Nucleic Acids (DNA)

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  • Created by: Ruhab21
  • Created on: 14-09-20 19:48
State what is the function of DNA?
It gives the genetic code for Protein Synthesis
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Describe the structure of DNA (2 marks)
1) Contains double strands that form a double helix 2) Contains a pentose sugar a phopshate group and a nitrogenous base
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Suggest the functions of a phosphate backbone?
1) Protects genetic info within the bases 2) Forms a polynucleotide
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How many bonds to the Purines and Pyrimidines have and what is a good way to remember these
Purine has three hydrogen bonds but Pyrimidines have three and good way to remember is Thymine begins with T so will be two
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Where does DNA Replication takes place in and when
It takes place in the nucleus and occurs in interphase
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State what is Conservative Replication?
1) Parent DNA remains the same 2) Newly Synthesised Molecule Produced
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State what is Semi-Conservative Replication?
1) Parent DNA splits into two strands and each strand acts a template strand 2) 1 Parent DNA + 1 Newly Synthesised is made
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State what is Dispersive Replication?
1) Parent DNA is fragmented 2) New Molecule has Fragment Parent DNA and Fragment Newly Synthesised Strand
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Suggest why E.coli is used ?
This is because easy to culture and DNA is not in nucleus
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Describe the experiment of Meselson-Stahl Experiment
1) E. coli grown in medium with 15N heavy isotope 2) DNA extracted and centrifuged 3) Bacteria washed and transferred to lighter isotope 14N medium and extracted and centrifuged 4) Bacteria divide again and CENTRIFUGED AGAIN!!!
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Explain why Conservation and Dispersion Replication were not considered in experiment?
1) Conservation wouldn't give a band at the middle 2) Dispersive had only a single band that just goes higher up
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Describe what happens in Semi Conservative Replication in the experiment
1) 15N is heavy 2) 14 and 15N have one heavy and light band 3) 14N is lighter so goes to the top and 15N stays in middle
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What does mRNA do?
Carries genetic code from nucleus to ribosomes
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What does tRNA do?
Transfers specific amino acids to ribsome
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What does rRNA do?
Forms a large complex molecule like polypeptides
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Suggest what Hypothesis does a Gene support?
One gene- One polypeptide hypothesis
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How many triplet codons and amino acids in our body
64 triplet codons and 20 amino acids
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Now Explain why there are more codons than amino acids?
Because more than one codon codes for one amino acid 2) Some codons don't even code
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Suggest what does Universal Gene means
Same triplet codes for same amino acids
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Describe Transcription ? (3 marks) Pt.1
1) DNA unwinds by DNA helicase by breaking Hydrogen Bonds 2) Each Strand is used as template 3) Free RNA Nucleotides form complementary bases with the template strands through Hydrogen Bonding.
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Describe Transcription ? (2 marks) Pt.2
4) RNA Polymerase catalyses the condensation reaction and joins the nucleotides together at 5 to 3 prime end. 5) Phophate sugar backbone is formed between the phosphodiester bonds and mRNA leaves the nuclear pore as pre mRNA
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Suggest when does RNA Polymerase stop catalysing condensation reactions to form Hydrogen Bonds
When a stop codon is REACHED!!!
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What does Enzyme removes Introns and what Enzyme splices Exons together
Endonuclease removes Introns and Ligase splices Exons
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Describe Translation? (3 marks) Pt.1
1) mRNA arrives at Ribosome 2) Attaches to small sub unit of Ribosome 3)tRNA with anti-codons binds to codons which are complementary and forms codon-anticodon complex and each tRNA have a specific amino acid
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Describe Translation? (3 marks) P.t 2
4) Second tRNA does the same at the second codon 5) Ribosomal Enzyme forms peptide bonds between amino acids 6) Ribosome moves along mRNA strand and stops at a stop codon and protein is FORMED!!!!!!!
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Suggest what is a Polysome?
SEVERAL ribosomes move along mRNA at once so many polypeptides are made
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Suggest what happens soon to the polypeptide made?
Golgi Body modifies and packages proteins
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State what is a Primary Structure Protein?
The no. and sequence of amino acids in a polypeptide chains
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State what is a Secondary Structure Protein?
The folding of amino acids that form Alpha helices and Beta Pleated Sheets
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State what is a Tertiary Structure?
EVEN MORE FOLDS into a more complex 3D Structure
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State what is a Quaternary Structure?
Made up of 3 or more polypeptides and can be globular proteins
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Suggest why is ATP the universal energy currency
Because it is the source of energy for ALL cells and ALL chemical reactions. It is released as small packets
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State uses of ATP
1) Metabolic Process by making large molecules from small ones 2) Active Transport because ATP changes shape of carrier proteins
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What are the advantages of ATP
1) Only one enzyme is needed for energy release 2) Easily transported across membranes
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Suggest why the total energy released from an exergonic is not available for an endergonic reaction
Energy lost as HEAT!!!
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Other cards in this set

Card 2

Front

Describe the structure of DNA (2 marks)

Back

1) Contains double strands that form a double helix 2) Contains a pentose sugar a phopshate group and a nitrogenous base

Card 3

Front

Suggest the functions of a phosphate backbone?

Back

Preview of the front of card 3

Card 4

Front

How many bonds to the Purines and Pyrimidines have and what is a good way to remember these

Back

Preview of the front of card 4

Card 5

Front

Where does DNA Replication takes place in and when

Back

Preview of the front of card 5
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