2010年1月15日星期五

chapter 13

Chapter 13
Questions
1) What’s heredity?
Heredity is the transmission of traits from parents to offspring.
2) What’s genetics?
Genetics is the scientific study of heredity.
3) What’s locus?
Locus is the physical location of a gene in a chromosome.



Factor
1) Reproduction is a method of copying genes to pass them on to offspring. Two main types:
Asexual reproduction Sexual reproduction
2)




1. Heredity: The transmission of traits from parents to offspring.
2. Gene: The DNA for a trait.
3. Locus: The physical location of a gene in a chromosome.
4. Reproduction: A method of copying genes to pass them on to offspring.
5. Diploid: 2 sets of chromosomes which is most common in somatic cells.
6. Haploid: 1 set of chromosomes. Number in the gametes or sex cells.
7. Crossing-over: The exchange of sister chromatids material during synapsis. It
occurs ONLY in prophase I.
8. Chiasmata: The point of contact where two chromosomes are crossing-over.
9. Synapsis: Tetrad formation or genetic rearrangement.
10. Interkinesis: No DNA synthesis occurs.




















http://www.youtube.com/watch?v=D1_-mQS_FZ0

chapter 12

Chapter 12
1) What’s genome?
It’s the cell's hereditary endowment of DNA. It usually packaged into chromosomes for manageability.
2) What’s chromosome?
It is made of a DNA and protein complex called Chromatin.
3) What’s the structure of chromosome?
At cell division, each chromosome has been duplicated. The duplicated chromosome consists of two sister chromatids.

Factor
1) There are G2 of interphase, prophase, prometaphase, metaphase, anaphase and telophase and cytokinesis in the mitotic division of an animal cell.
2) In the interphase, there are G1 which is the first gap, S which is synthesis, G2 which is second gap.
3) In G1, Cell grows and carries out regular biochemical functions. When the DNA is replicated or synthesized. Chromosomes are replicated and then Cell completes preparations for division.
4) Mitosis is division of replicated chromosomes. Cytokinesis is division of the cell’s cytoplasm.
5) The purpose of mitotic is to divide the 2 copies of the DNA equally.To separate the sister chromatids into separate cells.



Diagram
In this diagram, we can see G1, G2 and DNA synthesis. G1 called checkpoint also called restriction point in mammalian cells. Places cells in a non-dividing phase called the Go phase. Most important checkpoint according to some.




Key term
1, Centromere: The point where two sister chromatids are connected.
1. Chromosomes: Made of a DNA and protein complex called chromatin; during cell
division, the chromatin becomes highly condensed into the chromosomes.
2. Gametes: Sperm and eggs which have half as many chromosomes as somatic
cells.
3. Somatic cells: All body cells except the reproductive cells each contain 46
chromosomes made up of two sets of 23.
4. Chromatin: A complex of DNA and associated protein molecules.
5. Mitosis: The division of the nucleus.
6. Cytokinesis: The division of the cytoplasm.
7. Centromere: The point where two sister chromatids are connected.
8. Centrosome: Structure present in the cytoplasm of animals cells, important during
cell division; functions as a microtubule-organizing center. A Centrosome has two
centrioles.
9. Cyclin-dependent kinases or Cdks: A protein kinase that is active only when
attached to a particular cyclin.
10. Transformation: The process that converts a normal cell to a cancer cell.

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

chapter 11

Chapter 11
1) How does cell communicate?
Cells communicate with other cells by using signals.
2) Why does cell need communicate?
Because cells need to regulate themselves and Environmental Stimuli cells need to be able to respond to signals from their environment.
3) How many different signals are there?
There are local signals, they are paracrine signaling and synaptic signaling. And there is long distance (hormonal) signal.


Factors
!) There are three stages of cell signal. Reception is receiving signals. Transduction is passing on the signal. Response is cellular changes because of the signal.
2) In reception, The target cell’s detection of a signal coming from outside the cell. May occur by:
direct Contact and through signal molecules
3) direct contact means when molecules can flow directly from cell to cell without crossing membranes. For example, in plants there are plasmodesmata and in animals there are gap junctions.
4) Signal molecules are the actual chemical signal that travels from cell to cell. And they often water soluble, usually too large to travel through membranes. Double reason why they can’t cross cell membranes.
5) Reception molecules are usually made of protein. Change shape when bind to a signal molecule and transmits information from the exterior to the interior of a cell.

