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Refers to the observable characteristics of an individual ex.: size, shape, color



Refers to the set of genetic variants that an individual bears


--> plays a crucial role in giving rise to the phenotype



Refers to a DNA sequence coding for a protein

--> consist of alternations of axons + introns



Are organisms whose cells lack a distinct nucleus

ex.: bacteria



Refers to an organism whose cells have a distinct nucleus

--> all animals + plants



Are large molecules made up of long chains of amino acids

--> give cells their shape and make up about 12-18% of total body weight in humans


Amino acids

Are the molecular building blocks of proteins

--> its sequence along the chain determines what the properties of the protein will be




What where the 3 phases in genetics ?

1. Classical genetics

--> discovering the concept of the gene (Mendel)


2. Molecular genetics

--> discovery of the DNA (Watson + Crick)


3. Genomics

--> ability to read genes


Principles of classical genetics

1. Certain genes are based from parents to offspring

2. Genes often come in alternate forms, called alleles

3. Individuals have two copies of each gene, with one copy coming from each parent



Refers to a cell/organism containing 2 sets of genes, one from each parent



Refers to a cell/organism containing only one set of genes

--> in humans, only sperm + egg cells are haploid


Classical genetics established that genes have 2 functions.

Which are they ?

1. Genotype influences the PHENOTYPE

--> function a

2. Genes REPLICATE themselves to produce new cells

--> function b


Central dogma

Refers to the idea that changes in DNA sequences can lead to changes in proteins, but changes in proteins cannot change the sequence

--> the flow of information is one way

ex.: muscles that are built during a lifetime are not passed down to the next generation


Somatic cells

Refer to the cells in the body other than gametes

--> are only capable of function a (making more phenotype) by engaging in mitosis


Germ cells/ Gametes

Refer to sperm + egg cells

--> are only capable of function b (making more genotype) by engaging in meiosis



Refers to a process whereby cells split into genetically identical copies of themselves

--> 2n to 2n



Refers to a special cell division process that produces a haploid gamete from a diploid cell

  1. recombination occurs here
  2.  2n to 1n



Consists of DNA wound around proteins called histones


  1.  come in homologous pairs, one from each parent
  2. 23 pairs


Desoxyribonuclein acid (DNA)

Is a long chain molecule/poymer consisting of 2 strands bound to + twisted around each other in a double helix 


  1.  each strand is made up of a backbone of sugars + phosphates
  2. along each backbone are strung the bases


Which are the 4 Nitrogenous bases? How can you differentiate them ? Which bases binds to which (Basepairing) ?

  1. Adenine, Guanine, Cytosine, Thymine
  2. Adenine + Guanine are PURINBASES, Cytosine + Thymine are PYRIMIDINEBASES
  3.  Adenin + Thymin, Cytosin + Guanin


Hydrogen bonds

Refer to the bonds between the 2 strands


  1.  AT have 2 bonds whereas GC have 3, making them slightly stronger
  2. are weak and can be easily split apart


Process of Transcription

1. RNA Polymerase binds to Promotor + unzips double helix 

2. RNA is synthesized by copying the leading strand

--> done by Polymerase

3. When the Polymerase meets a terminator, copying ends + RNA separates from the DNA to become mRNA

4. Introns are cut out of the mRNA in a process of splicing

5. mRNA moves to Ribosomes


Process of Translation

1. Ribosome is the site of translation

2. The initiation codon (AUG) methionine signals the start for translation

3. Termination codons signal the end

4. tRNA consists of an amino acid at its top + the anticodon at its bottom, always binding to its component at the mRNA

5.  the tRNAs bind together their subsequent amino acids into a polypeptide chain

--> RESULT: Protein



Refer to triplets of bases from the mRNA, which stand for one particular amino acid


What is the Genetic code ?

Its the mapping from particular codons in the mRNA to particular amino acids in the assembled protein


ex.: AUG coding for Methionine


What are the properties of the Genetic code ?

1. Redundancy

--> several triplets may code for one amino acid, so errors made in reading the 3rd base may often make no difference to the amino acid

2. Robust against coding errors

3. Property of good design



Refer to stretches of codons that are translated into the protein

--> genes that will be expressed



Refer to non coding sequences inserted within the gene

--> are transcribed, but then deleted from the mRNA, thus not translated


Process of Replication

1. Helicase cuts open the Hydrogen bonds between the bases

--> develops Leading + Lagging strand

2. RNA primase synthesizes a Primer which binds to the 5' end of the Leading strand

3. RNA polymerase can now match the matching nucleotides in 5'-3' direction

4. On the lagging strand the RNA primase has to synthesize new primers over and over again so the RNA polymerase can work in 5'-3' direction

5. RNA fragments on the lagging strand are called okazaki fragments and are replaced by DNA nucleotides with help from the DNA polymerase

6. DNA ligase connects the former okazaki fragments with the rest of the DNA



Genes that have ceased to be translated