OCR Biology A2 (Unit 2) Processes 1

  • Created by: MJ
  • Created on: 02-06-13 14:14
Transcription (DNA unzips)
A gene to be transcribed unwinds and unzips by the hydrogen bonds between complementary bases of the template strand and coding strand break. The template strand dips into the nucleolus.
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Transcription (Transcribing)
U/A C/G base pair rule when activated RNA nucleotides H bind to complementary bases on template strand. This catalysed by RNA polymerase.
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Transcription (Binding)
The adjacent nucleotides bond when the two extra phosphyrll groups are released.
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The product of transcription
A strand of mRNA identical to the coding strand's base sequence and complementary to the template strand. mRNA is released through nuclear pore to ribosome in cytoplasm.
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Translation definition
2nd stage of protein sythesis where amino acids are assembled into polypeptide according to sequence of base pairs on mRNA.
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Translation `(Binding and exposure)
A molecule of RNA binds to a ribosome, six bases (two codons) bind to to the small subunit of the ribosome and are exposed to the large subunit. The first exposed codon is ALWAYS AUG!
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Translation (Amino acid retrieval)
AUG's complementary anti codon is UAC. A tRNA with a UAC anticodon forms hydrogen bonds with the complemtary AUG. The amino acid methoinine is joined at the other end of the tRNA. This requires ATP and an enzyme.
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Translation (Peptide bonds)
A second tRNA binds to the second exposed codon with a different amino acid. An enzyme in the large subunit catalyses the formation of a peptide bond between the adjacent amino acids.
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Translation (Ribosome movement)
The ribosome moves to read the next codon, a third amino arrives and binds with the dipeptide. The first tRNA (which brought methionine) leaves and is able to collect more methionine. This continues until a STOP codon is read (UAA, UAC, UGA)
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The Sliding Filament Model (The Power stroke)
Myosin heads attach to the surrounding actin filaments forming a cross bridge, the head bends causing pulling of the actin filament in (more overlap). ADP + Pi are released/
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The Sliding Filament Model (Back to normal)
ATP attaches to the myosin head, breaking the cross bridge. The head moves backwards as the ATP is hydrolysed to ADP and Pi. The head can bind to the filament further along and bend again.
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The Flight or Flight Response: The Brain
The cerebral cortex of a threat activates the hypothalamus which activates the sympathetic nervous system and releases CRF (corticotrpin releasing factor) which stimulates the pituitary gland.
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The FoF Response: The sympathetic nervous system
Activates the adrenal medulla and its impulses activate glands and smooth muscles
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The FoF Response: CRF
Stimulates the pituitary gland into releasing Adreno-corticotropic hormone (ACTH) from the anterior pit gland.
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The FoF Response: ACTH
arrives at Adrenal cortex and releases 30 hormones (corticosteriod), some of which help the body resist stressors
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The FoF Response: The Adrenal medulla
Releases adrenaline and noradrenaline into the bloodstream
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The FoF Response
Combines neural activty with hormones to constitute FOF response!
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Artificial Selection: The Dairy Cow
Each cow's milk yield measured, recorded. Progeny of bulls tested to find ones with high milk yielding daughters, only a few kept as sperm can artificially inseminate many cows. Elite cows giving egg multplying hormones. Eggs fertilised in vitro.
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(2)
Embryos planted in surrogate mothers, which can be cloned and divided into many more embryos
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Artificial selection: Triticum aestivum
Wild einkorn is domesticated and artificially selected to change phenotype, but not chromosome number. This creates Einkorn, which has 14 chromosomes, so 2 copies of each, 7=n
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Artificial selection: Triticum aestivum 2
Einkorn (Au Au) is bred with a wild grass (EG T.Turgidum, a tetraploid) This creates a sterile hybrid P
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Artificial selection: Triticum aestivum 3
Mutation causes the chromosome number to mutate from 14 to 28, so 4 sets of 7 - AuAu BB - Emmer Wheat
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Artificial selection: Triticum aestivum 4
The Emmer wheat is bred with goat grass (DD, such as Ae,Tauschii) producing Sterile hybrid Q, with a double chromosome number - 42 (6n) ( AuAuBBDD
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Sequencing and Copying DNA - Automated DNA Sequencing
Mixture contains DNA polymerase, DNA nucleotides, copies of the template single DNA strand (to be copied) modified free DNA nucleotides and primers
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2
The primer anneals (H bonds, comp. base) at the 3' end of template strand, allowing DNA polymerase to attach and add free nucleotides according to BP rules (AT GC)
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3
If a modified nucleotide (with a florescent marker) is added, the polymerase is thrown off and the reaction stops on that template strand causing generation in size of DNA. Each DNA has a different coloured end.
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4
A laser reads the colour sequence of each DNA sequence, from the shortest to the longest, when read/aligned together, the base sequence can be read.
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Coordinated movement (1)
Impulses arriving at neuromuscular junction cause vesicles to fuse with presynaptic membrane and release acetylcholine into gap which then binds to receptors on muscle fibre membrane (sarcolemma) causing depolarization
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2
Depolarisation travels down tubules (T system) and causes Calcium release from stores in sarcoplasmic reticulum. Ca2+ binds to proteins in muscles, causing contraction.
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3
Acetylcholinesterase in gap rapidly breaks down acetylcholine so that contraction only occurs when impulses arrive continuously
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Other cards in this set

Card 2

Front

U/A C/G base pair rule when activated RNA nucleotides H bind to complementary bases on template strand. This catalysed by RNA polymerase.

Back

Transcription (Transcribing)

Card 3

Front

The adjacent nucleotides bond when the two extra phosphyrll groups are released.

Back

Preview of the back of card 3

Card 4

Front

A strand of mRNA identical to the coding strand's base sequence and complementary to the template strand. mRNA is released through nuclear pore to ribosome in cytoplasm.

Back

Preview of the back of card 4

Card 5

Front

2nd stage of protein sythesis where amino acids are assembled into polypeptide according to sequence of base pairs on mRNA.

Back

Preview of the back of card 5
View more cards

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