Study and Master Life Sciences Grade 12 CAPS Study Guide
Summaries for grade 11 and 12 students. Summarised text which is still detailed and not missing any information. Includes the discovery of DNA (Rosalind Franklin etc), DNA/RNA structure, functions, DNA replication, protein synthesis etc. Includes diagrams to illustrate concepts, and informative det...
Summary notes on the Human reproduction system (Life sciences)
Biology( Life Sciences) Class notes: Nucleic acids(DNA and RNA)
Human Nervous System- Matric NSC Gr 12
All for this textbook (6)
Written for
12
Life Sciences
200
All documents for this subject (407)
Seller
Follow
callivarikas
Content preview
Life at molecular,
cellular and tissue level
Page 1 of 10
,Introduction to nucleic acids
Called the molecules of life
Function of nucleic acids
Nucleic acids store the information that controls cellular activity and the development of an entire
organism. They do this by controlling the synthesis of proteins (see protein synthesis later)
Because enzymes are proteins, they control chemical processes inside cells and ultimately control the
structure and functioning of all living organisms.
Deoxyribose nucleic acids (DNA)
Background information
The discovery of DNA
- London, early 1950’s
- Maurice Wilkins and Rosalind Franklin looked using xray crystallography (diffraction images of DNA)
- At the same time, Francis Crick and James Watson analysed Franklin’s data and arranged a twisted ladder model
(double helix)
Genetic replication discovery
- Watson and Crick developed ideas about genetic replication, including
- Pairing of bases
- Triplet code used in reading material (Crick and Sydney Brenner)
- ^^ Proved DNA molecules can replicate (exact copies) and carry genetic instructions
- The noble prize given to Wilkins, Crick and Watson (Franklin died of cancer when she was 37)
The DNA molecule
Where is DNA?
Found mainly in the nucleus
Molecule is piled so that it can fit inside the nucleus
Forms an important part of chromosones that make up the chromatin network
*Chromatin: chromosomal material made of DNA & histone proteins as found in a non dividing cell
Extranuclear DNA
Small amounts of DNA found outside the nucleus in mitochondria (in plants and animals) and chloroplasts
(in plants)
How is DNA made up?
Long twisted ladder shape
3D double helix
A DNA molecule is a long chain (polymer) made up of small units (monomers)
The monomer of a DNA molecule is a nucleotide, each nucleotide is made of:
• sugar molecule - deoxyribose (deoxy-2 oxygen) (S)
• phosphate molecule (P)
• nitrogenous base which can be:
- adenine Remember
- thymine Apples in the Tree
- guanine Cars in the Garage
- cytosine
*Monomers: Like building blocks, small units that make up polymers
Page 2 of 10
, Nitrogenous bases
- The nitrogenous bases are the foundation of the genetic code. Them and their order instruct cells on
how to synthesise proteins.
- As there are 4 nitrogenous bases, there are four different nucleotides.
- 4 nucleotides are the same in all animals and plants
- Nucleotides join by condensation (removal of a water molecule)
2 groups of nitrogenous bases - purines and pyrimidines
Purines
→ Made of 2 fused rings (nitrogen, carbon, hydrogen atoms) eg. guanine and adenine
Pyrimidines
→ Made of one ring of similar atoms, therefore smaller than purines eg. thymine, cytosine and uracil (see
RNA for uracil)
A base pair is made up of one pyrimidine and one purine
1) thymine and adenine, 2 hydrogen bonds
2) cytosine and guanine, 3 hydrogen bonds
Purine and pyrimidine similarities
• Both made of N,C,H
• Both made of rings
The structure of DNA
The double helix
- outer 2 strands formed by chain of alternating sugar/phosphate links, for which the bonds are strong
- rungs of ladder → base pairs (GC, AT), for which bonds are weak, hydrogen bonds
- base pairs attached to sugar molecules
How do organisms differ?
The difference is the sequence of nucleotides, which determines the genetic code of an organism.
What is the role of DNA?
1. Carry hereditary information in the form of genes
2. Provides blueprint for organisms growth by coding for protein synthesis (see later)
3. Can replicate, so that copies of genetic info can be passed down
However, only 2% of DNA actually codes for proteins
The other 98% is non-coding
Protein coding regions are called axons
^ Interrupted by non coding regions called introns
Complex organisms have much more non-coding DNA than simple
Non-coding DNA form functional RNA molecules with regulatory functions
Page 3 of 10
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 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 these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller callivarikas. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.40. You're not tied to anything after your purchase.
