Genetics
, - N DNA (deoxyribonucleic acid) is blueprint of info used to make an organism
- DNA is found in the nucleus & copied and passed onto new cells during mitosis
- DNA controls activities in cells by providing info to make proteins
- Everything is touched by or made of protein
- DNA forms a structure called a double helix made from subunits
called nucleotides
- Each nucleotide is made of
1. Deoxyribose → a sugar
a. 3’ → free sugar without phosphate group bonded to it
2. Phosphate group
3. Nitrogenous base → adenine, guanine, thymine, cytosine
Nucleotides
- Adenine and guanine are purines (double-ring structure)
- Cytosine and thymine are pyrimidines (single-ring structure)
- Diameter → static - equal lengths of all purines & all pyrimidines
- Nucleotides join to form chains. Phosphate & sugar form backbone.
- Double helix → 2 chains of nucleotides run in opposite directions
(antiparallel) and join in the middle
- Adenine pairs with thymine with 2 hydrogen bonds.
- Guanine pairs with cytosine with 3 hydrogen bonds.
RNA (ribonucleic acid) → assists in making proteins
- Made of nucleotides consisting of a phosphate group, a sugar (ribose), and a nitrogenous base
- Instead of thymine, RNA contains uracil
- RNA is single-stranded
- Difference between deoxyribose → hydrogen replaces hydroxyl (OH) group
DNA Makes Proteins
- Each protein is made up of a string of amino acids. There are 20 different amino acids.
- DNA contains instructions to correctly order amino acids or assemble them into proteins.
- Incorrect order → genetic disorder, new ability, no noticeable change
- RNA is intermediate between genes on DNA and proteins they code for.
1. Transcription → process of making RNA using DNA
- Produces messenger RNA (mRNA)
- 1 of 2 DNA strands called the template strand provides a model for
ordering the sequence of nucleotides in an RNA transcript.
, - To make mRNA, enzyme RNA polymerase catalyzes the reaction, pulling the DNA strands
apart & putting together RNA nucleotides.
- Promoter → starting sequence where RNA polymerase binds
- Terminator → sequence signalling end of transcription
- Order of transcription: initiation → elongation → termination
2. Translation → production of polypeptide, with mRNA
- Ribosomes → sites of translation (produce a polypeptide → incomplete
string of amino acid)
- A triplet code is used, meaning 3 nucleotides in a row of one amino acid
- Met can repeat throughout the sequence
- mRNA base triplets, called codons, are read in 5’ to 3’ direction
- 64 codons; 61 code for amino acids; 3 are “stop” ending translation
- Cell translates mRNA into protein with help of transfer RNA (tRNA).
- Molecules of tRNA are not identical:
- Each carries a specific amino acid on one end
- Each has an anticodon on the other end
- Anticodon base pairs with complementary codon on the mRNA
- tRNA molecule is about 80 nucleotides long made of single RNA strand
- Because of H-Bonds, tRNA twists and folds into 3D shape (L-shape)
- Each tRNA must be joined to correct amino acid
- Ribosomes help bring tRNA anticodon with mRNA codon in protein synthesis
- There are 2 parts to a ribosome (large & small)
- A ribosome has 3 binding sites for tRNA
- P site → hold the tRNA that carries growing polypeptide chain
- A site → holds tRNA that carries the next amino acid to be added to the chain
- E site → exit site; where empty tRNA leaves ribosome
- Initiation stage of translation → brings together mRNA, a tRNA with first amino acid,
and 2 parts of ribosome
- Small part of ribosome binds to mRNA and moves until it reaches codon start (AUG)
, Mutations → changes in cell’s genetic material
Point mutations → chemical changes in 1 base pair of gene
- Base-pair substitutions → replaces one (letter) nucleotide and its partner with
another pair of nucleotides
- Change of single nucleotide → production of abnormal protein
1. Silent mutation → no effect on amino acid produced by a codon due to
redundancy of genetic code
2. Missense mutation → changes and makes code for different amino acid
3. Nonsense mutation → introduced a stop codon (usually non-functional)
- Base-pair insertions/deletions → additions/losses of nucleotide pairs in a gene
- Frameshift mutation → creates shift in order of 3 letter sequences
- Worse than substitutions
- Sickle cell disease → flatter-shape of red blood cell
- Cells break apart; Shortness of breath
Chromatin → DNA arranged into fibres
Nucleosomes → formed when DNA molecule wraps around histone
proteins
- Nucleosomes condense into chromatin.
Chromosomes → formed when chromatin condenses
Organism’s Genome → complete DNA sequence in every cell of an
organism
When DNA is replicated, the double helix unwinds and each strand of
DNA serves as a template for a new strand.
