Biology - Combined Science

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Bacterial Cell

Bacterial Cell:

Chromosomal DNA - Controls activites and replication

Ribosomes - Transaltion of Genteic Material (synthesis of proteins)

Cell Membrane -  Holds cell together controls what is in and out

Plasmind DNA - Small loops of extra DNA contain genes for drug resistance 

Flagellum - Long hair which helps the bateria move

LINK TO GENTIC MODIFICATION

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Egg + Sperm Cells (Specialised Cells)

Egg Cell : carries female DNA and nourish embryo

- Contains Nutrients in the cytoplasm to feed embryo

- Haploid nucleus

- After fertalisation membrane changes structure to stop more sperm entering to get enough DNA

Sperm Cell : Transports male DNA to female's egg

- Long tail to swim to egg

- Mitochondria to provide energy for respiration to swim

- Acrosome stroes enzymes to digest into egg cell

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Microscopy

Light Microscopes: Passes light through the specimen to see nuclei and chloroplasts 

Electron Microscopes: Higher Magnification and resolution so you can see much smaller things in detail e.g. internal structure 

Drawing of specimen:

- use a sharp pencil

- Label important features

- Include scale and magnification size 

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CORE PRACTICAL - Microscopy

Core Practical: Investigate biological specimens using microscopes, including magnification calculations and labelled scientific drawings from observations

Total magnification = eyepiece lens X objective lens magnification

e.g. total magnification = 40 eyepice lens = x10 40 x 10 = 400 

Magnification = Image Size / Real Size

e.g. Specimen is 5 x 10-6 wide calculate the width of the image under a magnification of x100

image size = magnification x real size

image size = 100 x ( 5 x 10-6 m)

= 100 x 0.0000005 m

= 0.00005 m

= 5 x 10-4m

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Enzymes

Catalysts Produced by living things

Only work with one substrate - Lock and Key mechanism 

The active site can become denatured if the temperature increases

Low or High PH cannot denature the enzyme only temperature

Changing the temperature changes the rate of a catalysed reaction

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CORE PRACTICAL - Enzyme Activity

Core Practical: Investigate the effect of pH on enzyme activity

Amylase catalyses the breakdown of starch. Starch is detected using iodine

Process : (  control variables each time - concentration and volume of amylase) for a fair test

1) Drop of Iodine into each well in a spotting tile

2) Put a beaker of water on a bunsen burner and heat the water up to 35°

3) In a syringe add amylase solution and buffer solution with PH 5 to the beaker and wait 5 mins

4)  add starch solution to the boiling tube. Mix the solution and start a stop clock

5) Use a continuous sampling and record how long it takes the amylase to break down the starch very 10 seconds take a new sample

6) If the Iodine solution remains orangey brown, starch is no longer present

7) Repeat with different ph values and see how PH affects the time taken to break down starch

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Enzymes in Breakdown and Synthesis

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