Biology revision

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  • Created by: Emily:)<3
  • Created on: 07-12-12 09:41

RESOLUTION//MAGNIFICATION

The ability to see two distinct points ans seperate from eachother.                                   

The number of times greater an image is than the object.

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Scanning electron microscope//Transmission electro

SEM-electrons bounced off sample//3D image of surface//x100 000

TEM-electrons pass through denser parts of sample//2D image//x500 000

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MOVEMENT AND STABILITY IN CELLS.

Cytoskeleton-network of protein fibres to keep the cells shape//internal framework

Microtubules-protein called tubulin

Flagella(undulipodia) cilia-hair like extentions of cell//tail of sperm cell--moves the whole cell//cilia move substances across the surface of cells.

ENERGY FROM ATP USED.

Vesicles-membrane bound sacs//carry substances 

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GOLGI APPARATUS+MITOCHONDRIA

Golgi=Recieves proteins from ER and modifies them. Packages and modifies proteins into vesicles for transport. 

 

Mitochondria=ATP produced here during respiration.

ATP-energy carrier//nearly all activities that need energy in the cell are driven by ATP.

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CHLOROPLAST+LYSOSOMES+RIBOSOMES+CENTRIOLES

CHLORO-site of photosynthesis//carbohydrate molecules are made from carbon dioxide and water.

Lysosomes-Contain powerful digestive enzymes//breakdown of materials//E.G- WBC lysosomes breakdown invading microorganisms.

Ribosomes-site of protein synthesis//new proteins are made//coded information ~mRNA~ from nucleus is used to assemble proteins from amino acids

Centrioles-take part in cell division//form fibres known as spindle//move chromosomes during nuclear division.

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DIVISION OF LABOUR.

1. mRNA exits nuclear envelope through nuclear pore.

2.mRNA attaches to ribosome on ER and forms protein.

3. Vesicle is pinched off and travels towards golgi apparatus

4.Golgi apparatus modifies and packages molecules-pinched off in vesicle.

5.Vesicle fuses with cell surface membrane

6. Cell surface membrane opens to release insulin molecules outside of cell.

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Prokaryotes and Eukaryotes.

Eukaryotes-true nucleus

Prokaryotes-no membrane bound organelles

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PHOSPOLIPID BILAYER.

  • Phosphate group head=Hydrophillic//Fatty acid tails=Hydrophobic
  • If phospholipid molecules are surrounded by water completely a bilayer can form.
  • FLUID MOSAIC MODEL-Phospholipid molecules can move freely//the hydrophobic tails are held away from the water molecules//provides stability without bonding of molecules.
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FLUID MOSAIC MODEL.

Glycoproteins/Glycolipids-Cell communication//signalling

Channel proteins-allows the movement of some substances across the membrane

Carrier proteins-actively move some substances across the membrane.

Cholesterol-provides stability.

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HIGH/LOW WATER POTENTIAL BEFORE/AFTER IN CELLS.

High water potential solution-animal cell becomes haemolysed//plant cell turgid.

Low water potential solution-animal cell crenated//plant cell plasmolysed.

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MITOSIS///PMAT.

1. Prophase-nuclear envelope breaks down//DNA condenses into chromosome-visible//double structure=pair of chromosomes joined at centromere.

2. Metaphase-Alignment in equator//attached to spindle//no nuclear envelope.

3. Anaphase-contraction of spindle//pull apart chromatids-form chromosomes//each pair to each pole.

4.Telophase-nuclear envelope reforms around the 2 sets//chromosomes unravel-no longer visible.

5. Cytokinesis-Membrane pinches across middle of cell//proteins attached to inner surface of membrane//contraction until cell divides completely.

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Homologous chromosomes.

One from father, one from mother.

Sames genes and locus//different or same alleles//same shape and size.

Daughter cells that are produced will have 23 homologous pairs--46 chromosomes in total.

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