Summary
External signals are converted to responses within the cell. There are three stages of cell signaling. They are reception, transduction and response. Reception is a signaling molecule binds to a receptor protein, causing it to change shape. Transduction is cascades of molecular interactions relay signals from receptors to target molecules in the cells. Response is cell signaling leads to regulation of transcription ore cytoplasmic activities. Apoptosis integrates multiple cell-signaling pathways.

Diagram
In this diagram we can see there’re two kind of cell signaling, local signaling and long distance signaling. In local signaling there are paracrine signaling and synaptic signaling. And the long distance signaling is normally for hormonal.

Key terms
1. Signal transduction pathway: The process by which a signal on a cell’s surface is
converted to a specific cellular response.
2. Cell-cell recognition: Two cells in an animal may communicate by interaction
between molecules protruding from their surfaces.
3. Synaptic signaling: A nerve cell releases neurotransmitter molecules into a
synapse, stimulating the target cell. (Local signaling)
4. Local regulators: A secreted molecule that influences cells near where it is
secreted.
5. Hormone: In multicellular organisms, one of many types of secreted chemicals
that are formed in specialized cells, travel in body fluids, and act on specific target
cells in other parts of the body to change their functioning.
6. Reception: It is the target cell’s detection of a signaling molecule coming from
outside the cell.
7. Transduction: The binding of the signaling molecule changes the receptor protein
in some way, initiating the process of transduction.
8. Response: The transduced signal finally triggers a specific cellular response. In
cellular communication, the change in a specific cellular activity brought about by
a transduced signal from outside the cell.
9. Protein Kinase: An enzyme that transfers phosphate groups from ATP to a protein,
thus phosphorylating the protein.
10. Cyclic AMP: Also known as cAMP. It is a ring-shaped molecule made from ATP
that is a common intracellular signaling molecule (second messenger) in
eukaryotic cells. It is also a regulator of some bacterial operons.

http://www.youtube.com/watch?v=U6uHotlXvPo

chapter 10

Chapter 10
Question:
1) Dose photosynthesis has different stages like cell respiration?
There are two stages of photosynthesis, they are light reaction and calvin cycle.
2) Where does the photosynthesis take place?
Photosynthesis happens in the chloroplast.
3) What’s the formula for photosynthesis?
6CO2 + 6H2O + light energy = C6H12O6+ 6O2


Factors:
1) Light reaction converts solar energy to chemical energy.
2) Calvin cycle begin by incorporating CO2 from the air into organic molecules already present in the chloroplast. This initial incorporation of carbon into organic compounds is known as carbon fixation. The Calvin cycle then reduces the fixed carbon to carbohydrate by the addition of electrons.
3) Light reaction is a form of electromagnetic radiation. Visible light has the right energy for use in Ps.


Diagram


In this diagram, the chloroplast, the thylakoid membranes are the sites of the light reactions, whereas the Calvin cycle occurs in the stroma. The light reaction use solar energy to make ATP and NADPH, which supply chemical energy and reducing power, respectively, to the Calvin cycle. Calvin cycle incorporates CO2 into organic molecules, which are converted to sugar.


Summary:
Photosynthesis converts light energy to the chemical energy of food. The light reactions convert solar energy to the chemical energy of ATP and NADPH. The Calvin cycle uses ATP and NADPH. The Calvin cycle uses ATP and NADPH to convert CO2 to sugar. Alternative mechanisms of carbon fixation have evolved in hot, arid climates.

Key term
1. Autotrophs: Self-feeders.
2. Heterotrophs: Biosphere’s consumers.
3. Chlorophyll: The green pigment located within chloroplasts.
4. Stomata: A microscopic pore surrounded by guard cells in the epidermis of leaves
and stems that allow gas exchange between the environment and the interior of the
plant.
5. Stroma: The dense fluid within the chloroplast.
6. Thylakoid: A flattened membranous sac inside a chloroplast. Thylakoids exist in
an interconnected system in the chloroplast and contain the molecular
“machinery” used to convert light energy to chemical energy.
7. Photophosphorylation: The lights reactions also generate ATP, using
chemiosmosis to power the addition of a phosphate group to ADP.
8. Carbon fixation: The initial incorporation of carbon from CO2 into an organic
compound by an autotrophic organism.
9. Cyclic electron flow: A route of electron flow during the light reactions of
photosynthesis that involves only photosystem I and that produces ATP but not
NADPH or oxygen.
10. Linear electron flow: A route of electron flow during the light reactions of
photosynthesis that involves both Photosystems (I and II) and produces ATP,
NADPH and oxygen. The net electron flow is from H2O NADP+.



http://www.youtube.com/watch?v=Q_1mxZdF2TY