Biology - Gene Mapping, Protein Synthesis, Mutations, Biotechnology

Nondisjunction

chromosomal abnormalities where chromatids and chromosomes do not seperate during meiosis

Nondisjunction during Anaphase I

4 unhealthy cells:

• 2 (gamete) cells have extra chromosomes (2n+1 = 47 chromosomes)

• 2 other gamete cells have missing chromosomes (2n-1 = 45 chromo.)

How the process of Anaphase I is affected by a Nondisjunction

homologous chromosomes move to the same pole

Nondisjunction during Anaphase II

• 2 healthy cells (+1)

• 2 unhealthy (gamete) cells (-1)

How the process of Anaphase II is affected by a Nondisjunction

sister chromatids don’t seperate and move to the same pole

Trisomy

a type of nondisjunction where three chromosmes are present when their should only be 2 (47 chromosomes in total)

Turner’s syndrome

• also known as monosomy

• only a single chromosome instead of a pair (45 chromosomes)

• most babies are miscarried by 20 weeks if they are diagnosed

Symptoms of Turner’s syndrome

• underdeveloped ovaries

• poor breast and height development

Down syndrome

• also known as Trisomy 21

• results in lower cognitive ability and a decreased lifespan

• contains 47 chromosomes

• chances of children getting diagnosed increases as the mother ages (~ aged 39+)

Role of ligase on creation of recombination DNA

glues (bonds) “sticky” ends of the DNA together

Role of restricting enzyme on creation of recombination DNA

cuts the desired gene and inserts it into the desired DNA sequence

Frameshift

every DNA triplet after mutation is affected (BAD)

Why are frameshifts so dangerous?

it causes the DNA to change its function and/or stops coding at all

Non-frameshift

only one DNA triplet is affected (NOT GOOD)

Addition and Deletion are part of the….

Frameshift mutation

Addition mutation

extra nitrogenous bases are added

Why addition reactions are so dangerous

it adds and changes structure of bases

Deletion mutation

missing base(s) in a sequence

Substituion and Inversion are part of the….

Non-frameshift mutation

Substitution mutation

a single base replaces existing base

Inversion mutation

a single DNA triplet inverts itself

Silent mutation

a mutation that happens but doesn’t affect you

Where in the cell does transcription take place

inside the nucleus

What occurs during transcription

• DNA ——> mRNA

• free RNA nucleotides form complementary base pairs with coding strands of DNA through RNA polymerase

• ribose sugar and phosphate bond forms between RNA nucleotides

Where is RNA produced?

the nucleus

Where in the cell does translation take place

cytoplasm of nucleus (within ribosome)

What occurs during translation

• mRNA ——> Protein

• mRNA arrives at a ribosome in the cytoplasm and waits for tRNA molecules to bring corresposning amino acids

• Each mRNA codon wil correspond to a particular amino acid (becoming anticodons)

RNA polymerase

Enzyme that links together the growing chain of ribonucleotides during transcription

If there are 30 nucleotides in a strand of mRNA, how many amino acids will there be in the protein?

10 Amino acids (AA)

rRNA

type of DNA that makes up part of the ribosome