UNIT 1 - KA3
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What does gene expression involve
Gene expression involves the transcription and translation of DNA sequences
What are the three types of RNA involved in transcription and translation
mRNA - messenger RNA (mRNA) tRNA - transfer RNA (tRNA) rRNA - ribosomal RNA (rRNA)
What is the full name for RNA
Riobnucleic acid
What type of molecule is RNA
RNA is single stranded
What is in an RNA nucleotide
Phosphate , ribose sugar , base
What are the bases of RNA
A - Adenine U - Uracil G - Guanine C - Cytosine
What are the 3 main differences between DNA AND RNA
• RNA is single stranded, it’s complementary base partner of adenine is uracil and it had ribose sugar in the nucleotides • DNA is a double stranded molecule, its complementary base partner of adenine is Thymine and it has deoxyribose sugar in the nucleotides
What is the job of mRNA and where is it found
mRNA- carries complementary copy of the DNA code from the nucleus to the ribosome in the cytoplasm. It is found in
What is the job if tRNA and where is it found
tRNA - carries its specific amino acid to the ribosome in the cytoplasm. It is found in
What is the job of rRNA and where is it found
rRNA - forms the ribosome along with proteins in the cytoplasm. It is found in
Where is mRNA transcribed from
mRNA is transcribed from DNA in the nucleus
What does mRNA do - from and to
mRNA carried copy of the DNA code from the nucleus to the ribosome
What is each triplet of bases on an mRNA called
Each triplet of bases on an mRNA is called a CODON
What is the enzyme of transcription
RNA polymerase
What is the first step of transcription (what is unwound and broken)
1- RNA polymerase moves along DNA unwinding the double helix + breaking the hydrogen bonds between the bases of DNA coding for the gene to be expressed
What is the second step of transcription (what moves towards exposed bases and what does it form)
2- Free RNA nucleotides move towards the exposed bases of one strand and form complementary base pairs. Uracil pairs with adenine and guanine with cytosine
What is the third stage of transcription (what does RNA polymerase synthesise)
3- RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by base pairing
Modification of primary transcript - what is an INTRON
INTRON (IN THE BIN) - An intron is a non coding region of DNA. They do not code for the polypeptide chain and must be removed from the primary transcript before translation.
Modification of primary transcript - what is an EXON
EXON - An exon is a coding region of DNA. All of the exons must be joined together to make the mature mRNA transcript
What is RNA splicing
RNA splicing forms a mature mRNA transcript. The introns of the primary transcript are non coding regions and are removed. The exons are coding regions and are joined together to form the mature transcript.
What happens to the order of exons during splicing
The order of exons during splicing is unchanged
What type of RNA does translation involve
tRNA - transfer RNA
How big is tRNA
This is a smaller molecule than mRNA
What does tRNA do
The tRNAs job is to carry its specific Amino Acid to the ribosome for translation