Cell Division
, - N DNA (deoxyribonucleic acid) is blueprint of info used to make an organism
- DNA is found in the nucleus & copied and passed onto new cells during mitosis
- DNA controls activities in cells by providing info to make proteins
- Everything is touched by or made of protein
- DNA forms a structure called a double helix made from subunits
called nucleotides
- Each nucleotide is made of
1. Deoxyribose → a sugar
a. 3’ → free sugar without phosphate group bonded to it
2. Phosphate group
3. Nitrogenous base → adenine, guanine, thymine, cytosine
Nucleotides
- Adenine and guanine are purines (double-ring structure)
- Cytosine and thymine are pyrimidines (single-ring structure)
- Diameter → static - equal lengths of all purines & all pyrimidines
- Nucleotides join to form chains. Phosphate & sugar form backbone.
- Double helix → 2 chains of nucleotides run in opposite directions
(antiparallel) and join in the middle
- Adenine pairs with thymine with 2 hydrogen bonds.
- Guanine pairs with cytosine with 3 hydrogen bonds.
RNA (ribonucleic acid) → assists in making proteins
- Made of nucleotides consisting of a phosphate group, a sugar (ribose), and a nitrogenous base
- Instead of thymine, RNA contains uracil
- RNA is single-stranded
- Difference between deoxyribose → hydrogen replaces hydroxyl (OH) group
DNA Makes Proteins
- Each protein is made up of a string of amino acids. There are 20 different amino acids.
- DNA contains instructions to correctly order amino acids or assemble them into proteins.
- Incorrect order → genetic disorder, new ability, no noticeable change
- RNA is intermediate between genes on DNA and proteins they code for.
1. Transcription → process of making RNA using DNA
- Produces messenger RNA (mRNA)
- 1 of 2 DNA strands called the template strand provides a model for
ordering the sequence of nucleotides in an RNA transcript.
, - To make mRNA, enzyme RNA polymerase catalyzes the reaction, pulling the DNA strands
apart & putting together RNA nucleotides.
- Promoter → starting sequence where RNA polymerase binds
- Terminator → sequence signalling end of transcription
- Order of transcription: initiation → elongation → termination
2. Translation → production of polypeptide, with mRNA
- Ribosomes → sites of translation (produce a polypeptide → incomplete
string of amino acid)
- A triplet code is used, meaning 3 nucleotides in a row of one amino acid
- Met can repeat throughout the sequence
- mRNA base triplets, called codons, are read in 5’ to 3’ direction
- 64 codons; 61 code for amino acids; 3 are “stop” ending translation
- Cell translates mRNA into protein with help of transfer RNA (tRNA).
- Molecules of tRNA are not identical:
- Each carries a specific amino acid on one end
- Each has an anticodon on the other end
- Anticodon base pairs with complementary codon on the mRNA
- tRNA molecule is about 80 nucleotides long made of single RNA strand
- Because of H-Bonds, tRNA twists and folds into 3D shape (L-shape)
- Each tRNA must be joined to correct amino acid
- Ribosomes help bring tRNA anticodon with mRNA codon in protein synthesis
- There are 2 parts to a ribosome (large & small)
- A ribosome has 3 binding sites for tRNA
- P site → hold the tRNA that carries growing polypeptide chain
- A site → holds tRNA that carries the next amino acid to be added to the chain
- E site → exit site; where empty tRNA leaves ribosome
- Initiation stage of translation → brings together mRNA, a tRNA with first amino acid,
and 2 parts of ribosome
- Small part of ribosome binds to mRNA and moves until it reaches codon start (AUG)
, Mutations → changes in cell’s genetic material
Point mutations → chemical changes in 1 base pair of gene
- Base-pair substitutions → replaces one (letter) nucleotide and its partner with
another pair of nucleotides
- Change of single nucleotide → production of abnormal protein
1. Silent mutation → no effect on amino acid produced by a codon due to
redundancy of genetic code
2. Missense mutation → changes and makes code for different amino acid
3. Nonsense mutation → introduced a stop codon (usually non-functional)
- Base-pair insertions/deletions → additions/losses of nucleotide pairs in a gene
- Frameshift mutation → creates shift in order of 3 letter sequences
- Worse than substitutions
- Sickle cell disease → flatter-shape of red blood cell
- Cells break apart; Shortness of breath
Chromatin → DNA arranged into fibres
Nucleosomes → formed when DNA molecule wraps around histone
proteins
- Nucleosomes condense into chromatin.
Chromosomes → formed when chromatin condenses
Organism’s Genome → complete DNA sequence in every cell of an
organism
When DNA is replicated, the double helix unwinds and each strand of
DNA serves as a template for a new strand.
Cell Division
