Topic 5 Flashcards
Genetic information
What are different parts of the nucleus?
- nucleolus
- euchromatin
- heterochromatin
- nuclear membrane
- nuclear pore
- nucleoplasm
What is the nucleolus and what is its function?
- dense, non-membranous sub organelle
- site of synthesis of RNA
What is the euchromatin and what is its function?
- uncondensed chromatin
- strains poorly
- used in transcription
What is the heterochromatin and what is its function?
- condensed chromatin strains well
- nuclear envelope & nucleolus
- some remain packed, others can be activated in special tissue
What is the nuclear membrane and what is its function?
- double membrane
- separated by 200-400nm inner nuclear membrane
- contiguous with rough ER
What is the nuclear pore and what is its function?
- double membrane fused together at various points => pores
- sites allow for transport in/out of nucleus
What is the nucleoplasm and what is its function?
- matrix for nucleus
- similar to cytoplasm
- contains enzymes, hormones receptors & precursors
What are the components of DNA?
- DNA is double helix & made up of nucleotides
- phosphate backbone, 5’ carbon sugar & nitrogenous base (A-T, C-G)
Describe molecular structure of DNA, according to Watson and Crick, including types of bonds that maintain this structure.
Phosphodiester bond between individual nucleotides
What is the process of transcription?
Process whereby DNA is used as a template to synthesise RNA Facilitated by RNA polym. 1. Binding 2. Initiation 3. Elongation 4. Termination
What is the role of RNA polymerase in transcription?
- enzyme that catalyses RNA synthesis from DNA
- uses 1 of 2 strands as template
- reads DNA 3’ => 5’
- synthesises 5’ => 3’
- causes unwinding & rewinding of DNA
- needs a promotor sequence to begin reading DNA for RNA synthesis
What are the start and stop codons
Start: AUG
Stop: UAA, UAG, UGA
What are the different types of RNA?
ALL PRODUCTS OF TRANSCRIPTION
- rRNA: constitutes major part of ribosomes => site of protein
- tRNA: decoders info in mRNA into aa
- mRNA: messenger RNA, codes for aa sequence of protein
What is template strand?
- template => gene
- 3’ => 5’
- codes for aa sequence of corresponding protein
What is coding strand?
- segment within double-stranded DNA that runs 5’ => 3’
- synthesised strand
What is the steps in translation?
- Initiation
- Elongation 1
- Elongation 2
- Termination of translation
What is rRNA and its role in translation?
- ribosomal RNA
- codes of aa sequence of protein
What is mRNA and its role in translation?
- messenger RNA
- code of aa sequence of protein
What is tRNA and its role in translation?
- transfer RNA
- decodes info in mRNA into aa
What is aminoacyl-tRNA synthetases and its role in translation?
- enzyme that attaches the appropriate amino acid onto its tRNA
- important role in RNA translation, the expression of genes to create proteins
What is peptide transferase and its role in translation?
- primary enzymatic function of ribosome
- forms peptide bonds between adjacent amino acids using tRNAs during translation process
What is the process of translation?
- Initiation: small subunit bind wi/ mRNA
- Elongation 1: translating a polypeptide
- Elongation 2: translating a polypeptide
- Termination: UAA, UAG, UGA, triggered by polypeptide releasing enzyme
