KA3 U1 Flashcards
What is gene expression
A process where specific genes required by a cell are switched on to make certain proteins
Only what amount of genes are expressed?
Fraction of genes
Gene expression involved what 2 steps
Transcription and translation
Transcription and translation of what my guy?
Translation and transcription of base sequence which form genetic code
What does transcription & translation of dna base sequence to form genetic code involve?
Various forms of RNA
Types of RNA
= mRNA
Carries a copy of genetic code from the nucleus to the ribosome
tRNA
Carries a specific amino acid to the ribosome to be used in translation
rRNA
Combine with proteins to make up structure of ribosome
Transcription occurs where
Nucleus
Stages of Transcription
S1= the destruction of something and how
2= free somethings falls inlove with something base pairs
3= rna polymerase syntheses newborn by joining stuff
•RNA polymerase unwinds the DNA double stranded helix and breaks hydrogen bonds between bases
•free rna nucleotides pair with complementary dna base pairs
•rna polymerase synthesises primary mRNA transcript by joining together rna nucleotides
What’s a codon
A triplet of nucleotides that can be DNA or RNA
What do codons do
Code for a specific amino acid
RNA splicing is done why
As not all nucleotides have a role to play in coding for a amino acid sequence
A primary transcript contains regions called what
Exons and and Introns
Exons
Coding regions for proteins that are expressed and kept
Introns
Are non coding regions and are removed from the primary transcript
What happens to exons then if they are so useful?
They are spliced togther to form a mature mRNA transcript
Order of exons remain during splicing
Unchanged
One the mature mRNA transcript is made, where does it go
From the nucleus through the cytoplasm to a ribosome
Alternative RNA splicing is when one gene can create many proteins due to
Alternative RNA splicing
Why is this
Different mature mRNA molecules are produced from the same transcript
This is due to which exons are retained during RNA splicing
Translation stages lock in cuh
1: mmrna molecules binds to a ribosome
2: each tRNA molecules binds to a specific amino acid and transports to ribosome
Stages lock in translation part 2
•Anticodons on tRNA bond to codons on mRNA by complementary base pairing
= this translates genetic code into sequence of amino acids
•peptide bonds join amino acids togther to form a polypeptide
Final stage of translation
•each tRNA then leaves the ribosome as the polypeptide chain is formed and is free to collect another amino acid
