Exam 2 Flashcards
(42 cards)
DNA Structure
Phosphate, Sugar, Nitrogenous Base
Purine
Two rings- Adenine, Guanine
Prymidines
One ring- Cytosine,Thymine/Uracil
A-T, C,G chemical bond
Hydrogen
Basic definition of transcription
Transfers info from DNA to mRNA..happens in nucleus
Basic definition of translation
Transfers info from mRNA to polypeptide..happens in cytoplasm–>ribosomes
Initiation of transcription
- Enzymes unzip the DNA double helix-exposing template strand
- RNA polymerase binds to promoter
Elongation of transcription
- RNA polymerase moves along 3’ to 5’
- RNA polymerase adds nucleotides only to 3’
Termination of transcription
- Occurs at the terminator sequence in the gene
- RNA polymerase detaches from the DNA and releases new RNA
- DNA which returns to double helix
mRNA is altered before leaving the nucleus in Eukaryotes…
1) Addition of 5’ cap and 3’ Poly A Tail
2) Introns removed
3) Exons spliced together
4) Leaves nucleus to be translated
Initiation of Translation
1) Small ribosomal unit binds to 5’ end of the leader sequence
2) tRNA brings first amino acid
3) Large ribosomal subunit binds to small unit to complete initiation
Elongation of Translation
4) Another tRNA brings 2nd amino acid to bind to codon
5) Ribosome releases first tRNA
6) tRNA continue to be used and bring amino acids to the growing chain
Termination of Translation
1) No tRNA responds to the stop codon
2) Release factors bind to stop codon
3) Small & Large subunits separate and new polypeptide is released
Lac Operon (lactose example)
Repressor blocks transcription when no lactose is present, when lactose is present they bind to the repressor, releasing it from the DNA. RNA polymerase moves along and transcription of enzymes that breakdown lactose are produced.
Protein production transcription/translation (12 steps)
1) TATA binding protein attaches to TATA box
2) Transcription factors
3) DNA bends bringing transcription factors together w/ TATA binding protein
4) RNA polymerase starts reading template strand
5) RNA polymerase reaches terminator region
6) 5’ cap and 3’ poly A tail are added
7) Introns spliced out
8) Small ribosomal unit attaches to mRNA
9) 1st tRNA brings methionine to ribosome
10) Large ribosomal unit attaches to small
11) Dehydration synthesis joins amino acids
12) Stop codon enters ribosomal complex
DNA replication happens in..
Interphase, S phase
DNA replication order of proteins
- Helicase: unzips double helix
- Binding proteins: stabilize each strand
- Primase: adds short RNA primer to template
- DNA polymerase: binds nucleotides
- Ligase: Joins ozarki fragments and creates covalent bonds between adjacent DNA segments
Helicase
Unzips double helix
Primase
Adds short RNA primer to template strand
Ligase
Joins ozarki fragments (lagging strand)
Chromosomes condense, spindle fibers form
Prophase
Nuclear membrane assembles
Telephase
Crossing over occurs in…
Prophase 1
Homologous chromosomes are found in…
Meiosis 1
