Páginas: 6 (1315 palabras) Publicado: 15 de noviembre de 2010
Science review
Chapters 4, 5, 23, 24 and 26.1

Transport across the cell membrane
1. Active transport: Requires ATP energy, because it goes from low to high concentration.
Endocytosis: Bacteria and large molecules. Require formation of vesicle. Cell membrane expands and wraps around the molecule.
Exocytosis: Proteins (insulin). Requires formation of vesicle.
Active Transport:Requires protein carrier. Ions like sodium and potassium

2. Passive transport: Doesn’t require ATP energy, because the substance moves from high to low concentration.
Simple diffusion: Doesn’t require a protein carrier to get through. How we get gasses across the membrane (oxygen moves in and carbon dioxide moves out)
Facilitated diffusion: Needs a protein carrier. How we get glucose, aminoacids, and sodium ions.
Osmosis: Diffusion of water across a semi permeable membrane, to let water cross but not the solute.
Where you have more solute you’ll have less water, and if you have more water you’ll have less solute. Water moves to where there is less water.
Hypertonic: Solution with more solute and less water. Cell shrinks
Hypotonic: Solution with less solute and more water. Cellexpands
Isotonic Solution: Equal solution. No net movement of water. Cell stays the same.

3. Stages of Cell Cycle
Cell cycle: Set of stages that take place between the time a cell divides and the time the resulting cells also divide.
Interphase: Most of the cell cycle is spent in this stage.
* G1: GROWTH. Occurs before DNA synthesis. The organelles are doubled.
* S stage:GROWTH AND DNA REPLICATION. Includes DNA synthesis. The result is each chromosome with two identical DNA molecules, composed of two sister chromatids.
* G2: GROWTH AND FINAL PREPARATIONS FOR DIVISION. Occurs after DNA synthesis. Synthesis of proteins needed for cell division.

4. Types of RNA and functions.
* mRNA: Copies genes.
* tRNA: brings correct amino acids in proteinsynthesis.
* rRNA: makes the ribosome.
5. Describe process of DNA replication and protein synthesis
DNA Replication: DNA replicates itself. Happens before mitosis and meiosis. DNA is made of two strands composed of nucleotides. Each chromosome is one molecule of DNA
Transcription (txn): Making mRNA strand from DNA. Happens in the nucleus.
* Backbone made of sugar (deoxyribose) andphosphate.
* Bases: Adenine, Thymine, Guanine, Cytosine.
* DNA opens, and makes a copy of RNA from only one strand of DNA. RNA pairs with DNA in a process called complementary base paring.
U – A
G – C
A – T
C – G
* DNA has no change after the RNA is copied. It only goes back to place.
* mRNA is made. It leaves nucleus.
* Every RNA is madewith transcription
Translation: Making a protein with mRNA. Happens in the Ribosome.
* Uses the ribosome. RNA attaches to the small subunit of it.
* Ribosome is made of rRNA and protein.
* tRNA: Imports the proteins.
* Codon: three nucleotides long on the mRNA and attaches to the tRNA which has the amino acids. When amino acids are paired, the tRNA leaves and another comes andpairs.
* tRNA brings the correct amino acid to be paired.

6. Definitions:
* Diploid number: Twice the number of chromosomes found in the gametes.
* Haploid number: Half the diploid number; the number characteristic of gametes that contain only one set of chromosomes.
* Somatic cells: A body cell; excludes cells that undergo meiosis and become sperm of oocyte.
*Gametes: Haploid sex cell; an oocyte or a sperm that joins during fertilization to form a zygote.
* Mitosis: Type of cell division in which daughter cells receive the exact chromosomal and genetic makeup of the parental cell; occurs during growth and repair.
* Meiosis: Type of nuclear division that occurs as part of sexual reproduction in which the daughter cells receive haploid number of...
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