MYTUTOR SUBJECT ANSWERS

593 views

How does DNA code for proteins?

What is DNA? DNA is the chemical used to store genetic information (inherited traits and characteristics) in the body.  The shape of DNA is a double helix (two complementary chains, interwoven).  Every chain has four seperate components; 'bases' or 'nucleotides'.  The bases are Adenine (A), Thyamine (T), Cytosine (C) and Guanine (G).  Certain bases on one chain can only pair with certain bases on the other chain: A can only pair with T (A-T), C only with G (C-G).  The order in which these base pairs are linked together determines the DNA sequence.  Sequencing enables massive amounts of information to be stored simply in a small space.

Proteins? They are structures made from amino acids that are key to functioning in all cells in the body.

How do you get from DNA to proteins? Unique sequences of DNA are called genes.  Genes can be read to form proteins.  This is done by two main processes; transcription and translation.  

What is transcription? It is the synthesis of RNA from a DNA sequence.

What is RNA? RNA is a chemical used to transfer genetic material inside a cell.  It is a very similar compound to DNA; it has just one base different (Uracil instead of Thyamine).  Like Thyamine in a DNA strand, Uracil can only pair with Adenine (A-U) in a RNA strand.  There are many types of RNA.  Messenger RNA (mRNA) and Transfer RNA (tRNA) are used to help make proteins.  RNA is synthesised in the nucleus of the cell.

How does transcription work? One of the DNA strands is used as a template (remember two strands bound together to form a double helix).  The strands of DNA are unzipped during transcritpion and then zipped back up again afterwards.  RNA uses the DNA template to match its bases corresponding to the DNA ones, to form a mRNA chain.  (You could think of transcription like in music, where you transcribe a piece/sound of music into a notation on page, or in linguistics where you take sign language and write it down in text).

And translation? This is the process in which a mRNA  strand is read in order to form a sequence of amino acids (a polypeptide chain).  The mRNA strand is transported out of the nucleus and into the cytoplasm of the cell. Translation in the cytoplasm prevents damage to the DNA in the nucleus. The process occurs with the help of a ribosome.

How exactly does it work? A certain three bases of a mRNA chain forms a 'codon'.  To code for an amino acid, the codon must be read by tRNA.  Three complementary tRNA bases is called an 'anti-codon'. Codons match with anti-codons. Certain anti-codons have certain amino acids attached to them.  For example UAC has tyrosine.  So when multiple mRNA codons complement with multiple tRNA anti-codons, the amino acids attached can bind together to form an amino acid sequence.  The ribosome facilitates this process. (You could think of translation like studying a foreign language, translating French into English).

How do you form a protein? A chain of amino acids or 'polypeptide chain' can be further shaped and packaged in the rough endoplasmic reticulum of a cell to form a protein.

Patrick G. GCSE Biology tutor, A Level Biology tutor, GCSE Chemistry ...

1 year ago

Answered by Patrick, an A Level Biology tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

174 SUBJECT SPECIALISTS

£26 /hr

Sohini C.

Degree: Medicine,MBBCh (Bachelors) - Cardiff University

Subjects offered:Biology, Science+ 3 more

Biology
Science
Maths
-Personal Statements-
-Medical School Preparation-

“Hi, I'm Sohini. I'm a fourth year medical student at Cardiff uni and keen to help students with Science and Maths GCSE subjects. I can also help with medical school applications, especially personal statements and interviews. ”

£20 /hr

Odette F.

Degree: Biological Sciences (Bachelors) - Exeter University

Subjects offered:Biology, Geography+ 1 more

Biology
Geography
-Personal Statements-

“ABOUT ME: I am a 2nd Year Biology Student at the University of Exeter. Science as a whole, is a subject I am hugelyenthusiastic about and I would love to share this eagernesswith you! Having spent some of my Gap Year teaching abroad, I...”

£22 /hr

Samuel H.

Degree: Biological Sciences (Masters) - Durham University

Subjects offered:Biology, Maths

Biology
Maths

“Enthusiastic Post Graduate Biologist used to getting younger siblings through exams”

About the author

Patrick G.

Currently unavailable: for new students

Degree: Medicine (Other) - Newcastle University

Subjects offered:Biology, Spanish+ 2 more

Biology
Spanish
Human Biology
Chemistry

“I am a medical student at Newcastle University and have been studying here for 5 years.  I am very interested in Biology and Chemistry.  I have experience in revising and preparing for tests and exams throughout my time studying, incl...”

You may also like...

Other A Level Biology questions

What is the difference between the rough endoplasmic reticulum and the smooth endoplasmic reticulum?

What is genetic dominance?

Explain the sliding filament model of muscular contraction

What can endotherms do to reduce their body temperature?

View A Level Biology tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok