylation:electron transport

andchemiosmosis

Citricacidcycle

2AcetylCoA

Glycolysis

Glucose2

Pyruvate

2 NADH 2 NADH 6 NADH 2 FADH2

2 FADH2

2 NADHCYTOSOL Electron shuttles

span membrane

or

MITOCHONDRION

Rodney-464 page

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)

ChloroplastsChloroplasts

Granum

Outermembrane

Innermembrane

Thylakoidlumen

Thylakoidmembrane

1 m

StromaDo not post photos on Internet

Chloroplast

Light

H2O

Chloroplast

LightReactions

NADP+

P

ADP

i+

ATP

NADPH

O2

CalvinCycle

CO2

[CH2O]

(sugar)

Glucose + O2 ATP

CO2

H2O

CO2

H2OATP O2 Glucose

Aerobic respirationMitochondria (all eukaryotic cells)

PhotosynthesisChloroplasts (some plant and algal cells)

Light

++ +

Chloroplast Mitochondria

PhotosynthesisRespiration

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