Summary
Summary DNA - Code of life - Life Sciences
Summarised notes on Matric DNA - Code of Life from the Mind Action series Life Science textbook.
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Content preview
Dna - The Code of LifeNucleic acids are the molecules of life
They control synthesis of protein which make up the structure of the body but (as enzymes) control chemical
processes in cells
2 nucleic acids:
1. Deoxyribonucleic acid (DNA)
2. Ribonucleic acid (RNA)
Deoxyribonucleic Acid - DNA
Discovered by:
- Maurice Wilkins
- Rosalind Franklin
- Francis Crick
- James Watson
Location
- Found mainly in the nucleus where it forms part of the chromosomes in chromatin network
- DNA is coiled to fit in nucleus with ± 2 metres in each cell
- Extranuclear DNA: DNA found in mitochondria (plants & animals) and chloroplasts (plants only)
Structure
- Long, twisted ladder to form double helix
- DNA is a polymer made up of nucleotides (monomers)
- Each nucleotide is made up of
- Sugar molecule - deoxyribose
- Phosphate molecule
- nitrogenous bases
- Adenine
- Thymine
- Guanine
- Cytosine
- The bases are the foundation of the genetic code instructing cells on how to synthesise enzymes &
proteins
, How the double helix is made up
- 2 outer strands formed by chain of alternating sugar/phosphate links with strong bonds
- Rungs of the ladder are from pairs linked by weak hydrogen bonds
- Base pairs attached to sugar molecules
Base pairing
- Shape & size differ so that:
- Adenine will bond with thymine or uracil (RNA) by 2 hydrogen bonds
- Cytosine will only bond with guanine by 3 hydrogen bonds
Classification
- 2 groups: purines & pyrimidines
- Purines: 2 fused rings of nitrogen, carbon & hydrogen atoms. (G & A)
- Pyrimidines: 1 ring of similar atoms therefore small than purines (T, C & U)
- Bases are made of 1 pyrimidine & purine
- Four nucleotides are the same in all organisms difference comes in the sequence of them
- If the sequence is the same then identical organisms
- Therefore the sequence of nucleotides determines the genetic code of an organism
Role of DNA
- Carry hereditary info in cells in the form of genes
- Provide blueprint for coding of protein synthesis
- Replicate to pass on genetic info to daughter cells during mitosis
Non-coding DNA
- Less than 2% of DNA codes the rest is non-coding DNA
- Protein-coding is aka exons which is interrupted by introns (non-coding)
- Complex organism have more introns than less complex organism
- Intron regions were thought to be ‘evolutionary junk’ but now are known to form functional RNA
molecules which have functions
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller bonolomuvunyi. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R50,00. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
58716 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy summaries for 15 years now