• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Nucleic Acids and Proteins Exam Prep. Notes

Extracts from this document...

Introduction

Topic 7 – Nucleic Acids and Proteins 7.1 – DNA Structure 7.1.1 Describe the structure of DNA, including the antiparallel strands, 3’–5’ linkages and hydrogen bonding between purines and pyrimidines. ï At one end of each strand is a phosphate linked to carbon atom 5 of deoxyribose. This is the 5’ terminal. ï At the other end of the strand is a hydroxyl group attached to carbon atom 3 of deoxyribose. This is therefore the 3’ terminal. ï There are two hydrogen bonds between adenine and thymine and three hydrogen bonds between guanine and cytosine. Pyrimidine = thymine and cytosine; Purines = guanine and adenine. 7.1.2 Outline the structure of nucleosomes. Nucleosomes ï In Eukaryotes, the DNA is associated with proteins to form nucleosomes – globular structures that contain eight histone proteins, with DNA wrapped around. Another histone protein bonds the structure together. In an interphase nucleus in eukaryotes the DNA resembles a string of beads. ï Prokaryotes have naked DNA because there are no histone proteins. 7.1.3 State that nucleosomes help to supercoil chromosomes and help to regulate transcription. Nucleosomes have two functions: They help to package up the DNA during mitosis and meiosis by the process of supercoiling. They can be used to mark particular genes, either to promote gene expression by transcription and translation, or to cause silencing of a gene by preventing transcription. ...read more.

Middle

7.2.2 Explain the process of DNA replication in prokaryotes, including the role of enzymes (helicase, DNA polymerase, RNA primase and DNA ligase), Okazaki fragments and deoxynucleoside triphosphates. Leading strand: DNA replication takes place towards the replication fork. Lagging strand: DNA replication takes place away from the replication fork. 7.2.3 State that DNA replication is initiated at many points in eukaryotic chromosomes. The rate of replication in fruit flies (Drosophila) is 2600 nucleotides/minute. The largest chromosome of Drosophila is 6.5 x 107 nucleotides. If DNA replication started at both ends of the chromosome, it would take 8.5 days to replicate the chromosome. In fact, it only takes 3- 4 minutes. In order to explain this discrepancy, scientists have determined that replication must start at many points along the same DNA helix at the same time. This process is needed in eukaryotic cells because they have very large amounts of DNA, which would take much longer to replicate if replication was done from one end of the chromosomes to the other. 7.3 Transcription 7.3.1 State that transcription is carried out in a 5? ? 3? direction. Transcription is the enzyme-controlled process of synthesizing RNA from a DNA template. It is carried out in a 5? to 3? direction (of the new RNA strand). This means that new RNA nucleotides are added to the 3? end of the growing RNA strand. ...read more.

Conclusion

Termination Initiation mRNA binds to the small sub-unit of the ribosome ribosome slides along mRNA to start codon anticodon of tRNA pair with codon on mRNA complementary base pairing between codon and anti-codon anticodon of tRNA with methionine pairs with start codon/AUG is start codon second tRNA pairs with next codon Elongation Peptide bond forms between amino acids Ribosome moves along the mRNA by one codon Movement in 5? to 3? direction tRNA that has lost its amino acid detaches Another tRNA pairs with the next codon/moves to A site tRNA activating enzymes Link amino acids to specific tRNA 3. Termination 7.4.4 State that translation occurs in a 5? ? 3? direction. During translation, the ribosome moves along the mRNA towards the 3? end. The start codon is nearer to the 5? end. There are 3 stop codons. 7.4.5 Draw and label a diagram showing the structure of a peptide bond between two amino acids. 7.4.6 Explain the process of translation, including ribosomes, polysomes, start codons and stop codons. Codon: three consecutive bases in DNA (or RNA), which specify an amino acid. Anticodon: three consecutive bases in tRNA, complementary to a codon on RNA. 7.4.7 State that free ribosomes synthesize proteins for use primarily within the cell, and that bound ribosomes (in RER) synthesize proteins primarily for secretion or for lysosomes. 7.5 Proteins 7.5.1 Explain the four levels of protein structure, indicating the significance of each level. The bonds in a tertiary structure form between R groups. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Biology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Biology essays

  1. DNA Structure questions. Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and ...

    According to the base pair rule, the opposite complementary bases attract to one another which is why DNA nucleotides can be linked together into a single strand (Bowen 1).

  2. Genetics NOTES

    Haploid cells, however, are those which contain one type of chromosome, an example can be sperm cells - Mitosis: This is when each body cell reproduces and duplicates their chromosomes. This process occurs inside body cells - Meiosis: This is when a sperm cell meets a female egg; the resulting cell will have the correct number of chromosomes.

  1. Penicillin - its discovery, properties and uses.

    Wallace Herrell of the Mayo Clinic in Minnesota immediately started research into drugs after the news reports out. Also, few American drugs companies also began to do some preliminary research. Dr. Selman Waksman, a soil biologist at Rutgers University, convinced scientists there to look into penicillin.

  2. IB Biology notes on infection and the body's responses.

    antibody: a protein produced by the human body that is specific to a particular antigen (as a lock is for a key or vice versa) i. antibodies may make the antigen-carrying pathogen more recognizable to phagocytic cells, bind to viruses and prevent them from invading a host cell or cause agglutination/clumping of antigen-infected cells Here is an animation: http://glencoe.mcgraw-hill.com/sites/0035456775/student_view0/chapter33/the_immune_response.html C.

  1. IB Genetic Unit Notes

    They occur in a diploid cell, contain the same sequence of genes, but have come from different parents. 4.3.4: Outline the process of meiosis, including pairing of homologous chromosomes and crossing over, followed by two divisions, which results in four haploid cells.

  2. Experimental Design Notes

    to represent the population of all bean plants * Need to get a representative sample * Statistics: o helps sample small portions of habitats, communities, biological populations to draw conclusions about the larger population o Measures differences of the relationships between the sets of data o Compare small populations of bean plants in sunlight vs.

  1. Biology - Observing the Process of Guttation

    I obtained six containers, each with a diameter of 10cm and height of 15cm. Next, I placed the divided portions of soil into each of the containers. 4. I labeled the containers with a permanent marker. Container labels were: A, B, C, D, E, F.

  2. Genes of fruit fly practical write up

    Black coloured body and Ebony coloured body are the only two coloured body crosses that aren't affect by sex. i.e. a particular gender doesn't drop out that has a particular set of genes. This is probably due to the fact that this cross is more stable in that it doesn't have any diseases associated with it.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work