domingo, 18 de septiembre de 2011

Biology - Chapter 7 Notes

 Chapter 7
Section 1
The first person to record looking at water under a microscope was Anton van Leeuwenhoek. Compound light microscopes use a series of lenses to magnify objects in steps. These microscopes can magnify objects up to 1500 times.
Robert Hooke was an English scientist who lived at the same time as Leeuwenhoek. Hooke used a compound light microscope to study work, the dead cells of oak bark. Cells are the basic building blocks of all living things. Schwann was the first to observed animal cells, while Schleiden was the first to observe plant cells. 
The cell theory says that: 1. All organisms are composed of one or more cells. 
        2. The cell is the basic unit of organization of organisms.
        3. All cells have to come from preexisting cells.
The electron microscope was invented in the 1940’s. It uses a beam of electrons to magnify structures up to 500 000 times their actual size. There are two basic types of electron microscopes: SEM (scanning electron microscope - surface of the cell) and TEM (transmission electron microscope - structures within the cell).
Cells that do not contain internal membrane-bound structures are called prokaryotic cells. (no “true” nucleus). It is made up by: Ribosomes -make proteins, only organel-, DNA, plasma or cell membrane and cell wall. 
Cells containing membrane-bound structures are called eukaryotic cells. It is made up of the nucleus, nucleolus, chromosomes (DNA), plasma membrane and organelles. Most of the multi-cellular plants and animals we know are made up of cells containing membrane-bound structures and therefore called eukayotic. 

Plasma membrane: selectively permeable membrane.
Cell wall: outside cell membrane - support and protection 
Nucleus: control center of the cell - control DNA
Chromatin: DNA and protein... become chromosomes when the cell is about to separate
Nucleolus: produces ribosomes
Nuclear envelope: double layer of lipid... around the nucleous
ER: site of chemical reactions; makes proteins, lipids and metabolyzes carbohidrates
Golgi appartus: packages, sucretes and sends proteins in vesicles
Vacuole: stores temporarily materials (plant larger.. more water - animal smaller)
Lysosomes: are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles and engulfed viruses or bacteria.
Chloroplast: transforms light energy to chemical energy (glucose)... -Photosynthesis is the process... chlorophyll traps light and is green-.
Plastids: organelles used for storage and found in plants (leucoplasts: store starch, are found in potatoes and apples)
Mitochondria: transforms glucose to ATP, process is called cellular respiration
Cytoskeleton: tubules (back and forth) and filaments (bones)
Cillia and flagella: aid in locomotion or feeding; found in some mouths... Cillia short hairs, flagella long hairs: it’s like a whip
Cell walls: Plant (made of cellulose), fungi, some protest, bacteria; animals DON’T HAVE CELL WALLS
Note: Folds of the inner membrane used to provide greater efficency in the mitochondria are called cristae

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