Class 3-cell division & mito
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Transcript of Class 3-cell division & mito
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
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